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

Tue, 23 Feb 2010 23:14:34 -0500

author
tonyp
date
Tue, 23 Feb 2010 23:14:34 -0500
changeset 1718
1c72304f1885
parent 1717
b81f3572f355
child 1720
a1c410de27e4
permissions
-rw-r--r--

6928073: G1: use existing command line parameters for marking cycle initiation
Summary: replace the combination of the G1SteadyStateUsed / G1SteadyStateUsedDelta parameteres to decide the marking initiation threshold and instead use InitiatingHeapOccupancyPercent.
Reviewed-by: ysr, johnc

     1 /*
     2  * Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.
     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     4  *
     5  * This code is free software; you can redistribute it and/or modify it
     6  * under the terms of the GNU General Public License version 2 only, as
     7  * published by the Free Software Foundation.
     8  *
     9  * This code is distributed in the hope that it will be useful, but WITHOUT
    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    12  * version 2 for more details (a copy is included in the LICENSE file that
    13  * accompanied this code).
    14  *
    15  * You should have received a copy of the GNU General Public License version
    16  * 2 along with this work; if not, write to the Free Software Foundation,
    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    18  *
    19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
    20  * CA 95054 USA or visit www.sun.com if you need additional information or
    21  * have any questions.
    22  *
    23  */
    25 #include "incls/_precompiled.incl"
    26 #include "incls/_g1CollectorPolicy.cpp.incl"
    28 #define PREDICTIONS_VERBOSE 0
    30 // <NEW PREDICTION>
    32 // Different defaults for different number of GC threads
    33 // They were chosen by running GCOld and SPECjbb on debris with different
    34 //   numbers of GC threads and choosing them based on the results
    36 // all the same
    37 static double rs_length_diff_defaults[] = {
    38   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
    39 };
    41 static double cost_per_card_ms_defaults[] = {
    42   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
    43 };
    45 static double cost_per_scan_only_region_ms_defaults[] = {
    46   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
    47 };
    49 // all the same
    50 static double fully_young_cards_per_entry_ratio_defaults[] = {
    51   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
    52 };
    54 static double cost_per_entry_ms_defaults[] = {
    55   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
    56 };
    58 static double cost_per_byte_ms_defaults[] = {
    59   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
    60 };
    62 // these should be pretty consistent
    63 static double constant_other_time_ms_defaults[] = {
    64   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
    65 };
    68 static double young_other_cost_per_region_ms_defaults[] = {
    69   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
    70 };
    72 static double non_young_other_cost_per_region_ms_defaults[] = {
    73   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
    74 };
    76 // </NEW PREDICTION>
    78 G1CollectorPolicy::G1CollectorPolicy() :
    79   _parallel_gc_threads((ParallelGCThreads > 0) ? ParallelGCThreads : 1),
    80   _n_pauses(0),
    81   _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    82   _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    83   _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    84   _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    85   _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
    86   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    87   _all_pause_times_ms(new NumberSeq()),
    88   _stop_world_start(0.0),
    89   _all_stop_world_times_ms(new NumberSeq()),
    90   _all_yield_times_ms(new NumberSeq()),
    92   _all_mod_union_times_ms(new NumberSeq()),
    94   _summary(new Summary()),
    95   _abandoned_summary(new AbandonedSummary()),
    97 #ifndef PRODUCT
    98   _cur_clear_ct_time_ms(0.0),
    99   _min_clear_cc_time_ms(-1.0),
   100   _max_clear_cc_time_ms(-1.0),
   101   _cur_clear_cc_time_ms(0.0),
   102   _cum_clear_cc_time_ms(0.0),
   103   _num_cc_clears(0L),
   104 #endif
   106   _region_num_young(0),
   107   _region_num_tenured(0),
   108   _prev_region_num_young(0),
   109   _prev_region_num_tenured(0),
   111   _aux_num(10),
   112   _all_aux_times_ms(new NumberSeq[_aux_num]),
   113   _cur_aux_start_times_ms(new double[_aux_num]),
   114   _cur_aux_times_ms(new double[_aux_num]),
   115   _cur_aux_times_set(new bool[_aux_num]),
   117   _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   118   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   119   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   121   // <NEW PREDICTION>
   123   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   124   _prev_collection_pause_end_ms(0.0),
   125   _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   126   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   127   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   128   _cost_per_scan_only_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   129   _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
   130   _partially_young_cards_per_entry_ratio_seq(
   131                                          new TruncatedSeq(TruncatedSeqLength)),
   132   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   133   _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   134   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   135   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
   136   _cost_per_scan_only_region_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
   137   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   138   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   139   _non_young_other_cost_per_region_ms_seq(
   140                                          new TruncatedSeq(TruncatedSeqLength)),
   142   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   143   _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   144   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
   146   _pause_time_target_ms((double) MaxGCPauseMillis),
   148   // </NEW PREDICTION>
   150   _in_young_gc_mode(false),
   151   _full_young_gcs(true),
   152   _full_young_pause_num(0),
   153   _partial_young_pause_num(0),
   155   _during_marking(false),
   156   _in_marking_window(false),
   157   _in_marking_window_im(false),
   159   _known_garbage_ratio(0.0),
   160   _known_garbage_bytes(0),
   162   _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
   163   _target_pause_time_ms(-1.0),
   165    _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
   167   _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
   168   _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
   170   _recent_avg_pause_time_ratio(0.0),
   171   _num_markings(0),
   172   _n_marks(0),
   173   _n_pauses_at_mark_end(0),
   175   _all_full_gc_times_ms(new NumberSeq()),
   177   // G1PausesBtwnConcMark defaults to -1
   178   // so the hack is to do the cast  QQQ FIXME
   179   _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
   180   _n_marks_since_last_pause(0),
   181   _conc_mark_initiated(false),
   182   _should_initiate_conc_mark(false),
   183   _should_revert_to_full_young_gcs(false),
   184   _last_full_young_gc(false),
   186   _prev_collection_pause_used_at_end_bytes(0),
   188   _collection_set(NULL),
   189 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
   190 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
   191 #endif // _MSC_VER
   193   _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
   194                                                  G1YoungSurvRateNumRegionsSummary)),
   195   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
   196                                               G1YoungSurvRateNumRegionsSummary)),
   197   // add here any more surv rate groups
   198   _recorded_survivor_regions(0),
   199   _recorded_survivor_head(NULL),
   200   _recorded_survivor_tail(NULL),
   201   _survivors_age_table(true)
   203 {
   204   // Set up the region size and associated fields. Given that the
   205   // policy is created before the heap, we have to set this up here,
   206   // so it's done as soon as possible.
   207   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
   208   HeapRegionRemSet::setup_remset_size();
   210   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
   211   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
   213   _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
   214   _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
   215   _par_last_scan_only_times_ms = new double[_parallel_gc_threads];
   216   _par_last_scan_only_regions_scanned = new double[_parallel_gc_threads];
   218   _par_last_update_rs_start_times_ms = new double[_parallel_gc_threads];
   219   _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
   220   _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
   222   _par_last_scan_rs_start_times_ms = new double[_parallel_gc_threads];
   223   _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
   224   _par_last_scan_new_refs_times_ms = new double[_parallel_gc_threads];
   226   _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
   228   _par_last_termination_times_ms = new double[_parallel_gc_threads];
   230   // start conservatively
   231   _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
   233   // <NEW PREDICTION>
   235   int index;
   236   if (ParallelGCThreads == 0)
   237     index = 0;
   238   else if (ParallelGCThreads > 8)
   239     index = 7;
   240   else
   241     index = ParallelGCThreads - 1;
   243   _pending_card_diff_seq->add(0.0);
   244   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
   245   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
   246   _cost_per_scan_only_region_ms_seq->add(
   247                                  cost_per_scan_only_region_ms_defaults[index]);
   248   _fully_young_cards_per_entry_ratio_seq->add(
   249                             fully_young_cards_per_entry_ratio_defaults[index]);
   250   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
   251   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
   252   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
   253   _young_other_cost_per_region_ms_seq->add(
   254                                young_other_cost_per_region_ms_defaults[index]);
   255   _non_young_other_cost_per_region_ms_seq->add(
   256                            non_young_other_cost_per_region_ms_defaults[index]);
   258   // </NEW PREDICTION>
   260   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
   261   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
   262   guarantee(max_gc_time < time_slice,
   263             "Max GC time should not be greater than the time slice");
   264   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
   265   _sigma = (double) G1ConfidencePercent / 100.0;
   267   // start conservatively (around 50ms is about right)
   268   _concurrent_mark_init_times_ms->add(0.05);
   269   _concurrent_mark_remark_times_ms->add(0.05);
   270   _concurrent_mark_cleanup_times_ms->add(0.20);
   271   _tenuring_threshold = MaxTenuringThreshold;
   273   // if G1FixedSurvivorSpaceSize is 0 which means the size is not
   274   // fixed, then _max_survivor_regions will be calculated at
   275   // calculate_young_list_target_config during initialization
   276   _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
   278   initialize_all();
   279 }
   281 // Increment "i", mod "len"
   282 static void inc_mod(int& i, int len) {
   283   i++; if (i == len) i = 0;
   284 }
   286 void G1CollectorPolicy::initialize_flags() {
   287   set_min_alignment(HeapRegion::GrainBytes);
   288   set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
   289   if (SurvivorRatio < 1) {
   290     vm_exit_during_initialization("Invalid survivor ratio specified");
   291   }
   292   CollectorPolicy::initialize_flags();
   293 }
   295 void G1CollectorPolicy::init() {
   296   // Set aside an initial future to_space.
   297   _g1 = G1CollectedHeap::heap();
   298   size_t regions = Universe::heap()->capacity() / HeapRegion::GrainBytes;
   300   assert(Heap_lock->owned_by_self(), "Locking discipline.");
   302   initialize_gc_policy_counters();
   304   if (G1Gen) {
   305     _in_young_gc_mode = true;
   307     if (G1YoungGenSize == 0) {
   308       set_adaptive_young_list_length(true);
   309       _young_list_fixed_length = 0;
   310     } else {
   311       set_adaptive_young_list_length(false);
   312       _young_list_fixed_length = (G1YoungGenSize / HeapRegion::GrainBytes);
   313     }
   314      _free_regions_at_end_of_collection = _g1->free_regions();
   315      _scan_only_regions_at_end_of_collection = 0;
   316      calculate_young_list_min_length();
   317      guarantee( _young_list_min_length == 0, "invariant, not enough info" );
   318      calculate_young_list_target_config();
   319    } else {
   320      _young_list_fixed_length = 0;
   321     _in_young_gc_mode = false;
   322   }
   323 }
   325 // Create the jstat counters for the policy.
   326 void G1CollectorPolicy::initialize_gc_policy_counters()
   327 {
   328   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
   329 }
   331 void G1CollectorPolicy::calculate_young_list_min_length() {
   332   _young_list_min_length = 0;
   334   if (!adaptive_young_list_length())
   335     return;
   337   if (_alloc_rate_ms_seq->num() > 3) {
   338     double now_sec = os::elapsedTime();
   339     double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
   340     double alloc_rate_ms = predict_alloc_rate_ms();
   341     int min_regions = (int) ceil(alloc_rate_ms * when_ms);
   342     int current_region_num = (int) _g1->young_list_length();
   343     _young_list_min_length = min_regions + current_region_num;
   344   }
   345 }
   347 void G1CollectorPolicy::calculate_young_list_target_config() {
   348   if (adaptive_young_list_length()) {
   349     size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
   350     calculate_young_list_target_config(rs_lengths);
   351   } else {
   352     if (full_young_gcs())
   353       _young_list_target_length = _young_list_fixed_length;
   354     else
   355       _young_list_target_length = _young_list_fixed_length / 2;
   356     _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);
   357     size_t so_length = calculate_optimal_so_length(_young_list_target_length);
   358     guarantee( so_length < _young_list_target_length, "invariant" );
   359     _young_list_so_prefix_length = so_length;
   360   }
   361   calculate_survivors_policy();
   362 }
   364 // This method calculate the optimal scan-only set for a fixed young
   365 // gen size. I couldn't work out how to reuse the more elaborate one,
   366 // i.e. calculate_young_list_target_config(rs_length), as the loops are
   367 // fundamentally different (the other one finds a config for different
   368 // S-O lengths, whereas here we need to do the opposite).
   369 size_t G1CollectorPolicy::calculate_optimal_so_length(
   370                                                     size_t young_list_length) {
   371   if (!G1UseScanOnlyPrefix)
   372     return 0;
   374   if (_all_pause_times_ms->num() < 3) {
   375     // we won't use a scan-only set at the beginning to allow the rest
   376     // of the predictors to warm up
   377     return 0;
   378   }
   380   if (_cost_per_scan_only_region_ms_seq->num() < 3) {
   381     // then, we'll only set the S-O set to 1 for a little bit of time,
   382     // to get enough information on the scanning cost
   383     return 1;
   384   }
   386   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
   387   size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
   388   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
   389   size_t scanned_cards;
   390   if (full_young_gcs())
   391     scanned_cards = predict_young_card_num(adj_rs_lengths);
   392   else
   393     scanned_cards = predict_non_young_card_num(adj_rs_lengths);
   394   double base_time_ms = predict_base_elapsed_time_ms(pending_cards,
   395                                                      scanned_cards);
   397   size_t so_length = 0;
   398   double max_gc_eff = 0.0;
   399   for (size_t i = 0; i < young_list_length; ++i) {
   400     double gc_eff = 0.0;
   401     double pause_time_ms = 0.0;
   402     predict_gc_eff(young_list_length, i, base_time_ms,
   403                    &gc_eff, &pause_time_ms);
   404     if (gc_eff > max_gc_eff) {
   405       max_gc_eff = gc_eff;
   406       so_length = i;
   407     }
   408   }
   410   // set it to 95% of the optimal to make sure we sample the "area"
   411   // around the optimal length to get up-to-date survival rate data
   412   return so_length * 950 / 1000;
   413 }
   415 // This is a really cool piece of code! It finds the best
   416 // target configuration (young length / scan-only prefix length) so
   417 // that GC efficiency is maximized and that we also meet a pause
   418 // time. It's a triple nested loop. These loops are explained below
   419 // from the inside-out :-)
   420 //
   421 // (a) The innermost loop will try to find the optimal young length
   422 // for a fixed S-O length. It uses a binary search to speed up the
   423 // process. We assume that, for a fixed S-O length, as we add more
   424 // young regions to the CSet, the GC efficiency will only go up (I'll
   425 // skip the proof). So, using a binary search to optimize this process
   426 // makes perfect sense.
   427 //
   428 // (b) The middle loop will fix the S-O length before calling the
   429 // innermost one. It will vary it between two parameters, increasing
   430 // it by a given increment.
   431 //
   432 // (c) The outermost loop will call the middle loop three times.
   433 //   (1) The first time it will explore all possible S-O length values
   434 //   from 0 to as large as it can get, using a coarse increment (to
   435 //   quickly "home in" to where the optimal seems to be).
   436 //   (2) The second time it will explore the values around the optimal
   437 //   that was found by the first iteration using a fine increment.
   438 //   (3) Once the optimal config has been determined by the second
   439 //   iteration, we'll redo the calculation, but setting the S-O length
   440 //   to 95% of the optimal to make sure we sample the "area"
   441 //   around the optimal length to get up-to-date survival rate data
   442 //
   443 // Termination conditions for the iterations are several: the pause
   444 // time is over the limit, we do not have enough to-space, etc.
   446 void G1CollectorPolicy::calculate_young_list_target_config(size_t rs_lengths) {
   447   guarantee( adaptive_young_list_length(), "pre-condition" );
   449   double start_time_sec = os::elapsedTime();
   450   size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
   451   min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
   452   size_t reserve_regions =
   453     (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
   455   if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
   456     // we are in fully-young mode and there are free regions in the heap
   458     double survivor_regions_evac_time =
   459         predict_survivor_regions_evac_time();
   461     size_t min_so_length = 0;
   462     size_t max_so_length = 0;
   464     if (G1UseScanOnlyPrefix) {
   465       if (_all_pause_times_ms->num() < 3) {
   466         // we won't use a scan-only set at the beginning to allow the rest
   467         // of the predictors to warm up
   468         min_so_length = 0;
   469         max_so_length = 0;
   470       } else if (_cost_per_scan_only_region_ms_seq->num() < 3) {
   471         // then, we'll only set the S-O set to 1 for a little bit of time,
   472         // to get enough information on the scanning cost
   473         min_so_length = 1;
   474         max_so_length = 1;
   475       } else if (_in_marking_window || _last_full_young_gc) {
   476         // no S-O prefix during a marking phase either, as at the end
   477         // of the marking phase we'll have to use a very small young
   478         // length target to fill up the rest of the CSet with
   479         // non-young regions and, if we have lots of scan-only regions
   480         // left-over, we will not be able to add any more non-young
   481         // regions.
   482         min_so_length = 0;
   483         max_so_length = 0;
   484       } else {
   485         // this is the common case; we'll never reach the maximum, we
   486         // one of the end conditions will fire well before that
   487         // (hopefully!)
   488         min_so_length = 0;
   489         max_so_length = _free_regions_at_end_of_collection - 1;
   490       }
   491     } else {
   492       // no S-O prefix, as the switch is not set, but we still need to
   493       // do one iteration to calculate the best young target that
   494       // meets the pause time; this way we reuse the same code instead
   495       // of replicating it
   496       min_so_length = 0;
   497       max_so_length = 0;
   498     }
   500     double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
   501     size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
   502     size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
   503     size_t scanned_cards;
   504     if (full_young_gcs())
   505       scanned_cards = predict_young_card_num(adj_rs_lengths);
   506     else
   507       scanned_cards = predict_non_young_card_num(adj_rs_lengths);
   508     // calculate this once, so that we don't have to recalculate it in
   509     // the innermost loop
   510     double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
   511                           + survivor_regions_evac_time;
   512     // the result
   513     size_t final_young_length = 0;
   514     size_t final_so_length = 0;
   515     double final_gc_eff = 0.0;
   516     // we'll also keep track of how many times we go into the inner loop
   517     // this is for profiling reasons
   518     size_t calculations = 0;
   520     // this determines which of the three iterations the outer loop is in
   521     typedef enum {
   522       pass_type_coarse,
   523       pass_type_fine,
   524       pass_type_final
   525     } pass_type_t;
   527     // range of the outer loop's iteration
   528     size_t from_so_length   = min_so_length;
   529     size_t to_so_length     = max_so_length;
   530     guarantee( from_so_length <= to_so_length, "invariant" );
   532     // this will keep the S-O length that's found by the second
   533     // iteration of the outer loop; we'll keep it just in case the third
   534     // iteration fails to find something
   535     size_t fine_so_length   = 0;
   537     // the increment step for the coarse (first) iteration
   538     size_t so_coarse_increments = 5;
   540     // the common case, we'll start with the coarse iteration
   541     pass_type_t pass = pass_type_coarse;
   542     size_t so_length_incr = so_coarse_increments;
   544     if (from_so_length == to_so_length) {
   545       // not point in doing the coarse iteration, we'll go directly into
   546       // the fine one (we essentially trying to find the optimal young
   547       // length for a fixed S-O length).
   548       so_length_incr = 1;
   549       pass = pass_type_final;
   550     } else if (to_so_length - from_so_length < 3 * so_coarse_increments) {
   551       // again, the range is too short so no point in foind the coarse
   552       // iteration either
   553       so_length_incr = 1;
   554       pass = pass_type_fine;
   555     }
   557     bool done = false;
   558     // this is the outermost loop
   559     while (!done) {
   560 #ifdef TRACE_CALC_YOUNG_CONFIG
   561       // leave this in for debugging, just in case
   562       gclog_or_tty->print_cr("searching between " SIZE_FORMAT " and " SIZE_FORMAT
   563                              ", incr " SIZE_FORMAT ", pass %s",
   564                              from_so_length, to_so_length, so_length_incr,
   565                              (pass == pass_type_coarse) ? "coarse" :
   566                              (pass == pass_type_fine) ? "fine" : "final");
   567 #endif // TRACE_CALC_YOUNG_CONFIG
   569       size_t so_length = from_so_length;
   570       size_t init_free_regions =
   571         MAX2((size_t)0,
   572              _free_regions_at_end_of_collection +
   573              _scan_only_regions_at_end_of_collection - reserve_regions);
   575       // this determines whether a configuration was found
   576       bool gc_eff_set = false;
   577       // this is the middle loop
   578       while (so_length <= to_so_length) {
   579         // base time, which excludes region-related time; again we
   580         // calculate it once to avoid recalculating it in the
   581         // innermost loop
   582         double base_time_with_so_ms =
   583                            base_time_ms + predict_scan_only_time_ms(so_length);
   584         // it's already over the pause target, go around
   585         if (base_time_with_so_ms > target_pause_time_ms)
   586           break;
   588         size_t starting_young_length = so_length+1;
   590         // we make sure that the short young length that makes sense
   591         // (one more than the S-O length) is feasible
   592         size_t min_young_length = starting_young_length;
   593         double min_gc_eff;
   594         bool min_ok;
   595         ++calculations;
   596         min_ok = predict_gc_eff(min_young_length, so_length,
   597                                 base_time_with_so_ms,
   598                                 init_free_regions, target_pause_time_ms,
   599                                 &min_gc_eff);
   601         if (min_ok) {
   602           // the shortest young length is indeed feasible; we'll know
   603           // set up the max young length and we'll do a binary search
   604           // between min_young_length and max_young_length
   605           size_t max_young_length = _free_regions_at_end_of_collection - 1;
   606           double max_gc_eff = 0.0;
   607           bool max_ok = false;
   609           // the innermost loop! (finally!)
   610           while (max_young_length > min_young_length) {
   611             // we'll make sure that min_young_length is always at a
   612             // feasible config
   613             guarantee( min_ok, "invariant" );
   615             ++calculations;
   616             max_ok = predict_gc_eff(max_young_length, so_length,
   617                                     base_time_with_so_ms,
   618                                     init_free_regions, target_pause_time_ms,
   619                                     &max_gc_eff);
   621             size_t diff = (max_young_length - min_young_length) / 2;
   622             if (max_ok) {
   623               min_young_length = max_young_length;
   624               min_gc_eff = max_gc_eff;
   625               min_ok = true;
   626             }
   627             max_young_length = min_young_length + diff;
   628           }
   630           // the innermost loop found a config
   631           guarantee( min_ok, "invariant" );
   632           if (min_gc_eff > final_gc_eff) {
   633             // it's the best config so far, so we'll keep it
   634             final_gc_eff = min_gc_eff;
   635             final_young_length = min_young_length;
   636             final_so_length = so_length;
   637             gc_eff_set = true;
   638           }
   639         }
   641         // incremental the fixed S-O length and go around
   642         so_length += so_length_incr;
   643       }
   645       // this is the end of the outermost loop and we need to decide
   646       // what to do during the next iteration
   647       if (pass == pass_type_coarse) {
   648         // we just did the coarse pass (first iteration)
   650         if (!gc_eff_set)
   651           // we didn't find a feasible config so we'll just bail out; of
   652           // course, it might be the case that we missed it; but I'd say
   653           // it's a bit unlikely
   654           done = true;
   655         else {
   656           // We did find a feasible config with optimal GC eff during
   657           // the first pass. So the second pass we'll only consider the
   658           // S-O lengths around that config with a fine increment.
   660           guarantee( so_length_incr == so_coarse_increments, "invariant" );
   661           guarantee( final_so_length >= min_so_length, "invariant" );
   663 #ifdef TRACE_CALC_YOUNG_CONFIG
   664           // leave this in for debugging, just in case
   665           gclog_or_tty->print_cr("  coarse pass: SO length " SIZE_FORMAT,
   666                                  final_so_length);
   667 #endif // TRACE_CALC_YOUNG_CONFIG
   669           from_so_length =
   670             (final_so_length - min_so_length > so_coarse_increments) ?
   671             final_so_length - so_coarse_increments + 1 : min_so_length;
   672           to_so_length =
   673             (max_so_length - final_so_length > so_coarse_increments) ?
   674             final_so_length + so_coarse_increments - 1 : max_so_length;
   676           pass = pass_type_fine;
   677           so_length_incr = 1;
   678         }
   679       } else if (pass == pass_type_fine) {
   680         // we just finished the second pass
   682         if (!gc_eff_set) {
   683           // we didn't find a feasible config (yes, it's possible;
   684           // notice that, sometimes, we go directly into the fine
   685           // iteration and skip the coarse one) so we bail out
   686           done = true;
   687         } else {
   688           // We did find a feasible config with optimal GC eff
   689           guarantee( so_length_incr == 1, "invariant" );
   691           if (final_so_length == 0) {
   692             // The config is of an empty S-O set, so we'll just bail out
   693             done = true;
   694           } else {
   695             // we'll go around once more, setting the S-O length to 95%
   696             // of the optimal
   697             size_t new_so_length = 950 * final_so_length / 1000;
   699 #ifdef TRACE_CALC_YOUNG_CONFIG
   700             // leave this in for debugging, just in case
   701             gclog_or_tty->print_cr("  fine pass: SO length " SIZE_FORMAT
   702                                    ", setting it to " SIZE_FORMAT,
   703                                     final_so_length, new_so_length);
   704 #endif // TRACE_CALC_YOUNG_CONFIG
   706             from_so_length = new_so_length;
   707             to_so_length = new_so_length;
   708             fine_so_length = final_so_length;
   710             pass = pass_type_final;
   711           }
   712         }
   713       } else if (pass == pass_type_final) {
   714         // we just finished the final (third) pass
   716         if (!gc_eff_set)
   717           // we didn't find a feasible config, so we'll just use the one
   718           // we found during the second pass, which we saved
   719           final_so_length = fine_so_length;
   721         // and we're done!
   722         done = true;
   723       } else {
   724         guarantee( false, "should never reach here" );
   725       }
   727       // we now go around the outermost loop
   728     }
   730     // we should have at least one region in the target young length
   731     _young_list_target_length =
   732         MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);
   733     if (final_so_length >= final_young_length)
   734       // and we need to ensure that the S-O length is not greater than
   735       // the target young length (this is being a bit careful)
   736       final_so_length = 0;
   737     _young_list_so_prefix_length = final_so_length;
   738     guarantee( !_in_marking_window || !_last_full_young_gc ||
   739                _young_list_so_prefix_length == 0, "invariant" );
   741     // let's keep an eye of how long we spend on this calculation
   742     // right now, I assume that we'll print it when we need it; we
   743     // should really adde it to the breakdown of a pause
   744     double end_time_sec = os::elapsedTime();
   745     double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
   747 #ifdef TRACE_CALC_YOUNG_CONFIG
   748     // leave this in for debugging, just in case
   749     gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT
   750                            ", SO = " SIZE_FORMAT ", "
   751                            "elapsed %1.2lf ms, calcs: " SIZE_FORMAT " (%s%s) "
   752                            SIZE_FORMAT SIZE_FORMAT,
   753                            target_pause_time_ms,
   754                            _young_list_target_length - _young_list_so_prefix_length,
   755                            _young_list_so_prefix_length,
   756                            elapsed_time_ms,
   757                            calculations,
   758                            full_young_gcs() ? "full" : "partial",
   759                            should_initiate_conc_mark() ? " i-m" : "",
   760                            _in_marking_window,
   761                            _in_marking_window_im);
   762 #endif // TRACE_CALC_YOUNG_CONFIG
   764     if (_young_list_target_length < _young_list_min_length) {
   765       // bummer; this means that, if we do a pause when the optimal
   766       // config dictates, we'll violate the pause spacing target (the
   767       // min length was calculate based on the application's current
   768       // alloc rate);
   770       // so, we have to bite the bullet, and allocate the minimum
   771       // number. We'll violate our target, but we just can't meet it.
   773       size_t so_length = 0;
   774       // a note further up explains why we do not want an S-O length
   775       // during marking
   776       if (!_in_marking_window && !_last_full_young_gc)
   777         // but we can still try to see whether we can find an optimal
   778         // S-O length
   779         so_length = calculate_optimal_so_length(_young_list_min_length);
   781 #ifdef TRACE_CALC_YOUNG_CONFIG
   782       // leave this in for debugging, just in case
   783       gclog_or_tty->print_cr("adjusted target length from "
   784                              SIZE_FORMAT " to " SIZE_FORMAT
   785                              ", SO " SIZE_FORMAT,
   786                              _young_list_target_length, _young_list_min_length,
   787                              so_length);
   788 #endif // TRACE_CALC_YOUNG_CONFIG
   790       _young_list_target_length =
   791         MAX2(_young_list_min_length, (size_t)1);
   792       _young_list_so_prefix_length = so_length;
   793     }
   794   } else {
   795     // we are in a partially-young mode or we've run out of regions (due
   796     // to evacuation failure)
   798 #ifdef TRACE_CALC_YOUNG_CONFIG
   799     // leave this in for debugging, just in case
   800     gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
   801                            ", SO " SIZE_FORMAT,
   802                            _young_list_min_length, 0);
   803 #endif // TRACE_CALC_YOUNG_CONFIG
   805     // we'll do the pause as soon as possible and with no S-O prefix
   806     // (see above for the reasons behind the latter)
   807     _young_list_target_length =
   808       MAX2(_young_list_min_length, (size_t) 1);
   809     _young_list_so_prefix_length = 0;
   810   }
   812   _rs_lengths_prediction = rs_lengths;
   813 }
   815 // This is used by: calculate_optimal_so_length(length). It returns
   816 // the GC eff and predicted pause time for a particular config
   817 void
   818 G1CollectorPolicy::predict_gc_eff(size_t young_length,
   819                                   size_t so_length,
   820                                   double base_time_ms,
   821                                   double* ret_gc_eff,
   822                                   double* ret_pause_time_ms) {
   823   double so_time_ms = predict_scan_only_time_ms(so_length);
   824   double accum_surv_rate_adj = 0.0;
   825   if (so_length > 0)
   826     accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
   827   double accum_surv_rate =
   828     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
   829   size_t bytes_to_copy =
   830     (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   831   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   832   double young_other_time_ms =
   833                        predict_young_other_time_ms(young_length - so_length);
   834   double pause_time_ms =
   835                 base_time_ms + so_time_ms + copy_time_ms + young_other_time_ms;
   836   size_t reclaimed_bytes =
   837     (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
   838   double gc_eff = (double) reclaimed_bytes / pause_time_ms;
   840   *ret_gc_eff = gc_eff;
   841   *ret_pause_time_ms = pause_time_ms;
   842 }
   844 // This is used by: calculate_young_list_target_config(rs_length). It
   845 // returns the GC eff of a particular config. It returns false if that
   846 // config violates any of the end conditions of the search in the
   847 // calling method, or true upon success. The end conditions were put
   848 // here since it's called twice and it was best not to replicate them
   849 // in the caller. Also, passing the parameteres avoids having to
   850 // recalculate them in the innermost loop.
   851 bool
   852 G1CollectorPolicy::predict_gc_eff(size_t young_length,
   853                                   size_t so_length,
   854                                   double base_time_with_so_ms,
   855                                   size_t init_free_regions,
   856                                   double target_pause_time_ms,
   857                                   double* ret_gc_eff) {
   858   *ret_gc_eff = 0.0;
   860   if (young_length >= init_free_regions)
   861     // end condition 1: not enough space for the young regions
   862     return false;
   864   double accum_surv_rate_adj = 0.0;
   865   if (so_length > 0)
   866     accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
   867   double accum_surv_rate =
   868     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
   869   size_t bytes_to_copy =
   870     (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   871   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   872   double young_other_time_ms =
   873                        predict_young_other_time_ms(young_length - so_length);
   874   double pause_time_ms =
   875                    base_time_with_so_ms + copy_time_ms + young_other_time_ms;
   877   if (pause_time_ms > target_pause_time_ms)
   878     // end condition 2: over the target pause time
   879     return false;
   881   size_t reclaimed_bytes =
   882     (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
   883   size_t free_bytes =
   884                  (init_free_regions - young_length) * HeapRegion::GrainBytes;
   886   if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
   887     // end condition 3: out of to-space (conservatively)
   888     return false;
   890   // success!
   891   double gc_eff = (double) reclaimed_bytes / pause_time_ms;
   892   *ret_gc_eff = gc_eff;
   894   return true;
   895 }
   897 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
   898   double survivor_regions_evac_time = 0.0;
   899   for (HeapRegion * r = _recorded_survivor_head;
   900        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
   901        r = r->get_next_young_region()) {
   902     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
   903   }
   904   return survivor_regions_evac_time;
   905 }
   907 void G1CollectorPolicy::check_prediction_validity() {
   908   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
   910   size_t rs_lengths = _g1->young_list_sampled_rs_lengths();
   911   if (rs_lengths > _rs_lengths_prediction) {
   912     // add 10% to avoid having to recalculate often
   913     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
   914     calculate_young_list_target_config(rs_lengths_prediction);
   915   }
   916 }
   918 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
   919                                                bool is_tlab,
   920                                                bool* gc_overhead_limit_was_exceeded) {
   921   guarantee(false, "Not using this policy feature yet.");
   922   return NULL;
   923 }
   925 // This method controls how a collector handles one or more
   926 // of its generations being fully allocated.
   927 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
   928                                                        bool is_tlab) {
   929   guarantee(false, "Not using this policy feature yet.");
   930   return NULL;
   931 }
   934 #ifndef PRODUCT
   935 bool G1CollectorPolicy::verify_young_ages() {
   936   HeapRegion* head = _g1->young_list_first_region();
   937   return
   938     verify_young_ages(head, _short_lived_surv_rate_group);
   939   // also call verify_young_ages on any additional surv rate groups
   940 }
   942 bool
   943 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
   944                                      SurvRateGroup *surv_rate_group) {
   945   guarantee( surv_rate_group != NULL, "pre-condition" );
   947   const char* name = surv_rate_group->name();
   948   bool ret = true;
   949   int prev_age = -1;
   951   for (HeapRegion* curr = head;
   952        curr != NULL;
   953        curr = curr->get_next_young_region()) {
   954     SurvRateGroup* group = curr->surv_rate_group();
   955     if (group == NULL && !curr->is_survivor()) {
   956       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
   957       ret = false;
   958     }
   960     if (surv_rate_group == group) {
   961       int age = curr->age_in_surv_rate_group();
   963       if (age < 0) {
   964         gclog_or_tty->print_cr("## %s: encountered negative age", name);
   965         ret = false;
   966       }
   968       if (age <= prev_age) {
   969         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
   970                                "(%d, %d)", name, age, prev_age);
   971         ret = false;
   972       }
   973       prev_age = age;
   974     }
   975   }
   977   return ret;
   978 }
   979 #endif // PRODUCT
   981 void G1CollectorPolicy::record_full_collection_start() {
   982   _cur_collection_start_sec = os::elapsedTime();
   983   // Release the future to-space so that it is available for compaction into.
   984   _g1->set_full_collection();
   985 }
   987 void G1CollectorPolicy::record_full_collection_end() {
   988   // Consider this like a collection pause for the purposes of allocation
   989   // since last pause.
   990   double end_sec = os::elapsedTime();
   991   double full_gc_time_sec = end_sec - _cur_collection_start_sec;
   992   double full_gc_time_ms = full_gc_time_sec * 1000.0;
   994   _all_full_gc_times_ms->add(full_gc_time_ms);
   996   update_recent_gc_times(end_sec, full_gc_time_ms);
   998   _g1->clear_full_collection();
  1000   // "Nuke" the heuristics that control the fully/partially young GC
  1001   // transitions and make sure we start with fully young GCs after the
  1002   // Full GC.
  1003   set_full_young_gcs(true);
  1004   _last_full_young_gc = false;
  1005   _should_revert_to_full_young_gcs = false;
  1006   _should_initiate_conc_mark = false;
  1007   _known_garbage_bytes = 0;
  1008   _known_garbage_ratio = 0.0;
  1009   _in_marking_window = false;
  1010   _in_marking_window_im = false;
  1012   _short_lived_surv_rate_group->record_scan_only_prefix(0);
  1013   _short_lived_surv_rate_group->start_adding_regions();
  1014   // also call this on any additional surv rate groups
  1016   record_survivor_regions(0, NULL, NULL);
  1018   _prev_region_num_young   = _region_num_young;
  1019   _prev_region_num_tenured = _region_num_tenured;
  1021   _free_regions_at_end_of_collection = _g1->free_regions();
  1022   _scan_only_regions_at_end_of_collection = 0;
  1023   // Reset survivors SurvRateGroup.
  1024   _survivor_surv_rate_group->reset();
  1025   calculate_young_list_min_length();
  1026   calculate_young_list_target_config();
  1029 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
  1030   _bytes_in_to_space_before_gc += bytes;
  1033 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
  1034   _bytes_in_to_space_after_gc += bytes;
  1037 void G1CollectorPolicy::record_stop_world_start() {
  1038   _stop_world_start = os::elapsedTime();
  1041 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
  1042                                                       size_t start_used) {
  1043   if (PrintGCDetails) {
  1044     gclog_or_tty->stamp(PrintGCTimeStamps);
  1045     gclog_or_tty->print("[GC pause");
  1046     if (in_young_gc_mode())
  1047       gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
  1050   assert(_g1->used_regions() == _g1->recalculate_used_regions(),
  1051          "sanity");
  1052   assert(_g1->used() == _g1->recalculate_used(), "sanity");
  1054   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
  1055   _all_stop_world_times_ms->add(s_w_t_ms);
  1056   _stop_world_start = 0.0;
  1058   _cur_collection_start_sec = start_time_sec;
  1059   _cur_collection_pause_used_at_start_bytes = start_used;
  1060   _cur_collection_pause_used_regions_at_start = _g1->used_regions();
  1061   _pending_cards = _g1->pending_card_num();
  1062   _max_pending_cards = _g1->max_pending_card_num();
  1064   _bytes_in_to_space_before_gc = 0;
  1065   _bytes_in_to_space_after_gc = 0;
  1066   _bytes_in_collection_set_before_gc = 0;
  1068 #ifdef DEBUG
  1069   // initialise these to something well known so that we can spot
  1070   // if they are not set properly
  1072   for (int i = 0; i < _parallel_gc_threads; ++i) {
  1073     _par_last_ext_root_scan_times_ms[i] = -666.0;
  1074     _par_last_mark_stack_scan_times_ms[i] = -666.0;
  1075     _par_last_scan_only_times_ms[i] = -666.0;
  1076     _par_last_scan_only_regions_scanned[i] = -666.0;
  1077     _par_last_update_rs_start_times_ms[i] = -666.0;
  1078     _par_last_update_rs_times_ms[i] = -666.0;
  1079     _par_last_update_rs_processed_buffers[i] = -666.0;
  1080     _par_last_scan_rs_start_times_ms[i] = -666.0;
  1081     _par_last_scan_rs_times_ms[i] = -666.0;
  1082     _par_last_scan_new_refs_times_ms[i] = -666.0;
  1083     _par_last_obj_copy_times_ms[i] = -666.0;
  1084     _par_last_termination_times_ms[i] = -666.0;
  1086 #endif
  1088   for (int i = 0; i < _aux_num; ++i) {
  1089     _cur_aux_times_ms[i] = 0.0;
  1090     _cur_aux_times_set[i] = false;
  1093   _satb_drain_time_set = false;
  1094   _last_satb_drain_processed_buffers = -1;
  1096   if (in_young_gc_mode())
  1097     _last_young_gc_full = false;
  1100   // do that for any other surv rate groups
  1101   _short_lived_surv_rate_group->stop_adding_regions();
  1102   size_t short_lived_so_length = _young_list_so_prefix_length;
  1103   _short_lived_surv_rate_group->record_scan_only_prefix(short_lived_so_length);
  1104   tag_scan_only(short_lived_so_length);
  1105   _survivors_age_table.clear();
  1107   assert( verify_young_ages(), "region age verification" );
  1110 void G1CollectorPolicy::tag_scan_only(size_t short_lived_scan_only_length) {
  1111   // done in a way that it can be extended for other surv rate groups too...
  1113   HeapRegion* head = _g1->young_list_first_region();
  1114   bool finished_short_lived = (short_lived_scan_only_length == 0);
  1116   if (finished_short_lived)
  1117     return;
  1119   for (HeapRegion* curr = head;
  1120        curr != NULL;
  1121        curr = curr->get_next_young_region()) {
  1122     SurvRateGroup* surv_rate_group = curr->surv_rate_group();
  1123     int age = curr->age_in_surv_rate_group();
  1125     if (surv_rate_group == _short_lived_surv_rate_group) {
  1126       if ((size_t)age < short_lived_scan_only_length)
  1127         curr->set_scan_only();
  1128       else
  1129         finished_short_lived = true;
  1133     if (finished_short_lived)
  1134       return;
  1137   guarantee( false, "we should never reach here" );
  1140 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
  1141   _mark_closure_time_ms = mark_closure_time_ms;
  1144 void G1CollectorPolicy::record_concurrent_mark_init_start() {
  1145   _mark_init_start_sec = os::elapsedTime();
  1146   guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
  1149 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
  1150                                                    mark_init_elapsed_time_ms) {
  1151   _during_marking = true;
  1152   _should_initiate_conc_mark = false;
  1153   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
  1156 void G1CollectorPolicy::record_concurrent_mark_init_end() {
  1157   double end_time_sec = os::elapsedTime();
  1158   double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
  1159   _concurrent_mark_init_times_ms->add(elapsed_time_ms);
  1160   record_concurrent_mark_init_end_pre(elapsed_time_ms);
  1162   _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
  1165 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
  1166   _mark_remark_start_sec = os::elapsedTime();
  1167   _during_marking = false;
  1170 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
  1171   double end_time_sec = os::elapsedTime();
  1172   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
  1173   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
  1174   _cur_mark_stop_world_time_ms += elapsed_time_ms;
  1175   _prev_collection_pause_end_ms += elapsed_time_ms;
  1177   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
  1180 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
  1181   _mark_cleanup_start_sec = os::elapsedTime();
  1184 void
  1185 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
  1186                                                       size_t max_live_bytes) {
  1187   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
  1188   record_concurrent_mark_cleanup_end_work2();
  1191 void
  1192 G1CollectorPolicy::
  1193 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
  1194                                          size_t max_live_bytes) {
  1195   if (_n_marks < 2) _n_marks++;
  1196   if (G1PolicyVerbose > 0)
  1197     gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
  1198                            " (of " SIZE_FORMAT " MB heap).",
  1199                            max_live_bytes/M, _g1->capacity()/M);
  1202 // The important thing about this is that it includes "os::elapsedTime".
  1203 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
  1204   double end_time_sec = os::elapsedTime();
  1205   double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
  1206   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
  1207   _cur_mark_stop_world_time_ms += elapsed_time_ms;
  1208   _prev_collection_pause_end_ms += elapsed_time_ms;
  1210   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
  1212   _num_markings++;
  1214   // We did a marking, so reset the "since_last_mark" variables.
  1215   double considerConcMarkCost = 1.0;
  1216   // If there are available processors, concurrent activity is free...
  1217   if (Threads::number_of_non_daemon_threads() * 2 <
  1218       os::active_processor_count()) {
  1219     considerConcMarkCost = 0.0;
  1221   _n_pauses_at_mark_end = _n_pauses;
  1222   _n_marks_since_last_pause++;
  1223   _conc_mark_initiated = false;
  1226 void
  1227 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
  1228   if (in_young_gc_mode()) {
  1229     _should_revert_to_full_young_gcs = false;
  1230     _last_full_young_gc = true;
  1231     _in_marking_window = false;
  1232     if (adaptive_young_list_length())
  1233       calculate_young_list_target_config();
  1237 void G1CollectorPolicy::record_concurrent_pause() {
  1238   if (_stop_world_start > 0.0) {
  1239     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
  1240     _all_yield_times_ms->add(yield_ms);
  1244 void G1CollectorPolicy::record_concurrent_pause_end() {
  1247 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
  1248   _cur_CH_strong_roots_end_sec = os::elapsedTime();
  1249   _cur_CH_strong_roots_dur_ms =
  1250     (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
  1253 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
  1254   _cur_G1_strong_roots_end_sec = os::elapsedTime();
  1255   _cur_G1_strong_roots_dur_ms =
  1256     (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
  1259 template<class T>
  1260 T sum_of(T* sum_arr, int start, int n, int N) {
  1261   T sum = (T)0;
  1262   for (int i = 0; i < n; i++) {
  1263     int j = (start + i) % N;
  1264     sum += sum_arr[j];
  1266   return sum;
  1269 void G1CollectorPolicy::print_par_stats (int level,
  1270                                          const char* str,
  1271                                          double* data,
  1272                                          bool summary) {
  1273   double min = data[0], max = data[0];
  1274   double total = 0.0;
  1275   int j;
  1276   for (j = 0; j < level; ++j)
  1277     gclog_or_tty->print("   ");
  1278   gclog_or_tty->print("[%s (ms):", str);
  1279   for (uint i = 0; i < ParallelGCThreads; ++i) {
  1280     double val = data[i];
  1281     if (val < min)
  1282       min = val;
  1283     if (val > max)
  1284       max = val;
  1285     total += val;
  1286     gclog_or_tty->print("  %3.1lf", val);
  1288   if (summary) {
  1289     gclog_or_tty->print_cr("");
  1290     double avg = total / (double) ParallelGCThreads;
  1291     gclog_or_tty->print(" ");
  1292     for (j = 0; j < level; ++j)
  1293       gclog_or_tty->print("   ");
  1294     gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
  1295                         avg, min, max);
  1297   gclog_or_tty->print_cr("]");
  1300 void G1CollectorPolicy::print_par_buffers (int level,
  1301                                          const char* str,
  1302                                          double* data,
  1303                                          bool summary) {
  1304   double min = data[0], max = data[0];
  1305   double total = 0.0;
  1306   int j;
  1307   for (j = 0; j < level; ++j)
  1308     gclog_or_tty->print("   ");
  1309   gclog_or_tty->print("[%s :", str);
  1310   for (uint i = 0; i < ParallelGCThreads; ++i) {
  1311     double val = data[i];
  1312     if (val < min)
  1313       min = val;
  1314     if (val > max)
  1315       max = val;
  1316     total += val;
  1317     gclog_or_tty->print(" %d", (int) val);
  1319   if (summary) {
  1320     gclog_or_tty->print_cr("");
  1321     double avg = total / (double) ParallelGCThreads;
  1322     gclog_or_tty->print(" ");
  1323     for (j = 0; j < level; ++j)
  1324       gclog_or_tty->print("   ");
  1325     gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
  1326                (int)total, (int)avg, (int)min, (int)max);
  1328   gclog_or_tty->print_cr("]");
  1331 void G1CollectorPolicy::print_stats (int level,
  1332                                      const char* str,
  1333                                      double value) {
  1334   for (int j = 0; j < level; ++j)
  1335     gclog_or_tty->print("   ");
  1336   gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
  1339 void G1CollectorPolicy::print_stats (int level,
  1340                                      const char* str,
  1341                                      int value) {
  1342   for (int j = 0; j < level; ++j)
  1343     gclog_or_tty->print("   ");
  1344   gclog_or_tty->print_cr("[%s: %d]", str, value);
  1347 double G1CollectorPolicy::avg_value (double* data) {
  1348   if (ParallelGCThreads > 0) {
  1349     double ret = 0.0;
  1350     for (uint i = 0; i < ParallelGCThreads; ++i)
  1351       ret += data[i];
  1352     return ret / (double) ParallelGCThreads;
  1353   } else {
  1354     return data[0];
  1358 double G1CollectorPolicy::max_value (double* data) {
  1359   if (ParallelGCThreads > 0) {
  1360     double ret = data[0];
  1361     for (uint i = 1; i < ParallelGCThreads; ++i)
  1362       if (data[i] > ret)
  1363         ret = data[i];
  1364     return ret;
  1365   } else {
  1366     return data[0];
  1370 double G1CollectorPolicy::sum_of_values (double* data) {
  1371   if (ParallelGCThreads > 0) {
  1372     double sum = 0.0;
  1373     for (uint i = 0; i < ParallelGCThreads; i++)
  1374       sum += data[i];
  1375     return sum;
  1376   } else {
  1377     return data[0];
  1381 double G1CollectorPolicy::max_sum (double* data1,
  1382                                    double* data2) {
  1383   double ret = data1[0] + data2[0];
  1385   if (ParallelGCThreads > 0) {
  1386     for (uint i = 1; i < ParallelGCThreads; ++i) {
  1387       double data = data1[i] + data2[i];
  1388       if (data > ret)
  1389         ret = data;
  1392   return ret;
  1395 // Anything below that is considered to be zero
  1396 #define MIN_TIMER_GRANULARITY 0.0000001
  1398 void G1CollectorPolicy::record_collection_pause_end(bool abandoned) {
  1399   double end_time_sec = os::elapsedTime();
  1400   double elapsed_ms = _last_pause_time_ms;
  1401   bool parallel = ParallelGCThreads > 0;
  1402   double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
  1403   size_t rs_size =
  1404     _cur_collection_pause_used_regions_at_start - collection_set_size();
  1405   size_t cur_used_bytes = _g1->used();
  1406   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
  1407   bool last_pause_included_initial_mark = false;
  1408   bool update_stats = !abandoned && !_g1->evacuation_failed();
  1410 #ifndef PRODUCT
  1411   if (G1YoungSurvRateVerbose) {
  1412     gclog_or_tty->print_cr("");
  1413     _short_lived_surv_rate_group->print();
  1414     // do that for any other surv rate groups too
  1416 #endif // PRODUCT
  1418   if (in_young_gc_mode()) {
  1419     last_pause_included_initial_mark = _should_initiate_conc_mark;
  1420     if (last_pause_included_initial_mark)
  1421       record_concurrent_mark_init_end_pre(0.0);
  1423     size_t min_used_targ =
  1424       (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
  1426     if (cur_used_bytes > min_used_targ) {
  1427       if (cur_used_bytes <= _prev_collection_pause_used_at_end_bytes) {
  1428       } else if (!_g1->mark_in_progress() && !_last_full_young_gc) {
  1429         _should_initiate_conc_mark = true;
  1433     _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
  1436   _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
  1437                           end_time_sec, false);
  1439   guarantee(_cur_collection_pause_used_regions_at_start >=
  1440             collection_set_size(),
  1441             "Negative RS size?");
  1443   // This assert is exempted when we're doing parallel collection pauses,
  1444   // because the fragmentation caused by the parallel GC allocation buffers
  1445   // can lead to more memory being used during collection than was used
  1446   // before. Best leave this out until the fragmentation problem is fixed.
  1447   // Pauses in which evacuation failed can also lead to negative
  1448   // collections, since no space is reclaimed from a region containing an
  1449   // object whose evacuation failed.
  1450   // Further, we're now always doing parallel collection.  But I'm still
  1451   // leaving this here as a placeholder for a more precise assertion later.
  1452   // (DLD, 10/05.)
  1453   assert((true || parallel) // Always using GC LABs now.
  1454          || _g1->evacuation_failed()
  1455          || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
  1456          "Negative collection");
  1458   size_t freed_bytes =
  1459     _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
  1460   size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
  1461   double survival_fraction =
  1462     (double)surviving_bytes/
  1463     (double)_collection_set_bytes_used_before;
  1465   _n_pauses++;
  1467   if (update_stats) {
  1468     _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
  1469     _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
  1470     _recent_evac_times_ms->add(evac_ms);
  1471     _recent_pause_times_ms->add(elapsed_ms);
  1473     _recent_rs_sizes->add(rs_size);
  1475     // We exempt parallel collection from this check because Alloc Buffer
  1476     // fragmentation can produce negative collections.  Same with evac
  1477     // failure.
  1478     // Further, we're now always doing parallel collection.  But I'm still
  1479     // leaving this here as a placeholder for a more precise assertion later.
  1480     // (DLD, 10/05.
  1481     assert((true || parallel)
  1482            || _g1->evacuation_failed()
  1483            || surviving_bytes <= _collection_set_bytes_used_before,
  1484            "Or else negative collection!");
  1485     _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
  1486     _recent_CS_bytes_surviving->add(surviving_bytes);
  1488     // this is where we update the allocation rate of the application
  1489     double app_time_ms =
  1490       (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
  1491     if (app_time_ms < MIN_TIMER_GRANULARITY) {
  1492       // This usually happens due to the timer not having the required
  1493       // granularity. Some Linuxes are the usual culprits.
  1494       // We'll just set it to something (arbitrarily) small.
  1495       app_time_ms = 1.0;
  1497     size_t regions_allocated =
  1498       (_region_num_young - _prev_region_num_young) +
  1499       (_region_num_tenured - _prev_region_num_tenured);
  1500     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
  1501     _alloc_rate_ms_seq->add(alloc_rate_ms);
  1502     _prev_region_num_young   = _region_num_young;
  1503     _prev_region_num_tenured = _region_num_tenured;
  1505     double interval_ms =
  1506       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
  1507     update_recent_gc_times(end_time_sec, elapsed_ms);
  1508     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
  1509     if (recent_avg_pause_time_ratio() < 0.0 ||
  1510         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
  1511 #ifndef PRODUCT
  1512       // Dump info to allow post-facto debugging
  1513       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
  1514       gclog_or_tty->print_cr("-------------------------------------------");
  1515       gclog_or_tty->print_cr("Recent GC Times (ms):");
  1516       _recent_gc_times_ms->dump();
  1517       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
  1518       _recent_prev_end_times_for_all_gcs_sec->dump();
  1519       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
  1520                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
  1521       // In debug mode, terminate the JVM if the user wants to debug at this point.
  1522       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
  1523 #endif  // !PRODUCT
  1524       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
  1525       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
  1526       if (_recent_avg_pause_time_ratio < 0.0) {
  1527         _recent_avg_pause_time_ratio = 0.0;
  1528       } else {
  1529         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
  1530         _recent_avg_pause_time_ratio = 1.0;
  1535   if (G1PolicyVerbose > 1) {
  1536     gclog_or_tty->print_cr("   Recording collection pause(%d)", _n_pauses);
  1539   PauseSummary* summary;
  1540   if (abandoned) {
  1541     summary = _abandoned_summary;
  1542   } else {
  1543     summary = _summary;
  1546   double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
  1547   double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
  1548   double scan_only_time = avg_value(_par_last_scan_only_times_ms);
  1549   double scan_only_regions_scanned =
  1550     sum_of_values(_par_last_scan_only_regions_scanned);
  1551   double update_rs_time = avg_value(_par_last_update_rs_times_ms);
  1552   double update_rs_processed_buffers =
  1553     sum_of_values(_par_last_update_rs_processed_buffers);
  1554   double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
  1555   double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
  1556   double termination_time = avg_value(_par_last_termination_times_ms);
  1558   double parallel_other_time = _cur_collection_par_time_ms -
  1559     (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
  1560      scan_only_time + scan_rs_time + obj_copy_time + termination_time);
  1561   if (update_stats) {
  1562     MainBodySummary* body_summary = summary->main_body_summary();
  1563     guarantee(body_summary != NULL, "should not be null!");
  1565     if (_satb_drain_time_set)
  1566       body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
  1567     else
  1568       body_summary->record_satb_drain_time_ms(0.0);
  1569     body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
  1570     body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
  1571     body_summary->record_scan_only_time_ms(scan_only_time);
  1572     body_summary->record_update_rs_time_ms(update_rs_time);
  1573     body_summary->record_scan_rs_time_ms(scan_rs_time);
  1574     body_summary->record_obj_copy_time_ms(obj_copy_time);
  1575     if (parallel) {
  1576       body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
  1577       body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
  1578       body_summary->record_termination_time_ms(termination_time);
  1579       body_summary->record_parallel_other_time_ms(parallel_other_time);
  1581     body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
  1584   if (G1PolicyVerbose > 1) {
  1585     gclog_or_tty->print_cr("      ET: %10.6f ms           (avg: %10.6f ms)\n"
  1586                            "        CH Strong: %10.6f ms    (avg: %10.6f ms)\n"
  1587                            "        G1 Strong: %10.6f ms    (avg: %10.6f ms)\n"
  1588                            "        Evac:      %10.6f ms    (avg: %10.6f ms)\n"
  1589                            "       ET-RS:  %10.6f ms      (avg: %10.6f ms)\n"
  1590                            "      |RS|: " SIZE_FORMAT,
  1591                            elapsed_ms, recent_avg_time_for_pauses_ms(),
  1592                            _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
  1593                            _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
  1594                            evac_ms, recent_avg_time_for_evac_ms(),
  1595                            scan_rs_time,
  1596                            recent_avg_time_for_pauses_ms() -
  1597                            recent_avg_time_for_G1_strong_ms(),
  1598                            rs_size);
  1600     gclog_or_tty->print_cr("       Used at start: " SIZE_FORMAT"K"
  1601                            "       At end " SIZE_FORMAT "K\n"
  1602                            "       garbage      : " SIZE_FORMAT "K"
  1603                            "       of     " SIZE_FORMAT "K\n"
  1604                            "       survival     : %6.2f%%  (%6.2f%% avg)",
  1605                            _cur_collection_pause_used_at_start_bytes/K,
  1606                            _g1->used()/K, freed_bytes/K,
  1607                            _collection_set_bytes_used_before/K,
  1608                            survival_fraction*100.0,
  1609                            recent_avg_survival_fraction()*100.0);
  1610     gclog_or_tty->print_cr("       Recent %% gc pause time: %6.2f",
  1611                            recent_avg_pause_time_ratio() * 100.0);
  1614   double other_time_ms = elapsed_ms;
  1616   if (!abandoned) {
  1617     if (_satb_drain_time_set)
  1618       other_time_ms -= _cur_satb_drain_time_ms;
  1620     if (parallel)
  1621       other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
  1622     else
  1623       other_time_ms -=
  1624         update_rs_time +
  1625         ext_root_scan_time + mark_stack_scan_time + scan_only_time +
  1626         scan_rs_time + obj_copy_time;
  1629   if (PrintGCDetails) {
  1630     gclog_or_tty->print_cr("%s%s, %1.8lf secs]",
  1631                            abandoned ? " (abandoned)" : "",
  1632                            (last_pause_included_initial_mark) ? " (initial-mark)" : "",
  1633                            elapsed_ms / 1000.0);
  1635     if (!abandoned) {
  1636       if (_satb_drain_time_set) {
  1637         print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
  1639       if (_last_satb_drain_processed_buffers >= 0) {
  1640         print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
  1642       if (parallel) {
  1643         print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
  1644         print_par_stats(2, "Update RS (Start)", _par_last_update_rs_start_times_ms, false);
  1645         print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
  1646         print_par_buffers(3, "Processed Buffers",
  1647                           _par_last_update_rs_processed_buffers, true);
  1648         print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
  1649         print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
  1650         print_par_stats(2, "Scan-Only Scanning", _par_last_scan_only_times_ms);
  1651         print_par_buffers(3, "Scan-Only Regions",
  1652                           _par_last_scan_only_regions_scanned, true);
  1653         print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
  1654         print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
  1655         print_par_stats(2, "Termination", _par_last_termination_times_ms);
  1656         print_stats(2, "Other", parallel_other_time);
  1657         print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
  1658       } else {
  1659         print_stats(1, "Update RS", update_rs_time);
  1660         print_stats(2, "Processed Buffers",
  1661                     (int)update_rs_processed_buffers);
  1662         print_stats(1, "Ext Root Scanning", ext_root_scan_time);
  1663         print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
  1664         print_stats(1, "Scan-Only Scanning", scan_only_time);
  1665         print_stats(1, "Scan RS", scan_rs_time);
  1666         print_stats(1, "Object Copying", obj_copy_time);
  1669 #ifndef PRODUCT
  1670     print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
  1671     print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
  1672     print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
  1673     print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
  1674     if (_num_cc_clears > 0) {
  1675       print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
  1677 #endif
  1678     print_stats(1, "Other", other_time_ms);
  1679     for (int i = 0; i < _aux_num; ++i) {
  1680       if (_cur_aux_times_set[i]) {
  1681         char buffer[96];
  1682         sprintf(buffer, "Aux%d", i);
  1683         print_stats(1, buffer, _cur_aux_times_ms[i]);
  1687   if (PrintGCDetails)
  1688     gclog_or_tty->print("   [");
  1689   if (PrintGC || PrintGCDetails)
  1690     _g1->print_size_transition(gclog_or_tty,
  1691                                _cur_collection_pause_used_at_start_bytes,
  1692                                _g1->used(), _g1->capacity());
  1693   if (PrintGCDetails)
  1694     gclog_or_tty->print_cr("]");
  1696   _all_pause_times_ms->add(elapsed_ms);
  1697   if (update_stats) {
  1698     summary->record_total_time_ms(elapsed_ms);
  1699     summary->record_other_time_ms(other_time_ms);
  1701   for (int i = 0; i < _aux_num; ++i)
  1702     if (_cur_aux_times_set[i])
  1703       _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
  1705   // Reset marks-between-pauses counter.
  1706   _n_marks_since_last_pause = 0;
  1708   // Update the efficiency-since-mark vars.
  1709   double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
  1710   if (elapsed_ms < MIN_TIMER_GRANULARITY) {
  1711     // This usually happens due to the timer not having the required
  1712     // granularity. Some Linuxes are the usual culprits.
  1713     // We'll just set it to something (arbitrarily) small.
  1714     proc_ms = 1.0;
  1716   double cur_efficiency = (double) freed_bytes / proc_ms;
  1718   bool new_in_marking_window = _in_marking_window;
  1719   bool new_in_marking_window_im = false;
  1720   if (_should_initiate_conc_mark) {
  1721     new_in_marking_window = true;
  1722     new_in_marking_window_im = true;
  1725   if (in_young_gc_mode()) {
  1726     if (_last_full_young_gc) {
  1727       set_full_young_gcs(false);
  1728       _last_full_young_gc = false;
  1731     if ( !_last_young_gc_full ) {
  1732       if ( _should_revert_to_full_young_gcs ||
  1733            _known_garbage_ratio < 0.05 ||
  1734            (adaptive_young_list_length() &&
  1735            (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
  1736         set_full_young_gcs(true);
  1739     _should_revert_to_full_young_gcs = false;
  1741     if (_last_young_gc_full && !_during_marking)
  1742       _young_gc_eff_seq->add(cur_efficiency);
  1745   _short_lived_surv_rate_group->start_adding_regions();
  1746   // do that for any other surv rate groupsx
  1748   // <NEW PREDICTION>
  1750   if (update_stats) {
  1751     double pause_time_ms = elapsed_ms;
  1753     size_t diff = 0;
  1754     if (_max_pending_cards >= _pending_cards)
  1755       diff = _max_pending_cards - _pending_cards;
  1756     _pending_card_diff_seq->add((double) diff);
  1758     double cost_per_card_ms = 0.0;
  1759     if (_pending_cards > 0) {
  1760       cost_per_card_ms = update_rs_time / (double) _pending_cards;
  1761       _cost_per_card_ms_seq->add(cost_per_card_ms);
  1764     double cost_per_scan_only_region_ms = 0.0;
  1765     if (scan_only_regions_scanned > 0.0) {
  1766       cost_per_scan_only_region_ms =
  1767         scan_only_time / scan_only_regions_scanned;
  1768       if (_in_marking_window_im)
  1769         _cost_per_scan_only_region_ms_during_cm_seq->add(cost_per_scan_only_region_ms);
  1770       else
  1771         _cost_per_scan_only_region_ms_seq->add(cost_per_scan_only_region_ms);
  1774     size_t cards_scanned = _g1->cards_scanned();
  1776     double cost_per_entry_ms = 0.0;
  1777     if (cards_scanned > 10) {
  1778       cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
  1779       if (_last_young_gc_full)
  1780         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1781       else
  1782         _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1785     if (_max_rs_lengths > 0) {
  1786       double cards_per_entry_ratio =
  1787         (double) cards_scanned / (double) _max_rs_lengths;
  1788       if (_last_young_gc_full)
  1789         _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1790       else
  1791         _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1794     size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
  1795     if (rs_length_diff >= 0)
  1796       _rs_length_diff_seq->add((double) rs_length_diff);
  1798     size_t copied_bytes = surviving_bytes;
  1799     double cost_per_byte_ms = 0.0;
  1800     if (copied_bytes > 0) {
  1801       cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
  1802       if (_in_marking_window)
  1803         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
  1804       else
  1805         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
  1808     double all_other_time_ms = pause_time_ms -
  1809       (update_rs_time + scan_only_time + scan_rs_time + obj_copy_time +
  1810        _mark_closure_time_ms + termination_time);
  1812     double young_other_time_ms = 0.0;
  1813     if (_recorded_young_regions > 0) {
  1814       young_other_time_ms =
  1815         _recorded_young_cset_choice_time_ms +
  1816         _recorded_young_free_cset_time_ms;
  1817       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
  1818                                              (double) _recorded_young_regions);
  1820     double non_young_other_time_ms = 0.0;
  1821     if (_recorded_non_young_regions > 0) {
  1822       non_young_other_time_ms =
  1823         _recorded_non_young_cset_choice_time_ms +
  1824         _recorded_non_young_free_cset_time_ms;
  1826       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
  1827                                          (double) _recorded_non_young_regions);
  1830     double constant_other_time_ms = all_other_time_ms -
  1831       (young_other_time_ms + non_young_other_time_ms);
  1832     _constant_other_time_ms_seq->add(constant_other_time_ms);
  1834     double survival_ratio = 0.0;
  1835     if (_bytes_in_collection_set_before_gc > 0) {
  1836       survival_ratio = (double) bytes_in_to_space_during_gc() /
  1837         (double) _bytes_in_collection_set_before_gc;
  1840     _pending_cards_seq->add((double) _pending_cards);
  1841     _scanned_cards_seq->add((double) cards_scanned);
  1842     _rs_lengths_seq->add((double) _max_rs_lengths);
  1844     double expensive_region_limit_ms =
  1845       (double) MaxGCPauseMillis - predict_constant_other_time_ms();
  1846     if (expensive_region_limit_ms < 0.0) {
  1847       // this means that the other time was predicted to be longer than
  1848       // than the max pause time
  1849       expensive_region_limit_ms = (double) MaxGCPauseMillis;
  1851     _expensive_region_limit_ms = expensive_region_limit_ms;
  1853     if (PREDICTIONS_VERBOSE) {
  1854       gclog_or_tty->print_cr("");
  1855       gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
  1856                     "REGIONS %d %d %d %d "
  1857                     "PENDING_CARDS %d %d "
  1858                     "CARDS_SCANNED %d %d "
  1859                     "RS_LENGTHS %d %d "
  1860                     "SCAN_ONLY_SCAN %1.6lf %1.6lf "
  1861                     "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
  1862                     "SURVIVAL_RATIO %1.6lf %1.6lf "
  1863                     "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
  1864                     "OTHER_YOUNG %1.6lf %1.6lf "
  1865                     "OTHER_NON_YOUNG %1.6lf %1.6lf "
  1866                     "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
  1867                     "ELAPSED %1.6lf %1.6lf ",
  1868                     _cur_collection_start_sec,
  1869                     (!_last_young_gc_full) ? 2 :
  1870                     (last_pause_included_initial_mark) ? 1 : 0,
  1871                     _recorded_region_num,
  1872                     _recorded_young_regions,
  1873                     _recorded_scan_only_regions,
  1874                     _recorded_non_young_regions,
  1875                     _predicted_pending_cards, _pending_cards,
  1876                     _predicted_cards_scanned, cards_scanned,
  1877                     _predicted_rs_lengths, _max_rs_lengths,
  1878                     _predicted_scan_only_scan_time_ms, scan_only_time,
  1879                     _predicted_rs_update_time_ms, update_rs_time,
  1880                     _predicted_rs_scan_time_ms, scan_rs_time,
  1881                     _predicted_survival_ratio, survival_ratio,
  1882                     _predicted_object_copy_time_ms, obj_copy_time,
  1883                     _predicted_constant_other_time_ms, constant_other_time_ms,
  1884                     _predicted_young_other_time_ms, young_other_time_ms,
  1885                     _predicted_non_young_other_time_ms,
  1886                     non_young_other_time_ms,
  1887                     _vtime_diff_ms, termination_time,
  1888                     _predicted_pause_time_ms, elapsed_ms);
  1891     if (G1PolicyVerbose > 0) {
  1892       gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
  1893                     _predicted_pause_time_ms,
  1894                     (_within_target) ? "within" : "outside",
  1895                     elapsed_ms);
  1900   _in_marking_window = new_in_marking_window;
  1901   _in_marking_window_im = new_in_marking_window_im;
  1902   _free_regions_at_end_of_collection = _g1->free_regions();
  1903   _scan_only_regions_at_end_of_collection = _g1->young_list_length();
  1904   calculate_young_list_min_length();
  1905   calculate_young_list_target_config();
  1907   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
  1908   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
  1909   adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
  1911   // </NEW PREDICTION>
  1913   _target_pause_time_ms = -1.0;
  1916 // <NEW PREDICTION>
  1918 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
  1919                                                      double update_rs_processed_buffers,
  1920                                                      double goal_ms) {
  1921   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  1922   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
  1924   if (G1UseAdaptiveConcRefinement) {
  1925     const int k_gy = 3, k_gr = 6;
  1926     const double inc_k = 1.1, dec_k = 0.9;
  1928     int g = cg1r->green_zone();
  1929     if (update_rs_time > goal_ms) {
  1930       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
  1931     } else {
  1932       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
  1933         g = (int)MAX2(g * inc_k, g + 1.0);
  1936     // Change the refinement threads params
  1937     cg1r->set_green_zone(g);
  1938     cg1r->set_yellow_zone(g * k_gy);
  1939     cg1r->set_red_zone(g * k_gr);
  1940     cg1r->reinitialize_threads();
  1942     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
  1943     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
  1944                                     cg1r->yellow_zone());
  1945     // Change the barrier params
  1946     dcqs.set_process_completed_threshold(processing_threshold);
  1947     dcqs.set_max_completed_queue(cg1r->red_zone());
  1950   int curr_queue_size = dcqs.completed_buffers_num();
  1951   if (curr_queue_size >= cg1r->yellow_zone()) {
  1952     dcqs.set_completed_queue_padding(curr_queue_size);
  1953   } else {
  1954     dcqs.set_completed_queue_padding(0);
  1956   dcqs.notify_if_necessary();
  1959 double
  1960 G1CollectorPolicy::
  1961 predict_young_collection_elapsed_time_ms(size_t adjustment) {
  1962   guarantee( adjustment == 0 || adjustment == 1, "invariant" );
  1964   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  1965   size_t young_num = g1h->young_list_length();
  1966   if (young_num == 0)
  1967     return 0.0;
  1969   young_num += adjustment;
  1970   size_t pending_cards = predict_pending_cards();
  1971   size_t rs_lengths = g1h->young_list_sampled_rs_lengths() +
  1972                       predict_rs_length_diff();
  1973   size_t card_num;
  1974   if (full_young_gcs())
  1975     card_num = predict_young_card_num(rs_lengths);
  1976   else
  1977     card_num = predict_non_young_card_num(rs_lengths);
  1978   size_t young_byte_size = young_num * HeapRegion::GrainBytes;
  1979   double accum_yg_surv_rate =
  1980     _short_lived_surv_rate_group->accum_surv_rate(adjustment);
  1982   size_t bytes_to_copy =
  1983     (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
  1985   return
  1986     predict_rs_update_time_ms(pending_cards) +
  1987     predict_rs_scan_time_ms(card_num) +
  1988     predict_object_copy_time_ms(bytes_to_copy) +
  1989     predict_young_other_time_ms(young_num) +
  1990     predict_constant_other_time_ms();
  1993 double
  1994 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
  1995   size_t rs_length = predict_rs_length_diff();
  1996   size_t card_num;
  1997   if (full_young_gcs())
  1998     card_num = predict_young_card_num(rs_length);
  1999   else
  2000     card_num = predict_non_young_card_num(rs_length);
  2001   return predict_base_elapsed_time_ms(pending_cards, card_num);
  2004 double
  2005 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
  2006                                                 size_t scanned_cards) {
  2007   return
  2008     predict_rs_update_time_ms(pending_cards) +
  2009     predict_rs_scan_time_ms(scanned_cards) +
  2010     predict_constant_other_time_ms();
  2013 double
  2014 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
  2015                                                   bool young) {
  2016   size_t rs_length = hr->rem_set()->occupied();
  2017   size_t card_num;
  2018   if (full_young_gcs())
  2019     card_num = predict_young_card_num(rs_length);
  2020   else
  2021     card_num = predict_non_young_card_num(rs_length);
  2022   size_t bytes_to_copy = predict_bytes_to_copy(hr);
  2024   double region_elapsed_time_ms =
  2025     predict_rs_scan_time_ms(card_num) +
  2026     predict_object_copy_time_ms(bytes_to_copy);
  2028   if (young)
  2029     region_elapsed_time_ms += predict_young_other_time_ms(1);
  2030   else
  2031     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
  2033   return region_elapsed_time_ms;
  2036 size_t
  2037 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
  2038   size_t bytes_to_copy;
  2039   if (hr->is_marked())
  2040     bytes_to_copy = hr->max_live_bytes();
  2041   else {
  2042     guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
  2043                "invariant" );
  2044     int age = hr->age_in_surv_rate_group();
  2045     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
  2046     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
  2049   return bytes_to_copy;
  2052 void
  2053 G1CollectorPolicy::start_recording_regions() {
  2054   _recorded_rs_lengths            = 0;
  2055   _recorded_scan_only_regions     = 0;
  2056   _recorded_young_regions         = 0;
  2057   _recorded_non_young_regions     = 0;
  2059 #if PREDICTIONS_VERBOSE
  2060   _predicted_rs_lengths           = 0;
  2061   _predicted_cards_scanned        = 0;
  2063   _recorded_marked_bytes          = 0;
  2064   _recorded_young_bytes           = 0;
  2065   _predicted_bytes_to_copy        = 0;
  2066 #endif // PREDICTIONS_VERBOSE
  2069 void
  2070 G1CollectorPolicy::record_cset_region(HeapRegion* hr, bool young) {
  2071   if (young) {
  2072     ++_recorded_young_regions;
  2073   } else {
  2074     ++_recorded_non_young_regions;
  2076 #if PREDICTIONS_VERBOSE
  2077   if (young) {
  2078     _recorded_young_bytes += hr->used();
  2079   } else {
  2080     _recorded_marked_bytes += hr->max_live_bytes();
  2082   _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
  2083 #endif // PREDICTIONS_VERBOSE
  2085   size_t rs_length = hr->rem_set()->occupied();
  2086   _recorded_rs_lengths += rs_length;
  2089 void
  2090 G1CollectorPolicy::record_scan_only_regions(size_t scan_only_length) {
  2091   _recorded_scan_only_regions = scan_only_length;
  2094 void
  2095 G1CollectorPolicy::end_recording_regions() {
  2096 #if PREDICTIONS_VERBOSE
  2097   _predicted_pending_cards = predict_pending_cards();
  2098   _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
  2099   if (full_young_gcs())
  2100     _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
  2101   else
  2102     _predicted_cards_scanned +=
  2103       predict_non_young_card_num(_predicted_rs_lengths);
  2104   _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
  2106   _predicted_scan_only_scan_time_ms =
  2107     predict_scan_only_time_ms(_recorded_scan_only_regions);
  2108   _predicted_rs_update_time_ms =
  2109     predict_rs_update_time_ms(_g1->pending_card_num());
  2110   _predicted_rs_scan_time_ms =
  2111     predict_rs_scan_time_ms(_predicted_cards_scanned);
  2112   _predicted_object_copy_time_ms =
  2113     predict_object_copy_time_ms(_predicted_bytes_to_copy);
  2114   _predicted_constant_other_time_ms =
  2115     predict_constant_other_time_ms();
  2116   _predicted_young_other_time_ms =
  2117     predict_young_other_time_ms(_recorded_young_regions);
  2118   _predicted_non_young_other_time_ms =
  2119     predict_non_young_other_time_ms(_recorded_non_young_regions);
  2121   _predicted_pause_time_ms =
  2122     _predicted_scan_only_scan_time_ms +
  2123     _predicted_rs_update_time_ms +
  2124     _predicted_rs_scan_time_ms +
  2125     _predicted_object_copy_time_ms +
  2126     _predicted_constant_other_time_ms +
  2127     _predicted_young_other_time_ms +
  2128     _predicted_non_young_other_time_ms;
  2129 #endif // PREDICTIONS_VERBOSE
  2132 void G1CollectorPolicy::check_if_region_is_too_expensive(double
  2133                                                            predicted_time_ms) {
  2134   // I don't think we need to do this when in young GC mode since
  2135   // marking will be initiated next time we hit the soft limit anyway...
  2136   if (predicted_time_ms > _expensive_region_limit_ms) {
  2137     if (!in_young_gc_mode()) {
  2138         set_full_young_gcs(true);
  2139       _should_initiate_conc_mark = true;
  2140     } else
  2141       // no point in doing another partial one
  2142       _should_revert_to_full_young_gcs = true;
  2146 // </NEW PREDICTION>
  2149 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
  2150                                                double elapsed_ms) {
  2151   _recent_gc_times_ms->add(elapsed_ms);
  2152   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
  2153   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
  2156 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
  2157   if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
  2158   else return _recent_pause_times_ms->avg();
  2161 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
  2162   if (_recent_CH_strong_roots_times_ms->num() == 0)
  2163     return (double)MaxGCPauseMillis/3.0;
  2164   else return _recent_CH_strong_roots_times_ms->avg();
  2167 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
  2168   if (_recent_G1_strong_roots_times_ms->num() == 0)
  2169     return (double)MaxGCPauseMillis/3.0;
  2170   else return _recent_G1_strong_roots_times_ms->avg();
  2173 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
  2174   if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
  2175   else return _recent_evac_times_ms->avg();
  2178 int G1CollectorPolicy::number_of_recent_gcs() {
  2179   assert(_recent_CH_strong_roots_times_ms->num() ==
  2180          _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
  2181   assert(_recent_G1_strong_roots_times_ms->num() ==
  2182          _recent_evac_times_ms->num(), "Sequence out of sync");
  2183   assert(_recent_evac_times_ms->num() ==
  2184          _recent_pause_times_ms->num(), "Sequence out of sync");
  2185   assert(_recent_pause_times_ms->num() ==
  2186          _recent_CS_bytes_used_before->num(), "Sequence out of sync");
  2187   assert(_recent_CS_bytes_used_before->num() ==
  2188          _recent_CS_bytes_surviving->num(), "Sequence out of sync");
  2189   return _recent_pause_times_ms->num();
  2192 double G1CollectorPolicy::recent_avg_survival_fraction() {
  2193   return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
  2194                                            _recent_CS_bytes_used_before);
  2197 double G1CollectorPolicy::last_survival_fraction() {
  2198   return last_survival_fraction_work(_recent_CS_bytes_surviving,
  2199                                      _recent_CS_bytes_used_before);
  2202 double
  2203 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
  2204                                                      TruncatedSeq* before) {
  2205   assert(surviving->num() == before->num(), "Sequence out of sync");
  2206   if (before->sum() > 0.0) {
  2207       double recent_survival_rate = surviving->sum() / before->sum();
  2208       // We exempt parallel collection from this check because Alloc Buffer
  2209       // fragmentation can produce negative collections.
  2210       // Further, we're now always doing parallel collection.  But I'm still
  2211       // leaving this here as a placeholder for a more precise assertion later.
  2212       // (DLD, 10/05.)
  2213       assert((true || ParallelGCThreads > 0) ||
  2214              _g1->evacuation_failed() ||
  2215              recent_survival_rate <= 1.0, "Or bad frac");
  2216       return recent_survival_rate;
  2217   } else {
  2218     return 1.0; // Be conservative.
  2222 double
  2223 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
  2224                                                TruncatedSeq* before) {
  2225   assert(surviving->num() == before->num(), "Sequence out of sync");
  2226   if (surviving->num() > 0 && before->last() > 0.0) {
  2227     double last_survival_rate = surviving->last() / before->last();
  2228     // We exempt parallel collection from this check because Alloc Buffer
  2229     // fragmentation can produce negative collections.
  2230     // Further, we're now always doing parallel collection.  But I'm still
  2231     // leaving this here as a placeholder for a more precise assertion later.
  2232     // (DLD, 10/05.)
  2233     assert((true || ParallelGCThreads > 0) ||
  2234            last_survival_rate <= 1.0, "Or bad frac");
  2235     return last_survival_rate;
  2236   } else {
  2237     return 1.0;
  2241 static const int survival_min_obs = 5;
  2242 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
  2243 static const double min_survival_rate = 0.1;
  2245 double
  2246 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
  2247                                                            double latest) {
  2248   double res = avg;
  2249   if (number_of_recent_gcs() < survival_min_obs) {
  2250     res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
  2252   res = MAX2(res, latest);
  2253   res = MAX2(res, min_survival_rate);
  2254   // In the parallel case, LAB fragmentation can produce "negative
  2255   // collections"; so can evac failure.  Cap at 1.0
  2256   res = MIN2(res, 1.0);
  2257   return res;
  2260 size_t G1CollectorPolicy::expansion_amount() {
  2261   if ((int)(recent_avg_pause_time_ratio() * 100.0) > G1GCPercent) {
  2262     // We will double the existing space, or take
  2263     // G1ExpandByPercentOfAvailable % of the available expansion
  2264     // space, whichever is smaller, bounded below by a minimum
  2265     // expansion (unless that's all that's left.)
  2266     const size_t min_expand_bytes = 1*M;
  2267     size_t reserved_bytes = _g1->g1_reserved_obj_bytes();
  2268     size_t committed_bytes = _g1->capacity();
  2269     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
  2270     size_t expand_bytes;
  2271     size_t expand_bytes_via_pct =
  2272       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
  2273     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
  2274     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
  2275     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
  2276     if (G1PolicyVerbose > 1) {
  2277       gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
  2278                  "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
  2279                  "                   Answer = %d.\n",
  2280                  recent_avg_pause_time_ratio(),
  2281                  byte_size_in_proper_unit(committed_bytes),
  2282                  proper_unit_for_byte_size(committed_bytes),
  2283                  byte_size_in_proper_unit(uncommitted_bytes),
  2284                  proper_unit_for_byte_size(uncommitted_bytes),
  2285                  byte_size_in_proper_unit(expand_bytes_via_pct),
  2286                  proper_unit_for_byte_size(expand_bytes_via_pct),
  2287                  byte_size_in_proper_unit(expand_bytes),
  2288                  proper_unit_for_byte_size(expand_bytes));
  2290     return expand_bytes;
  2291   } else {
  2292     return 0;
  2296 void G1CollectorPolicy::note_start_of_mark_thread() {
  2297   _mark_thread_startup_sec = os::elapsedTime();
  2300 class CountCSClosure: public HeapRegionClosure {
  2301   G1CollectorPolicy* _g1_policy;
  2302 public:
  2303   CountCSClosure(G1CollectorPolicy* g1_policy) :
  2304     _g1_policy(g1_policy) {}
  2305   bool doHeapRegion(HeapRegion* r) {
  2306     _g1_policy->_bytes_in_collection_set_before_gc += r->used();
  2307     return false;
  2309 };
  2311 void G1CollectorPolicy::count_CS_bytes_used() {
  2312   CountCSClosure cs_closure(this);
  2313   _g1->collection_set_iterate(&cs_closure);
  2316 static void print_indent(int level) {
  2317   for (int j = 0; j < level+1; ++j)
  2318     gclog_or_tty->print("   ");
  2321 void G1CollectorPolicy::print_summary (int level,
  2322                                        const char* str,
  2323                                        NumberSeq* seq) const {
  2324   double sum = seq->sum();
  2325   print_indent(level);
  2326   gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
  2327                 str, sum / 1000.0, seq->avg());
  2330 void G1CollectorPolicy::print_summary_sd (int level,
  2331                                           const char* str,
  2332                                           NumberSeq* seq) const {
  2333   print_summary(level, str, seq);
  2334   print_indent(level + 5);
  2335   gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
  2336                 seq->num(), seq->sd(), seq->maximum());
  2339 void G1CollectorPolicy::check_other_times(int level,
  2340                                         NumberSeq* other_times_ms,
  2341                                         NumberSeq* calc_other_times_ms) const {
  2342   bool should_print = false;
  2344   double max_sum = MAX2(fabs(other_times_ms->sum()),
  2345                         fabs(calc_other_times_ms->sum()));
  2346   double min_sum = MIN2(fabs(other_times_ms->sum()),
  2347                         fabs(calc_other_times_ms->sum()));
  2348   double sum_ratio = max_sum / min_sum;
  2349   if (sum_ratio > 1.1) {
  2350     should_print = true;
  2351     print_indent(level + 1);
  2352     gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
  2355   double max_avg = MAX2(fabs(other_times_ms->avg()),
  2356                         fabs(calc_other_times_ms->avg()));
  2357   double min_avg = MIN2(fabs(other_times_ms->avg()),
  2358                         fabs(calc_other_times_ms->avg()));
  2359   double avg_ratio = max_avg / min_avg;
  2360   if (avg_ratio > 1.1) {
  2361     should_print = true;
  2362     print_indent(level + 1);
  2363     gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
  2366   if (other_times_ms->sum() < -0.01) {
  2367     print_indent(level + 1);
  2368     gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
  2371   if (other_times_ms->avg() < -0.01) {
  2372     print_indent(level + 1);
  2373     gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
  2376   if (calc_other_times_ms->sum() < -0.01) {
  2377     should_print = true;
  2378     print_indent(level + 1);
  2379     gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
  2382   if (calc_other_times_ms->avg() < -0.01) {
  2383     should_print = true;
  2384     print_indent(level + 1);
  2385     gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
  2388   if (should_print)
  2389     print_summary(level, "Other(Calc)", calc_other_times_ms);
  2392 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
  2393   bool parallel = ParallelGCThreads > 0;
  2394   MainBodySummary*    body_summary = summary->main_body_summary();
  2395   if (summary->get_total_seq()->num() > 0) {
  2396     print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
  2397     if (body_summary != NULL) {
  2398       print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
  2399       if (parallel) {
  2400         print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
  2401         print_summary(2, "Update RS", body_summary->get_update_rs_seq());
  2402         print_summary(2, "Ext Root Scanning",
  2403                       body_summary->get_ext_root_scan_seq());
  2404         print_summary(2, "Mark Stack Scanning",
  2405                       body_summary->get_mark_stack_scan_seq());
  2406         print_summary(2, "Scan-Only Scanning",
  2407                       body_summary->get_scan_only_seq());
  2408         print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
  2409         print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
  2410         print_summary(2, "Termination", body_summary->get_termination_seq());
  2411         print_summary(2, "Other", body_summary->get_parallel_other_seq());
  2413           NumberSeq* other_parts[] = {
  2414             body_summary->get_update_rs_seq(),
  2415             body_summary->get_ext_root_scan_seq(),
  2416             body_summary->get_mark_stack_scan_seq(),
  2417             body_summary->get_scan_only_seq(),
  2418             body_summary->get_scan_rs_seq(),
  2419             body_summary->get_obj_copy_seq(),
  2420             body_summary->get_termination_seq()
  2421           };
  2422           NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
  2423                                         7, other_parts);
  2424           check_other_times(2, body_summary->get_parallel_other_seq(),
  2425                             &calc_other_times_ms);
  2427         print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
  2428         print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
  2429       } else {
  2430         print_summary(1, "Update RS", body_summary->get_update_rs_seq());
  2431         print_summary(1, "Ext Root Scanning",
  2432                       body_summary->get_ext_root_scan_seq());
  2433         print_summary(1, "Mark Stack Scanning",
  2434                       body_summary->get_mark_stack_scan_seq());
  2435         print_summary(1, "Scan-Only Scanning",
  2436                       body_summary->get_scan_only_seq());
  2437         print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
  2438         print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
  2441     print_summary(1, "Other", summary->get_other_seq());
  2443       NumberSeq calc_other_times_ms;
  2444       if (body_summary != NULL) {
  2445         // not abandoned
  2446         if (parallel) {
  2447           // parallel
  2448           NumberSeq* other_parts[] = {
  2449             body_summary->get_satb_drain_seq(),
  2450             body_summary->get_parallel_seq(),
  2451             body_summary->get_clear_ct_seq()
  2452           };
  2453           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2454                                           3, other_parts);
  2455         } else {
  2456           // serial
  2457           NumberSeq* other_parts[] = {
  2458             body_summary->get_satb_drain_seq(),
  2459             body_summary->get_update_rs_seq(),
  2460             body_summary->get_ext_root_scan_seq(),
  2461             body_summary->get_mark_stack_scan_seq(),
  2462             body_summary->get_scan_only_seq(),
  2463             body_summary->get_scan_rs_seq(),
  2464             body_summary->get_obj_copy_seq()
  2465           };
  2466           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2467                                           7, other_parts);
  2469       } else {
  2470         // abandoned
  2471         calc_other_times_ms = NumberSeq();
  2473       check_other_times(1,  summary->get_other_seq(), &calc_other_times_ms);
  2475   } else {
  2476     print_indent(0);
  2477     gclog_or_tty->print_cr("none");
  2479   gclog_or_tty->print_cr("");
  2482 void
  2483 G1CollectorPolicy::print_abandoned_summary(PauseSummary* summary) const {
  2484   bool printed = false;
  2485   if (summary->get_total_seq()->num() > 0) {
  2486     printed = true;
  2487     print_summary(summary);
  2489   if (!printed) {
  2490     print_indent(0);
  2491     gclog_or_tty->print_cr("none");
  2492     gclog_or_tty->print_cr("");
  2496 void G1CollectorPolicy::print_tracing_info() const {
  2497   if (TraceGen0Time) {
  2498     gclog_or_tty->print_cr("ALL PAUSES");
  2499     print_summary_sd(0, "Total", _all_pause_times_ms);
  2500     gclog_or_tty->print_cr("");
  2501     gclog_or_tty->print_cr("");
  2502     gclog_or_tty->print_cr("   Full Young GC Pauses:    %8d", _full_young_pause_num);
  2503     gclog_or_tty->print_cr("   Partial Young GC Pauses: %8d", _partial_young_pause_num);
  2504     gclog_or_tty->print_cr("");
  2506     gclog_or_tty->print_cr("EVACUATION PAUSES");
  2507     print_summary(_summary);
  2509     gclog_or_tty->print_cr("ABANDONED PAUSES");
  2510     print_abandoned_summary(_abandoned_summary);
  2512     gclog_or_tty->print_cr("MISC");
  2513     print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
  2514     print_summary_sd(0, "Yields", _all_yield_times_ms);
  2515     for (int i = 0; i < _aux_num; ++i) {
  2516       if (_all_aux_times_ms[i].num() > 0) {
  2517         char buffer[96];
  2518         sprintf(buffer, "Aux%d", i);
  2519         print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
  2523     size_t all_region_num = _region_num_young + _region_num_tenured;
  2524     gclog_or_tty->print_cr("   New Regions %8d, Young %8d (%6.2lf%%), "
  2525                "Tenured %8d (%6.2lf%%)",
  2526                all_region_num,
  2527                _region_num_young,
  2528                (double) _region_num_young / (double) all_region_num * 100.0,
  2529                _region_num_tenured,
  2530                (double) _region_num_tenured / (double) all_region_num * 100.0);
  2532   if (TraceGen1Time) {
  2533     if (_all_full_gc_times_ms->num() > 0) {
  2534       gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
  2535                  _all_full_gc_times_ms->num(),
  2536                  _all_full_gc_times_ms->sum() / 1000.0);
  2537       gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
  2538       gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
  2539                     _all_full_gc_times_ms->sd(),
  2540                     _all_full_gc_times_ms->maximum());
  2545 void G1CollectorPolicy::print_yg_surv_rate_info() const {
  2546 #ifndef PRODUCT
  2547   _short_lived_surv_rate_group->print_surv_rate_summary();
  2548   // add this call for any other surv rate groups
  2549 #endif // PRODUCT
  2552 bool
  2553 G1CollectorPolicy::should_add_next_region_to_young_list() {
  2554   assert(in_young_gc_mode(), "should be in young GC mode");
  2555   bool ret;
  2556   size_t young_list_length = _g1->young_list_length();
  2557   size_t young_list_max_length = _young_list_target_length;
  2558   if (G1FixedEdenSize) {
  2559     young_list_max_length -= _max_survivor_regions;
  2561   if (young_list_length < young_list_max_length) {
  2562     ret = true;
  2563     ++_region_num_young;
  2564   } else {
  2565     ret = false;
  2566     ++_region_num_tenured;
  2569   return ret;
  2572 #ifndef PRODUCT
  2573 // for debugging, bit of a hack...
  2574 static char*
  2575 region_num_to_mbs(int length) {
  2576   static char buffer[64];
  2577   double bytes = (double) (length * HeapRegion::GrainBytes);
  2578   double mbs = bytes / (double) (1024 * 1024);
  2579   sprintf(buffer, "%7.2lfMB", mbs);
  2580   return buffer;
  2582 #endif // PRODUCT
  2584 size_t G1CollectorPolicy::max_regions(int purpose) {
  2585   switch (purpose) {
  2586     case GCAllocForSurvived:
  2587       return _max_survivor_regions;
  2588     case GCAllocForTenured:
  2589       return REGIONS_UNLIMITED;
  2590     default:
  2591       ShouldNotReachHere();
  2592       return REGIONS_UNLIMITED;
  2593   };
  2596 // Calculates survivor space parameters.
  2597 void G1CollectorPolicy::calculate_survivors_policy()
  2599   if (G1FixedSurvivorSpaceSize == 0) {
  2600     _max_survivor_regions = _young_list_target_length / SurvivorRatio;
  2601   } else {
  2602     _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
  2605   if (G1FixedTenuringThreshold) {
  2606     _tenuring_threshold = MaxTenuringThreshold;
  2607   } else {
  2608     _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
  2609         HeapRegion::GrainWords * _max_survivor_regions);
  2613 bool
  2614 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t
  2615                                                                word_size) {
  2616   assert(_g1->regions_accounted_for(), "Region leakage!");
  2617   double max_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
  2619   size_t young_list_length = _g1->young_list_length();
  2620   size_t young_list_max_length = _young_list_target_length;
  2621   if (G1FixedEdenSize) {
  2622     young_list_max_length -= _max_survivor_regions;
  2624   bool reached_target_length = young_list_length >= young_list_max_length;
  2626   if (in_young_gc_mode()) {
  2627     if (reached_target_length) {
  2628       assert( young_list_length > 0 && _g1->young_list_length() > 0,
  2629               "invariant" );
  2630       _target_pause_time_ms = max_pause_time_ms;
  2631       return true;
  2633   } else {
  2634     guarantee( false, "should not reach here" );
  2637   return false;
  2640 #ifndef PRODUCT
  2641 class HRSortIndexIsOKClosure: public HeapRegionClosure {
  2642   CollectionSetChooser* _chooser;
  2643 public:
  2644   HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
  2645     _chooser(chooser) {}
  2647   bool doHeapRegion(HeapRegion* r) {
  2648     if (!r->continuesHumongous()) {
  2649       assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
  2651     return false;
  2653 };
  2655 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
  2656   HRSortIndexIsOKClosure cl(_collectionSetChooser);
  2657   _g1->heap_region_iterate(&cl);
  2658   return true;
  2660 #endif
  2662 void
  2663 G1CollectorPolicy_BestRegionsFirst::
  2664 record_collection_pause_start(double start_time_sec, size_t start_used) {
  2665   G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
  2668 class NextNonCSElemFinder: public HeapRegionClosure {
  2669   HeapRegion* _res;
  2670 public:
  2671   NextNonCSElemFinder(): _res(NULL) {}
  2672   bool doHeapRegion(HeapRegion* r) {
  2673     if (!r->in_collection_set()) {
  2674       _res = r;
  2675       return true;
  2676     } else {
  2677       return false;
  2680   HeapRegion* res() { return _res; }
  2681 };
  2683 class KnownGarbageClosure: public HeapRegionClosure {
  2684   CollectionSetChooser* _hrSorted;
  2686 public:
  2687   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
  2688     _hrSorted(hrSorted)
  2689   {}
  2691   bool doHeapRegion(HeapRegion* r) {
  2692     // We only include humongous regions in collection
  2693     // sets when concurrent mark shows that their contained object is
  2694     // unreachable.
  2696     // Do we have any marking information for this region?
  2697     if (r->is_marked()) {
  2698       // We don't include humongous regions in collection
  2699       // sets because we collect them immediately at the end of a marking
  2700       // cycle.  We also don't include young regions because we *must*
  2701       // include them in the next collection pause.
  2702       if (!r->isHumongous() && !r->is_young()) {
  2703         _hrSorted->addMarkedHeapRegion(r);
  2706     return false;
  2708 };
  2710 class ParKnownGarbageHRClosure: public HeapRegionClosure {
  2711   CollectionSetChooser* _hrSorted;
  2712   jint _marked_regions_added;
  2713   jint _chunk_size;
  2714   jint _cur_chunk_idx;
  2715   jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
  2716   int _worker;
  2717   int _invokes;
  2719   void get_new_chunk() {
  2720     _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
  2721     _cur_chunk_end = _cur_chunk_idx + _chunk_size;
  2723   void add_region(HeapRegion* r) {
  2724     if (_cur_chunk_idx == _cur_chunk_end) {
  2725       get_new_chunk();
  2727     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
  2728     _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
  2729     _marked_regions_added++;
  2730     _cur_chunk_idx++;
  2733 public:
  2734   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
  2735                            jint chunk_size,
  2736                            int worker) :
  2737     _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
  2738     _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
  2739     _invokes(0)
  2740   {}
  2742   bool doHeapRegion(HeapRegion* r) {
  2743     // We only include humongous regions in collection
  2744     // sets when concurrent mark shows that their contained object is
  2745     // unreachable.
  2746     _invokes++;
  2748     // Do we have any marking information for this region?
  2749     if (r->is_marked()) {
  2750       // We don't include humongous regions in collection
  2751       // sets because we collect them immediately at the end of a marking
  2752       // cycle.
  2753       // We also do not include young regions in collection sets
  2754       if (!r->isHumongous() && !r->is_young()) {
  2755         add_region(r);
  2758     return false;
  2760   jint marked_regions_added() { return _marked_regions_added; }
  2761   int invokes() { return _invokes; }
  2762 };
  2764 class ParKnownGarbageTask: public AbstractGangTask {
  2765   CollectionSetChooser* _hrSorted;
  2766   jint _chunk_size;
  2767   G1CollectedHeap* _g1;
  2768 public:
  2769   ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
  2770     AbstractGangTask("ParKnownGarbageTask"),
  2771     _hrSorted(hrSorted), _chunk_size(chunk_size),
  2772     _g1(G1CollectedHeap::heap())
  2773   {}
  2775   void work(int i) {
  2776     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
  2777     // Back to zero for the claim value.
  2778     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
  2779                                          HeapRegion::InitialClaimValue);
  2780     jint regions_added = parKnownGarbageCl.marked_regions_added();
  2781     _hrSorted->incNumMarkedHeapRegions(regions_added);
  2782     if (G1PrintParCleanupStats) {
  2783       gclog_or_tty->print("     Thread %d called %d times, added %d regions to list.\n",
  2784                  i, parKnownGarbageCl.invokes(), regions_added);
  2787 };
  2789 void
  2790 G1CollectorPolicy_BestRegionsFirst::
  2791 record_concurrent_mark_cleanup_end(size_t freed_bytes,
  2792                                    size_t max_live_bytes) {
  2793   double start;
  2794   if (G1PrintParCleanupStats) start = os::elapsedTime();
  2795   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
  2797   _collectionSetChooser->clearMarkedHeapRegions();
  2798   double clear_marked_end;
  2799   if (G1PrintParCleanupStats) {
  2800     clear_marked_end = os::elapsedTime();
  2801     gclog_or_tty->print_cr("  clear marked regions + work1: %8.3f ms.",
  2802                   (clear_marked_end - start)*1000.0);
  2804   if (ParallelGCThreads > 0) {
  2805     const size_t OverpartitionFactor = 4;
  2806     const size_t MinChunkSize = 8;
  2807     const size_t ChunkSize =
  2808       MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
  2809            MinChunkSize);
  2810     _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
  2811                                                              ChunkSize);
  2812     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
  2813                                             (int) ChunkSize);
  2814     _g1->workers()->run_task(&parKnownGarbageTask);
  2816     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
  2817            "sanity check");
  2818   } else {
  2819     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
  2820     _g1->heap_region_iterate(&knownGarbagecl);
  2822   double known_garbage_end;
  2823   if (G1PrintParCleanupStats) {
  2824     known_garbage_end = os::elapsedTime();
  2825     gclog_or_tty->print_cr("  compute known garbage: %8.3f ms.",
  2826                   (known_garbage_end - clear_marked_end)*1000.0);
  2828   _collectionSetChooser->sortMarkedHeapRegions();
  2829   double sort_end;
  2830   if (G1PrintParCleanupStats) {
  2831     sort_end = os::elapsedTime();
  2832     gclog_or_tty->print_cr("  sorting: %8.3f ms.",
  2833                   (sort_end - known_garbage_end)*1000.0);
  2836   record_concurrent_mark_cleanup_end_work2();
  2837   double work2_end;
  2838   if (G1PrintParCleanupStats) {
  2839     work2_end = os::elapsedTime();
  2840     gclog_or_tty->print_cr("  work2: %8.3f ms.",
  2841                   (work2_end - sort_end)*1000.0);
  2845 // Add the heap region to the collection set and return the conservative
  2846 // estimate of the number of live bytes.
  2847 void G1CollectorPolicy::
  2848 add_to_collection_set(HeapRegion* hr) {
  2849   if (G1PrintHeapRegions) {
  2850     gclog_or_tty->print_cr("added region to cset %d:["PTR_FORMAT", "PTR_FORMAT"], "
  2851                   "top "PTR_FORMAT", young %s",
  2852                   hr->hrs_index(), hr->bottom(), hr->end(),
  2853                   hr->top(), (hr->is_young()) ? "YES" : "NO");
  2856   if (_g1->mark_in_progress())
  2857     _g1->concurrent_mark()->registerCSetRegion(hr);
  2859   assert(!hr->in_collection_set(),
  2860               "should not already be in the CSet");
  2861   hr->set_in_collection_set(true);
  2862   hr->set_next_in_collection_set(_collection_set);
  2863   _collection_set = hr;
  2864   _collection_set_size++;
  2865   _collection_set_bytes_used_before += hr->used();
  2866   _g1->register_region_with_in_cset_fast_test(hr);
  2869 void
  2870 G1CollectorPolicy_BestRegionsFirst::
  2871 choose_collection_set() {
  2872   double non_young_start_time_sec;
  2873   start_recording_regions();
  2875   guarantee(_target_pause_time_ms > -1.0
  2876             NOT_PRODUCT(|| Universe::heap()->gc_cause() == GCCause::_scavenge_alot),
  2877             "_target_pause_time_ms should have been set!");
  2878 #ifndef PRODUCT
  2879   if (_target_pause_time_ms <= -1.0) {
  2880     assert(ScavengeALot && Universe::heap()->gc_cause() == GCCause::_scavenge_alot, "Error");
  2881     _target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
  2883 #endif
  2884   assert(_collection_set == NULL, "Precondition");
  2886   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
  2887   double predicted_pause_time_ms = base_time_ms;
  2889   double target_time_ms = _target_pause_time_ms;
  2890   double time_remaining_ms = target_time_ms - base_time_ms;
  2892   // the 10% and 50% values are arbitrary...
  2893   if (time_remaining_ms < 0.10*target_time_ms) {
  2894     time_remaining_ms = 0.50 * target_time_ms;
  2895     _within_target = false;
  2896   } else {
  2897     _within_target = true;
  2900   // We figure out the number of bytes available for future to-space.
  2901   // For new regions without marking information, we must assume the
  2902   // worst-case of complete survival.  If we have marking information for a
  2903   // region, we can bound the amount of live data.  We can add a number of
  2904   // such regions, as long as the sum of the live data bounds does not
  2905   // exceed the available evacuation space.
  2906   size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
  2908   size_t expansion_bytes =
  2909     _g1->expansion_regions() * HeapRegion::GrainBytes;
  2911   _collection_set_bytes_used_before = 0;
  2912   _collection_set_size = 0;
  2914   // Adjust for expansion and slop.
  2915   max_live_bytes = max_live_bytes + expansion_bytes;
  2917   assert(_g1->regions_accounted_for(), "Region leakage!");
  2919   HeapRegion* hr;
  2920   if (in_young_gc_mode()) {
  2921     double young_start_time_sec = os::elapsedTime();
  2923     if (G1PolicyVerbose > 0) {
  2924       gclog_or_tty->print_cr("Adding %d young regions to the CSet",
  2925                     _g1->young_list_length());
  2927     _young_cset_length  = 0;
  2928     _last_young_gc_full = full_young_gcs() ? true : false;
  2929     if (_last_young_gc_full)
  2930       ++_full_young_pause_num;
  2931     else
  2932       ++_partial_young_pause_num;
  2933     hr = _g1->pop_region_from_young_list();
  2934     while (hr != NULL) {
  2936       assert( hr->young_index_in_cset() == -1, "invariant" );
  2937       assert( hr->age_in_surv_rate_group() != -1, "invariant" );
  2938       hr->set_young_index_in_cset((int) _young_cset_length);
  2940       ++_young_cset_length;
  2941       double predicted_time_ms = predict_region_elapsed_time_ms(hr, true);
  2942       time_remaining_ms -= predicted_time_ms;
  2943       predicted_pause_time_ms += predicted_time_ms;
  2944       assert(!hr->in_collection_set(), "invariant");
  2945       add_to_collection_set(hr);
  2946       record_cset_region(hr, true);
  2947       max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
  2948       if (G1PolicyVerbose > 0) {
  2949         gclog_or_tty->print_cr("  Added [" PTR_FORMAT ", " PTR_FORMAT") to CS.",
  2950                       hr->bottom(), hr->end());
  2951         gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  2952                       max_live_bytes/K);
  2954       hr = _g1->pop_region_from_young_list();
  2957     record_scan_only_regions(_g1->young_list_scan_only_length());
  2959     double young_end_time_sec = os::elapsedTime();
  2960     _recorded_young_cset_choice_time_ms =
  2961       (young_end_time_sec - young_start_time_sec) * 1000.0;
  2963     non_young_start_time_sec = os::elapsedTime();
  2965     if (_young_cset_length > 0 && _last_young_gc_full) {
  2966       // don't bother adding more regions...
  2967       goto choose_collection_set_end;
  2971   if (!in_young_gc_mode() || !full_young_gcs()) {
  2972     bool should_continue = true;
  2973     NumberSeq seq;
  2974     double avg_prediction = 100000000000000000.0; // something very large
  2975     do {
  2976       hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
  2977                                                       avg_prediction);
  2978       if (hr != NULL) {
  2979         double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
  2980         time_remaining_ms -= predicted_time_ms;
  2981         predicted_pause_time_ms += predicted_time_ms;
  2982         add_to_collection_set(hr);
  2983         record_cset_region(hr, false);
  2984         max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
  2985         if (G1PolicyVerbose > 0) {
  2986           gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  2987                         max_live_bytes/K);
  2989         seq.add(predicted_time_ms);
  2990         avg_prediction = seq.avg() + seq.sd();
  2992       should_continue =
  2993         ( hr != NULL) &&
  2994         ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
  2995           : _collection_set_size < _young_list_fixed_length );
  2996     } while (should_continue);
  2998     if (!adaptive_young_list_length() &&
  2999         _collection_set_size < _young_list_fixed_length)
  3000       _should_revert_to_full_young_gcs  = true;
  3003 choose_collection_set_end:
  3004   count_CS_bytes_used();
  3006   end_recording_regions();
  3008   double non_young_end_time_sec = os::elapsedTime();
  3009   _recorded_non_young_cset_choice_time_ms =
  3010     (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
  3013 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
  3014   G1CollectorPolicy::record_full_collection_end();
  3015   _collectionSetChooser->updateAfterFullCollection();
  3018 void G1CollectorPolicy_BestRegionsFirst::
  3019 expand_if_possible(size_t numRegions) {
  3020   size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
  3021   _g1->expand(expansion_bytes);
  3024 void G1CollectorPolicy_BestRegionsFirst::
  3025 record_collection_pause_end(bool abandoned) {
  3026   G1CollectorPolicy::record_collection_pause_end(abandoned);
  3027   assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");

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