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

Tue, 30 Mar 2010 15:43:03 -0400

author
tonyp
date
Tue, 30 Mar 2010 15:43:03 -0400
changeset 1823
7666957bc44d
parent 1794
23b1b27ac76c
child 1826
79e419e5ea3b
permissions
-rw-r--r--

6937142: G1: improvements to debugging output (S-M)
Summary: Various fixes to the G1 debugging output.
Reviewed-by: johnc, iveresov

     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   _initiate_conc_mark_if_possible(false),
   182   _during_initial_mark_pause(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   _gc_overhead_perc(0.0)
   205 {
   206   // Set up the region size and associated fields. Given that the
   207   // policy is created before the heap, we have to set this up here,
   208   // so it's done as soon as possible.
   209   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
   210   HeapRegionRemSet::setup_remset_size();
   212   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
   213   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
   215   _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
   216   _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
   217   _par_last_scan_only_times_ms = new double[_parallel_gc_threads];
   218   _par_last_scan_only_regions_scanned = new double[_parallel_gc_threads];
   220   _par_last_update_rs_start_times_ms = new double[_parallel_gc_threads];
   221   _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
   222   _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
   224   _par_last_scan_rs_start_times_ms = new double[_parallel_gc_threads];
   225   _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
   226   _par_last_scan_new_refs_times_ms = new double[_parallel_gc_threads];
   228   _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
   230   _par_last_termination_times_ms = new double[_parallel_gc_threads];
   232   // start conservatively
   233   _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
   235   // <NEW PREDICTION>
   237   int index;
   238   if (ParallelGCThreads == 0)
   239     index = 0;
   240   else if (ParallelGCThreads > 8)
   241     index = 7;
   242   else
   243     index = ParallelGCThreads - 1;
   245   _pending_card_diff_seq->add(0.0);
   246   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
   247   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
   248   _cost_per_scan_only_region_ms_seq->add(
   249                                  cost_per_scan_only_region_ms_defaults[index]);
   250   _fully_young_cards_per_entry_ratio_seq->add(
   251                             fully_young_cards_per_entry_ratio_defaults[index]);
   252   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
   253   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
   254   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
   255   _young_other_cost_per_region_ms_seq->add(
   256                                young_other_cost_per_region_ms_defaults[index]);
   257   _non_young_other_cost_per_region_ms_seq->add(
   258                            non_young_other_cost_per_region_ms_defaults[index]);
   260   // </NEW PREDICTION>
   262   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
   263   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
   264   guarantee(max_gc_time < time_slice,
   265             "Max GC time should not be greater than the time slice");
   266   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
   267   _sigma = (double) G1ConfidencePercent / 100.0;
   269   // start conservatively (around 50ms is about right)
   270   _concurrent_mark_init_times_ms->add(0.05);
   271   _concurrent_mark_remark_times_ms->add(0.05);
   272   _concurrent_mark_cleanup_times_ms->add(0.20);
   273   _tenuring_threshold = MaxTenuringThreshold;
   275   // if G1FixedSurvivorSpaceSize is 0 which means the size is not
   276   // fixed, then _max_survivor_regions will be calculated at
   277   // calculate_young_list_target_config during initialization
   278   _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
   280   assert(GCTimeRatio > 0,
   281          "we should have set it to a default value set_g1_gc_flags() "
   282          "if a user set it to 0");
   283   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
   285   initialize_all();
   286 }
   288 // Increment "i", mod "len"
   289 static void inc_mod(int& i, int len) {
   290   i++; if (i == len) i = 0;
   291 }
   293 void G1CollectorPolicy::initialize_flags() {
   294   set_min_alignment(HeapRegion::GrainBytes);
   295   set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
   296   if (SurvivorRatio < 1) {
   297     vm_exit_during_initialization("Invalid survivor ratio specified");
   298   }
   299   CollectorPolicy::initialize_flags();
   300 }
   302 // The easiest way to deal with the parsing of the NewSize /
   303 // MaxNewSize / etc. parameteres is to re-use the code in the
   304 // TwoGenerationCollectorPolicy class. This is similar to what
   305 // ParallelScavenge does with its GenerationSizer class (see
   306 // ParallelScavengeHeap::initialize()). We might change this in the
   307 // future, but it's a good start.
   308 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
   309   size_t size_to_region_num(size_t byte_size) {
   310     return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
   311   }
   313 public:
   314   G1YoungGenSizer() {
   315     initialize_flags();
   316     initialize_size_info();
   317   }
   319   size_t min_young_region_num() {
   320     return size_to_region_num(_min_gen0_size);
   321   }
   322   size_t initial_young_region_num() {
   323     return size_to_region_num(_initial_gen0_size);
   324   }
   325   size_t max_young_region_num() {
   326     return size_to_region_num(_max_gen0_size);
   327   }
   328 };
   330 void G1CollectorPolicy::init() {
   331   // Set aside an initial future to_space.
   332   _g1 = G1CollectedHeap::heap();
   334   assert(Heap_lock->owned_by_self(), "Locking discipline.");
   336   initialize_gc_policy_counters();
   338   if (G1Gen) {
   339     _in_young_gc_mode = true;
   341     G1YoungGenSizer sizer;
   342     size_t initial_region_num = sizer.initial_young_region_num();
   344     if (UseAdaptiveSizePolicy) {
   345       set_adaptive_young_list_length(true);
   346       _young_list_fixed_length = 0;
   347     } else {
   348       set_adaptive_young_list_length(false);
   349       _young_list_fixed_length = initial_region_num;
   350     }
   351      _free_regions_at_end_of_collection = _g1->free_regions();
   352      _scan_only_regions_at_end_of_collection = 0;
   353      calculate_young_list_min_length();
   354      guarantee( _young_list_min_length == 0, "invariant, not enough info" );
   355      calculate_young_list_target_config();
   356    } else {
   357      _young_list_fixed_length = 0;
   358     _in_young_gc_mode = false;
   359   }
   360 }
   362 // Create the jstat counters for the policy.
   363 void G1CollectorPolicy::initialize_gc_policy_counters()
   364 {
   365   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
   366 }
   368 void G1CollectorPolicy::calculate_young_list_min_length() {
   369   _young_list_min_length = 0;
   371   if (!adaptive_young_list_length())
   372     return;
   374   if (_alloc_rate_ms_seq->num() > 3) {
   375     double now_sec = os::elapsedTime();
   376     double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
   377     double alloc_rate_ms = predict_alloc_rate_ms();
   378     int min_regions = (int) ceil(alloc_rate_ms * when_ms);
   379     int current_region_num = (int) _g1->young_list_length();
   380     _young_list_min_length = min_regions + current_region_num;
   381   }
   382 }
   384 void G1CollectorPolicy::calculate_young_list_target_config() {
   385   if (adaptive_young_list_length()) {
   386     size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
   387     calculate_young_list_target_config(rs_lengths);
   388   } else {
   389     if (full_young_gcs())
   390       _young_list_target_length = _young_list_fixed_length;
   391     else
   392       _young_list_target_length = _young_list_fixed_length / 2;
   393     _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);
   394     size_t so_length = calculate_optimal_so_length(_young_list_target_length);
   395     guarantee( so_length < _young_list_target_length, "invariant" );
   396     _young_list_so_prefix_length = so_length;
   397   }
   398   calculate_survivors_policy();
   399 }
   401 // This method calculate the optimal scan-only set for a fixed young
   402 // gen size. I couldn't work out how to reuse the more elaborate one,
   403 // i.e. calculate_young_list_target_config(rs_length), as the loops are
   404 // fundamentally different (the other one finds a config for different
   405 // S-O lengths, whereas here we need to do the opposite).
   406 size_t G1CollectorPolicy::calculate_optimal_so_length(
   407                                                     size_t young_list_length) {
   408   if (!G1UseScanOnlyPrefix)
   409     return 0;
   411   if (_all_pause_times_ms->num() < 3) {
   412     // we won't use a scan-only set at the beginning to allow the rest
   413     // of the predictors to warm up
   414     return 0;
   415   }
   417   if (_cost_per_scan_only_region_ms_seq->num() < 3) {
   418     // then, we'll only set the S-O set to 1 for a little bit of time,
   419     // to get enough information on the scanning cost
   420     return 1;
   421   }
   423   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
   424   size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
   425   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
   426   size_t scanned_cards;
   427   if (full_young_gcs())
   428     scanned_cards = predict_young_card_num(adj_rs_lengths);
   429   else
   430     scanned_cards = predict_non_young_card_num(adj_rs_lengths);
   431   double base_time_ms = predict_base_elapsed_time_ms(pending_cards,
   432                                                      scanned_cards);
   434   size_t so_length = 0;
   435   double max_gc_eff = 0.0;
   436   for (size_t i = 0; i < young_list_length; ++i) {
   437     double gc_eff = 0.0;
   438     double pause_time_ms = 0.0;
   439     predict_gc_eff(young_list_length, i, base_time_ms,
   440                    &gc_eff, &pause_time_ms);
   441     if (gc_eff > max_gc_eff) {
   442       max_gc_eff = gc_eff;
   443       so_length = i;
   444     }
   445   }
   447   // set it to 95% of the optimal to make sure we sample the "area"
   448   // around the optimal length to get up-to-date survival rate data
   449   return so_length * 950 / 1000;
   450 }
   452 // This is a really cool piece of code! It finds the best
   453 // target configuration (young length / scan-only prefix length) so
   454 // that GC efficiency is maximized and that we also meet a pause
   455 // time. It's a triple nested loop. These loops are explained below
   456 // from the inside-out :-)
   457 //
   458 // (a) The innermost loop will try to find the optimal young length
   459 // for a fixed S-O length. It uses a binary search to speed up the
   460 // process. We assume that, for a fixed S-O length, as we add more
   461 // young regions to the CSet, the GC efficiency will only go up (I'll
   462 // skip the proof). So, using a binary search to optimize this process
   463 // makes perfect sense.
   464 //
   465 // (b) The middle loop will fix the S-O length before calling the
   466 // innermost one. It will vary it between two parameters, increasing
   467 // it by a given increment.
   468 //
   469 // (c) The outermost loop will call the middle loop three times.
   470 //   (1) The first time it will explore all possible S-O length values
   471 //   from 0 to as large as it can get, using a coarse increment (to
   472 //   quickly "home in" to where the optimal seems to be).
   473 //   (2) The second time it will explore the values around the optimal
   474 //   that was found by the first iteration using a fine increment.
   475 //   (3) Once the optimal config has been determined by the second
   476 //   iteration, we'll redo the calculation, but setting the S-O length
   477 //   to 95% of the optimal to make sure we sample the "area"
   478 //   around the optimal length to get up-to-date survival rate data
   479 //
   480 // Termination conditions for the iterations are several: the pause
   481 // time is over the limit, we do not have enough to-space, etc.
   483 void G1CollectorPolicy::calculate_young_list_target_config(size_t rs_lengths) {
   484   guarantee( adaptive_young_list_length(), "pre-condition" );
   486   double start_time_sec = os::elapsedTime();
   487   size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
   488   min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
   489   size_t reserve_regions =
   490     (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
   492   if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
   493     // we are in fully-young mode and there are free regions in the heap
   495     double survivor_regions_evac_time =
   496         predict_survivor_regions_evac_time();
   498     size_t min_so_length = 0;
   499     size_t max_so_length = 0;
   501     if (G1UseScanOnlyPrefix) {
   502       if (_all_pause_times_ms->num() < 3) {
   503         // we won't use a scan-only set at the beginning to allow the rest
   504         // of the predictors to warm up
   505         min_so_length = 0;
   506         max_so_length = 0;
   507       } else if (_cost_per_scan_only_region_ms_seq->num() < 3) {
   508         // then, we'll only set the S-O set to 1 for a little bit of time,
   509         // to get enough information on the scanning cost
   510         min_so_length = 1;
   511         max_so_length = 1;
   512       } else if (_in_marking_window || _last_full_young_gc) {
   513         // no S-O prefix during a marking phase either, as at the end
   514         // of the marking phase we'll have to use a very small young
   515         // length target to fill up the rest of the CSet with
   516         // non-young regions and, if we have lots of scan-only regions
   517         // left-over, we will not be able to add any more non-young
   518         // regions.
   519         min_so_length = 0;
   520         max_so_length = 0;
   521       } else {
   522         // this is the common case; we'll never reach the maximum, we
   523         // one of the end conditions will fire well before that
   524         // (hopefully!)
   525         min_so_length = 0;
   526         max_so_length = _free_regions_at_end_of_collection - 1;
   527       }
   528     } else {
   529       // no S-O prefix, as the switch is not set, but we still need to
   530       // do one iteration to calculate the best young target that
   531       // meets the pause time; this way we reuse the same code instead
   532       // of replicating it
   533       min_so_length = 0;
   534       max_so_length = 0;
   535     }
   537     double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
   538     size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
   539     size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
   540     size_t scanned_cards;
   541     if (full_young_gcs())
   542       scanned_cards = predict_young_card_num(adj_rs_lengths);
   543     else
   544       scanned_cards = predict_non_young_card_num(adj_rs_lengths);
   545     // calculate this once, so that we don't have to recalculate it in
   546     // the innermost loop
   547     double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
   548                           + survivor_regions_evac_time;
   549     // the result
   550     size_t final_young_length = 0;
   551     size_t final_so_length = 0;
   552     double final_gc_eff = 0.0;
   553     // we'll also keep track of how many times we go into the inner loop
   554     // this is for profiling reasons
   555     size_t calculations = 0;
   557     // this determines which of the three iterations the outer loop is in
   558     typedef enum {
   559       pass_type_coarse,
   560       pass_type_fine,
   561       pass_type_final
   562     } pass_type_t;
   564     // range of the outer loop's iteration
   565     size_t from_so_length   = min_so_length;
   566     size_t to_so_length     = max_so_length;
   567     guarantee( from_so_length <= to_so_length, "invariant" );
   569     // this will keep the S-O length that's found by the second
   570     // iteration of the outer loop; we'll keep it just in case the third
   571     // iteration fails to find something
   572     size_t fine_so_length   = 0;
   574     // the increment step for the coarse (first) iteration
   575     size_t so_coarse_increments = 5;
   577     // the common case, we'll start with the coarse iteration
   578     pass_type_t pass = pass_type_coarse;
   579     size_t so_length_incr = so_coarse_increments;
   581     if (from_so_length == to_so_length) {
   582       // not point in doing the coarse iteration, we'll go directly into
   583       // the fine one (we essentially trying to find the optimal young
   584       // length for a fixed S-O length).
   585       so_length_incr = 1;
   586       pass = pass_type_final;
   587     } else if (to_so_length - from_so_length < 3 * so_coarse_increments) {
   588       // again, the range is too short so no point in foind the coarse
   589       // iteration either
   590       so_length_incr = 1;
   591       pass = pass_type_fine;
   592     }
   594     bool done = false;
   595     // this is the outermost loop
   596     while (!done) {
   597 #ifdef TRACE_CALC_YOUNG_CONFIG
   598       // leave this in for debugging, just in case
   599       gclog_or_tty->print_cr("searching between " SIZE_FORMAT " and " SIZE_FORMAT
   600                              ", incr " SIZE_FORMAT ", pass %s",
   601                              from_so_length, to_so_length, so_length_incr,
   602                              (pass == pass_type_coarse) ? "coarse" :
   603                              (pass == pass_type_fine) ? "fine" : "final");
   604 #endif // TRACE_CALC_YOUNG_CONFIG
   606       size_t so_length = from_so_length;
   607       size_t init_free_regions =
   608         MAX2((size_t)0,
   609              _free_regions_at_end_of_collection +
   610              _scan_only_regions_at_end_of_collection - reserve_regions);
   612       // this determines whether a configuration was found
   613       bool gc_eff_set = false;
   614       // this is the middle loop
   615       while (so_length <= to_so_length) {
   616         // base time, which excludes region-related time; again we
   617         // calculate it once to avoid recalculating it in the
   618         // innermost loop
   619         double base_time_with_so_ms =
   620                            base_time_ms + predict_scan_only_time_ms(so_length);
   621         // it's already over the pause target, go around
   622         if (base_time_with_so_ms > target_pause_time_ms)
   623           break;
   625         size_t starting_young_length = so_length+1;
   627         // we make sure that the short young length that makes sense
   628         // (one more than the S-O length) is feasible
   629         size_t min_young_length = starting_young_length;
   630         double min_gc_eff;
   631         bool min_ok;
   632         ++calculations;
   633         min_ok = predict_gc_eff(min_young_length, so_length,
   634                                 base_time_with_so_ms,
   635                                 init_free_regions, target_pause_time_ms,
   636                                 &min_gc_eff);
   638         if (min_ok) {
   639           // the shortest young length is indeed feasible; we'll know
   640           // set up the max young length and we'll do a binary search
   641           // between min_young_length and max_young_length
   642           size_t max_young_length = _free_regions_at_end_of_collection - 1;
   643           double max_gc_eff = 0.0;
   644           bool max_ok = false;
   646           // the innermost loop! (finally!)
   647           while (max_young_length > min_young_length) {
   648             // we'll make sure that min_young_length is always at a
   649             // feasible config
   650             guarantee( min_ok, "invariant" );
   652             ++calculations;
   653             max_ok = predict_gc_eff(max_young_length, so_length,
   654                                     base_time_with_so_ms,
   655                                     init_free_regions, target_pause_time_ms,
   656                                     &max_gc_eff);
   658             size_t diff = (max_young_length - min_young_length) / 2;
   659             if (max_ok) {
   660               min_young_length = max_young_length;
   661               min_gc_eff = max_gc_eff;
   662               min_ok = true;
   663             }
   664             max_young_length = min_young_length + diff;
   665           }
   667           // the innermost loop found a config
   668           guarantee( min_ok, "invariant" );
   669           if (min_gc_eff > final_gc_eff) {
   670             // it's the best config so far, so we'll keep it
   671             final_gc_eff = min_gc_eff;
   672             final_young_length = min_young_length;
   673             final_so_length = so_length;
   674             gc_eff_set = true;
   675           }
   676         }
   678         // incremental the fixed S-O length and go around
   679         so_length += so_length_incr;
   680       }
   682       // this is the end of the outermost loop and we need to decide
   683       // what to do during the next iteration
   684       if (pass == pass_type_coarse) {
   685         // we just did the coarse pass (first iteration)
   687         if (!gc_eff_set)
   688           // we didn't find a feasible config so we'll just bail out; of
   689           // course, it might be the case that we missed it; but I'd say
   690           // it's a bit unlikely
   691           done = true;
   692         else {
   693           // We did find a feasible config with optimal GC eff during
   694           // the first pass. So the second pass we'll only consider the
   695           // S-O lengths around that config with a fine increment.
   697           guarantee( so_length_incr == so_coarse_increments, "invariant" );
   698           guarantee( final_so_length >= min_so_length, "invariant" );
   700 #ifdef TRACE_CALC_YOUNG_CONFIG
   701           // leave this in for debugging, just in case
   702           gclog_or_tty->print_cr("  coarse pass: SO length " SIZE_FORMAT,
   703                                  final_so_length);
   704 #endif // TRACE_CALC_YOUNG_CONFIG
   706           from_so_length =
   707             (final_so_length - min_so_length > so_coarse_increments) ?
   708             final_so_length - so_coarse_increments + 1 : min_so_length;
   709           to_so_length =
   710             (max_so_length - final_so_length > so_coarse_increments) ?
   711             final_so_length + so_coarse_increments - 1 : max_so_length;
   713           pass = pass_type_fine;
   714           so_length_incr = 1;
   715         }
   716       } else if (pass == pass_type_fine) {
   717         // we just finished the second pass
   719         if (!gc_eff_set) {
   720           // we didn't find a feasible config (yes, it's possible;
   721           // notice that, sometimes, we go directly into the fine
   722           // iteration and skip the coarse one) so we bail out
   723           done = true;
   724         } else {
   725           // We did find a feasible config with optimal GC eff
   726           guarantee( so_length_incr == 1, "invariant" );
   728           if (final_so_length == 0) {
   729             // The config is of an empty S-O set, so we'll just bail out
   730             done = true;
   731           } else {
   732             // we'll go around once more, setting the S-O length to 95%
   733             // of the optimal
   734             size_t new_so_length = 950 * final_so_length / 1000;
   736 #ifdef TRACE_CALC_YOUNG_CONFIG
   737             // leave this in for debugging, just in case
   738             gclog_or_tty->print_cr("  fine pass: SO length " SIZE_FORMAT
   739                                    ", setting it to " SIZE_FORMAT,
   740                                     final_so_length, new_so_length);
   741 #endif // TRACE_CALC_YOUNG_CONFIG
   743             from_so_length = new_so_length;
   744             to_so_length = new_so_length;
   745             fine_so_length = final_so_length;
   747             pass = pass_type_final;
   748           }
   749         }
   750       } else if (pass == pass_type_final) {
   751         // we just finished the final (third) pass
   753         if (!gc_eff_set)
   754           // we didn't find a feasible config, so we'll just use the one
   755           // we found during the second pass, which we saved
   756           final_so_length = fine_so_length;
   758         // and we're done!
   759         done = true;
   760       } else {
   761         guarantee( false, "should never reach here" );
   762       }
   764       // we now go around the outermost loop
   765     }
   767     // we should have at least one region in the target young length
   768     _young_list_target_length =
   769         MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);
   770     if (final_so_length >= final_young_length)
   771       // and we need to ensure that the S-O length is not greater than
   772       // the target young length (this is being a bit careful)
   773       final_so_length = 0;
   774     _young_list_so_prefix_length = final_so_length;
   775     guarantee( !_in_marking_window || !_last_full_young_gc ||
   776                _young_list_so_prefix_length == 0, "invariant" );
   778     // let's keep an eye of how long we spend on this calculation
   779     // right now, I assume that we'll print it when we need it; we
   780     // should really adde it to the breakdown of a pause
   781     double end_time_sec = os::elapsedTime();
   782     double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
   784 #ifdef TRACE_CALC_YOUNG_CONFIG
   785     // leave this in for debugging, just in case
   786     gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT
   787                            ", SO = " SIZE_FORMAT ", "
   788                            "elapsed %1.2lf ms, calcs: " SIZE_FORMAT " (%s%s) "
   789                            SIZE_FORMAT SIZE_FORMAT,
   790                            target_pause_time_ms,
   791                            _young_list_target_length - _young_list_so_prefix_length,
   792                            _young_list_so_prefix_length,
   793                            elapsed_time_ms,
   794                            calculations,
   795                            full_young_gcs() ? "full" : "partial",
   796                            during_initial_mark_pause() ? " i-m" : "",
   797                            _in_marking_window,
   798                            _in_marking_window_im);
   799 #endif // TRACE_CALC_YOUNG_CONFIG
   801     if (_young_list_target_length < _young_list_min_length) {
   802       // bummer; this means that, if we do a pause when the optimal
   803       // config dictates, we'll violate the pause spacing target (the
   804       // min length was calculate based on the application's current
   805       // alloc rate);
   807       // so, we have to bite the bullet, and allocate the minimum
   808       // number. We'll violate our target, but we just can't meet it.
   810       size_t so_length = 0;
   811       // a note further up explains why we do not want an S-O length
   812       // during marking
   813       if (!_in_marking_window && !_last_full_young_gc)
   814         // but we can still try to see whether we can find an optimal
   815         // S-O length
   816         so_length = calculate_optimal_so_length(_young_list_min_length);
   818 #ifdef TRACE_CALC_YOUNG_CONFIG
   819       // leave this in for debugging, just in case
   820       gclog_or_tty->print_cr("adjusted target length from "
   821                              SIZE_FORMAT " to " SIZE_FORMAT
   822                              ", SO " SIZE_FORMAT,
   823                              _young_list_target_length, _young_list_min_length,
   824                              so_length);
   825 #endif // TRACE_CALC_YOUNG_CONFIG
   827       _young_list_target_length =
   828         MAX2(_young_list_min_length, (size_t)1);
   829       _young_list_so_prefix_length = so_length;
   830     }
   831   } else {
   832     // we are in a partially-young mode or we've run out of regions (due
   833     // to evacuation failure)
   835 #ifdef TRACE_CALC_YOUNG_CONFIG
   836     // leave this in for debugging, just in case
   837     gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
   838                            ", SO " SIZE_FORMAT,
   839                            _young_list_min_length, 0);
   840 #endif // TRACE_CALC_YOUNG_CONFIG
   842     // we'll do the pause as soon as possible and with no S-O prefix
   843     // (see above for the reasons behind the latter)
   844     _young_list_target_length =
   845       MAX2(_young_list_min_length, (size_t) 1);
   846     _young_list_so_prefix_length = 0;
   847   }
   849   _rs_lengths_prediction = rs_lengths;
   850 }
   852 // This is used by: calculate_optimal_so_length(length). It returns
   853 // the GC eff and predicted pause time for a particular config
   854 void
   855 G1CollectorPolicy::predict_gc_eff(size_t young_length,
   856                                   size_t so_length,
   857                                   double base_time_ms,
   858                                   double* ret_gc_eff,
   859                                   double* ret_pause_time_ms) {
   860   double so_time_ms = predict_scan_only_time_ms(so_length);
   861   double accum_surv_rate_adj = 0.0;
   862   if (so_length > 0)
   863     accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
   864   double accum_surv_rate =
   865     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
   866   size_t bytes_to_copy =
   867     (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   868   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   869   double young_other_time_ms =
   870                        predict_young_other_time_ms(young_length - so_length);
   871   double pause_time_ms =
   872                 base_time_ms + so_time_ms + copy_time_ms + young_other_time_ms;
   873   size_t reclaimed_bytes =
   874     (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
   875   double gc_eff = (double) reclaimed_bytes / pause_time_ms;
   877   *ret_gc_eff = gc_eff;
   878   *ret_pause_time_ms = pause_time_ms;
   879 }
   881 // This is used by: calculate_young_list_target_config(rs_length). It
   882 // returns the GC eff of a particular config. It returns false if that
   883 // config violates any of the end conditions of the search in the
   884 // calling method, or true upon success. The end conditions were put
   885 // here since it's called twice and it was best not to replicate them
   886 // in the caller. Also, passing the parameteres avoids having to
   887 // recalculate them in the innermost loop.
   888 bool
   889 G1CollectorPolicy::predict_gc_eff(size_t young_length,
   890                                   size_t so_length,
   891                                   double base_time_with_so_ms,
   892                                   size_t init_free_regions,
   893                                   double target_pause_time_ms,
   894                                   double* ret_gc_eff) {
   895   *ret_gc_eff = 0.0;
   897   if (young_length >= init_free_regions)
   898     // end condition 1: not enough space for the young regions
   899     return false;
   901   double accum_surv_rate_adj = 0.0;
   902   if (so_length > 0)
   903     accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
   904   double accum_surv_rate =
   905     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
   906   size_t bytes_to_copy =
   907     (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   908   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   909   double young_other_time_ms =
   910                        predict_young_other_time_ms(young_length - so_length);
   911   double pause_time_ms =
   912                    base_time_with_so_ms + copy_time_ms + young_other_time_ms;
   914   if (pause_time_ms > target_pause_time_ms)
   915     // end condition 2: over the target pause time
   916     return false;
   918   size_t reclaimed_bytes =
   919     (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
   920   size_t free_bytes =
   921                  (init_free_regions - young_length) * HeapRegion::GrainBytes;
   923   if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
   924     // end condition 3: out of to-space (conservatively)
   925     return false;
   927   // success!
   928   double gc_eff = (double) reclaimed_bytes / pause_time_ms;
   929   *ret_gc_eff = gc_eff;
   931   return true;
   932 }
   934 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
   935   double survivor_regions_evac_time = 0.0;
   936   for (HeapRegion * r = _recorded_survivor_head;
   937        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
   938        r = r->get_next_young_region()) {
   939     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
   940   }
   941   return survivor_regions_evac_time;
   942 }
   944 void G1CollectorPolicy::check_prediction_validity() {
   945   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
   947   size_t rs_lengths = _g1->young_list_sampled_rs_lengths();
   948   if (rs_lengths > _rs_lengths_prediction) {
   949     // add 10% to avoid having to recalculate often
   950     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
   951     calculate_young_list_target_config(rs_lengths_prediction);
   952   }
   953 }
   955 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
   956                                                bool is_tlab,
   957                                                bool* gc_overhead_limit_was_exceeded) {
   958   guarantee(false, "Not using this policy feature yet.");
   959   return NULL;
   960 }
   962 // This method controls how a collector handles one or more
   963 // of its generations being fully allocated.
   964 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
   965                                                        bool is_tlab) {
   966   guarantee(false, "Not using this policy feature yet.");
   967   return NULL;
   968 }
   971 #ifndef PRODUCT
   972 bool G1CollectorPolicy::verify_young_ages() {
   973   HeapRegion* head = _g1->young_list_first_region();
   974   return
   975     verify_young_ages(head, _short_lived_surv_rate_group);
   976   // also call verify_young_ages on any additional surv rate groups
   977 }
   979 bool
   980 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
   981                                      SurvRateGroup *surv_rate_group) {
   982   guarantee( surv_rate_group != NULL, "pre-condition" );
   984   const char* name = surv_rate_group->name();
   985   bool ret = true;
   986   int prev_age = -1;
   988   for (HeapRegion* curr = head;
   989        curr != NULL;
   990        curr = curr->get_next_young_region()) {
   991     SurvRateGroup* group = curr->surv_rate_group();
   992     if (group == NULL && !curr->is_survivor()) {
   993       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
   994       ret = false;
   995     }
   997     if (surv_rate_group == group) {
   998       int age = curr->age_in_surv_rate_group();
  1000       if (age < 0) {
  1001         gclog_or_tty->print_cr("## %s: encountered negative age", name);
  1002         ret = false;
  1005       if (age <= prev_age) {
  1006         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
  1007                                "(%d, %d)", name, age, prev_age);
  1008         ret = false;
  1010       prev_age = age;
  1014   return ret;
  1016 #endif // PRODUCT
  1018 void G1CollectorPolicy::record_full_collection_start() {
  1019   _cur_collection_start_sec = os::elapsedTime();
  1020   // Release the future to-space so that it is available for compaction into.
  1021   _g1->set_full_collection();
  1024 void G1CollectorPolicy::record_full_collection_end() {
  1025   // Consider this like a collection pause for the purposes of allocation
  1026   // since last pause.
  1027   double end_sec = os::elapsedTime();
  1028   double full_gc_time_sec = end_sec - _cur_collection_start_sec;
  1029   double full_gc_time_ms = full_gc_time_sec * 1000.0;
  1031   _all_full_gc_times_ms->add(full_gc_time_ms);
  1033   update_recent_gc_times(end_sec, full_gc_time_ms);
  1035   _g1->clear_full_collection();
  1037   // "Nuke" the heuristics that control the fully/partially young GC
  1038   // transitions and make sure we start with fully young GCs after the
  1039   // Full GC.
  1040   set_full_young_gcs(true);
  1041   _last_full_young_gc = false;
  1042   _should_revert_to_full_young_gcs = false;
  1043   clear_initiate_conc_mark_if_possible();
  1044   clear_during_initial_mark_pause();
  1045   _known_garbage_bytes = 0;
  1046   _known_garbage_ratio = 0.0;
  1047   _in_marking_window = false;
  1048   _in_marking_window_im = false;
  1050   _short_lived_surv_rate_group->record_scan_only_prefix(0);
  1051   _short_lived_surv_rate_group->start_adding_regions();
  1052   // also call this on any additional surv rate groups
  1054   record_survivor_regions(0, NULL, NULL);
  1056   _prev_region_num_young   = _region_num_young;
  1057   _prev_region_num_tenured = _region_num_tenured;
  1059   _free_regions_at_end_of_collection = _g1->free_regions();
  1060   _scan_only_regions_at_end_of_collection = 0;
  1061   // Reset survivors SurvRateGroup.
  1062   _survivor_surv_rate_group->reset();
  1063   calculate_young_list_min_length();
  1064   calculate_young_list_target_config();
  1067 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
  1068   _bytes_in_to_space_before_gc += bytes;
  1071 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
  1072   _bytes_in_to_space_after_gc += bytes;
  1075 void G1CollectorPolicy::record_stop_world_start() {
  1076   _stop_world_start = os::elapsedTime();
  1079 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
  1080                                                       size_t start_used) {
  1081   if (PrintGCDetails) {
  1082     gclog_or_tty->stamp(PrintGCTimeStamps);
  1083     gclog_or_tty->print("[GC pause");
  1084     if (in_young_gc_mode())
  1085       gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
  1088   assert(_g1->used_regions() == _g1->recalculate_used_regions(),
  1089          "sanity");
  1090   assert(_g1->used() == _g1->recalculate_used(), "sanity");
  1092   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
  1093   _all_stop_world_times_ms->add(s_w_t_ms);
  1094   _stop_world_start = 0.0;
  1096   _cur_collection_start_sec = start_time_sec;
  1097   _cur_collection_pause_used_at_start_bytes = start_used;
  1098   _cur_collection_pause_used_regions_at_start = _g1->used_regions();
  1099   _pending_cards = _g1->pending_card_num();
  1100   _max_pending_cards = _g1->max_pending_card_num();
  1102   _bytes_in_to_space_before_gc = 0;
  1103   _bytes_in_to_space_after_gc = 0;
  1104   _bytes_in_collection_set_before_gc = 0;
  1106 #ifdef DEBUG
  1107   // initialise these to something well known so that we can spot
  1108   // if they are not set properly
  1110   for (int i = 0; i < _parallel_gc_threads; ++i) {
  1111     _par_last_ext_root_scan_times_ms[i] = -666.0;
  1112     _par_last_mark_stack_scan_times_ms[i] = -666.0;
  1113     _par_last_scan_only_times_ms[i] = -666.0;
  1114     _par_last_scan_only_regions_scanned[i] = -666.0;
  1115     _par_last_update_rs_start_times_ms[i] = -666.0;
  1116     _par_last_update_rs_times_ms[i] = -666.0;
  1117     _par_last_update_rs_processed_buffers[i] = -666.0;
  1118     _par_last_scan_rs_start_times_ms[i] = -666.0;
  1119     _par_last_scan_rs_times_ms[i] = -666.0;
  1120     _par_last_scan_new_refs_times_ms[i] = -666.0;
  1121     _par_last_obj_copy_times_ms[i] = -666.0;
  1122     _par_last_termination_times_ms[i] = -666.0;
  1124 #endif
  1126   for (int i = 0; i < _aux_num; ++i) {
  1127     _cur_aux_times_ms[i] = 0.0;
  1128     _cur_aux_times_set[i] = false;
  1131   _satb_drain_time_set = false;
  1132   _last_satb_drain_processed_buffers = -1;
  1134   if (in_young_gc_mode())
  1135     _last_young_gc_full = false;
  1138   // do that for any other surv rate groups
  1139   _short_lived_surv_rate_group->stop_adding_regions();
  1140   size_t short_lived_so_length = _young_list_so_prefix_length;
  1141   _short_lived_surv_rate_group->record_scan_only_prefix(short_lived_so_length);
  1142   tag_scan_only(short_lived_so_length);
  1143   _survivors_age_table.clear();
  1145   assert( verify_young_ages(), "region age verification" );
  1148 void G1CollectorPolicy::tag_scan_only(size_t short_lived_scan_only_length) {
  1149   // done in a way that it can be extended for other surv rate groups too...
  1151   HeapRegion* head = _g1->young_list_first_region();
  1152   bool finished_short_lived = (short_lived_scan_only_length == 0);
  1154   if (finished_short_lived)
  1155     return;
  1157   for (HeapRegion* curr = head;
  1158        curr != NULL;
  1159        curr = curr->get_next_young_region()) {
  1160     SurvRateGroup* surv_rate_group = curr->surv_rate_group();
  1161     int age = curr->age_in_surv_rate_group();
  1163     if (surv_rate_group == _short_lived_surv_rate_group) {
  1164       if ((size_t)age < short_lived_scan_only_length)
  1165         curr->set_scan_only();
  1166       else
  1167         finished_short_lived = true;
  1171     if (finished_short_lived)
  1172       return;
  1175   guarantee( false, "we should never reach here" );
  1178 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
  1179   _mark_closure_time_ms = mark_closure_time_ms;
  1182 void G1CollectorPolicy::record_concurrent_mark_init_start() {
  1183   _mark_init_start_sec = os::elapsedTime();
  1184   guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
  1187 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
  1188                                                    mark_init_elapsed_time_ms) {
  1189   _during_marking = true;
  1190   assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
  1191   clear_during_initial_mark_pause();
  1192   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
  1195 void G1CollectorPolicy::record_concurrent_mark_init_end() {
  1196   double end_time_sec = os::elapsedTime();
  1197   double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
  1198   _concurrent_mark_init_times_ms->add(elapsed_time_ms);
  1199   record_concurrent_mark_init_end_pre(elapsed_time_ms);
  1201   _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
  1204 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
  1205   _mark_remark_start_sec = os::elapsedTime();
  1206   _during_marking = false;
  1209 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
  1210   double end_time_sec = os::elapsedTime();
  1211   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
  1212   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
  1213   _cur_mark_stop_world_time_ms += elapsed_time_ms;
  1214   _prev_collection_pause_end_ms += elapsed_time_ms;
  1216   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
  1219 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
  1220   _mark_cleanup_start_sec = os::elapsedTime();
  1223 void
  1224 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
  1225                                                       size_t max_live_bytes) {
  1226   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
  1227   record_concurrent_mark_cleanup_end_work2();
  1230 void
  1231 G1CollectorPolicy::
  1232 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
  1233                                          size_t max_live_bytes) {
  1234   if (_n_marks < 2) _n_marks++;
  1235   if (G1PolicyVerbose > 0)
  1236     gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
  1237                            " (of " SIZE_FORMAT " MB heap).",
  1238                            max_live_bytes/M, _g1->capacity()/M);
  1241 // The important thing about this is that it includes "os::elapsedTime".
  1242 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
  1243   double end_time_sec = os::elapsedTime();
  1244   double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
  1245   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
  1246   _cur_mark_stop_world_time_ms += elapsed_time_ms;
  1247   _prev_collection_pause_end_ms += elapsed_time_ms;
  1249   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
  1251   _num_markings++;
  1253   // We did a marking, so reset the "since_last_mark" variables.
  1254   double considerConcMarkCost = 1.0;
  1255   // If there are available processors, concurrent activity is free...
  1256   if (Threads::number_of_non_daemon_threads() * 2 <
  1257       os::active_processor_count()) {
  1258     considerConcMarkCost = 0.0;
  1260   _n_pauses_at_mark_end = _n_pauses;
  1261   _n_marks_since_last_pause++;
  1264 void
  1265 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
  1266   if (in_young_gc_mode()) {
  1267     _should_revert_to_full_young_gcs = false;
  1268     _last_full_young_gc = true;
  1269     _in_marking_window = false;
  1270     if (adaptive_young_list_length())
  1271       calculate_young_list_target_config();
  1275 void G1CollectorPolicy::record_concurrent_pause() {
  1276   if (_stop_world_start > 0.0) {
  1277     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
  1278     _all_yield_times_ms->add(yield_ms);
  1282 void G1CollectorPolicy::record_concurrent_pause_end() {
  1285 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
  1286   _cur_CH_strong_roots_end_sec = os::elapsedTime();
  1287   _cur_CH_strong_roots_dur_ms =
  1288     (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
  1291 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
  1292   _cur_G1_strong_roots_end_sec = os::elapsedTime();
  1293   _cur_G1_strong_roots_dur_ms =
  1294     (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
  1297 template<class T>
  1298 T sum_of(T* sum_arr, int start, int n, int N) {
  1299   T sum = (T)0;
  1300   for (int i = 0; i < n; i++) {
  1301     int j = (start + i) % N;
  1302     sum += sum_arr[j];
  1304   return sum;
  1307 void G1CollectorPolicy::print_par_stats (int level,
  1308                                          const char* str,
  1309                                          double* data,
  1310                                          bool summary) {
  1311   double min = data[0], max = data[0];
  1312   double total = 0.0;
  1313   int j;
  1314   for (j = 0; j < level; ++j)
  1315     gclog_or_tty->print("   ");
  1316   gclog_or_tty->print("[%s (ms):", str);
  1317   for (uint i = 0; i < ParallelGCThreads; ++i) {
  1318     double val = data[i];
  1319     if (val < min)
  1320       min = val;
  1321     if (val > max)
  1322       max = val;
  1323     total += val;
  1324     gclog_or_tty->print("  %3.1lf", val);
  1326   if (summary) {
  1327     gclog_or_tty->print_cr("");
  1328     double avg = total / (double) ParallelGCThreads;
  1329     gclog_or_tty->print(" ");
  1330     for (j = 0; j < level; ++j)
  1331       gclog_or_tty->print("   ");
  1332     gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
  1333                         avg, min, max);
  1335   gclog_or_tty->print_cr("]");
  1338 void G1CollectorPolicy::print_par_buffers (int level,
  1339                                          const char* str,
  1340                                          double* data,
  1341                                          bool summary) {
  1342   double min = data[0], max = data[0];
  1343   double total = 0.0;
  1344   int j;
  1345   for (j = 0; j < level; ++j)
  1346     gclog_or_tty->print("   ");
  1347   gclog_or_tty->print("[%s :", str);
  1348   for (uint i = 0; i < ParallelGCThreads; ++i) {
  1349     double val = data[i];
  1350     if (val < min)
  1351       min = val;
  1352     if (val > max)
  1353       max = val;
  1354     total += val;
  1355     gclog_or_tty->print(" %d", (int) val);
  1357   if (summary) {
  1358     gclog_or_tty->print_cr("");
  1359     double avg = total / (double) ParallelGCThreads;
  1360     gclog_or_tty->print(" ");
  1361     for (j = 0; j < level; ++j)
  1362       gclog_or_tty->print("   ");
  1363     gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
  1364                (int)total, (int)avg, (int)min, (int)max);
  1366   gclog_or_tty->print_cr("]");
  1369 void G1CollectorPolicy::print_stats (int level,
  1370                                      const char* str,
  1371                                      double value) {
  1372   for (int j = 0; j < level; ++j)
  1373     gclog_or_tty->print("   ");
  1374   gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
  1377 void G1CollectorPolicy::print_stats (int level,
  1378                                      const char* str,
  1379                                      int value) {
  1380   for (int j = 0; j < level; ++j)
  1381     gclog_or_tty->print("   ");
  1382   gclog_or_tty->print_cr("[%s: %d]", str, value);
  1385 double G1CollectorPolicy::avg_value (double* data) {
  1386   if (ParallelGCThreads > 0) {
  1387     double ret = 0.0;
  1388     for (uint i = 0; i < ParallelGCThreads; ++i)
  1389       ret += data[i];
  1390     return ret / (double) ParallelGCThreads;
  1391   } else {
  1392     return data[0];
  1396 double G1CollectorPolicy::max_value (double* data) {
  1397   if (ParallelGCThreads > 0) {
  1398     double ret = data[0];
  1399     for (uint i = 1; i < ParallelGCThreads; ++i)
  1400       if (data[i] > ret)
  1401         ret = data[i];
  1402     return ret;
  1403   } else {
  1404     return data[0];
  1408 double G1CollectorPolicy::sum_of_values (double* data) {
  1409   if (ParallelGCThreads > 0) {
  1410     double sum = 0.0;
  1411     for (uint i = 0; i < ParallelGCThreads; i++)
  1412       sum += data[i];
  1413     return sum;
  1414   } else {
  1415     return data[0];
  1419 double G1CollectorPolicy::max_sum (double* data1,
  1420                                    double* data2) {
  1421   double ret = data1[0] + data2[0];
  1423   if (ParallelGCThreads > 0) {
  1424     for (uint i = 1; i < ParallelGCThreads; ++i) {
  1425       double data = data1[i] + data2[i];
  1426       if (data > ret)
  1427         ret = data;
  1430   return ret;
  1433 // Anything below that is considered to be zero
  1434 #define MIN_TIMER_GRANULARITY 0.0000001
  1436 void G1CollectorPolicy::record_collection_pause_end(bool abandoned) {
  1437   double end_time_sec = os::elapsedTime();
  1438   double elapsed_ms = _last_pause_time_ms;
  1439   bool parallel = ParallelGCThreads > 0;
  1440   double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
  1441   size_t rs_size =
  1442     _cur_collection_pause_used_regions_at_start - collection_set_size();
  1443   size_t cur_used_bytes = _g1->used();
  1444   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
  1445   bool last_pause_included_initial_mark = false;
  1446   bool update_stats = !abandoned && !_g1->evacuation_failed();
  1448 #ifndef PRODUCT
  1449   if (G1YoungSurvRateVerbose) {
  1450     gclog_or_tty->print_cr("");
  1451     _short_lived_surv_rate_group->print();
  1452     // do that for any other surv rate groups too
  1454 #endif // PRODUCT
  1456   if (in_young_gc_mode()) {
  1457     last_pause_included_initial_mark = during_initial_mark_pause();
  1458     if (last_pause_included_initial_mark)
  1459       record_concurrent_mark_init_end_pre(0.0);
  1461     size_t min_used_targ =
  1462       (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
  1465     if (!_g1->mark_in_progress() && !_last_full_young_gc) {
  1466       assert(!last_pause_included_initial_mark, "invariant");
  1467       if (cur_used_bytes > min_used_targ &&
  1468           cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
  1469         assert(!during_initial_mark_pause(), "we should not see this here");
  1471         // Note: this might have already been set, if during the last
  1472         // pause we decided to start a cycle but at the beginning of
  1473         // this pause we decided to postpone it. That's OK.
  1474         set_initiate_conc_mark_if_possible();
  1478     _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
  1481   _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
  1482                           end_time_sec, false);
  1484   guarantee(_cur_collection_pause_used_regions_at_start >=
  1485             collection_set_size(),
  1486             "Negative RS size?");
  1488   // This assert is exempted when we're doing parallel collection pauses,
  1489   // because the fragmentation caused by the parallel GC allocation buffers
  1490   // can lead to more memory being used during collection than was used
  1491   // before. Best leave this out until the fragmentation problem is fixed.
  1492   // Pauses in which evacuation failed can also lead to negative
  1493   // collections, since no space is reclaimed from a region containing an
  1494   // object whose evacuation failed.
  1495   // Further, we're now always doing parallel collection.  But I'm still
  1496   // leaving this here as a placeholder for a more precise assertion later.
  1497   // (DLD, 10/05.)
  1498   assert((true || parallel) // Always using GC LABs now.
  1499          || _g1->evacuation_failed()
  1500          || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
  1501          "Negative collection");
  1503   size_t freed_bytes =
  1504     _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
  1505   size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
  1506   double survival_fraction =
  1507     (double)surviving_bytes/
  1508     (double)_collection_set_bytes_used_before;
  1510   _n_pauses++;
  1512   if (update_stats) {
  1513     _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
  1514     _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
  1515     _recent_evac_times_ms->add(evac_ms);
  1516     _recent_pause_times_ms->add(elapsed_ms);
  1518     _recent_rs_sizes->add(rs_size);
  1520     // We exempt parallel collection from this check because Alloc Buffer
  1521     // fragmentation can produce negative collections.  Same with evac
  1522     // failure.
  1523     // Further, we're now always doing parallel collection.  But I'm still
  1524     // leaving this here as a placeholder for a more precise assertion later.
  1525     // (DLD, 10/05.
  1526     assert((true || parallel)
  1527            || _g1->evacuation_failed()
  1528            || surviving_bytes <= _collection_set_bytes_used_before,
  1529            "Or else negative collection!");
  1530     _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
  1531     _recent_CS_bytes_surviving->add(surviving_bytes);
  1533     // this is where we update the allocation rate of the application
  1534     double app_time_ms =
  1535       (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
  1536     if (app_time_ms < MIN_TIMER_GRANULARITY) {
  1537       // This usually happens due to the timer not having the required
  1538       // granularity. Some Linuxes are the usual culprits.
  1539       // We'll just set it to something (arbitrarily) small.
  1540       app_time_ms = 1.0;
  1542     size_t regions_allocated =
  1543       (_region_num_young - _prev_region_num_young) +
  1544       (_region_num_tenured - _prev_region_num_tenured);
  1545     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
  1546     _alloc_rate_ms_seq->add(alloc_rate_ms);
  1547     _prev_region_num_young   = _region_num_young;
  1548     _prev_region_num_tenured = _region_num_tenured;
  1550     double interval_ms =
  1551       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
  1552     update_recent_gc_times(end_time_sec, elapsed_ms);
  1553     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
  1554     if (recent_avg_pause_time_ratio() < 0.0 ||
  1555         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
  1556 #ifndef PRODUCT
  1557       // Dump info to allow post-facto debugging
  1558       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
  1559       gclog_or_tty->print_cr("-------------------------------------------");
  1560       gclog_or_tty->print_cr("Recent GC Times (ms):");
  1561       _recent_gc_times_ms->dump();
  1562       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
  1563       _recent_prev_end_times_for_all_gcs_sec->dump();
  1564       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
  1565                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
  1566       // In debug mode, terminate the JVM if the user wants to debug at this point.
  1567       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
  1568 #endif  // !PRODUCT
  1569       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
  1570       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
  1571       if (_recent_avg_pause_time_ratio < 0.0) {
  1572         _recent_avg_pause_time_ratio = 0.0;
  1573       } else {
  1574         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
  1575         _recent_avg_pause_time_ratio = 1.0;
  1580   if (G1PolicyVerbose > 1) {
  1581     gclog_or_tty->print_cr("   Recording collection pause(%d)", _n_pauses);
  1584   PauseSummary* summary;
  1585   if (abandoned) {
  1586     summary = _abandoned_summary;
  1587   } else {
  1588     summary = _summary;
  1591   double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
  1592   double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
  1593   double scan_only_time = avg_value(_par_last_scan_only_times_ms);
  1594   double scan_only_regions_scanned =
  1595     sum_of_values(_par_last_scan_only_regions_scanned);
  1596   double update_rs_time = avg_value(_par_last_update_rs_times_ms);
  1597   double update_rs_processed_buffers =
  1598     sum_of_values(_par_last_update_rs_processed_buffers);
  1599   double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
  1600   double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
  1601   double termination_time = avg_value(_par_last_termination_times_ms);
  1603   double parallel_other_time = _cur_collection_par_time_ms -
  1604     (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
  1605      scan_only_time + scan_rs_time + obj_copy_time + termination_time);
  1606   if (update_stats) {
  1607     MainBodySummary* body_summary = summary->main_body_summary();
  1608     guarantee(body_summary != NULL, "should not be null!");
  1610     if (_satb_drain_time_set)
  1611       body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
  1612     else
  1613       body_summary->record_satb_drain_time_ms(0.0);
  1614     body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
  1615     body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
  1616     body_summary->record_scan_only_time_ms(scan_only_time);
  1617     body_summary->record_update_rs_time_ms(update_rs_time);
  1618     body_summary->record_scan_rs_time_ms(scan_rs_time);
  1619     body_summary->record_obj_copy_time_ms(obj_copy_time);
  1620     if (parallel) {
  1621       body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
  1622       body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
  1623       body_summary->record_termination_time_ms(termination_time);
  1624       body_summary->record_parallel_other_time_ms(parallel_other_time);
  1626     body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
  1629   if (G1PolicyVerbose > 1) {
  1630     gclog_or_tty->print_cr("      ET: %10.6f ms           (avg: %10.6f ms)\n"
  1631                            "        CH Strong: %10.6f ms    (avg: %10.6f ms)\n"
  1632                            "        G1 Strong: %10.6f ms    (avg: %10.6f ms)\n"
  1633                            "        Evac:      %10.6f ms    (avg: %10.6f ms)\n"
  1634                            "       ET-RS:  %10.6f ms      (avg: %10.6f ms)\n"
  1635                            "      |RS|: " SIZE_FORMAT,
  1636                            elapsed_ms, recent_avg_time_for_pauses_ms(),
  1637                            _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
  1638                            _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
  1639                            evac_ms, recent_avg_time_for_evac_ms(),
  1640                            scan_rs_time,
  1641                            recent_avg_time_for_pauses_ms() -
  1642                            recent_avg_time_for_G1_strong_ms(),
  1643                            rs_size);
  1645     gclog_or_tty->print_cr("       Used at start: " SIZE_FORMAT"K"
  1646                            "       At end " SIZE_FORMAT "K\n"
  1647                            "       garbage      : " SIZE_FORMAT "K"
  1648                            "       of     " SIZE_FORMAT "K\n"
  1649                            "       survival     : %6.2f%%  (%6.2f%% avg)",
  1650                            _cur_collection_pause_used_at_start_bytes/K,
  1651                            _g1->used()/K, freed_bytes/K,
  1652                            _collection_set_bytes_used_before/K,
  1653                            survival_fraction*100.0,
  1654                            recent_avg_survival_fraction()*100.0);
  1655     gclog_or_tty->print_cr("       Recent %% gc pause time: %6.2f",
  1656                            recent_avg_pause_time_ratio() * 100.0);
  1659   double other_time_ms = elapsed_ms;
  1661   if (!abandoned) {
  1662     if (_satb_drain_time_set)
  1663       other_time_ms -= _cur_satb_drain_time_ms;
  1665     if (parallel)
  1666       other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
  1667     else
  1668       other_time_ms -=
  1669         update_rs_time +
  1670         ext_root_scan_time + mark_stack_scan_time + scan_only_time +
  1671         scan_rs_time + obj_copy_time;
  1674   if (PrintGCDetails) {
  1675     gclog_or_tty->print_cr("%s%s, %1.8lf secs]",
  1676                            abandoned ? " (abandoned)" : "",
  1677                            (last_pause_included_initial_mark) ? " (initial-mark)" : "",
  1678                            elapsed_ms / 1000.0);
  1680     if (!abandoned) {
  1681       if (_satb_drain_time_set) {
  1682         print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
  1684       if (_last_satb_drain_processed_buffers >= 0) {
  1685         print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
  1687       if (parallel) {
  1688         print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
  1689         print_par_stats(2, "Update RS (Start)", _par_last_update_rs_start_times_ms, false);
  1690         print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
  1691         print_par_buffers(3, "Processed Buffers",
  1692                           _par_last_update_rs_processed_buffers, true);
  1693         print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
  1694         print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
  1695         print_par_stats(2, "Scan-Only Scanning", _par_last_scan_only_times_ms);
  1696         print_par_buffers(3, "Scan-Only Regions",
  1697                           _par_last_scan_only_regions_scanned, true);
  1698         print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
  1699         print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
  1700         print_par_stats(2, "Termination", _par_last_termination_times_ms);
  1701         print_stats(2, "Other", parallel_other_time);
  1702         print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
  1703       } else {
  1704         print_stats(1, "Update RS", update_rs_time);
  1705         print_stats(2, "Processed Buffers",
  1706                     (int)update_rs_processed_buffers);
  1707         print_stats(1, "Ext Root Scanning", ext_root_scan_time);
  1708         print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
  1709         print_stats(1, "Scan-Only Scanning", scan_only_time);
  1710         print_stats(1, "Scan RS", scan_rs_time);
  1711         print_stats(1, "Object Copying", obj_copy_time);
  1714 #ifndef PRODUCT
  1715     print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
  1716     print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
  1717     print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
  1718     print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
  1719     if (_num_cc_clears > 0) {
  1720       print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
  1722 #endif
  1723     print_stats(1, "Other", other_time_ms);
  1724     for (int i = 0; i < _aux_num; ++i) {
  1725       if (_cur_aux_times_set[i]) {
  1726         char buffer[96];
  1727         sprintf(buffer, "Aux%d", i);
  1728         print_stats(1, buffer, _cur_aux_times_ms[i]);
  1732   if (PrintGCDetails)
  1733     gclog_or_tty->print("   [");
  1734   if (PrintGC || PrintGCDetails)
  1735     _g1->print_size_transition(gclog_or_tty,
  1736                                _cur_collection_pause_used_at_start_bytes,
  1737                                _g1->used(), _g1->capacity());
  1738   if (PrintGCDetails)
  1739     gclog_or_tty->print_cr("]");
  1741   _all_pause_times_ms->add(elapsed_ms);
  1742   if (update_stats) {
  1743     summary->record_total_time_ms(elapsed_ms);
  1744     summary->record_other_time_ms(other_time_ms);
  1746   for (int i = 0; i < _aux_num; ++i)
  1747     if (_cur_aux_times_set[i])
  1748       _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
  1750   // Reset marks-between-pauses counter.
  1751   _n_marks_since_last_pause = 0;
  1753   // Update the efficiency-since-mark vars.
  1754   double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
  1755   if (elapsed_ms < MIN_TIMER_GRANULARITY) {
  1756     // This usually happens due to the timer not having the required
  1757     // granularity. Some Linuxes are the usual culprits.
  1758     // We'll just set it to something (arbitrarily) small.
  1759     proc_ms = 1.0;
  1761   double cur_efficiency = (double) freed_bytes / proc_ms;
  1763   bool new_in_marking_window = _in_marking_window;
  1764   bool new_in_marking_window_im = false;
  1765   if (during_initial_mark_pause()) {
  1766     new_in_marking_window = true;
  1767     new_in_marking_window_im = true;
  1770   if (in_young_gc_mode()) {
  1771     if (_last_full_young_gc) {
  1772       set_full_young_gcs(false);
  1773       _last_full_young_gc = false;
  1776     if ( !_last_young_gc_full ) {
  1777       if ( _should_revert_to_full_young_gcs ||
  1778            _known_garbage_ratio < 0.05 ||
  1779            (adaptive_young_list_length() &&
  1780            (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
  1781         set_full_young_gcs(true);
  1784     _should_revert_to_full_young_gcs = false;
  1786     if (_last_young_gc_full && !_during_marking)
  1787       _young_gc_eff_seq->add(cur_efficiency);
  1790   _short_lived_surv_rate_group->start_adding_regions();
  1791   // do that for any other surv rate groupsx
  1793   // <NEW PREDICTION>
  1795   if (update_stats) {
  1796     double pause_time_ms = elapsed_ms;
  1798     size_t diff = 0;
  1799     if (_max_pending_cards >= _pending_cards)
  1800       diff = _max_pending_cards - _pending_cards;
  1801     _pending_card_diff_seq->add((double) diff);
  1803     double cost_per_card_ms = 0.0;
  1804     if (_pending_cards > 0) {
  1805       cost_per_card_ms = update_rs_time / (double) _pending_cards;
  1806       _cost_per_card_ms_seq->add(cost_per_card_ms);
  1809     double cost_per_scan_only_region_ms = 0.0;
  1810     if (scan_only_regions_scanned > 0.0) {
  1811       cost_per_scan_only_region_ms =
  1812         scan_only_time / scan_only_regions_scanned;
  1813       if (_in_marking_window_im)
  1814         _cost_per_scan_only_region_ms_during_cm_seq->add(cost_per_scan_only_region_ms);
  1815       else
  1816         _cost_per_scan_only_region_ms_seq->add(cost_per_scan_only_region_ms);
  1819     size_t cards_scanned = _g1->cards_scanned();
  1821     double cost_per_entry_ms = 0.0;
  1822     if (cards_scanned > 10) {
  1823       cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
  1824       if (_last_young_gc_full)
  1825         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1826       else
  1827         _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1830     if (_max_rs_lengths > 0) {
  1831       double cards_per_entry_ratio =
  1832         (double) cards_scanned / (double) _max_rs_lengths;
  1833       if (_last_young_gc_full)
  1834         _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1835       else
  1836         _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1839     size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
  1840     if (rs_length_diff >= 0)
  1841       _rs_length_diff_seq->add((double) rs_length_diff);
  1843     size_t copied_bytes = surviving_bytes;
  1844     double cost_per_byte_ms = 0.0;
  1845     if (copied_bytes > 0) {
  1846       cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
  1847       if (_in_marking_window)
  1848         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
  1849       else
  1850         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
  1853     double all_other_time_ms = pause_time_ms -
  1854       (update_rs_time + scan_only_time + scan_rs_time + obj_copy_time +
  1855        _mark_closure_time_ms + termination_time);
  1857     double young_other_time_ms = 0.0;
  1858     if (_recorded_young_regions > 0) {
  1859       young_other_time_ms =
  1860         _recorded_young_cset_choice_time_ms +
  1861         _recorded_young_free_cset_time_ms;
  1862       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
  1863                                              (double) _recorded_young_regions);
  1865     double non_young_other_time_ms = 0.0;
  1866     if (_recorded_non_young_regions > 0) {
  1867       non_young_other_time_ms =
  1868         _recorded_non_young_cset_choice_time_ms +
  1869         _recorded_non_young_free_cset_time_ms;
  1871       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
  1872                                          (double) _recorded_non_young_regions);
  1875     double constant_other_time_ms = all_other_time_ms -
  1876       (young_other_time_ms + non_young_other_time_ms);
  1877     _constant_other_time_ms_seq->add(constant_other_time_ms);
  1879     double survival_ratio = 0.0;
  1880     if (_bytes_in_collection_set_before_gc > 0) {
  1881       survival_ratio = (double) bytes_in_to_space_during_gc() /
  1882         (double) _bytes_in_collection_set_before_gc;
  1885     _pending_cards_seq->add((double) _pending_cards);
  1886     _scanned_cards_seq->add((double) cards_scanned);
  1887     _rs_lengths_seq->add((double) _max_rs_lengths);
  1889     double expensive_region_limit_ms =
  1890       (double) MaxGCPauseMillis - predict_constant_other_time_ms();
  1891     if (expensive_region_limit_ms < 0.0) {
  1892       // this means that the other time was predicted to be longer than
  1893       // than the max pause time
  1894       expensive_region_limit_ms = (double) MaxGCPauseMillis;
  1896     _expensive_region_limit_ms = expensive_region_limit_ms;
  1898     if (PREDICTIONS_VERBOSE) {
  1899       gclog_or_tty->print_cr("");
  1900       gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
  1901                     "REGIONS %d %d %d %d "
  1902                     "PENDING_CARDS %d %d "
  1903                     "CARDS_SCANNED %d %d "
  1904                     "RS_LENGTHS %d %d "
  1905                     "SCAN_ONLY_SCAN %1.6lf %1.6lf "
  1906                     "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
  1907                     "SURVIVAL_RATIO %1.6lf %1.6lf "
  1908                     "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
  1909                     "OTHER_YOUNG %1.6lf %1.6lf "
  1910                     "OTHER_NON_YOUNG %1.6lf %1.6lf "
  1911                     "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
  1912                     "ELAPSED %1.6lf %1.6lf ",
  1913                     _cur_collection_start_sec,
  1914                     (!_last_young_gc_full) ? 2 :
  1915                     (last_pause_included_initial_mark) ? 1 : 0,
  1916                     _recorded_region_num,
  1917                     _recorded_young_regions,
  1918                     _recorded_scan_only_regions,
  1919                     _recorded_non_young_regions,
  1920                     _predicted_pending_cards, _pending_cards,
  1921                     _predicted_cards_scanned, cards_scanned,
  1922                     _predicted_rs_lengths, _max_rs_lengths,
  1923                     _predicted_scan_only_scan_time_ms, scan_only_time,
  1924                     _predicted_rs_update_time_ms, update_rs_time,
  1925                     _predicted_rs_scan_time_ms, scan_rs_time,
  1926                     _predicted_survival_ratio, survival_ratio,
  1927                     _predicted_object_copy_time_ms, obj_copy_time,
  1928                     _predicted_constant_other_time_ms, constant_other_time_ms,
  1929                     _predicted_young_other_time_ms, young_other_time_ms,
  1930                     _predicted_non_young_other_time_ms,
  1931                     non_young_other_time_ms,
  1932                     _vtime_diff_ms, termination_time,
  1933                     _predicted_pause_time_ms, elapsed_ms);
  1936     if (G1PolicyVerbose > 0) {
  1937       gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
  1938                     _predicted_pause_time_ms,
  1939                     (_within_target) ? "within" : "outside",
  1940                     elapsed_ms);
  1945   _in_marking_window = new_in_marking_window;
  1946   _in_marking_window_im = new_in_marking_window_im;
  1947   _free_regions_at_end_of_collection = _g1->free_regions();
  1948   _scan_only_regions_at_end_of_collection = _g1->young_list_length();
  1949   calculate_young_list_min_length();
  1950   calculate_young_list_target_config();
  1952   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
  1953   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
  1954   adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
  1956   // </NEW PREDICTION>
  1958   _target_pause_time_ms = -1.0;
  1961 // <NEW PREDICTION>
  1963 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
  1964                                                      double update_rs_processed_buffers,
  1965                                                      double goal_ms) {
  1966   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  1967   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
  1969   if (G1UseAdaptiveConcRefinement) {
  1970     const int k_gy = 3, k_gr = 6;
  1971     const double inc_k = 1.1, dec_k = 0.9;
  1973     int g = cg1r->green_zone();
  1974     if (update_rs_time > goal_ms) {
  1975       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
  1976     } else {
  1977       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
  1978         g = (int)MAX2(g * inc_k, g + 1.0);
  1981     // Change the refinement threads params
  1982     cg1r->set_green_zone(g);
  1983     cg1r->set_yellow_zone(g * k_gy);
  1984     cg1r->set_red_zone(g * k_gr);
  1985     cg1r->reinitialize_threads();
  1987     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
  1988     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
  1989                                     cg1r->yellow_zone());
  1990     // Change the barrier params
  1991     dcqs.set_process_completed_threshold(processing_threshold);
  1992     dcqs.set_max_completed_queue(cg1r->red_zone());
  1995   int curr_queue_size = dcqs.completed_buffers_num();
  1996   if (curr_queue_size >= cg1r->yellow_zone()) {
  1997     dcqs.set_completed_queue_padding(curr_queue_size);
  1998   } else {
  1999     dcqs.set_completed_queue_padding(0);
  2001   dcqs.notify_if_necessary();
  2004 double
  2005 G1CollectorPolicy::
  2006 predict_young_collection_elapsed_time_ms(size_t adjustment) {
  2007   guarantee( adjustment == 0 || adjustment == 1, "invariant" );
  2009   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  2010   size_t young_num = g1h->young_list_length();
  2011   if (young_num == 0)
  2012     return 0.0;
  2014   young_num += adjustment;
  2015   size_t pending_cards = predict_pending_cards();
  2016   size_t rs_lengths = g1h->young_list_sampled_rs_lengths() +
  2017                       predict_rs_length_diff();
  2018   size_t card_num;
  2019   if (full_young_gcs())
  2020     card_num = predict_young_card_num(rs_lengths);
  2021   else
  2022     card_num = predict_non_young_card_num(rs_lengths);
  2023   size_t young_byte_size = young_num * HeapRegion::GrainBytes;
  2024   double accum_yg_surv_rate =
  2025     _short_lived_surv_rate_group->accum_surv_rate(adjustment);
  2027   size_t bytes_to_copy =
  2028     (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
  2030   return
  2031     predict_rs_update_time_ms(pending_cards) +
  2032     predict_rs_scan_time_ms(card_num) +
  2033     predict_object_copy_time_ms(bytes_to_copy) +
  2034     predict_young_other_time_ms(young_num) +
  2035     predict_constant_other_time_ms();
  2038 double
  2039 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
  2040   size_t rs_length = predict_rs_length_diff();
  2041   size_t card_num;
  2042   if (full_young_gcs())
  2043     card_num = predict_young_card_num(rs_length);
  2044   else
  2045     card_num = predict_non_young_card_num(rs_length);
  2046   return predict_base_elapsed_time_ms(pending_cards, card_num);
  2049 double
  2050 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
  2051                                                 size_t scanned_cards) {
  2052   return
  2053     predict_rs_update_time_ms(pending_cards) +
  2054     predict_rs_scan_time_ms(scanned_cards) +
  2055     predict_constant_other_time_ms();
  2058 double
  2059 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
  2060                                                   bool young) {
  2061   size_t rs_length = hr->rem_set()->occupied();
  2062   size_t card_num;
  2063   if (full_young_gcs())
  2064     card_num = predict_young_card_num(rs_length);
  2065   else
  2066     card_num = predict_non_young_card_num(rs_length);
  2067   size_t bytes_to_copy = predict_bytes_to_copy(hr);
  2069   double region_elapsed_time_ms =
  2070     predict_rs_scan_time_ms(card_num) +
  2071     predict_object_copy_time_ms(bytes_to_copy);
  2073   if (young)
  2074     region_elapsed_time_ms += predict_young_other_time_ms(1);
  2075   else
  2076     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
  2078   return region_elapsed_time_ms;
  2081 size_t
  2082 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
  2083   size_t bytes_to_copy;
  2084   if (hr->is_marked())
  2085     bytes_to_copy = hr->max_live_bytes();
  2086   else {
  2087     guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
  2088                "invariant" );
  2089     int age = hr->age_in_surv_rate_group();
  2090     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
  2091     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
  2094   return bytes_to_copy;
  2097 void
  2098 G1CollectorPolicy::start_recording_regions() {
  2099   _recorded_rs_lengths            = 0;
  2100   _recorded_scan_only_regions     = 0;
  2101   _recorded_young_regions         = 0;
  2102   _recorded_non_young_regions     = 0;
  2104 #if PREDICTIONS_VERBOSE
  2105   _predicted_rs_lengths           = 0;
  2106   _predicted_cards_scanned        = 0;
  2108   _recorded_marked_bytes          = 0;
  2109   _recorded_young_bytes           = 0;
  2110   _predicted_bytes_to_copy        = 0;
  2111 #endif // PREDICTIONS_VERBOSE
  2114 void
  2115 G1CollectorPolicy::record_cset_region(HeapRegion* hr, bool young) {
  2116   if (young) {
  2117     ++_recorded_young_regions;
  2118   } else {
  2119     ++_recorded_non_young_regions;
  2121 #if PREDICTIONS_VERBOSE
  2122   if (young) {
  2123     _recorded_young_bytes += hr->used();
  2124   } else {
  2125     _recorded_marked_bytes += hr->max_live_bytes();
  2127   _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
  2128 #endif // PREDICTIONS_VERBOSE
  2130   size_t rs_length = hr->rem_set()->occupied();
  2131   _recorded_rs_lengths += rs_length;
  2134 void
  2135 G1CollectorPolicy::record_scan_only_regions(size_t scan_only_length) {
  2136   _recorded_scan_only_regions = scan_only_length;
  2139 void
  2140 G1CollectorPolicy::end_recording_regions() {
  2141 #if PREDICTIONS_VERBOSE
  2142   _predicted_pending_cards = predict_pending_cards();
  2143   _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
  2144   if (full_young_gcs())
  2145     _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
  2146   else
  2147     _predicted_cards_scanned +=
  2148       predict_non_young_card_num(_predicted_rs_lengths);
  2149   _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
  2151   _predicted_scan_only_scan_time_ms =
  2152     predict_scan_only_time_ms(_recorded_scan_only_regions);
  2153   _predicted_rs_update_time_ms =
  2154     predict_rs_update_time_ms(_g1->pending_card_num());
  2155   _predicted_rs_scan_time_ms =
  2156     predict_rs_scan_time_ms(_predicted_cards_scanned);
  2157   _predicted_object_copy_time_ms =
  2158     predict_object_copy_time_ms(_predicted_bytes_to_copy);
  2159   _predicted_constant_other_time_ms =
  2160     predict_constant_other_time_ms();
  2161   _predicted_young_other_time_ms =
  2162     predict_young_other_time_ms(_recorded_young_regions);
  2163   _predicted_non_young_other_time_ms =
  2164     predict_non_young_other_time_ms(_recorded_non_young_regions);
  2166   _predicted_pause_time_ms =
  2167     _predicted_scan_only_scan_time_ms +
  2168     _predicted_rs_update_time_ms +
  2169     _predicted_rs_scan_time_ms +
  2170     _predicted_object_copy_time_ms +
  2171     _predicted_constant_other_time_ms +
  2172     _predicted_young_other_time_ms +
  2173     _predicted_non_young_other_time_ms;
  2174 #endif // PREDICTIONS_VERBOSE
  2177 void G1CollectorPolicy::check_if_region_is_too_expensive(double
  2178                                                            predicted_time_ms) {
  2179   // I don't think we need to do this when in young GC mode since
  2180   // marking will be initiated next time we hit the soft limit anyway...
  2181   if (predicted_time_ms > _expensive_region_limit_ms) {
  2182     if (!in_young_gc_mode()) {
  2183         set_full_young_gcs(true);
  2184         // We might want to do something different here. However,
  2185         // right now we don't support the non-generational G1 mode
  2186         // (and in fact we are planning to remove the associated code,
  2187         // see CR 6814390). So, let's leave it as is and this will be
  2188         // removed some time in the future
  2189         ShouldNotReachHere();
  2190         set_during_initial_mark_pause();
  2191     } else
  2192       // no point in doing another partial one
  2193       _should_revert_to_full_young_gcs = true;
  2197 // </NEW PREDICTION>
  2200 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
  2201                                                double elapsed_ms) {
  2202   _recent_gc_times_ms->add(elapsed_ms);
  2203   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
  2204   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
  2207 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
  2208   if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
  2209   else return _recent_pause_times_ms->avg();
  2212 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
  2213   if (_recent_CH_strong_roots_times_ms->num() == 0)
  2214     return (double)MaxGCPauseMillis/3.0;
  2215   else return _recent_CH_strong_roots_times_ms->avg();
  2218 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
  2219   if (_recent_G1_strong_roots_times_ms->num() == 0)
  2220     return (double)MaxGCPauseMillis/3.0;
  2221   else return _recent_G1_strong_roots_times_ms->avg();
  2224 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
  2225   if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
  2226   else return _recent_evac_times_ms->avg();
  2229 int G1CollectorPolicy::number_of_recent_gcs() {
  2230   assert(_recent_CH_strong_roots_times_ms->num() ==
  2231          _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
  2232   assert(_recent_G1_strong_roots_times_ms->num() ==
  2233          _recent_evac_times_ms->num(), "Sequence out of sync");
  2234   assert(_recent_evac_times_ms->num() ==
  2235          _recent_pause_times_ms->num(), "Sequence out of sync");
  2236   assert(_recent_pause_times_ms->num() ==
  2237          _recent_CS_bytes_used_before->num(), "Sequence out of sync");
  2238   assert(_recent_CS_bytes_used_before->num() ==
  2239          _recent_CS_bytes_surviving->num(), "Sequence out of sync");
  2240   return _recent_pause_times_ms->num();
  2243 double G1CollectorPolicy::recent_avg_survival_fraction() {
  2244   return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
  2245                                            _recent_CS_bytes_used_before);
  2248 double G1CollectorPolicy::last_survival_fraction() {
  2249   return last_survival_fraction_work(_recent_CS_bytes_surviving,
  2250                                      _recent_CS_bytes_used_before);
  2253 double
  2254 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
  2255                                                      TruncatedSeq* before) {
  2256   assert(surviving->num() == before->num(), "Sequence out of sync");
  2257   if (before->sum() > 0.0) {
  2258       double recent_survival_rate = surviving->sum() / before->sum();
  2259       // We exempt parallel collection from this check because Alloc Buffer
  2260       // fragmentation can produce negative collections.
  2261       // Further, we're now always doing parallel collection.  But I'm still
  2262       // leaving this here as a placeholder for a more precise assertion later.
  2263       // (DLD, 10/05.)
  2264       assert((true || ParallelGCThreads > 0) ||
  2265              _g1->evacuation_failed() ||
  2266              recent_survival_rate <= 1.0, "Or bad frac");
  2267       return recent_survival_rate;
  2268   } else {
  2269     return 1.0; // Be conservative.
  2273 double
  2274 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
  2275                                                TruncatedSeq* before) {
  2276   assert(surviving->num() == before->num(), "Sequence out of sync");
  2277   if (surviving->num() > 0 && before->last() > 0.0) {
  2278     double last_survival_rate = surviving->last() / before->last();
  2279     // We exempt parallel collection from this check because Alloc Buffer
  2280     // fragmentation can produce negative collections.
  2281     // Further, we're now always doing parallel collection.  But I'm still
  2282     // leaving this here as a placeholder for a more precise assertion later.
  2283     // (DLD, 10/05.)
  2284     assert((true || ParallelGCThreads > 0) ||
  2285            last_survival_rate <= 1.0, "Or bad frac");
  2286     return last_survival_rate;
  2287   } else {
  2288     return 1.0;
  2292 static const int survival_min_obs = 5;
  2293 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
  2294 static const double min_survival_rate = 0.1;
  2296 double
  2297 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
  2298                                                            double latest) {
  2299   double res = avg;
  2300   if (number_of_recent_gcs() < survival_min_obs) {
  2301     res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
  2303   res = MAX2(res, latest);
  2304   res = MAX2(res, min_survival_rate);
  2305   // In the parallel case, LAB fragmentation can produce "negative
  2306   // collections"; so can evac failure.  Cap at 1.0
  2307   res = MIN2(res, 1.0);
  2308   return res;
  2311 size_t G1CollectorPolicy::expansion_amount() {
  2312   if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
  2313     // We will double the existing space, or take
  2314     // G1ExpandByPercentOfAvailable % of the available expansion
  2315     // space, whichever is smaller, bounded below by a minimum
  2316     // expansion (unless that's all that's left.)
  2317     const size_t min_expand_bytes = 1*M;
  2318     size_t reserved_bytes = _g1->g1_reserved_obj_bytes();
  2319     size_t committed_bytes = _g1->capacity();
  2320     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
  2321     size_t expand_bytes;
  2322     size_t expand_bytes_via_pct =
  2323       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
  2324     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
  2325     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
  2326     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
  2327     if (G1PolicyVerbose > 1) {
  2328       gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
  2329                  "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
  2330                  "                   Answer = %d.\n",
  2331                  recent_avg_pause_time_ratio(),
  2332                  byte_size_in_proper_unit(committed_bytes),
  2333                  proper_unit_for_byte_size(committed_bytes),
  2334                  byte_size_in_proper_unit(uncommitted_bytes),
  2335                  proper_unit_for_byte_size(uncommitted_bytes),
  2336                  byte_size_in_proper_unit(expand_bytes_via_pct),
  2337                  proper_unit_for_byte_size(expand_bytes_via_pct),
  2338                  byte_size_in_proper_unit(expand_bytes),
  2339                  proper_unit_for_byte_size(expand_bytes));
  2341     return expand_bytes;
  2342   } else {
  2343     return 0;
  2347 void G1CollectorPolicy::note_start_of_mark_thread() {
  2348   _mark_thread_startup_sec = os::elapsedTime();
  2351 class CountCSClosure: public HeapRegionClosure {
  2352   G1CollectorPolicy* _g1_policy;
  2353 public:
  2354   CountCSClosure(G1CollectorPolicy* g1_policy) :
  2355     _g1_policy(g1_policy) {}
  2356   bool doHeapRegion(HeapRegion* r) {
  2357     _g1_policy->_bytes_in_collection_set_before_gc += r->used();
  2358     return false;
  2360 };
  2362 void G1CollectorPolicy::count_CS_bytes_used() {
  2363   CountCSClosure cs_closure(this);
  2364   _g1->collection_set_iterate(&cs_closure);
  2367 static void print_indent(int level) {
  2368   for (int j = 0; j < level+1; ++j)
  2369     gclog_or_tty->print("   ");
  2372 void G1CollectorPolicy::print_summary (int level,
  2373                                        const char* str,
  2374                                        NumberSeq* seq) const {
  2375   double sum = seq->sum();
  2376   print_indent(level);
  2377   gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
  2378                 str, sum / 1000.0, seq->avg());
  2381 void G1CollectorPolicy::print_summary_sd (int level,
  2382                                           const char* str,
  2383                                           NumberSeq* seq) const {
  2384   print_summary(level, str, seq);
  2385   print_indent(level + 5);
  2386   gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
  2387                 seq->num(), seq->sd(), seq->maximum());
  2390 void G1CollectorPolicy::check_other_times(int level,
  2391                                         NumberSeq* other_times_ms,
  2392                                         NumberSeq* calc_other_times_ms) const {
  2393   bool should_print = false;
  2395   double max_sum = MAX2(fabs(other_times_ms->sum()),
  2396                         fabs(calc_other_times_ms->sum()));
  2397   double min_sum = MIN2(fabs(other_times_ms->sum()),
  2398                         fabs(calc_other_times_ms->sum()));
  2399   double sum_ratio = max_sum / min_sum;
  2400   if (sum_ratio > 1.1) {
  2401     should_print = true;
  2402     print_indent(level + 1);
  2403     gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
  2406   double max_avg = MAX2(fabs(other_times_ms->avg()),
  2407                         fabs(calc_other_times_ms->avg()));
  2408   double min_avg = MIN2(fabs(other_times_ms->avg()),
  2409                         fabs(calc_other_times_ms->avg()));
  2410   double avg_ratio = max_avg / min_avg;
  2411   if (avg_ratio > 1.1) {
  2412     should_print = true;
  2413     print_indent(level + 1);
  2414     gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
  2417   if (other_times_ms->sum() < -0.01) {
  2418     print_indent(level + 1);
  2419     gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
  2422   if (other_times_ms->avg() < -0.01) {
  2423     print_indent(level + 1);
  2424     gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
  2427   if (calc_other_times_ms->sum() < -0.01) {
  2428     should_print = true;
  2429     print_indent(level + 1);
  2430     gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
  2433   if (calc_other_times_ms->avg() < -0.01) {
  2434     should_print = true;
  2435     print_indent(level + 1);
  2436     gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
  2439   if (should_print)
  2440     print_summary(level, "Other(Calc)", calc_other_times_ms);
  2443 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
  2444   bool parallel = ParallelGCThreads > 0;
  2445   MainBodySummary*    body_summary = summary->main_body_summary();
  2446   if (summary->get_total_seq()->num() > 0) {
  2447     print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
  2448     if (body_summary != NULL) {
  2449       print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
  2450       if (parallel) {
  2451         print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
  2452         print_summary(2, "Update RS", body_summary->get_update_rs_seq());
  2453         print_summary(2, "Ext Root Scanning",
  2454                       body_summary->get_ext_root_scan_seq());
  2455         print_summary(2, "Mark Stack Scanning",
  2456                       body_summary->get_mark_stack_scan_seq());
  2457         print_summary(2, "Scan-Only Scanning",
  2458                       body_summary->get_scan_only_seq());
  2459         print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
  2460         print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
  2461         print_summary(2, "Termination", body_summary->get_termination_seq());
  2462         print_summary(2, "Other", body_summary->get_parallel_other_seq());
  2464           NumberSeq* other_parts[] = {
  2465             body_summary->get_update_rs_seq(),
  2466             body_summary->get_ext_root_scan_seq(),
  2467             body_summary->get_mark_stack_scan_seq(),
  2468             body_summary->get_scan_only_seq(),
  2469             body_summary->get_scan_rs_seq(),
  2470             body_summary->get_obj_copy_seq(),
  2471             body_summary->get_termination_seq()
  2472           };
  2473           NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
  2474                                         7, other_parts);
  2475           check_other_times(2, body_summary->get_parallel_other_seq(),
  2476                             &calc_other_times_ms);
  2478         print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
  2479         print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
  2480       } else {
  2481         print_summary(1, "Update RS", body_summary->get_update_rs_seq());
  2482         print_summary(1, "Ext Root Scanning",
  2483                       body_summary->get_ext_root_scan_seq());
  2484         print_summary(1, "Mark Stack Scanning",
  2485                       body_summary->get_mark_stack_scan_seq());
  2486         print_summary(1, "Scan-Only Scanning",
  2487                       body_summary->get_scan_only_seq());
  2488         print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
  2489         print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
  2492     print_summary(1, "Other", summary->get_other_seq());
  2494       NumberSeq calc_other_times_ms;
  2495       if (body_summary != NULL) {
  2496         // not abandoned
  2497         if (parallel) {
  2498           // parallel
  2499           NumberSeq* other_parts[] = {
  2500             body_summary->get_satb_drain_seq(),
  2501             body_summary->get_parallel_seq(),
  2502             body_summary->get_clear_ct_seq()
  2503           };
  2504           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2505                                           3, other_parts);
  2506         } else {
  2507           // serial
  2508           NumberSeq* other_parts[] = {
  2509             body_summary->get_satb_drain_seq(),
  2510             body_summary->get_update_rs_seq(),
  2511             body_summary->get_ext_root_scan_seq(),
  2512             body_summary->get_mark_stack_scan_seq(),
  2513             body_summary->get_scan_only_seq(),
  2514             body_summary->get_scan_rs_seq(),
  2515             body_summary->get_obj_copy_seq()
  2516           };
  2517           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2518                                           7, other_parts);
  2520       } else {
  2521         // abandoned
  2522         calc_other_times_ms = NumberSeq();
  2524       check_other_times(1,  summary->get_other_seq(), &calc_other_times_ms);
  2526   } else {
  2527     print_indent(0);
  2528     gclog_or_tty->print_cr("none");
  2530   gclog_or_tty->print_cr("");
  2533 void
  2534 G1CollectorPolicy::print_abandoned_summary(PauseSummary* summary) const {
  2535   bool printed = false;
  2536   if (summary->get_total_seq()->num() > 0) {
  2537     printed = true;
  2538     print_summary(summary);
  2540   if (!printed) {
  2541     print_indent(0);
  2542     gclog_or_tty->print_cr("none");
  2543     gclog_or_tty->print_cr("");
  2547 void G1CollectorPolicy::print_tracing_info() const {
  2548   if (TraceGen0Time) {
  2549     gclog_or_tty->print_cr("ALL PAUSES");
  2550     print_summary_sd(0, "Total", _all_pause_times_ms);
  2551     gclog_or_tty->print_cr("");
  2552     gclog_or_tty->print_cr("");
  2553     gclog_or_tty->print_cr("   Full Young GC Pauses:    %8d", _full_young_pause_num);
  2554     gclog_or_tty->print_cr("   Partial Young GC Pauses: %8d", _partial_young_pause_num);
  2555     gclog_or_tty->print_cr("");
  2557     gclog_or_tty->print_cr("EVACUATION PAUSES");
  2558     print_summary(_summary);
  2560     gclog_or_tty->print_cr("ABANDONED PAUSES");
  2561     print_abandoned_summary(_abandoned_summary);
  2563     gclog_or_tty->print_cr("MISC");
  2564     print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
  2565     print_summary_sd(0, "Yields", _all_yield_times_ms);
  2566     for (int i = 0; i < _aux_num; ++i) {
  2567       if (_all_aux_times_ms[i].num() > 0) {
  2568         char buffer[96];
  2569         sprintf(buffer, "Aux%d", i);
  2570         print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
  2574     size_t all_region_num = _region_num_young + _region_num_tenured;
  2575     gclog_or_tty->print_cr("   New Regions %8d, Young %8d (%6.2lf%%), "
  2576                "Tenured %8d (%6.2lf%%)",
  2577                all_region_num,
  2578                _region_num_young,
  2579                (double) _region_num_young / (double) all_region_num * 100.0,
  2580                _region_num_tenured,
  2581                (double) _region_num_tenured / (double) all_region_num * 100.0);
  2583   if (TraceGen1Time) {
  2584     if (_all_full_gc_times_ms->num() > 0) {
  2585       gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
  2586                  _all_full_gc_times_ms->num(),
  2587                  _all_full_gc_times_ms->sum() / 1000.0);
  2588       gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
  2589       gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
  2590                     _all_full_gc_times_ms->sd(),
  2591                     _all_full_gc_times_ms->maximum());
  2596 void G1CollectorPolicy::print_yg_surv_rate_info() const {
  2597 #ifndef PRODUCT
  2598   _short_lived_surv_rate_group->print_surv_rate_summary();
  2599   // add this call for any other surv rate groups
  2600 #endif // PRODUCT
  2603 bool
  2604 G1CollectorPolicy::should_add_next_region_to_young_list() {
  2605   assert(in_young_gc_mode(), "should be in young GC mode");
  2606   bool ret;
  2607   size_t young_list_length = _g1->young_list_length();
  2608   size_t young_list_max_length = _young_list_target_length;
  2609   if (G1FixedEdenSize) {
  2610     young_list_max_length -= _max_survivor_regions;
  2612   if (young_list_length < young_list_max_length) {
  2613     ret = true;
  2614     ++_region_num_young;
  2615   } else {
  2616     ret = false;
  2617     ++_region_num_tenured;
  2620   return ret;
  2623 #ifndef PRODUCT
  2624 // for debugging, bit of a hack...
  2625 static char*
  2626 region_num_to_mbs(int length) {
  2627   static char buffer[64];
  2628   double bytes = (double) (length * HeapRegion::GrainBytes);
  2629   double mbs = bytes / (double) (1024 * 1024);
  2630   sprintf(buffer, "%7.2lfMB", mbs);
  2631   return buffer;
  2633 #endif // PRODUCT
  2635 size_t G1CollectorPolicy::max_regions(int purpose) {
  2636   switch (purpose) {
  2637     case GCAllocForSurvived:
  2638       return _max_survivor_regions;
  2639     case GCAllocForTenured:
  2640       return REGIONS_UNLIMITED;
  2641     default:
  2642       ShouldNotReachHere();
  2643       return REGIONS_UNLIMITED;
  2644   };
  2647 // Calculates survivor space parameters.
  2648 void G1CollectorPolicy::calculate_survivors_policy()
  2650   if (G1FixedSurvivorSpaceSize == 0) {
  2651     _max_survivor_regions = _young_list_target_length / SurvivorRatio;
  2652   } else {
  2653     _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
  2656   if (G1FixedTenuringThreshold) {
  2657     _tenuring_threshold = MaxTenuringThreshold;
  2658   } else {
  2659     _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
  2660         HeapRegion::GrainWords * _max_survivor_regions);
  2664 bool
  2665 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t
  2666                                                                word_size) {
  2667   assert(_g1->regions_accounted_for(), "Region leakage!");
  2668   double max_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
  2670   size_t young_list_length = _g1->young_list_length();
  2671   size_t young_list_max_length = _young_list_target_length;
  2672   if (G1FixedEdenSize) {
  2673     young_list_max_length -= _max_survivor_regions;
  2675   bool reached_target_length = young_list_length >= young_list_max_length;
  2677   if (in_young_gc_mode()) {
  2678     if (reached_target_length) {
  2679       assert( young_list_length > 0 && _g1->young_list_length() > 0,
  2680               "invariant" );
  2681       _target_pause_time_ms = max_pause_time_ms;
  2682       return true;
  2684   } else {
  2685     guarantee( false, "should not reach here" );
  2688   return false;
  2691 #ifndef PRODUCT
  2692 class HRSortIndexIsOKClosure: public HeapRegionClosure {
  2693   CollectionSetChooser* _chooser;
  2694 public:
  2695   HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
  2696     _chooser(chooser) {}
  2698   bool doHeapRegion(HeapRegion* r) {
  2699     if (!r->continuesHumongous()) {
  2700       assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
  2702     return false;
  2704 };
  2706 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
  2707   HRSortIndexIsOKClosure cl(_collectionSetChooser);
  2708   _g1->heap_region_iterate(&cl);
  2709   return true;
  2711 #endif
  2713 void
  2714 G1CollectorPolicy::decide_on_conc_mark_initiation() {
  2715   // We are about to decide on whether this pause will be an
  2716   // initial-mark pause.
  2718   // First, during_initial_mark_pause() should not be already set. We
  2719   // will set it here if we have to. However, it should be cleared by
  2720   // the end of the pause (it's only set for the duration of an
  2721   // initial-mark pause).
  2722   assert(!during_initial_mark_pause(), "pre-condition");
  2724   if (initiate_conc_mark_if_possible()) {
  2725     // We had noticed on a previous pause that the heap occupancy has
  2726     // gone over the initiating threshold and we should start a
  2727     // concurrent marking cycle. So we might initiate one.
  2729     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
  2730     if (!during_cycle) {
  2731       // The concurrent marking thread is not "during a cycle", i.e.,
  2732       // it has completed the last one. So we can go ahead and
  2733       // initiate a new cycle.
  2735       set_during_initial_mark_pause();
  2737       // And we can now clear initiate_conc_mark_if_possible() as
  2738       // we've already acted on it.
  2739       clear_initiate_conc_mark_if_possible();
  2740     } else {
  2741       // The concurrent marking thread is still finishing up the
  2742       // previous cycle. If we start one right now the two cycles
  2743       // overlap. In particular, the concurrent marking thread might
  2744       // be in the process of clearing the next marking bitmap (which
  2745       // we will use for the next cycle if we start one). Starting a
  2746       // cycle now will be bad given that parts of the marking
  2747       // information might get cleared by the marking thread. And we
  2748       // cannot wait for the marking thread to finish the cycle as it
  2749       // periodically yields while clearing the next marking bitmap
  2750       // and, if it's in a yield point, it's waiting for us to
  2751       // finish. So, at this point we will not start a cycle and we'll
  2752       // let the concurrent marking thread complete the last one.
  2757 void
  2758 G1CollectorPolicy_BestRegionsFirst::
  2759 record_collection_pause_start(double start_time_sec, size_t start_used) {
  2760   G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
  2763 class NextNonCSElemFinder: public HeapRegionClosure {
  2764   HeapRegion* _res;
  2765 public:
  2766   NextNonCSElemFinder(): _res(NULL) {}
  2767   bool doHeapRegion(HeapRegion* r) {
  2768     if (!r->in_collection_set()) {
  2769       _res = r;
  2770       return true;
  2771     } else {
  2772       return false;
  2775   HeapRegion* res() { return _res; }
  2776 };
  2778 class KnownGarbageClosure: public HeapRegionClosure {
  2779   CollectionSetChooser* _hrSorted;
  2781 public:
  2782   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
  2783     _hrSorted(hrSorted)
  2784   {}
  2786   bool doHeapRegion(HeapRegion* r) {
  2787     // We only include humongous regions in collection
  2788     // sets when concurrent mark shows that their contained object is
  2789     // unreachable.
  2791     // Do we have any marking information for this region?
  2792     if (r->is_marked()) {
  2793       // We don't include humongous regions in collection
  2794       // sets because we collect them immediately at the end of a marking
  2795       // cycle.  We also don't include young regions because we *must*
  2796       // include them in the next collection pause.
  2797       if (!r->isHumongous() && !r->is_young()) {
  2798         _hrSorted->addMarkedHeapRegion(r);
  2801     return false;
  2803 };
  2805 class ParKnownGarbageHRClosure: public HeapRegionClosure {
  2806   CollectionSetChooser* _hrSorted;
  2807   jint _marked_regions_added;
  2808   jint _chunk_size;
  2809   jint _cur_chunk_idx;
  2810   jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
  2811   int _worker;
  2812   int _invokes;
  2814   void get_new_chunk() {
  2815     _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
  2816     _cur_chunk_end = _cur_chunk_idx + _chunk_size;
  2818   void add_region(HeapRegion* r) {
  2819     if (_cur_chunk_idx == _cur_chunk_end) {
  2820       get_new_chunk();
  2822     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
  2823     _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
  2824     _marked_regions_added++;
  2825     _cur_chunk_idx++;
  2828 public:
  2829   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
  2830                            jint chunk_size,
  2831                            int worker) :
  2832     _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
  2833     _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
  2834     _invokes(0)
  2835   {}
  2837   bool doHeapRegion(HeapRegion* r) {
  2838     // We only include humongous regions in collection
  2839     // sets when concurrent mark shows that their contained object is
  2840     // unreachable.
  2841     _invokes++;
  2843     // Do we have any marking information for this region?
  2844     if (r->is_marked()) {
  2845       // We don't include humongous regions in collection
  2846       // sets because we collect them immediately at the end of a marking
  2847       // cycle.
  2848       // We also do not include young regions in collection sets
  2849       if (!r->isHumongous() && !r->is_young()) {
  2850         add_region(r);
  2853     return false;
  2855   jint marked_regions_added() { return _marked_regions_added; }
  2856   int invokes() { return _invokes; }
  2857 };
  2859 class ParKnownGarbageTask: public AbstractGangTask {
  2860   CollectionSetChooser* _hrSorted;
  2861   jint _chunk_size;
  2862   G1CollectedHeap* _g1;
  2863 public:
  2864   ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
  2865     AbstractGangTask("ParKnownGarbageTask"),
  2866     _hrSorted(hrSorted), _chunk_size(chunk_size),
  2867     _g1(G1CollectedHeap::heap())
  2868   {}
  2870   void work(int i) {
  2871     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
  2872     // Back to zero for the claim value.
  2873     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
  2874                                          HeapRegion::InitialClaimValue);
  2875     jint regions_added = parKnownGarbageCl.marked_regions_added();
  2876     _hrSorted->incNumMarkedHeapRegions(regions_added);
  2877     if (G1PrintParCleanupStats) {
  2878       gclog_or_tty->print("     Thread %d called %d times, added %d regions to list.\n",
  2879                  i, parKnownGarbageCl.invokes(), regions_added);
  2882 };
  2884 void
  2885 G1CollectorPolicy_BestRegionsFirst::
  2886 record_concurrent_mark_cleanup_end(size_t freed_bytes,
  2887                                    size_t max_live_bytes) {
  2888   double start;
  2889   if (G1PrintParCleanupStats) start = os::elapsedTime();
  2890   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
  2892   _collectionSetChooser->clearMarkedHeapRegions();
  2893   double clear_marked_end;
  2894   if (G1PrintParCleanupStats) {
  2895     clear_marked_end = os::elapsedTime();
  2896     gclog_or_tty->print_cr("  clear marked regions + work1: %8.3f ms.",
  2897                   (clear_marked_end - start)*1000.0);
  2899   if (ParallelGCThreads > 0) {
  2900     const size_t OverpartitionFactor = 4;
  2901     const size_t MinChunkSize = 8;
  2902     const size_t ChunkSize =
  2903       MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
  2904            MinChunkSize);
  2905     _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
  2906                                                              ChunkSize);
  2907     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
  2908                                             (int) ChunkSize);
  2909     _g1->workers()->run_task(&parKnownGarbageTask);
  2911     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
  2912            "sanity check");
  2913   } else {
  2914     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
  2915     _g1->heap_region_iterate(&knownGarbagecl);
  2917   double known_garbage_end;
  2918   if (G1PrintParCleanupStats) {
  2919     known_garbage_end = os::elapsedTime();
  2920     gclog_or_tty->print_cr("  compute known garbage: %8.3f ms.",
  2921                   (known_garbage_end - clear_marked_end)*1000.0);
  2923   _collectionSetChooser->sortMarkedHeapRegions();
  2924   double sort_end;
  2925   if (G1PrintParCleanupStats) {
  2926     sort_end = os::elapsedTime();
  2927     gclog_or_tty->print_cr("  sorting: %8.3f ms.",
  2928                   (sort_end - known_garbage_end)*1000.0);
  2931   record_concurrent_mark_cleanup_end_work2();
  2932   double work2_end;
  2933   if (G1PrintParCleanupStats) {
  2934     work2_end = os::elapsedTime();
  2935     gclog_or_tty->print_cr("  work2: %8.3f ms.",
  2936                   (work2_end - sort_end)*1000.0);
  2940 // Add the heap region to the collection set and return the conservative
  2941 // estimate of the number of live bytes.
  2942 void G1CollectorPolicy::
  2943 add_to_collection_set(HeapRegion* hr) {
  2944   if (G1PrintHeapRegions) {
  2945     gclog_or_tty->print_cr("added region to cset "
  2946                            "%d:["PTR_FORMAT", "PTR_FORMAT"], "
  2947                            "top "PTR_FORMAT", %s",
  2948                            hr->hrs_index(), hr->bottom(), hr->end(),
  2949                            hr->top(), hr->is_young() ? "YOUNG" : "NOT_YOUNG");
  2952   if (_g1->mark_in_progress())
  2953     _g1->concurrent_mark()->registerCSetRegion(hr);
  2955   assert(!hr->in_collection_set(),
  2956               "should not already be in the CSet");
  2957   hr->set_in_collection_set(true);
  2958   hr->set_next_in_collection_set(_collection_set);
  2959   _collection_set = hr;
  2960   _collection_set_size++;
  2961   _collection_set_bytes_used_before += hr->used();
  2962   _g1->register_region_with_in_cset_fast_test(hr);
  2965 void
  2966 G1CollectorPolicy_BestRegionsFirst::
  2967 choose_collection_set() {
  2968   double non_young_start_time_sec;
  2969   start_recording_regions();
  2971   guarantee(_target_pause_time_ms > -1.0
  2972             NOT_PRODUCT(|| Universe::heap()->gc_cause() == GCCause::_scavenge_alot),
  2973             "_target_pause_time_ms should have been set!");
  2974 #ifndef PRODUCT
  2975   if (_target_pause_time_ms <= -1.0) {
  2976     assert(ScavengeALot && Universe::heap()->gc_cause() == GCCause::_scavenge_alot, "Error");
  2977     _target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
  2979 #endif
  2980   assert(_collection_set == NULL, "Precondition");
  2982   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
  2983   double predicted_pause_time_ms = base_time_ms;
  2985   double target_time_ms = _target_pause_time_ms;
  2986   double time_remaining_ms = target_time_ms - base_time_ms;
  2988   // the 10% and 50% values are arbitrary...
  2989   if (time_remaining_ms < 0.10*target_time_ms) {
  2990     time_remaining_ms = 0.50 * target_time_ms;
  2991     _within_target = false;
  2992   } else {
  2993     _within_target = true;
  2996   // We figure out the number of bytes available for future to-space.
  2997   // For new regions without marking information, we must assume the
  2998   // worst-case of complete survival.  If we have marking information for a
  2999   // region, we can bound the amount of live data.  We can add a number of
  3000   // such regions, as long as the sum of the live data bounds does not
  3001   // exceed the available evacuation space.
  3002   size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
  3004   size_t expansion_bytes =
  3005     _g1->expansion_regions() * HeapRegion::GrainBytes;
  3007   _collection_set_bytes_used_before = 0;
  3008   _collection_set_size = 0;
  3010   // Adjust for expansion and slop.
  3011   max_live_bytes = max_live_bytes + expansion_bytes;
  3013   assert(_g1->regions_accounted_for(), "Region leakage!");
  3015   HeapRegion* hr;
  3016   if (in_young_gc_mode()) {
  3017     double young_start_time_sec = os::elapsedTime();
  3019     if (G1PolicyVerbose > 0) {
  3020       gclog_or_tty->print_cr("Adding %d young regions to the CSet",
  3021                     _g1->young_list_length());
  3023     _young_cset_length  = 0;
  3024     _last_young_gc_full = full_young_gcs() ? true : false;
  3025     if (_last_young_gc_full)
  3026       ++_full_young_pause_num;
  3027     else
  3028       ++_partial_young_pause_num;
  3029     hr = _g1->pop_region_from_young_list();
  3030     while (hr != NULL) {
  3032       assert( hr->young_index_in_cset() == -1, "invariant" );
  3033       assert( hr->age_in_surv_rate_group() != -1, "invariant" );
  3034       hr->set_young_index_in_cset((int) _young_cset_length);
  3036       ++_young_cset_length;
  3037       double predicted_time_ms = predict_region_elapsed_time_ms(hr, true);
  3038       time_remaining_ms -= predicted_time_ms;
  3039       predicted_pause_time_ms += predicted_time_ms;
  3040       assert(!hr->in_collection_set(), "invariant");
  3041       add_to_collection_set(hr);
  3042       record_cset_region(hr, true);
  3043       max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
  3044       if (G1PolicyVerbose > 0) {
  3045         gclog_or_tty->print_cr("  Added [" PTR_FORMAT ", " PTR_FORMAT") to CS.",
  3046                       hr->bottom(), hr->end());
  3047         gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  3048                       max_live_bytes/K);
  3050       hr = _g1->pop_region_from_young_list();
  3053     record_scan_only_regions(_g1->young_list_scan_only_length());
  3055     double young_end_time_sec = os::elapsedTime();
  3056     _recorded_young_cset_choice_time_ms =
  3057       (young_end_time_sec - young_start_time_sec) * 1000.0;
  3059     non_young_start_time_sec = os::elapsedTime();
  3061     if (_young_cset_length > 0 && _last_young_gc_full) {
  3062       // don't bother adding more regions...
  3063       goto choose_collection_set_end;
  3067   if (!in_young_gc_mode() || !full_young_gcs()) {
  3068     bool should_continue = true;
  3069     NumberSeq seq;
  3070     double avg_prediction = 100000000000000000.0; // something very large
  3071     do {
  3072       hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
  3073                                                       avg_prediction);
  3074       if (hr != NULL) {
  3075         double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
  3076         time_remaining_ms -= predicted_time_ms;
  3077         predicted_pause_time_ms += predicted_time_ms;
  3078         add_to_collection_set(hr);
  3079         record_cset_region(hr, false);
  3080         max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
  3081         if (G1PolicyVerbose > 0) {
  3082           gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  3083                         max_live_bytes/K);
  3085         seq.add(predicted_time_ms);
  3086         avg_prediction = seq.avg() + seq.sd();
  3088       should_continue =
  3089         ( hr != NULL) &&
  3090         ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
  3091           : _collection_set_size < _young_list_fixed_length );
  3092     } while (should_continue);
  3094     if (!adaptive_young_list_length() &&
  3095         _collection_set_size < _young_list_fixed_length)
  3096       _should_revert_to_full_young_gcs  = true;
  3099 choose_collection_set_end:
  3100   count_CS_bytes_used();
  3102   end_recording_regions();
  3104   double non_young_end_time_sec = os::elapsedTime();
  3105   _recorded_non_young_cset_choice_time_ms =
  3106     (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
  3109 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
  3110   G1CollectorPolicy::record_full_collection_end();
  3111   _collectionSetChooser->updateAfterFullCollection();
  3114 void G1CollectorPolicy_BestRegionsFirst::
  3115 expand_if_possible(size_t numRegions) {
  3116   size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
  3117   _g1->expand(expansion_bytes);
  3120 void G1CollectorPolicy_BestRegionsFirst::
  3121 record_collection_pause_end(bool abandoned) {
  3122   G1CollectorPolicy::record_collection_pause_end(abandoned);
  3123   assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");

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