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

Wed, 02 Jun 2010 22:45:42 -0700

author
jrose
date
Wed, 02 Jun 2010 22:45:42 -0700
changeset 1934
e9ff18c4ace7
parent 1907
c18cbe5936b8
parent 1926
2d127394260e
child 1965
79107c3a6bd5
permissions
-rw-r--r--

Merge

     1 /*
     2  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
    20  * or visit www.oracle.com if you need additional information or have any
    21  * 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 // all the same
    46 static double fully_young_cards_per_entry_ratio_defaults[] = {
    47   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
    48 };
    50 static double cost_per_entry_ms_defaults[] = {
    51   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
    52 };
    54 static double cost_per_byte_ms_defaults[] = {
    55   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
    56 };
    58 // these should be pretty consistent
    59 static double constant_other_time_ms_defaults[] = {
    60   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
    61 };
    64 static double young_other_cost_per_region_ms_defaults[] = {
    65   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
    66 };
    68 static double non_young_other_cost_per_region_ms_defaults[] = {
    69   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
    70 };
    72 // </NEW PREDICTION>
    74 G1CollectorPolicy::G1CollectorPolicy() :
    75   _parallel_gc_threads((ParallelGCThreads > 0) ? ParallelGCThreads : 1),
    76   _n_pauses(0),
    77   _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    78   _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    79   _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    80   _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    81   _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
    82   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    83   _all_pause_times_ms(new NumberSeq()),
    84   _stop_world_start(0.0),
    85   _all_stop_world_times_ms(new NumberSeq()),
    86   _all_yield_times_ms(new NumberSeq()),
    88   _all_mod_union_times_ms(new NumberSeq()),
    90   _summary(new Summary()),
    91   _abandoned_summary(new AbandonedSummary()),
    93 #ifndef PRODUCT
    94   _cur_clear_ct_time_ms(0.0),
    95   _min_clear_cc_time_ms(-1.0),
    96   _max_clear_cc_time_ms(-1.0),
    97   _cur_clear_cc_time_ms(0.0),
    98   _cum_clear_cc_time_ms(0.0),
    99   _num_cc_clears(0L),
   100 #endif
   102   _region_num_young(0),
   103   _region_num_tenured(0),
   104   _prev_region_num_young(0),
   105   _prev_region_num_tenured(0),
   107   _aux_num(10),
   108   _all_aux_times_ms(new NumberSeq[_aux_num]),
   109   _cur_aux_start_times_ms(new double[_aux_num]),
   110   _cur_aux_times_ms(new double[_aux_num]),
   111   _cur_aux_times_set(new bool[_aux_num]),
   113   _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   114   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   115   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   117   // <NEW PREDICTION>
   119   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   120   _prev_collection_pause_end_ms(0.0),
   121   _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   122   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   123   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   124   _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
   125   _partially_young_cards_per_entry_ratio_seq(
   126                                          new TruncatedSeq(TruncatedSeqLength)),
   127   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   128   _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   129   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   130   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
   131   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   132   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   133   _non_young_other_cost_per_region_ms_seq(
   134                                          new TruncatedSeq(TruncatedSeqLength)),
   136   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   137   _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   138   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
   140   _pause_time_target_ms((double) MaxGCPauseMillis),
   142   // </NEW PREDICTION>
   144   _in_young_gc_mode(false),
   145   _full_young_gcs(true),
   146   _full_young_pause_num(0),
   147   _partial_young_pause_num(0),
   149   _during_marking(false),
   150   _in_marking_window(false),
   151   _in_marking_window_im(false),
   153   _known_garbage_ratio(0.0),
   154   _known_garbage_bytes(0),
   156   _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
   157   _target_pause_time_ms(-1.0),
   159    _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
   161   _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
   162   _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
   164   _recent_avg_pause_time_ratio(0.0),
   165   _num_markings(0),
   166   _n_marks(0),
   167   _n_pauses_at_mark_end(0),
   169   _all_full_gc_times_ms(new NumberSeq()),
   171   // G1PausesBtwnConcMark defaults to -1
   172   // so the hack is to do the cast  QQQ FIXME
   173   _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
   174   _n_marks_since_last_pause(0),
   175   _initiate_conc_mark_if_possible(false),
   176   _during_initial_mark_pause(false),
   177   _should_revert_to_full_young_gcs(false),
   178   _last_full_young_gc(false),
   180   _prev_collection_pause_used_at_end_bytes(0),
   182   _collection_set(NULL),
   183   _collection_set_size(0),
   184   _collection_set_bytes_used_before(0),
   186   // Incremental CSet attributes
   187   _inc_cset_build_state(Inactive),
   188   _inc_cset_head(NULL),
   189   _inc_cset_tail(NULL),
   190   _inc_cset_size(0),
   191   _inc_cset_young_index(0),
   192   _inc_cset_bytes_used_before(0),
   193   _inc_cset_max_finger(NULL),
   194   _inc_cset_recorded_young_bytes(0),
   195   _inc_cset_recorded_rs_lengths(0),
   196   _inc_cset_predicted_elapsed_time_ms(0.0),
   197   _inc_cset_predicted_bytes_to_copy(0),
   199 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
   200 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
   201 #endif // _MSC_VER
   203   _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
   204                                                  G1YoungSurvRateNumRegionsSummary)),
   205   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
   206                                               G1YoungSurvRateNumRegionsSummary)),
   207   // add here any more surv rate groups
   208   _recorded_survivor_regions(0),
   209   _recorded_survivor_head(NULL),
   210   _recorded_survivor_tail(NULL),
   211   _survivors_age_table(true),
   213   _gc_overhead_perc(0.0)
   215 {
   216   // Set up the region size and associated fields. Given that the
   217   // policy is created before the heap, we have to set this up here,
   218   // so it's done as soon as possible.
   219   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
   220   HeapRegionRemSet::setup_remset_size();
   222   // Verify PLAB sizes
   223   const uint region_size = HeapRegion::GrainWords;
   224   if (YoungPLABSize > region_size || OldPLABSize > region_size) {
   225     char buffer[128];
   226     jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
   227                  OldPLABSize > region_size ? "Old" : "Young", region_size);
   228     vm_exit_during_initialization(buffer);
   229   }
   231   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
   232   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
   234   _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
   235   _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
   237   _par_last_update_rs_start_times_ms = new double[_parallel_gc_threads];
   238   _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
   239   _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
   241   _par_last_scan_rs_start_times_ms = new double[_parallel_gc_threads];
   242   _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
   243   _par_last_scan_new_refs_times_ms = new double[_parallel_gc_threads];
   245   _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
   247   _par_last_termination_times_ms = new double[_parallel_gc_threads];
   249   // start conservatively
   250   _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
   252   // <NEW PREDICTION>
   254   int index;
   255   if (ParallelGCThreads == 0)
   256     index = 0;
   257   else if (ParallelGCThreads > 8)
   258     index = 7;
   259   else
   260     index = ParallelGCThreads - 1;
   262   _pending_card_diff_seq->add(0.0);
   263   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
   264   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
   265   _fully_young_cards_per_entry_ratio_seq->add(
   266                             fully_young_cards_per_entry_ratio_defaults[index]);
   267   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
   268   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
   269   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
   270   _young_other_cost_per_region_ms_seq->add(
   271                                young_other_cost_per_region_ms_defaults[index]);
   272   _non_young_other_cost_per_region_ms_seq->add(
   273                            non_young_other_cost_per_region_ms_defaults[index]);
   275   // </NEW PREDICTION>
   277   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
   278   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
   279   guarantee(max_gc_time < time_slice,
   280             "Max GC time should not be greater than the time slice");
   281   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
   282   _sigma = (double) G1ConfidencePercent / 100.0;
   284   // start conservatively (around 50ms is about right)
   285   _concurrent_mark_init_times_ms->add(0.05);
   286   _concurrent_mark_remark_times_ms->add(0.05);
   287   _concurrent_mark_cleanup_times_ms->add(0.20);
   288   _tenuring_threshold = MaxTenuringThreshold;
   290   // if G1FixedSurvivorSpaceSize is 0 which means the size is not
   291   // fixed, then _max_survivor_regions will be calculated at
   292   // calculate_young_list_target_length during initialization
   293   _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
   295   assert(GCTimeRatio > 0,
   296          "we should have set it to a default value set_g1_gc_flags() "
   297          "if a user set it to 0");
   298   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
   300   initialize_all();
   301 }
   303 // Increment "i", mod "len"
   304 static void inc_mod(int& i, int len) {
   305   i++; if (i == len) i = 0;
   306 }
   308 void G1CollectorPolicy::initialize_flags() {
   309   set_min_alignment(HeapRegion::GrainBytes);
   310   set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
   311   if (SurvivorRatio < 1) {
   312     vm_exit_during_initialization("Invalid survivor ratio specified");
   313   }
   314   CollectorPolicy::initialize_flags();
   315 }
   317 // The easiest way to deal with the parsing of the NewSize /
   318 // MaxNewSize / etc. parameteres is to re-use the code in the
   319 // TwoGenerationCollectorPolicy class. This is similar to what
   320 // ParallelScavenge does with its GenerationSizer class (see
   321 // ParallelScavengeHeap::initialize()). We might change this in the
   322 // future, but it's a good start.
   323 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
   324   size_t size_to_region_num(size_t byte_size) {
   325     return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
   326   }
   328 public:
   329   G1YoungGenSizer() {
   330     initialize_flags();
   331     initialize_size_info();
   332   }
   334   size_t min_young_region_num() {
   335     return size_to_region_num(_min_gen0_size);
   336   }
   337   size_t initial_young_region_num() {
   338     return size_to_region_num(_initial_gen0_size);
   339   }
   340   size_t max_young_region_num() {
   341     return size_to_region_num(_max_gen0_size);
   342   }
   343 };
   345 void G1CollectorPolicy::init() {
   346   // Set aside an initial future to_space.
   347   _g1 = G1CollectedHeap::heap();
   349   assert(Heap_lock->owned_by_self(), "Locking discipline.");
   351   initialize_gc_policy_counters();
   353   if (G1Gen) {
   354     _in_young_gc_mode = true;
   356     G1YoungGenSizer sizer;
   357     size_t initial_region_num = sizer.initial_young_region_num();
   359     if (UseAdaptiveSizePolicy) {
   360       set_adaptive_young_list_length(true);
   361       _young_list_fixed_length = 0;
   362     } else {
   363       set_adaptive_young_list_length(false);
   364       _young_list_fixed_length = initial_region_num;
   365     }
   366     _free_regions_at_end_of_collection = _g1->free_regions();
   367     calculate_young_list_min_length();
   368     guarantee( _young_list_min_length == 0, "invariant, not enough info" );
   369     calculate_young_list_target_length();
   370   } else {
   371      _young_list_fixed_length = 0;
   372     _in_young_gc_mode = false;
   373   }
   375   // We may immediately start allocating regions and placing them on the
   376   // collection set list. Initialize the per-collection set info
   377   start_incremental_cset_building();
   378 }
   380 // Create the jstat counters for the policy.
   381 void G1CollectorPolicy::initialize_gc_policy_counters()
   382 {
   383   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
   384 }
   386 void G1CollectorPolicy::calculate_young_list_min_length() {
   387   _young_list_min_length = 0;
   389   if (!adaptive_young_list_length())
   390     return;
   392   if (_alloc_rate_ms_seq->num() > 3) {
   393     double now_sec = os::elapsedTime();
   394     double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
   395     double alloc_rate_ms = predict_alloc_rate_ms();
   396     int min_regions = (int) ceil(alloc_rate_ms * when_ms);
   397     int current_region_num = (int) _g1->young_list()->length();
   398     _young_list_min_length = min_regions + current_region_num;
   399   }
   400 }
   402 void G1CollectorPolicy::calculate_young_list_target_length() {
   403   if (adaptive_young_list_length()) {
   404     size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
   405     calculate_young_list_target_length(rs_lengths);
   406   } else {
   407     if (full_young_gcs())
   408       _young_list_target_length = _young_list_fixed_length;
   409     else
   410       _young_list_target_length = _young_list_fixed_length / 2;
   412     _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);
   413   }
   414   calculate_survivors_policy();
   415 }
   417 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
   418   guarantee( adaptive_young_list_length(), "pre-condition" );
   419   guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
   421   double start_time_sec = os::elapsedTime();
   422   size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
   423   min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
   424   size_t reserve_regions =
   425     (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
   427   if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
   428     // we are in fully-young mode and there are free regions in the heap
   430     double survivor_regions_evac_time =
   431         predict_survivor_regions_evac_time();
   433     double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
   434     size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
   435     size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
   436     size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
   437     double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
   438                           + survivor_regions_evac_time;
   440     // the result
   441     size_t final_young_length = 0;
   443     size_t init_free_regions =
   444       MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
   446     // if we're still under the pause target...
   447     if (base_time_ms <= target_pause_time_ms) {
   448       // We make sure that the shortest young length that makes sense
   449       // fits within the target pause time.
   450       size_t min_young_length = 1;
   452       if (predict_will_fit(min_young_length, base_time_ms,
   453                                      init_free_regions, target_pause_time_ms)) {
   454         // The shortest young length will fit within the target pause time;
   455         // we'll now check whether the absolute maximum number of young
   456         // regions will fit in the target pause time. If not, we'll do
   457         // a binary search between min_young_length and max_young_length
   458         size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
   459         size_t max_young_length = abs_max_young_length;
   461         if (max_young_length > min_young_length) {
   462           // Let's check if the initial max young length will fit within the
   463           // target pause. If so then there is no need to search for a maximal
   464           // young length - we'll return the initial maximum
   466           if (predict_will_fit(max_young_length, base_time_ms,
   467                                 init_free_regions, target_pause_time_ms)) {
   468             // The maximum young length will satisfy the target pause time.
   469             // We are done so set min young length to this maximum length.
   470             // The code after the loop will then set final_young_length using
   471             // the value cached in the minimum length.
   472             min_young_length = max_young_length;
   473           } else {
   474             // The maximum possible number of young regions will not fit within
   475             // the target pause time so let's search....
   477             size_t diff = (max_young_length - min_young_length) / 2;
   478             max_young_length = min_young_length + diff;
   480             while (max_young_length > min_young_length) {
   481               if (predict_will_fit(max_young_length, base_time_ms,
   482                                         init_free_regions, target_pause_time_ms)) {
   484                 // The current max young length will fit within the target
   485                 // pause time. Note we do not exit the loop here. By setting
   486                 // min = max, and then increasing the max below means that
   487                 // we will continue searching for an upper bound in the
   488                 // range [max..max+diff]
   489                 min_young_length = max_young_length;
   490               }
   491               diff = (max_young_length - min_young_length) / 2;
   492               max_young_length = min_young_length + diff;
   493             }
   494             // the above loop found a maximal young length that will fit
   495             // within the target pause time.
   496           }
   497           assert(min_young_length <= abs_max_young_length, "just checking");
   498         }
   499         final_young_length = min_young_length;
   500       }
   501     }
   502     // and we're done!
   504     // we should have at least one region in the target young length
   505     _young_list_target_length =
   506         MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);
   508     // let's keep an eye of how long we spend on this calculation
   509     // right now, I assume that we'll print it when we need it; we
   510     // should really adde it to the breakdown of a pause
   511     double end_time_sec = os::elapsedTime();
   512     double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
   514 #ifdef TRACE_CALC_YOUNG_LENGTH
   515     // leave this in for debugging, just in case
   516     gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
   517                            "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
   518                            target_pause_time_ms,
   519                            _young_list_target_length
   520                            elapsed_time_ms,
   521                            full_young_gcs() ? "full" : "partial",
   522                            during_initial_mark_pause() ? " i-m" : "",
   523                            _in_marking_window,
   524                            _in_marking_window_im);
   525 #endif // TRACE_CALC_YOUNG_LENGTH
   527     if (_young_list_target_length < _young_list_min_length) {
   528       // bummer; this means that, if we do a pause when the maximal
   529       // length dictates, we'll violate the pause spacing target (the
   530       // min length was calculate based on the application's current
   531       // alloc rate);
   533       // so, we have to bite the bullet, and allocate the minimum
   534       // number. We'll violate our target, but we just can't meet it.
   536 #ifdef TRACE_CALC_YOUNG_LENGTH
   537       // leave this in for debugging, just in case
   538       gclog_or_tty->print_cr("adjusted target length from "
   539                              SIZE_FORMAT " to " SIZE_FORMAT,
   540                              _young_list_target_length, _young_list_min_length);
   541 #endif // TRACE_CALC_YOUNG_LENGTH
   543       _young_list_target_length = _young_list_min_length;
   544     }
   545   } else {
   546     // we are in a partially-young mode or we've run out of regions (due
   547     // to evacuation failure)
   549 #ifdef TRACE_CALC_YOUNG_LENGTH
   550     // leave this in for debugging, just in case
   551     gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
   552                            _young_list_min_length);
   553 #endif // TRACE_CALC_YOUNG_LENGTH
   554     // we'll do the pause as soon as possible by choosing the minimum
   555     _young_list_target_length =
   556       MAX2(_young_list_min_length, (size_t) 1);
   557   }
   559   _rs_lengths_prediction = rs_lengths;
   560 }
   562 // This is used by: calculate_young_list_target_length(rs_length). It
   563 // returns true iff:
   564 //   the predicted pause time for the given young list will not overflow
   565 //   the target pause time
   566 // and:
   567 //   the predicted amount of surviving data will not overflow the
   568 //   the amount of free space available for survivor regions.
   569 //
   570 bool
   571 G1CollectorPolicy::predict_will_fit(size_t young_length,
   572                                     double base_time_ms,
   573                                     size_t init_free_regions,
   574                                     double target_pause_time_ms) {
   576   if (young_length >= init_free_regions)
   577     // end condition 1: not enough space for the young regions
   578     return false;
   580   double accum_surv_rate_adj = 0.0;
   581   double accum_surv_rate =
   582     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
   584   size_t bytes_to_copy =
   585     (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   587   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   589   double young_other_time_ms =
   590                        predict_young_other_time_ms(young_length);
   592   double pause_time_ms =
   593                    base_time_ms + copy_time_ms + young_other_time_ms;
   595   if (pause_time_ms > target_pause_time_ms)
   596     // end condition 2: over the target pause time
   597     return false;
   599   size_t free_bytes =
   600                  (init_free_regions - young_length) * HeapRegion::GrainBytes;
   602   if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
   603     // end condition 3: out of to-space (conservatively)
   604     return false;
   606   // success!
   607   return true;
   608 }
   610 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
   611   double survivor_regions_evac_time = 0.0;
   612   for (HeapRegion * r = _recorded_survivor_head;
   613        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
   614        r = r->get_next_young_region()) {
   615     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
   616   }
   617   return survivor_regions_evac_time;
   618 }
   620 void G1CollectorPolicy::check_prediction_validity() {
   621   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
   623   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
   624   if (rs_lengths > _rs_lengths_prediction) {
   625     // add 10% to avoid having to recalculate often
   626     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
   627     calculate_young_list_target_length(rs_lengths_prediction);
   628   }
   629 }
   631 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
   632                                                bool is_tlab,
   633                                                bool* gc_overhead_limit_was_exceeded) {
   634   guarantee(false, "Not using this policy feature yet.");
   635   return NULL;
   636 }
   638 // This method controls how a collector handles one or more
   639 // of its generations being fully allocated.
   640 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
   641                                                        bool is_tlab) {
   642   guarantee(false, "Not using this policy feature yet.");
   643   return NULL;
   644 }
   647 #ifndef PRODUCT
   648 bool G1CollectorPolicy::verify_young_ages() {
   649   HeapRegion* head = _g1->young_list()->first_region();
   650   return
   651     verify_young_ages(head, _short_lived_surv_rate_group);
   652   // also call verify_young_ages on any additional surv rate groups
   653 }
   655 bool
   656 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
   657                                      SurvRateGroup *surv_rate_group) {
   658   guarantee( surv_rate_group != NULL, "pre-condition" );
   660   const char* name = surv_rate_group->name();
   661   bool ret = true;
   662   int prev_age = -1;
   664   for (HeapRegion* curr = head;
   665        curr != NULL;
   666        curr = curr->get_next_young_region()) {
   667     SurvRateGroup* group = curr->surv_rate_group();
   668     if (group == NULL && !curr->is_survivor()) {
   669       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
   670       ret = false;
   671     }
   673     if (surv_rate_group == group) {
   674       int age = curr->age_in_surv_rate_group();
   676       if (age < 0) {
   677         gclog_or_tty->print_cr("## %s: encountered negative age", name);
   678         ret = false;
   679       }
   681       if (age <= prev_age) {
   682         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
   683                                "(%d, %d)", name, age, prev_age);
   684         ret = false;
   685       }
   686       prev_age = age;
   687     }
   688   }
   690   return ret;
   691 }
   692 #endif // PRODUCT
   694 void G1CollectorPolicy::record_full_collection_start() {
   695   _cur_collection_start_sec = os::elapsedTime();
   696   // Release the future to-space so that it is available for compaction into.
   697   _g1->set_full_collection();
   698 }
   700 void G1CollectorPolicy::record_full_collection_end() {
   701   // Consider this like a collection pause for the purposes of allocation
   702   // since last pause.
   703   double end_sec = os::elapsedTime();
   704   double full_gc_time_sec = end_sec - _cur_collection_start_sec;
   705   double full_gc_time_ms = full_gc_time_sec * 1000.0;
   707   _all_full_gc_times_ms->add(full_gc_time_ms);
   709   update_recent_gc_times(end_sec, full_gc_time_ms);
   711   _g1->clear_full_collection();
   713   // "Nuke" the heuristics that control the fully/partially young GC
   714   // transitions and make sure we start with fully young GCs after the
   715   // Full GC.
   716   set_full_young_gcs(true);
   717   _last_full_young_gc = false;
   718   _should_revert_to_full_young_gcs = false;
   719   clear_initiate_conc_mark_if_possible();
   720   clear_during_initial_mark_pause();
   721   _known_garbage_bytes = 0;
   722   _known_garbage_ratio = 0.0;
   723   _in_marking_window = false;
   724   _in_marking_window_im = false;
   726   _short_lived_surv_rate_group->start_adding_regions();
   727   // also call this on any additional surv rate groups
   729   record_survivor_regions(0, NULL, NULL);
   731   _prev_region_num_young   = _region_num_young;
   732   _prev_region_num_tenured = _region_num_tenured;
   734   _free_regions_at_end_of_collection = _g1->free_regions();
   735   // Reset survivors SurvRateGroup.
   736   _survivor_surv_rate_group->reset();
   737   calculate_young_list_min_length();
   738   calculate_young_list_target_length();
   739  }
   741 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
   742   _bytes_in_to_space_before_gc += bytes;
   743 }
   745 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
   746   _bytes_in_to_space_after_gc += bytes;
   747 }
   749 void G1CollectorPolicy::record_stop_world_start() {
   750   _stop_world_start = os::elapsedTime();
   751 }
   753 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
   754                                                       size_t start_used) {
   755   if (PrintGCDetails) {
   756     gclog_or_tty->stamp(PrintGCTimeStamps);
   757     gclog_or_tty->print("[GC pause");
   758     if (in_young_gc_mode())
   759       gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
   760   }
   762   assert(_g1->used_regions() == _g1->recalculate_used_regions(),
   763          "sanity");
   764   assert(_g1->used() == _g1->recalculate_used(), "sanity");
   766   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
   767   _all_stop_world_times_ms->add(s_w_t_ms);
   768   _stop_world_start = 0.0;
   770   _cur_collection_start_sec = start_time_sec;
   771   _cur_collection_pause_used_at_start_bytes = start_used;
   772   _cur_collection_pause_used_regions_at_start = _g1->used_regions();
   773   _pending_cards = _g1->pending_card_num();
   774   _max_pending_cards = _g1->max_pending_card_num();
   776   _bytes_in_to_space_before_gc = 0;
   777   _bytes_in_to_space_after_gc = 0;
   778   _bytes_in_collection_set_before_gc = 0;
   780 #ifdef DEBUG
   781   // initialise these to something well known so that we can spot
   782   // if they are not set properly
   784   for (int i = 0; i < _parallel_gc_threads; ++i) {
   785     _par_last_ext_root_scan_times_ms[i] = -666.0;
   786     _par_last_mark_stack_scan_times_ms[i] = -666.0;
   787     _par_last_update_rs_start_times_ms[i] = -666.0;
   788     _par_last_update_rs_times_ms[i] = -666.0;
   789     _par_last_update_rs_processed_buffers[i] = -666.0;
   790     _par_last_scan_rs_start_times_ms[i] = -666.0;
   791     _par_last_scan_rs_times_ms[i] = -666.0;
   792     _par_last_scan_new_refs_times_ms[i] = -666.0;
   793     _par_last_obj_copy_times_ms[i] = -666.0;
   794     _par_last_termination_times_ms[i] = -666.0;
   795   }
   796 #endif
   798   for (int i = 0; i < _aux_num; ++i) {
   799     _cur_aux_times_ms[i] = 0.0;
   800     _cur_aux_times_set[i] = false;
   801   }
   803   _satb_drain_time_set = false;
   804   _last_satb_drain_processed_buffers = -1;
   806   if (in_young_gc_mode())
   807     _last_young_gc_full = false;
   809   // do that for any other surv rate groups
   810   _short_lived_surv_rate_group->stop_adding_regions();
   811   _survivors_age_table.clear();
   813   assert( verify_young_ages(), "region age verification" );
   814 }
   816 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
   817   _mark_closure_time_ms = mark_closure_time_ms;
   818 }
   820 void G1CollectorPolicy::record_concurrent_mark_init_start() {
   821   _mark_init_start_sec = os::elapsedTime();
   822   guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
   823 }
   825 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
   826                                                    mark_init_elapsed_time_ms) {
   827   _during_marking = true;
   828   assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
   829   clear_during_initial_mark_pause();
   830   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
   831 }
   833 void G1CollectorPolicy::record_concurrent_mark_init_end() {
   834   double end_time_sec = os::elapsedTime();
   835   double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
   836   _concurrent_mark_init_times_ms->add(elapsed_time_ms);
   837   record_concurrent_mark_init_end_pre(elapsed_time_ms);
   839   _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
   840 }
   842 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
   843   _mark_remark_start_sec = os::elapsedTime();
   844   _during_marking = false;
   845 }
   847 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
   848   double end_time_sec = os::elapsedTime();
   849   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
   850   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
   851   _cur_mark_stop_world_time_ms += elapsed_time_ms;
   852   _prev_collection_pause_end_ms += elapsed_time_ms;
   854   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
   855 }
   857 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
   858   _mark_cleanup_start_sec = os::elapsedTime();
   859 }
   861 void
   862 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
   863                                                       size_t max_live_bytes) {
   864   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
   865   record_concurrent_mark_cleanup_end_work2();
   866 }
   868 void
   869 G1CollectorPolicy::
   870 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
   871                                          size_t max_live_bytes) {
   872   if (_n_marks < 2) _n_marks++;
   873   if (G1PolicyVerbose > 0)
   874     gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
   875                            " (of " SIZE_FORMAT " MB heap).",
   876                            max_live_bytes/M, _g1->capacity()/M);
   877 }
   879 // The important thing about this is that it includes "os::elapsedTime".
   880 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
   881   double end_time_sec = os::elapsedTime();
   882   double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
   883   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
   884   _cur_mark_stop_world_time_ms += elapsed_time_ms;
   885   _prev_collection_pause_end_ms += elapsed_time_ms;
   887   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
   889   _num_markings++;
   891   // We did a marking, so reset the "since_last_mark" variables.
   892   double considerConcMarkCost = 1.0;
   893   // If there are available processors, concurrent activity is free...
   894   if (Threads::number_of_non_daemon_threads() * 2 <
   895       os::active_processor_count()) {
   896     considerConcMarkCost = 0.0;
   897   }
   898   _n_pauses_at_mark_end = _n_pauses;
   899   _n_marks_since_last_pause++;
   900 }
   902 void
   903 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
   904   if (in_young_gc_mode()) {
   905     _should_revert_to_full_young_gcs = false;
   906     _last_full_young_gc = true;
   907     _in_marking_window = false;
   908     if (adaptive_young_list_length())
   909       calculate_young_list_target_length();
   910   }
   911 }
   913 void G1CollectorPolicy::record_concurrent_pause() {
   914   if (_stop_world_start > 0.0) {
   915     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
   916     _all_yield_times_ms->add(yield_ms);
   917   }
   918 }
   920 void G1CollectorPolicy::record_concurrent_pause_end() {
   921 }
   923 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
   924   _cur_CH_strong_roots_end_sec = os::elapsedTime();
   925   _cur_CH_strong_roots_dur_ms =
   926     (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
   927 }
   929 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
   930   _cur_G1_strong_roots_end_sec = os::elapsedTime();
   931   _cur_G1_strong_roots_dur_ms =
   932     (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
   933 }
   935 template<class T>
   936 T sum_of(T* sum_arr, int start, int n, int N) {
   937   T sum = (T)0;
   938   for (int i = 0; i < n; i++) {
   939     int j = (start + i) % N;
   940     sum += sum_arr[j];
   941   }
   942   return sum;
   943 }
   945 void G1CollectorPolicy::print_par_stats (int level,
   946                                          const char* str,
   947                                          double* data,
   948                                          bool summary) {
   949   double min = data[0], max = data[0];
   950   double total = 0.0;
   951   int j;
   952   for (j = 0; j < level; ++j)
   953     gclog_or_tty->print("   ");
   954   gclog_or_tty->print("[%s (ms):", str);
   955   for (uint i = 0; i < ParallelGCThreads; ++i) {
   956     double val = data[i];
   957     if (val < min)
   958       min = val;
   959     if (val > max)
   960       max = val;
   961     total += val;
   962     gclog_or_tty->print("  %3.1lf", val);
   963   }
   964   if (summary) {
   965     gclog_or_tty->print_cr("");
   966     double avg = total / (double) ParallelGCThreads;
   967     gclog_or_tty->print(" ");
   968     for (j = 0; j < level; ++j)
   969       gclog_or_tty->print("   ");
   970     gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
   971                         avg, min, max);
   972   }
   973   gclog_or_tty->print_cr("]");
   974 }
   976 void G1CollectorPolicy::print_par_buffers (int level,
   977                                          const char* str,
   978                                          double* data,
   979                                          bool summary) {
   980   double min = data[0], max = data[0];
   981   double total = 0.0;
   982   int j;
   983   for (j = 0; j < level; ++j)
   984     gclog_or_tty->print("   ");
   985   gclog_or_tty->print("[%s :", str);
   986   for (uint i = 0; i < ParallelGCThreads; ++i) {
   987     double val = data[i];
   988     if (val < min)
   989       min = val;
   990     if (val > max)
   991       max = val;
   992     total += val;
   993     gclog_or_tty->print(" %d", (int) val);
   994   }
   995   if (summary) {
   996     gclog_or_tty->print_cr("");
   997     double avg = total / (double) ParallelGCThreads;
   998     gclog_or_tty->print(" ");
   999     for (j = 0; j < level; ++j)
  1000       gclog_or_tty->print("   ");
  1001     gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
  1002                (int)total, (int)avg, (int)min, (int)max);
  1004   gclog_or_tty->print_cr("]");
  1007 void G1CollectorPolicy::print_stats (int level,
  1008                                      const char* str,
  1009                                      double value) {
  1010   for (int j = 0; j < level; ++j)
  1011     gclog_or_tty->print("   ");
  1012   gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
  1015 void G1CollectorPolicy::print_stats (int level,
  1016                                      const char* str,
  1017                                      int value) {
  1018   for (int j = 0; j < level; ++j)
  1019     gclog_or_tty->print("   ");
  1020   gclog_or_tty->print_cr("[%s: %d]", str, value);
  1023 double G1CollectorPolicy::avg_value (double* data) {
  1024   if (ParallelGCThreads > 0) {
  1025     double ret = 0.0;
  1026     for (uint i = 0; i < ParallelGCThreads; ++i)
  1027       ret += data[i];
  1028     return ret / (double) ParallelGCThreads;
  1029   } else {
  1030     return data[0];
  1034 double G1CollectorPolicy::max_value (double* data) {
  1035   if (ParallelGCThreads > 0) {
  1036     double ret = data[0];
  1037     for (uint i = 1; i < ParallelGCThreads; ++i)
  1038       if (data[i] > ret)
  1039         ret = data[i];
  1040     return ret;
  1041   } else {
  1042     return data[0];
  1046 double G1CollectorPolicy::sum_of_values (double* data) {
  1047   if (ParallelGCThreads > 0) {
  1048     double sum = 0.0;
  1049     for (uint i = 0; i < ParallelGCThreads; i++)
  1050       sum += data[i];
  1051     return sum;
  1052   } else {
  1053     return data[0];
  1057 double G1CollectorPolicy::max_sum (double* data1,
  1058                                    double* data2) {
  1059   double ret = data1[0] + data2[0];
  1061   if (ParallelGCThreads > 0) {
  1062     for (uint i = 1; i < ParallelGCThreads; ++i) {
  1063       double data = data1[i] + data2[i];
  1064       if (data > ret)
  1065         ret = data;
  1068   return ret;
  1071 // Anything below that is considered to be zero
  1072 #define MIN_TIMER_GRANULARITY 0.0000001
  1074 void G1CollectorPolicy::record_collection_pause_end(bool abandoned) {
  1075   double end_time_sec = os::elapsedTime();
  1076   double elapsed_ms = _last_pause_time_ms;
  1077   bool parallel = ParallelGCThreads > 0;
  1078   double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
  1079   size_t rs_size =
  1080     _cur_collection_pause_used_regions_at_start - collection_set_size();
  1081   size_t cur_used_bytes = _g1->used();
  1082   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
  1083   bool last_pause_included_initial_mark = false;
  1084   bool update_stats = !abandoned && !_g1->evacuation_failed();
  1086 #ifndef PRODUCT
  1087   if (G1YoungSurvRateVerbose) {
  1088     gclog_or_tty->print_cr("");
  1089     _short_lived_surv_rate_group->print();
  1090     // do that for any other surv rate groups too
  1092 #endif // PRODUCT
  1094   if (in_young_gc_mode()) {
  1095     last_pause_included_initial_mark = during_initial_mark_pause();
  1096     if (last_pause_included_initial_mark)
  1097       record_concurrent_mark_init_end_pre(0.0);
  1099     size_t min_used_targ =
  1100       (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
  1103     if (!_g1->mark_in_progress() && !_last_full_young_gc) {
  1104       assert(!last_pause_included_initial_mark, "invariant");
  1105       if (cur_used_bytes > min_used_targ &&
  1106           cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
  1107         assert(!during_initial_mark_pause(), "we should not see this here");
  1109         // Note: this might have already been set, if during the last
  1110         // pause we decided to start a cycle but at the beginning of
  1111         // this pause we decided to postpone it. That's OK.
  1112         set_initiate_conc_mark_if_possible();
  1116     _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
  1119   _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
  1120                           end_time_sec, false);
  1122   guarantee(_cur_collection_pause_used_regions_at_start >=
  1123             collection_set_size(),
  1124             "Negative RS size?");
  1126   // This assert is exempted when we're doing parallel collection pauses,
  1127   // because the fragmentation caused by the parallel GC allocation buffers
  1128   // can lead to more memory being used during collection than was used
  1129   // before. Best leave this out until the fragmentation problem is fixed.
  1130   // Pauses in which evacuation failed can also lead to negative
  1131   // collections, since no space is reclaimed from a region containing an
  1132   // object whose evacuation failed.
  1133   // Further, we're now always doing parallel collection.  But I'm still
  1134   // leaving this here as a placeholder for a more precise assertion later.
  1135   // (DLD, 10/05.)
  1136   assert((true || parallel) // Always using GC LABs now.
  1137          || _g1->evacuation_failed()
  1138          || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
  1139          "Negative collection");
  1141   size_t freed_bytes =
  1142     _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
  1143   size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
  1145   double survival_fraction =
  1146     (double)surviving_bytes/
  1147     (double)_collection_set_bytes_used_before;
  1149   _n_pauses++;
  1151   if (update_stats) {
  1152     _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
  1153     _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
  1154     _recent_evac_times_ms->add(evac_ms);
  1155     _recent_pause_times_ms->add(elapsed_ms);
  1157     _recent_rs_sizes->add(rs_size);
  1159     // We exempt parallel collection from this check because Alloc Buffer
  1160     // fragmentation can produce negative collections.  Same with evac
  1161     // failure.
  1162     // Further, we're now always doing parallel collection.  But I'm still
  1163     // leaving this here as a placeholder for a more precise assertion later.
  1164     // (DLD, 10/05.
  1165     assert((true || parallel)
  1166            || _g1->evacuation_failed()
  1167            || surviving_bytes <= _collection_set_bytes_used_before,
  1168            "Or else negative collection!");
  1169     _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
  1170     _recent_CS_bytes_surviving->add(surviving_bytes);
  1172     // this is where we update the allocation rate of the application
  1173     double app_time_ms =
  1174       (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
  1175     if (app_time_ms < MIN_TIMER_GRANULARITY) {
  1176       // This usually happens due to the timer not having the required
  1177       // granularity. Some Linuxes are the usual culprits.
  1178       // We'll just set it to something (arbitrarily) small.
  1179       app_time_ms = 1.0;
  1181     size_t regions_allocated =
  1182       (_region_num_young - _prev_region_num_young) +
  1183       (_region_num_tenured - _prev_region_num_tenured);
  1184     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
  1185     _alloc_rate_ms_seq->add(alloc_rate_ms);
  1186     _prev_region_num_young   = _region_num_young;
  1187     _prev_region_num_tenured = _region_num_tenured;
  1189     double interval_ms =
  1190       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
  1191     update_recent_gc_times(end_time_sec, elapsed_ms);
  1192     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
  1193     if (recent_avg_pause_time_ratio() < 0.0 ||
  1194         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
  1195 #ifndef PRODUCT
  1196       // Dump info to allow post-facto debugging
  1197       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
  1198       gclog_or_tty->print_cr("-------------------------------------------");
  1199       gclog_or_tty->print_cr("Recent GC Times (ms):");
  1200       _recent_gc_times_ms->dump();
  1201       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
  1202       _recent_prev_end_times_for_all_gcs_sec->dump();
  1203       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
  1204                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
  1205       // In debug mode, terminate the JVM if the user wants to debug at this point.
  1206       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
  1207 #endif  // !PRODUCT
  1208       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
  1209       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
  1210       if (_recent_avg_pause_time_ratio < 0.0) {
  1211         _recent_avg_pause_time_ratio = 0.0;
  1212       } else {
  1213         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
  1214         _recent_avg_pause_time_ratio = 1.0;
  1219   if (G1PolicyVerbose > 1) {
  1220     gclog_or_tty->print_cr("   Recording collection pause(%d)", _n_pauses);
  1223   PauseSummary* summary;
  1224   if (abandoned) {
  1225     summary = _abandoned_summary;
  1226   } else {
  1227     summary = _summary;
  1230   double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
  1231   double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
  1232   double update_rs_time = avg_value(_par_last_update_rs_times_ms);
  1233   double update_rs_processed_buffers =
  1234     sum_of_values(_par_last_update_rs_processed_buffers);
  1235   double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
  1236   double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
  1237   double termination_time = avg_value(_par_last_termination_times_ms);
  1239   double parallel_other_time = _cur_collection_par_time_ms -
  1240     (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
  1241      scan_rs_time + obj_copy_time + termination_time);
  1242   if (update_stats) {
  1243     MainBodySummary* body_summary = summary->main_body_summary();
  1244     guarantee(body_summary != NULL, "should not be null!");
  1246     if (_satb_drain_time_set)
  1247       body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
  1248     else
  1249       body_summary->record_satb_drain_time_ms(0.0);
  1250     body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
  1251     body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
  1252     body_summary->record_update_rs_time_ms(update_rs_time);
  1253     body_summary->record_scan_rs_time_ms(scan_rs_time);
  1254     body_summary->record_obj_copy_time_ms(obj_copy_time);
  1255     if (parallel) {
  1256       body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
  1257       body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
  1258       body_summary->record_termination_time_ms(termination_time);
  1259       body_summary->record_parallel_other_time_ms(parallel_other_time);
  1261     body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
  1264   if (G1PolicyVerbose > 1) {
  1265     gclog_or_tty->print_cr("      ET: %10.6f ms           (avg: %10.6f ms)\n"
  1266                            "        CH Strong: %10.6f ms    (avg: %10.6f ms)\n"
  1267                            "        G1 Strong: %10.6f ms    (avg: %10.6f ms)\n"
  1268                            "        Evac:      %10.6f ms    (avg: %10.6f ms)\n"
  1269                            "       ET-RS:  %10.6f ms      (avg: %10.6f ms)\n"
  1270                            "      |RS|: " SIZE_FORMAT,
  1271                            elapsed_ms, recent_avg_time_for_pauses_ms(),
  1272                            _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
  1273                            _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
  1274                            evac_ms, recent_avg_time_for_evac_ms(),
  1275                            scan_rs_time,
  1276                            recent_avg_time_for_pauses_ms() -
  1277                            recent_avg_time_for_G1_strong_ms(),
  1278                            rs_size);
  1280     gclog_or_tty->print_cr("       Used at start: " SIZE_FORMAT"K"
  1281                            "       At end " SIZE_FORMAT "K\n"
  1282                            "       garbage      : " SIZE_FORMAT "K"
  1283                            "       of     " SIZE_FORMAT "K\n"
  1284                            "       survival     : %6.2f%%  (%6.2f%% avg)",
  1285                            _cur_collection_pause_used_at_start_bytes/K,
  1286                            _g1->used()/K, freed_bytes/K,
  1287                            _collection_set_bytes_used_before/K,
  1288                            survival_fraction*100.0,
  1289                            recent_avg_survival_fraction()*100.0);
  1290     gclog_or_tty->print_cr("       Recent %% gc pause time: %6.2f",
  1291                            recent_avg_pause_time_ratio() * 100.0);
  1294   double other_time_ms = elapsed_ms;
  1296   if (!abandoned) {
  1297     if (_satb_drain_time_set)
  1298       other_time_ms -= _cur_satb_drain_time_ms;
  1300     if (parallel)
  1301       other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
  1302     else
  1303       other_time_ms -=
  1304         update_rs_time +
  1305         ext_root_scan_time + mark_stack_scan_time +
  1306         scan_rs_time + obj_copy_time;
  1309   if (PrintGCDetails) {
  1310     gclog_or_tty->print_cr("%s%s, %1.8lf secs]",
  1311                            abandoned ? " (abandoned)" : "",
  1312                            (last_pause_included_initial_mark) ? " (initial-mark)" : "",
  1313                            elapsed_ms / 1000.0);
  1315     if (!abandoned) {
  1316       if (_satb_drain_time_set) {
  1317         print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
  1319       if (_last_satb_drain_processed_buffers >= 0) {
  1320         print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
  1322       if (parallel) {
  1323         print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
  1324         print_par_stats(2, "Update RS (Start)", _par_last_update_rs_start_times_ms, false);
  1325         print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
  1326         print_par_buffers(3, "Processed Buffers",
  1327                           _par_last_update_rs_processed_buffers, true);
  1328         print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
  1329         print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
  1330         print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
  1331         print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
  1332         print_par_stats(2, "Termination", _par_last_termination_times_ms);
  1333         print_stats(2, "Other", parallel_other_time);
  1334         print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
  1335       } else {
  1336         print_stats(1, "Update RS", update_rs_time);
  1337         print_stats(2, "Processed Buffers",
  1338                     (int)update_rs_processed_buffers);
  1339         print_stats(1, "Ext Root Scanning", ext_root_scan_time);
  1340         print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
  1341         print_stats(1, "Scan RS", scan_rs_time);
  1342         print_stats(1, "Object Copying", obj_copy_time);
  1345 #ifndef PRODUCT
  1346     print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
  1347     print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
  1348     print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
  1349     print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
  1350     if (_num_cc_clears > 0) {
  1351       print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
  1353 #endif
  1354     print_stats(1, "Other", other_time_ms);
  1355     print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
  1357     for (int i = 0; i < _aux_num; ++i) {
  1358       if (_cur_aux_times_set[i]) {
  1359         char buffer[96];
  1360         sprintf(buffer, "Aux%d", i);
  1361         print_stats(1, buffer, _cur_aux_times_ms[i]);
  1365   if (PrintGCDetails)
  1366     gclog_or_tty->print("   [");
  1367   if (PrintGC || PrintGCDetails)
  1368     _g1->print_size_transition(gclog_or_tty,
  1369                                _cur_collection_pause_used_at_start_bytes,
  1370                                _g1->used(), _g1->capacity());
  1371   if (PrintGCDetails)
  1372     gclog_or_tty->print_cr("]");
  1374   _all_pause_times_ms->add(elapsed_ms);
  1375   if (update_stats) {
  1376     summary->record_total_time_ms(elapsed_ms);
  1377     summary->record_other_time_ms(other_time_ms);
  1379   for (int i = 0; i < _aux_num; ++i)
  1380     if (_cur_aux_times_set[i])
  1381       _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
  1383   // Reset marks-between-pauses counter.
  1384   _n_marks_since_last_pause = 0;
  1386   // Update the efficiency-since-mark vars.
  1387   double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
  1388   if (elapsed_ms < MIN_TIMER_GRANULARITY) {
  1389     // This usually happens due to the timer not having the required
  1390     // granularity. Some Linuxes are the usual culprits.
  1391     // We'll just set it to something (arbitrarily) small.
  1392     proc_ms = 1.0;
  1394   double cur_efficiency = (double) freed_bytes / proc_ms;
  1396   bool new_in_marking_window = _in_marking_window;
  1397   bool new_in_marking_window_im = false;
  1398   if (during_initial_mark_pause()) {
  1399     new_in_marking_window = true;
  1400     new_in_marking_window_im = true;
  1403   if (in_young_gc_mode()) {
  1404     if (_last_full_young_gc) {
  1405       set_full_young_gcs(false);
  1406       _last_full_young_gc = false;
  1409     if ( !_last_young_gc_full ) {
  1410       if ( _should_revert_to_full_young_gcs ||
  1411            _known_garbage_ratio < 0.05 ||
  1412            (adaptive_young_list_length() &&
  1413            (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
  1414         set_full_young_gcs(true);
  1417     _should_revert_to_full_young_gcs = false;
  1419     if (_last_young_gc_full && !_during_marking)
  1420       _young_gc_eff_seq->add(cur_efficiency);
  1423   _short_lived_surv_rate_group->start_adding_regions();
  1424   // do that for any other surv rate groupsx
  1426   // <NEW PREDICTION>
  1428   if (update_stats) {
  1429     double pause_time_ms = elapsed_ms;
  1431     size_t diff = 0;
  1432     if (_max_pending_cards >= _pending_cards)
  1433       diff = _max_pending_cards - _pending_cards;
  1434     _pending_card_diff_seq->add((double) diff);
  1436     double cost_per_card_ms = 0.0;
  1437     if (_pending_cards > 0) {
  1438       cost_per_card_ms = update_rs_time / (double) _pending_cards;
  1439       _cost_per_card_ms_seq->add(cost_per_card_ms);
  1442     size_t cards_scanned = _g1->cards_scanned();
  1444     double cost_per_entry_ms = 0.0;
  1445     if (cards_scanned > 10) {
  1446       cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
  1447       if (_last_young_gc_full)
  1448         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1449       else
  1450         _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1453     if (_max_rs_lengths > 0) {
  1454       double cards_per_entry_ratio =
  1455         (double) cards_scanned / (double) _max_rs_lengths;
  1456       if (_last_young_gc_full)
  1457         _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1458       else
  1459         _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1462     size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
  1463     if (rs_length_diff >= 0)
  1464       _rs_length_diff_seq->add((double) rs_length_diff);
  1466     size_t copied_bytes = surviving_bytes;
  1467     double cost_per_byte_ms = 0.0;
  1468     if (copied_bytes > 0) {
  1469       cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
  1470       if (_in_marking_window)
  1471         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
  1472       else
  1473         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
  1476     double all_other_time_ms = pause_time_ms -
  1477       (update_rs_time + scan_rs_time + obj_copy_time +
  1478        _mark_closure_time_ms + termination_time);
  1480     double young_other_time_ms = 0.0;
  1481     if (_recorded_young_regions > 0) {
  1482       young_other_time_ms =
  1483         _recorded_young_cset_choice_time_ms +
  1484         _recorded_young_free_cset_time_ms;
  1485       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
  1486                                              (double) _recorded_young_regions);
  1488     double non_young_other_time_ms = 0.0;
  1489     if (_recorded_non_young_regions > 0) {
  1490       non_young_other_time_ms =
  1491         _recorded_non_young_cset_choice_time_ms +
  1492         _recorded_non_young_free_cset_time_ms;
  1494       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
  1495                                          (double) _recorded_non_young_regions);
  1498     double constant_other_time_ms = all_other_time_ms -
  1499       (young_other_time_ms + non_young_other_time_ms);
  1500     _constant_other_time_ms_seq->add(constant_other_time_ms);
  1502     double survival_ratio = 0.0;
  1503     if (_bytes_in_collection_set_before_gc > 0) {
  1504       survival_ratio = (double) bytes_in_to_space_during_gc() /
  1505         (double) _bytes_in_collection_set_before_gc;
  1508     _pending_cards_seq->add((double) _pending_cards);
  1509     _scanned_cards_seq->add((double) cards_scanned);
  1510     _rs_lengths_seq->add((double) _max_rs_lengths);
  1512     double expensive_region_limit_ms =
  1513       (double) MaxGCPauseMillis - predict_constant_other_time_ms();
  1514     if (expensive_region_limit_ms < 0.0) {
  1515       // this means that the other time was predicted to be longer than
  1516       // than the max pause time
  1517       expensive_region_limit_ms = (double) MaxGCPauseMillis;
  1519     _expensive_region_limit_ms = expensive_region_limit_ms;
  1521     if (PREDICTIONS_VERBOSE) {
  1522       gclog_or_tty->print_cr("");
  1523       gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
  1524                     "REGIONS %d %d %d "
  1525                     "PENDING_CARDS %d %d "
  1526                     "CARDS_SCANNED %d %d "
  1527                     "RS_LENGTHS %d %d "
  1528                     "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
  1529                     "SURVIVAL_RATIO %1.6lf %1.6lf "
  1530                     "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
  1531                     "OTHER_YOUNG %1.6lf %1.6lf "
  1532                     "OTHER_NON_YOUNG %1.6lf %1.6lf "
  1533                     "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
  1534                     "ELAPSED %1.6lf %1.6lf ",
  1535                     _cur_collection_start_sec,
  1536                     (!_last_young_gc_full) ? 2 :
  1537                     (last_pause_included_initial_mark) ? 1 : 0,
  1538                     _recorded_region_num,
  1539                     _recorded_young_regions,
  1540                     _recorded_non_young_regions,
  1541                     _predicted_pending_cards, _pending_cards,
  1542                     _predicted_cards_scanned, cards_scanned,
  1543                     _predicted_rs_lengths, _max_rs_lengths,
  1544                     _predicted_rs_update_time_ms, update_rs_time,
  1545                     _predicted_rs_scan_time_ms, scan_rs_time,
  1546                     _predicted_survival_ratio, survival_ratio,
  1547                     _predicted_object_copy_time_ms, obj_copy_time,
  1548                     _predicted_constant_other_time_ms, constant_other_time_ms,
  1549                     _predicted_young_other_time_ms, young_other_time_ms,
  1550                     _predicted_non_young_other_time_ms,
  1551                     non_young_other_time_ms,
  1552                     _vtime_diff_ms, termination_time,
  1553                     _predicted_pause_time_ms, elapsed_ms);
  1556     if (G1PolicyVerbose > 0) {
  1557       gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
  1558                     _predicted_pause_time_ms,
  1559                     (_within_target) ? "within" : "outside",
  1560                     elapsed_ms);
  1565   _in_marking_window = new_in_marking_window;
  1566   _in_marking_window_im = new_in_marking_window_im;
  1567   _free_regions_at_end_of_collection = _g1->free_regions();
  1568   calculate_young_list_min_length();
  1569   calculate_young_list_target_length();
  1571   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
  1572   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
  1573   adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
  1574   // </NEW PREDICTION>
  1576   _target_pause_time_ms = -1.0;
  1579 // <NEW PREDICTION>
  1581 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
  1582                                                      double update_rs_processed_buffers,
  1583                                                      double goal_ms) {
  1584   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  1585   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
  1587   if (G1UseAdaptiveConcRefinement) {
  1588     const int k_gy = 3, k_gr = 6;
  1589     const double inc_k = 1.1, dec_k = 0.9;
  1591     int g = cg1r->green_zone();
  1592     if (update_rs_time > goal_ms) {
  1593       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
  1594     } else {
  1595       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
  1596         g = (int)MAX2(g * inc_k, g + 1.0);
  1599     // Change the refinement threads params
  1600     cg1r->set_green_zone(g);
  1601     cg1r->set_yellow_zone(g * k_gy);
  1602     cg1r->set_red_zone(g * k_gr);
  1603     cg1r->reinitialize_threads();
  1605     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
  1606     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
  1607                                     cg1r->yellow_zone());
  1608     // Change the barrier params
  1609     dcqs.set_process_completed_threshold(processing_threshold);
  1610     dcqs.set_max_completed_queue(cg1r->red_zone());
  1613   int curr_queue_size = dcqs.completed_buffers_num();
  1614   if (curr_queue_size >= cg1r->yellow_zone()) {
  1615     dcqs.set_completed_queue_padding(curr_queue_size);
  1616   } else {
  1617     dcqs.set_completed_queue_padding(0);
  1619   dcqs.notify_if_necessary();
  1622 double
  1623 G1CollectorPolicy::
  1624 predict_young_collection_elapsed_time_ms(size_t adjustment) {
  1625   guarantee( adjustment == 0 || adjustment == 1, "invariant" );
  1627   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  1628   size_t young_num = g1h->young_list()->length();
  1629   if (young_num == 0)
  1630     return 0.0;
  1632   young_num += adjustment;
  1633   size_t pending_cards = predict_pending_cards();
  1634   size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
  1635                       predict_rs_length_diff();
  1636   size_t card_num;
  1637   if (full_young_gcs())
  1638     card_num = predict_young_card_num(rs_lengths);
  1639   else
  1640     card_num = predict_non_young_card_num(rs_lengths);
  1641   size_t young_byte_size = young_num * HeapRegion::GrainBytes;
  1642   double accum_yg_surv_rate =
  1643     _short_lived_surv_rate_group->accum_surv_rate(adjustment);
  1645   size_t bytes_to_copy =
  1646     (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
  1648   return
  1649     predict_rs_update_time_ms(pending_cards) +
  1650     predict_rs_scan_time_ms(card_num) +
  1651     predict_object_copy_time_ms(bytes_to_copy) +
  1652     predict_young_other_time_ms(young_num) +
  1653     predict_constant_other_time_ms();
  1656 double
  1657 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
  1658   size_t rs_length = predict_rs_length_diff();
  1659   size_t card_num;
  1660   if (full_young_gcs())
  1661     card_num = predict_young_card_num(rs_length);
  1662   else
  1663     card_num = predict_non_young_card_num(rs_length);
  1664   return predict_base_elapsed_time_ms(pending_cards, card_num);
  1667 double
  1668 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
  1669                                                 size_t scanned_cards) {
  1670   return
  1671     predict_rs_update_time_ms(pending_cards) +
  1672     predict_rs_scan_time_ms(scanned_cards) +
  1673     predict_constant_other_time_ms();
  1676 double
  1677 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
  1678                                                   bool young) {
  1679   size_t rs_length = hr->rem_set()->occupied();
  1680   size_t card_num;
  1681   if (full_young_gcs())
  1682     card_num = predict_young_card_num(rs_length);
  1683   else
  1684     card_num = predict_non_young_card_num(rs_length);
  1685   size_t bytes_to_copy = predict_bytes_to_copy(hr);
  1687   double region_elapsed_time_ms =
  1688     predict_rs_scan_time_ms(card_num) +
  1689     predict_object_copy_time_ms(bytes_to_copy);
  1691   if (young)
  1692     region_elapsed_time_ms += predict_young_other_time_ms(1);
  1693   else
  1694     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
  1696   return region_elapsed_time_ms;
  1699 size_t
  1700 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
  1701   size_t bytes_to_copy;
  1702   if (hr->is_marked())
  1703     bytes_to_copy = hr->max_live_bytes();
  1704   else {
  1705     guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
  1706                "invariant" );
  1707     int age = hr->age_in_surv_rate_group();
  1708     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
  1709     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
  1712   return bytes_to_copy;
  1715 void
  1716 G1CollectorPolicy::start_recording_regions() {
  1717   _recorded_rs_lengths            = 0;
  1718   _recorded_young_regions         = 0;
  1719   _recorded_non_young_regions     = 0;
  1721 #if PREDICTIONS_VERBOSE
  1722   _recorded_marked_bytes          = 0;
  1723   _recorded_young_bytes           = 0;
  1724   _predicted_bytes_to_copy        = 0;
  1725   _predicted_rs_lengths           = 0;
  1726   _predicted_cards_scanned        = 0;
  1727 #endif // PREDICTIONS_VERBOSE
  1730 void
  1731 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
  1732 #if PREDICTIONS_VERBOSE
  1733   if (!young) {
  1734     _recorded_marked_bytes += hr->max_live_bytes();
  1736   _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
  1737 #endif // PREDICTIONS_VERBOSE
  1739   size_t rs_length = hr->rem_set()->occupied();
  1740   _recorded_rs_lengths += rs_length;
  1743 void
  1744 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
  1745   assert(!hr->is_young(), "should not call this");
  1746   ++_recorded_non_young_regions;
  1747   record_cset_region_info(hr, false);
  1750 void
  1751 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
  1752   _recorded_young_regions = n_regions;
  1755 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
  1756 #if PREDICTIONS_VERBOSE
  1757   _recorded_young_bytes = bytes;
  1758 #endif // PREDICTIONS_VERBOSE
  1761 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
  1762   _recorded_rs_lengths = rs_lengths;
  1765 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
  1766   _predicted_bytes_to_copy = bytes;
  1769 void
  1770 G1CollectorPolicy::end_recording_regions() {
  1771   // The _predicted_pause_time_ms field is referenced in code
  1772   // not under PREDICTIONS_VERBOSE. Let's initialize it.
  1773   _predicted_pause_time_ms = -1.0;
  1775 #if PREDICTIONS_VERBOSE
  1776   _predicted_pending_cards = predict_pending_cards();
  1777   _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
  1778   if (full_young_gcs())
  1779     _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
  1780   else
  1781     _predicted_cards_scanned +=
  1782       predict_non_young_card_num(_predicted_rs_lengths);
  1783   _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
  1785   _predicted_rs_update_time_ms =
  1786     predict_rs_update_time_ms(_g1->pending_card_num());
  1787   _predicted_rs_scan_time_ms =
  1788     predict_rs_scan_time_ms(_predicted_cards_scanned);
  1789   _predicted_object_copy_time_ms =
  1790     predict_object_copy_time_ms(_predicted_bytes_to_copy);
  1791   _predicted_constant_other_time_ms =
  1792     predict_constant_other_time_ms();
  1793   _predicted_young_other_time_ms =
  1794     predict_young_other_time_ms(_recorded_young_regions);
  1795   _predicted_non_young_other_time_ms =
  1796     predict_non_young_other_time_ms(_recorded_non_young_regions);
  1798   _predicted_pause_time_ms =
  1799     _predicted_rs_update_time_ms +
  1800     _predicted_rs_scan_time_ms +
  1801     _predicted_object_copy_time_ms +
  1802     _predicted_constant_other_time_ms +
  1803     _predicted_young_other_time_ms +
  1804     _predicted_non_young_other_time_ms;
  1805 #endif // PREDICTIONS_VERBOSE
  1808 void G1CollectorPolicy::check_if_region_is_too_expensive(double
  1809                                                            predicted_time_ms) {
  1810   // I don't think we need to do this when in young GC mode since
  1811   // marking will be initiated next time we hit the soft limit anyway...
  1812   if (predicted_time_ms > _expensive_region_limit_ms) {
  1813     if (!in_young_gc_mode()) {
  1814         set_full_young_gcs(true);
  1815         // We might want to do something different here. However,
  1816         // right now we don't support the non-generational G1 mode
  1817         // (and in fact we are planning to remove the associated code,
  1818         // see CR 6814390). So, let's leave it as is and this will be
  1819         // removed some time in the future
  1820         ShouldNotReachHere();
  1821         set_during_initial_mark_pause();
  1822     } else
  1823       // no point in doing another partial one
  1824       _should_revert_to_full_young_gcs = true;
  1828 // </NEW PREDICTION>
  1831 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
  1832                                                double elapsed_ms) {
  1833   _recent_gc_times_ms->add(elapsed_ms);
  1834   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
  1835   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
  1838 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
  1839   if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
  1840   else return _recent_pause_times_ms->avg();
  1843 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
  1844   if (_recent_CH_strong_roots_times_ms->num() == 0)
  1845     return (double)MaxGCPauseMillis/3.0;
  1846   else return _recent_CH_strong_roots_times_ms->avg();
  1849 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
  1850   if (_recent_G1_strong_roots_times_ms->num() == 0)
  1851     return (double)MaxGCPauseMillis/3.0;
  1852   else return _recent_G1_strong_roots_times_ms->avg();
  1855 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
  1856   if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
  1857   else return _recent_evac_times_ms->avg();
  1860 int G1CollectorPolicy::number_of_recent_gcs() {
  1861   assert(_recent_CH_strong_roots_times_ms->num() ==
  1862          _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
  1863   assert(_recent_G1_strong_roots_times_ms->num() ==
  1864          _recent_evac_times_ms->num(), "Sequence out of sync");
  1865   assert(_recent_evac_times_ms->num() ==
  1866          _recent_pause_times_ms->num(), "Sequence out of sync");
  1867   assert(_recent_pause_times_ms->num() ==
  1868          _recent_CS_bytes_used_before->num(), "Sequence out of sync");
  1869   assert(_recent_CS_bytes_used_before->num() ==
  1870          _recent_CS_bytes_surviving->num(), "Sequence out of sync");
  1871   return _recent_pause_times_ms->num();
  1874 double G1CollectorPolicy::recent_avg_survival_fraction() {
  1875   return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
  1876                                            _recent_CS_bytes_used_before);
  1879 double G1CollectorPolicy::last_survival_fraction() {
  1880   return last_survival_fraction_work(_recent_CS_bytes_surviving,
  1881                                      _recent_CS_bytes_used_before);
  1884 double
  1885 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
  1886                                                      TruncatedSeq* before) {
  1887   assert(surviving->num() == before->num(), "Sequence out of sync");
  1888   if (before->sum() > 0.0) {
  1889       double recent_survival_rate = surviving->sum() / before->sum();
  1890       // We exempt parallel collection from this check because Alloc Buffer
  1891       // fragmentation can produce negative collections.
  1892       // Further, we're now always doing parallel collection.  But I'm still
  1893       // leaving this here as a placeholder for a more precise assertion later.
  1894       // (DLD, 10/05.)
  1895       assert((true || ParallelGCThreads > 0) ||
  1896              _g1->evacuation_failed() ||
  1897              recent_survival_rate <= 1.0, "Or bad frac");
  1898       return recent_survival_rate;
  1899   } else {
  1900     return 1.0; // Be conservative.
  1904 double
  1905 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
  1906                                                TruncatedSeq* before) {
  1907   assert(surviving->num() == before->num(), "Sequence out of sync");
  1908   if (surviving->num() > 0 && before->last() > 0.0) {
  1909     double last_survival_rate = surviving->last() / before->last();
  1910     // We exempt parallel collection from this check because Alloc Buffer
  1911     // fragmentation can produce negative collections.
  1912     // Further, we're now always doing parallel collection.  But I'm still
  1913     // leaving this here as a placeholder for a more precise assertion later.
  1914     // (DLD, 10/05.)
  1915     assert((true || ParallelGCThreads > 0) ||
  1916            last_survival_rate <= 1.0, "Or bad frac");
  1917     return last_survival_rate;
  1918   } else {
  1919     return 1.0;
  1923 static const int survival_min_obs = 5;
  1924 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
  1925 static const double min_survival_rate = 0.1;
  1927 double
  1928 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
  1929                                                            double latest) {
  1930   double res = avg;
  1931   if (number_of_recent_gcs() < survival_min_obs) {
  1932     res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
  1934   res = MAX2(res, latest);
  1935   res = MAX2(res, min_survival_rate);
  1936   // In the parallel case, LAB fragmentation can produce "negative
  1937   // collections"; so can evac failure.  Cap at 1.0
  1938   res = MIN2(res, 1.0);
  1939   return res;
  1942 size_t G1CollectorPolicy::expansion_amount() {
  1943   if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
  1944     // We will double the existing space, or take
  1945     // G1ExpandByPercentOfAvailable % of the available expansion
  1946     // space, whichever is smaller, bounded below by a minimum
  1947     // expansion (unless that's all that's left.)
  1948     const size_t min_expand_bytes = 1*M;
  1949     size_t reserved_bytes = _g1->g1_reserved_obj_bytes();
  1950     size_t committed_bytes = _g1->capacity();
  1951     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
  1952     size_t expand_bytes;
  1953     size_t expand_bytes_via_pct =
  1954       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
  1955     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
  1956     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
  1957     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
  1958     if (G1PolicyVerbose > 1) {
  1959       gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
  1960                  "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
  1961                  "                   Answer = %d.\n",
  1962                  recent_avg_pause_time_ratio(),
  1963                  byte_size_in_proper_unit(committed_bytes),
  1964                  proper_unit_for_byte_size(committed_bytes),
  1965                  byte_size_in_proper_unit(uncommitted_bytes),
  1966                  proper_unit_for_byte_size(uncommitted_bytes),
  1967                  byte_size_in_proper_unit(expand_bytes_via_pct),
  1968                  proper_unit_for_byte_size(expand_bytes_via_pct),
  1969                  byte_size_in_proper_unit(expand_bytes),
  1970                  proper_unit_for_byte_size(expand_bytes));
  1972     return expand_bytes;
  1973   } else {
  1974     return 0;
  1978 void G1CollectorPolicy::note_start_of_mark_thread() {
  1979   _mark_thread_startup_sec = os::elapsedTime();
  1982 class CountCSClosure: public HeapRegionClosure {
  1983   G1CollectorPolicy* _g1_policy;
  1984 public:
  1985   CountCSClosure(G1CollectorPolicy* g1_policy) :
  1986     _g1_policy(g1_policy) {}
  1987   bool doHeapRegion(HeapRegion* r) {
  1988     _g1_policy->_bytes_in_collection_set_before_gc += r->used();
  1989     return false;
  1991 };
  1993 void G1CollectorPolicy::count_CS_bytes_used() {
  1994   CountCSClosure cs_closure(this);
  1995   _g1->collection_set_iterate(&cs_closure);
  1998 static void print_indent(int level) {
  1999   for (int j = 0; j < level+1; ++j)
  2000     gclog_or_tty->print("   ");
  2003 void G1CollectorPolicy::print_summary (int level,
  2004                                        const char* str,
  2005                                        NumberSeq* seq) const {
  2006   double sum = seq->sum();
  2007   print_indent(level);
  2008   gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
  2009                 str, sum / 1000.0, seq->avg());
  2012 void G1CollectorPolicy::print_summary_sd (int level,
  2013                                           const char* str,
  2014                                           NumberSeq* seq) const {
  2015   print_summary(level, str, seq);
  2016   print_indent(level + 5);
  2017   gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
  2018                 seq->num(), seq->sd(), seq->maximum());
  2021 void G1CollectorPolicy::check_other_times(int level,
  2022                                         NumberSeq* other_times_ms,
  2023                                         NumberSeq* calc_other_times_ms) const {
  2024   bool should_print = false;
  2026   double max_sum = MAX2(fabs(other_times_ms->sum()),
  2027                         fabs(calc_other_times_ms->sum()));
  2028   double min_sum = MIN2(fabs(other_times_ms->sum()),
  2029                         fabs(calc_other_times_ms->sum()));
  2030   double sum_ratio = max_sum / min_sum;
  2031   if (sum_ratio > 1.1) {
  2032     should_print = true;
  2033     print_indent(level + 1);
  2034     gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
  2037   double max_avg = MAX2(fabs(other_times_ms->avg()),
  2038                         fabs(calc_other_times_ms->avg()));
  2039   double min_avg = MIN2(fabs(other_times_ms->avg()),
  2040                         fabs(calc_other_times_ms->avg()));
  2041   double avg_ratio = max_avg / min_avg;
  2042   if (avg_ratio > 1.1) {
  2043     should_print = true;
  2044     print_indent(level + 1);
  2045     gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
  2048   if (other_times_ms->sum() < -0.01) {
  2049     print_indent(level + 1);
  2050     gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
  2053   if (other_times_ms->avg() < -0.01) {
  2054     print_indent(level + 1);
  2055     gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
  2058   if (calc_other_times_ms->sum() < -0.01) {
  2059     should_print = true;
  2060     print_indent(level + 1);
  2061     gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
  2064   if (calc_other_times_ms->avg() < -0.01) {
  2065     should_print = true;
  2066     print_indent(level + 1);
  2067     gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
  2070   if (should_print)
  2071     print_summary(level, "Other(Calc)", calc_other_times_ms);
  2074 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
  2075   bool parallel = ParallelGCThreads > 0;
  2076   MainBodySummary*    body_summary = summary->main_body_summary();
  2077   if (summary->get_total_seq()->num() > 0) {
  2078     print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
  2079     if (body_summary != NULL) {
  2080       print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
  2081       if (parallel) {
  2082         print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
  2083         print_summary(2, "Update RS", body_summary->get_update_rs_seq());
  2084         print_summary(2, "Ext Root Scanning",
  2085                       body_summary->get_ext_root_scan_seq());
  2086         print_summary(2, "Mark Stack Scanning",
  2087                       body_summary->get_mark_stack_scan_seq());
  2088         print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
  2089         print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
  2090         print_summary(2, "Termination", body_summary->get_termination_seq());
  2091         print_summary(2, "Other", body_summary->get_parallel_other_seq());
  2093           NumberSeq* other_parts[] = {
  2094             body_summary->get_update_rs_seq(),
  2095             body_summary->get_ext_root_scan_seq(),
  2096             body_summary->get_mark_stack_scan_seq(),
  2097             body_summary->get_scan_rs_seq(),
  2098             body_summary->get_obj_copy_seq(),
  2099             body_summary->get_termination_seq()
  2100           };
  2101           NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
  2102                                         7, other_parts);
  2103           check_other_times(2, body_summary->get_parallel_other_seq(),
  2104                             &calc_other_times_ms);
  2106         print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
  2107         print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
  2108       } else {
  2109         print_summary(1, "Update RS", body_summary->get_update_rs_seq());
  2110         print_summary(1, "Ext Root Scanning",
  2111                       body_summary->get_ext_root_scan_seq());
  2112         print_summary(1, "Mark Stack Scanning",
  2113                       body_summary->get_mark_stack_scan_seq());
  2114         print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
  2115         print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
  2118     print_summary(1, "Other", summary->get_other_seq());
  2120       NumberSeq calc_other_times_ms;
  2121       if (body_summary != NULL) {
  2122         // not abandoned
  2123         if (parallel) {
  2124           // parallel
  2125           NumberSeq* other_parts[] = {
  2126             body_summary->get_satb_drain_seq(),
  2127             body_summary->get_parallel_seq(),
  2128             body_summary->get_clear_ct_seq()
  2129           };
  2130           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2131                                           3, other_parts);
  2132         } else {
  2133           // serial
  2134           NumberSeq* other_parts[] = {
  2135             body_summary->get_satb_drain_seq(),
  2136             body_summary->get_update_rs_seq(),
  2137             body_summary->get_ext_root_scan_seq(),
  2138             body_summary->get_mark_stack_scan_seq(),
  2139             body_summary->get_scan_rs_seq(),
  2140             body_summary->get_obj_copy_seq()
  2141           };
  2142           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2143                                           7, other_parts);
  2145       } else {
  2146         // abandoned
  2147         calc_other_times_ms = NumberSeq();
  2149       check_other_times(1,  summary->get_other_seq(), &calc_other_times_ms);
  2151   } else {
  2152     print_indent(0);
  2153     gclog_or_tty->print_cr("none");
  2155   gclog_or_tty->print_cr("");
  2158 void
  2159 G1CollectorPolicy::print_abandoned_summary(PauseSummary* summary) const {
  2160   bool printed = false;
  2161   if (summary->get_total_seq()->num() > 0) {
  2162     printed = true;
  2163     print_summary(summary);
  2165   if (!printed) {
  2166     print_indent(0);
  2167     gclog_or_tty->print_cr("none");
  2168     gclog_or_tty->print_cr("");
  2172 void G1CollectorPolicy::print_tracing_info() const {
  2173   if (TraceGen0Time) {
  2174     gclog_or_tty->print_cr("ALL PAUSES");
  2175     print_summary_sd(0, "Total", _all_pause_times_ms);
  2176     gclog_or_tty->print_cr("");
  2177     gclog_or_tty->print_cr("");
  2178     gclog_or_tty->print_cr("   Full Young GC Pauses:    %8d", _full_young_pause_num);
  2179     gclog_or_tty->print_cr("   Partial Young GC Pauses: %8d", _partial_young_pause_num);
  2180     gclog_or_tty->print_cr("");
  2182     gclog_or_tty->print_cr("EVACUATION PAUSES");
  2183     print_summary(_summary);
  2185     gclog_or_tty->print_cr("ABANDONED PAUSES");
  2186     print_abandoned_summary(_abandoned_summary);
  2188     gclog_or_tty->print_cr("MISC");
  2189     print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
  2190     print_summary_sd(0, "Yields", _all_yield_times_ms);
  2191     for (int i = 0; i < _aux_num; ++i) {
  2192       if (_all_aux_times_ms[i].num() > 0) {
  2193         char buffer[96];
  2194         sprintf(buffer, "Aux%d", i);
  2195         print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
  2199     size_t all_region_num = _region_num_young + _region_num_tenured;
  2200     gclog_or_tty->print_cr("   New Regions %8d, Young %8d (%6.2lf%%), "
  2201                "Tenured %8d (%6.2lf%%)",
  2202                all_region_num,
  2203                _region_num_young,
  2204                (double) _region_num_young / (double) all_region_num * 100.0,
  2205                _region_num_tenured,
  2206                (double) _region_num_tenured / (double) all_region_num * 100.0);
  2208   if (TraceGen1Time) {
  2209     if (_all_full_gc_times_ms->num() > 0) {
  2210       gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
  2211                  _all_full_gc_times_ms->num(),
  2212                  _all_full_gc_times_ms->sum() / 1000.0);
  2213       gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
  2214       gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
  2215                     _all_full_gc_times_ms->sd(),
  2216                     _all_full_gc_times_ms->maximum());
  2221 void G1CollectorPolicy::print_yg_surv_rate_info() const {
  2222 #ifndef PRODUCT
  2223   _short_lived_surv_rate_group->print_surv_rate_summary();
  2224   // add this call for any other surv rate groups
  2225 #endif // PRODUCT
  2228 bool
  2229 G1CollectorPolicy::should_add_next_region_to_young_list() {
  2230   assert(in_young_gc_mode(), "should be in young GC mode");
  2231   bool ret;
  2232   size_t young_list_length = _g1->young_list()->length();
  2233   size_t young_list_max_length = _young_list_target_length;
  2234   if (G1FixedEdenSize) {
  2235     young_list_max_length -= _max_survivor_regions;
  2237   if (young_list_length < young_list_max_length) {
  2238     ret = true;
  2239     ++_region_num_young;
  2240   } else {
  2241     ret = false;
  2242     ++_region_num_tenured;
  2245   return ret;
  2248 #ifndef PRODUCT
  2249 // for debugging, bit of a hack...
  2250 static char*
  2251 region_num_to_mbs(int length) {
  2252   static char buffer[64];
  2253   double bytes = (double) (length * HeapRegion::GrainBytes);
  2254   double mbs = bytes / (double) (1024 * 1024);
  2255   sprintf(buffer, "%7.2lfMB", mbs);
  2256   return buffer;
  2258 #endif // PRODUCT
  2260 size_t G1CollectorPolicy::max_regions(int purpose) {
  2261   switch (purpose) {
  2262     case GCAllocForSurvived:
  2263       return _max_survivor_regions;
  2264     case GCAllocForTenured:
  2265       return REGIONS_UNLIMITED;
  2266     default:
  2267       ShouldNotReachHere();
  2268       return REGIONS_UNLIMITED;
  2269   };
  2272 // Calculates survivor space parameters.
  2273 void G1CollectorPolicy::calculate_survivors_policy()
  2275   if (G1FixedSurvivorSpaceSize == 0) {
  2276     _max_survivor_regions = _young_list_target_length / SurvivorRatio;
  2277   } else {
  2278     _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
  2281   if (G1FixedTenuringThreshold) {
  2282     _tenuring_threshold = MaxTenuringThreshold;
  2283   } else {
  2284     _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
  2285         HeapRegion::GrainWords * _max_survivor_regions);
  2289 bool
  2290 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t
  2291                                                                word_size) {
  2292   assert(_g1->regions_accounted_for(), "Region leakage!");
  2293   double max_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
  2295   size_t young_list_length = _g1->young_list()->length();
  2296   size_t young_list_max_length = _young_list_target_length;
  2297   if (G1FixedEdenSize) {
  2298     young_list_max_length -= _max_survivor_regions;
  2300   bool reached_target_length = young_list_length >= young_list_max_length;
  2302   if (in_young_gc_mode()) {
  2303     if (reached_target_length) {
  2304       assert( young_list_length > 0 && _g1->young_list()->length() > 0,
  2305               "invariant" );
  2306       _target_pause_time_ms = max_pause_time_ms;
  2307       return true;
  2309   } else {
  2310     guarantee( false, "should not reach here" );
  2313   return false;
  2316 #ifndef PRODUCT
  2317 class HRSortIndexIsOKClosure: public HeapRegionClosure {
  2318   CollectionSetChooser* _chooser;
  2319 public:
  2320   HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
  2321     _chooser(chooser) {}
  2323   bool doHeapRegion(HeapRegion* r) {
  2324     if (!r->continuesHumongous()) {
  2325       assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
  2327     return false;
  2329 };
  2331 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
  2332   HRSortIndexIsOKClosure cl(_collectionSetChooser);
  2333   _g1->heap_region_iterate(&cl);
  2334   return true;
  2336 #endif
  2338 void
  2339 G1CollectorPolicy::decide_on_conc_mark_initiation() {
  2340   // We are about to decide on whether this pause will be an
  2341   // initial-mark pause.
  2343   // First, during_initial_mark_pause() should not be already set. We
  2344   // will set it here if we have to. However, it should be cleared by
  2345   // the end of the pause (it's only set for the duration of an
  2346   // initial-mark pause).
  2347   assert(!during_initial_mark_pause(), "pre-condition");
  2349   if (initiate_conc_mark_if_possible()) {
  2350     // We had noticed on a previous pause that the heap occupancy has
  2351     // gone over the initiating threshold and we should start a
  2352     // concurrent marking cycle. So we might initiate one.
  2354     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
  2355     if (!during_cycle) {
  2356       // The concurrent marking thread is not "during a cycle", i.e.,
  2357       // it has completed the last one. So we can go ahead and
  2358       // initiate a new cycle.
  2360       set_during_initial_mark_pause();
  2362       // And we can now clear initiate_conc_mark_if_possible() as
  2363       // we've already acted on it.
  2364       clear_initiate_conc_mark_if_possible();
  2365     } else {
  2366       // The concurrent marking thread is still finishing up the
  2367       // previous cycle. If we start one right now the two cycles
  2368       // overlap. In particular, the concurrent marking thread might
  2369       // be in the process of clearing the next marking bitmap (which
  2370       // we will use for the next cycle if we start one). Starting a
  2371       // cycle now will be bad given that parts of the marking
  2372       // information might get cleared by the marking thread. And we
  2373       // cannot wait for the marking thread to finish the cycle as it
  2374       // periodically yields while clearing the next marking bitmap
  2375       // and, if it's in a yield point, it's waiting for us to
  2376       // finish. So, at this point we will not start a cycle and we'll
  2377       // let the concurrent marking thread complete the last one.
  2382 void
  2383 G1CollectorPolicy_BestRegionsFirst::
  2384 record_collection_pause_start(double start_time_sec, size_t start_used) {
  2385   G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
  2388 class NextNonCSElemFinder: public HeapRegionClosure {
  2389   HeapRegion* _res;
  2390 public:
  2391   NextNonCSElemFinder(): _res(NULL) {}
  2392   bool doHeapRegion(HeapRegion* r) {
  2393     if (!r->in_collection_set()) {
  2394       _res = r;
  2395       return true;
  2396     } else {
  2397       return false;
  2400   HeapRegion* res() { return _res; }
  2401 };
  2403 class KnownGarbageClosure: public HeapRegionClosure {
  2404   CollectionSetChooser* _hrSorted;
  2406 public:
  2407   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
  2408     _hrSorted(hrSorted)
  2409   {}
  2411   bool doHeapRegion(HeapRegion* r) {
  2412     // We only include humongous regions in collection
  2413     // sets when concurrent mark shows that their contained object is
  2414     // unreachable.
  2416     // Do we have any marking information for this region?
  2417     if (r->is_marked()) {
  2418       // We don't include humongous regions in collection
  2419       // sets because we collect them immediately at the end of a marking
  2420       // cycle.  We also don't include young regions because we *must*
  2421       // include them in the next collection pause.
  2422       if (!r->isHumongous() && !r->is_young()) {
  2423         _hrSorted->addMarkedHeapRegion(r);
  2426     return false;
  2428 };
  2430 class ParKnownGarbageHRClosure: public HeapRegionClosure {
  2431   CollectionSetChooser* _hrSorted;
  2432   jint _marked_regions_added;
  2433   jint _chunk_size;
  2434   jint _cur_chunk_idx;
  2435   jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
  2436   int _worker;
  2437   int _invokes;
  2439   void get_new_chunk() {
  2440     _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
  2441     _cur_chunk_end = _cur_chunk_idx + _chunk_size;
  2443   void add_region(HeapRegion* r) {
  2444     if (_cur_chunk_idx == _cur_chunk_end) {
  2445       get_new_chunk();
  2447     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
  2448     _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
  2449     _marked_regions_added++;
  2450     _cur_chunk_idx++;
  2453 public:
  2454   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
  2455                            jint chunk_size,
  2456                            int worker) :
  2457     _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
  2458     _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
  2459     _invokes(0)
  2460   {}
  2462   bool doHeapRegion(HeapRegion* r) {
  2463     // We only include humongous regions in collection
  2464     // sets when concurrent mark shows that their contained object is
  2465     // unreachable.
  2466     _invokes++;
  2468     // Do we have any marking information for this region?
  2469     if (r->is_marked()) {
  2470       // We don't include humongous regions in collection
  2471       // sets because we collect them immediately at the end of a marking
  2472       // cycle.
  2473       // We also do not include young regions in collection sets
  2474       if (!r->isHumongous() && !r->is_young()) {
  2475         add_region(r);
  2478     return false;
  2480   jint marked_regions_added() { return _marked_regions_added; }
  2481   int invokes() { return _invokes; }
  2482 };
  2484 class ParKnownGarbageTask: public AbstractGangTask {
  2485   CollectionSetChooser* _hrSorted;
  2486   jint _chunk_size;
  2487   G1CollectedHeap* _g1;
  2488 public:
  2489   ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
  2490     AbstractGangTask("ParKnownGarbageTask"),
  2491     _hrSorted(hrSorted), _chunk_size(chunk_size),
  2492     _g1(G1CollectedHeap::heap())
  2493   {}
  2495   void work(int i) {
  2496     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
  2497     // Back to zero for the claim value.
  2498     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
  2499                                          HeapRegion::InitialClaimValue);
  2500     jint regions_added = parKnownGarbageCl.marked_regions_added();
  2501     _hrSorted->incNumMarkedHeapRegions(regions_added);
  2502     if (G1PrintParCleanupStats) {
  2503       gclog_or_tty->print("     Thread %d called %d times, added %d regions to list.\n",
  2504                  i, parKnownGarbageCl.invokes(), regions_added);
  2507 };
  2509 void
  2510 G1CollectorPolicy_BestRegionsFirst::
  2511 record_concurrent_mark_cleanup_end(size_t freed_bytes,
  2512                                    size_t max_live_bytes) {
  2513   double start;
  2514   if (G1PrintParCleanupStats) start = os::elapsedTime();
  2515   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
  2517   _collectionSetChooser->clearMarkedHeapRegions();
  2518   double clear_marked_end;
  2519   if (G1PrintParCleanupStats) {
  2520     clear_marked_end = os::elapsedTime();
  2521     gclog_or_tty->print_cr("  clear marked regions + work1: %8.3f ms.",
  2522                   (clear_marked_end - start)*1000.0);
  2524   if (ParallelGCThreads > 0) {
  2525     const size_t OverpartitionFactor = 4;
  2526     const size_t MinWorkUnit = 8;
  2527     const size_t WorkUnit =
  2528       MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
  2529            MinWorkUnit);
  2530     _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
  2531                                                              WorkUnit);
  2532     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
  2533                                             (int) WorkUnit);
  2534     _g1->workers()->run_task(&parKnownGarbageTask);
  2536     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
  2537            "sanity check");
  2538   } else {
  2539     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
  2540     _g1->heap_region_iterate(&knownGarbagecl);
  2542   double known_garbage_end;
  2543   if (G1PrintParCleanupStats) {
  2544     known_garbage_end = os::elapsedTime();
  2545     gclog_or_tty->print_cr("  compute known garbage: %8.3f ms.",
  2546                   (known_garbage_end - clear_marked_end)*1000.0);
  2548   _collectionSetChooser->sortMarkedHeapRegions();
  2549   double sort_end;
  2550   if (G1PrintParCleanupStats) {
  2551     sort_end = os::elapsedTime();
  2552     gclog_or_tty->print_cr("  sorting: %8.3f ms.",
  2553                   (sort_end - known_garbage_end)*1000.0);
  2556   record_concurrent_mark_cleanup_end_work2();
  2557   double work2_end;
  2558   if (G1PrintParCleanupStats) {
  2559     work2_end = os::elapsedTime();
  2560     gclog_or_tty->print_cr("  work2: %8.3f ms.",
  2561                   (work2_end - sort_end)*1000.0);
  2565 // Add the heap region at the head of the non-incremental collection set
  2566 void G1CollectorPolicy::
  2567 add_to_collection_set(HeapRegion* hr) {
  2568   assert(_inc_cset_build_state == Active, "Precondition");
  2569   assert(!hr->is_young(), "non-incremental add of young region");
  2571   if (G1PrintHeapRegions) {
  2572     gclog_or_tty->print_cr("added region to cset "
  2573                            "%d:["PTR_FORMAT", "PTR_FORMAT"], "
  2574                            "top "PTR_FORMAT", %s",
  2575                            hr->hrs_index(), hr->bottom(), hr->end(),
  2576                            hr->top(), hr->is_young() ? "YOUNG" : "NOT_YOUNG");
  2579   if (_g1->mark_in_progress())
  2580     _g1->concurrent_mark()->registerCSetRegion(hr);
  2582   assert(!hr->in_collection_set(), "should not already be in the CSet");
  2583   hr->set_in_collection_set(true);
  2584   hr->set_next_in_collection_set(_collection_set);
  2585   _collection_set = hr;
  2586   _collection_set_size++;
  2587   _collection_set_bytes_used_before += hr->used();
  2588   _g1->register_region_with_in_cset_fast_test(hr);
  2591 // Initialize the per-collection-set information
  2592 void G1CollectorPolicy::start_incremental_cset_building() {
  2593   assert(_inc_cset_build_state == Inactive, "Precondition");
  2595   _inc_cset_head = NULL;
  2596   _inc_cset_tail = NULL;
  2597   _inc_cset_size = 0;
  2598   _inc_cset_bytes_used_before = 0;
  2600   if (in_young_gc_mode()) {
  2601     _inc_cset_young_index = 0;
  2604   _inc_cset_max_finger = 0;
  2605   _inc_cset_recorded_young_bytes = 0;
  2606   _inc_cset_recorded_rs_lengths = 0;
  2607   _inc_cset_predicted_elapsed_time_ms = 0;
  2608   _inc_cset_predicted_bytes_to_copy = 0;
  2609   _inc_cset_build_state = Active;
  2612 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
  2613   // This routine is used when:
  2614   // * adding survivor regions to the incremental cset at the end of an
  2615   //   evacuation pause,
  2616   // * adding the current allocation region to the incremental cset
  2617   //   when it is retired, and
  2618   // * updating existing policy information for a region in the
  2619   //   incremental cset via young list RSet sampling.
  2620   // Therefore this routine may be called at a safepoint by the
  2621   // VM thread, or in-between safepoints by mutator threads (when
  2622   // retiring the current allocation region) or a concurrent
  2623   // refine thread (RSet sampling).
  2625   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
  2626   size_t used_bytes = hr->used();
  2628   _inc_cset_recorded_rs_lengths += rs_length;
  2629   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
  2631   _inc_cset_bytes_used_before += used_bytes;
  2633   // Cache the values we have added to the aggregated informtion
  2634   // in the heap region in case we have to remove this region from
  2635   // the incremental collection set, or it is updated by the
  2636   // rset sampling code
  2637   hr->set_recorded_rs_length(rs_length);
  2638   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
  2640 #if PREDICTIONS_VERBOSE
  2641   size_t bytes_to_copy = predict_bytes_to_copy(hr);
  2642   _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
  2644   // Record the number of bytes used in this region
  2645   _inc_cset_recorded_young_bytes += used_bytes;
  2647   // Cache the values we have added to the aggregated informtion
  2648   // in the heap region in case we have to remove this region from
  2649   // the incremental collection set, or it is updated by the
  2650   // rset sampling code
  2651   hr->set_predicted_bytes_to_copy(bytes_to_copy);
  2652 #endif // PREDICTIONS_VERBOSE
  2655 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
  2656   // This routine is currently only called as part of the updating of
  2657   // existing policy information for regions in the incremental cset that
  2658   // is performed by the concurrent refine thread(s) as part of young list
  2659   // RSet sampling. Therefore we should not be at a safepoint.
  2661   assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
  2662   assert(hr->is_young(), "it should be");
  2664   size_t used_bytes = hr->used();
  2665   size_t old_rs_length = hr->recorded_rs_length();
  2666   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
  2668   // Subtract the old recorded/predicted policy information for
  2669   // the given heap region from the collection set info.
  2670   _inc_cset_recorded_rs_lengths -= old_rs_length;
  2671   _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
  2673   _inc_cset_bytes_used_before -= used_bytes;
  2675   // Clear the values cached in the heap region
  2676   hr->set_recorded_rs_length(0);
  2677   hr->set_predicted_elapsed_time_ms(0);
  2679 #if PREDICTIONS_VERBOSE
  2680   size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
  2681   _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
  2683   // Subtract the number of bytes used in this region
  2684   _inc_cset_recorded_young_bytes -= used_bytes;
  2686   // Clear the values cached in the heap region
  2687   hr->set_predicted_bytes_to_copy(0);
  2688 #endif // PREDICTIONS_VERBOSE
  2691 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
  2692   // Update the collection set information that is dependent on the new RS length
  2693   assert(hr->is_young(), "Precondition");
  2695   remove_from_incremental_cset_info(hr);
  2696   add_to_incremental_cset_info(hr, new_rs_length);
  2699 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
  2700   assert( hr->is_young(), "invariant");
  2701   assert( hr->young_index_in_cset() == -1, "invariant" );
  2702   assert(_inc_cset_build_state == Active, "Precondition");
  2704   // We need to clear and set the cached recorded/cached collection set
  2705   // information in the heap region here (before the region gets added
  2706   // to the collection set). An individual heap region's cached values
  2707   // are calculated, aggregated with the policy collection set info,
  2708   // and cached in the heap region here (initially) and (subsequently)
  2709   // by the Young List sampling code.
  2711   size_t rs_length = hr->rem_set()->occupied();
  2712   add_to_incremental_cset_info(hr, rs_length);
  2714   HeapWord* hr_end = hr->end();
  2715   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
  2717   assert(!hr->in_collection_set(), "invariant");
  2718   hr->set_in_collection_set(true);
  2719   assert( hr->next_in_collection_set() == NULL, "invariant");
  2721   _inc_cset_size++;
  2722   _g1->register_region_with_in_cset_fast_test(hr);
  2724   hr->set_young_index_in_cset((int) _inc_cset_young_index);
  2725   ++_inc_cset_young_index;
  2728 // Add the region at the RHS of the incremental cset
  2729 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
  2730   // We should only ever be appending survivors at the end of a pause
  2731   assert( hr->is_survivor(), "Logic");
  2733   // Do the 'common' stuff
  2734   add_region_to_incremental_cset_common(hr);
  2736   // Now add the region at the right hand side
  2737   if (_inc_cset_tail == NULL) {
  2738     assert(_inc_cset_head == NULL, "invariant");
  2739     _inc_cset_head = hr;
  2740   } else {
  2741     _inc_cset_tail->set_next_in_collection_set(hr);
  2743   _inc_cset_tail = hr;
  2745   if (G1PrintHeapRegions) {
  2746     gclog_or_tty->print_cr(" added region to incremental cset (RHS) "
  2747                   "%d:["PTR_FORMAT", "PTR_FORMAT"], "
  2748                   "top "PTR_FORMAT", young %s",
  2749                   hr->hrs_index(), hr->bottom(), hr->end(),
  2750                   hr->top(), (hr->is_young()) ? "YES" : "NO");
  2754 // Add the region to the LHS of the incremental cset
  2755 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
  2756   // Survivors should be added to the RHS at the end of a pause
  2757   assert(!hr->is_survivor(), "Logic");
  2759   // Do the 'common' stuff
  2760   add_region_to_incremental_cset_common(hr);
  2762   // Add the region at the left hand side
  2763   hr->set_next_in_collection_set(_inc_cset_head);
  2764   if (_inc_cset_head == NULL) {
  2765     assert(_inc_cset_tail == NULL, "Invariant");
  2766     _inc_cset_tail = hr;
  2768   _inc_cset_head = hr;
  2770   if (G1PrintHeapRegions) {
  2771     gclog_or_tty->print_cr(" added region to incremental cset (LHS) "
  2772                   "%d:["PTR_FORMAT", "PTR_FORMAT"], "
  2773                   "top "PTR_FORMAT", young %s",
  2774                   hr->hrs_index(), hr->bottom(), hr->end(),
  2775                   hr->top(), (hr->is_young()) ? "YES" : "NO");
  2779 #ifndef PRODUCT
  2780 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
  2781   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
  2783   st->print_cr("\nCollection_set:");
  2784   HeapRegion* csr = list_head;
  2785   while (csr != NULL) {
  2786     HeapRegion* next = csr->next_in_collection_set();
  2787     assert(csr->in_collection_set(), "bad CS");
  2788     st->print_cr("  [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
  2789                  "age: %4d, y: %d, surv: %d",
  2790                         csr->bottom(), csr->end(),
  2791                         csr->top(),
  2792                         csr->prev_top_at_mark_start(),
  2793                         csr->next_top_at_mark_start(),
  2794                         csr->top_at_conc_mark_count(),
  2795                         csr->age_in_surv_rate_group_cond(),
  2796                         csr->is_young(),
  2797                         csr->is_survivor());
  2798     csr = next;
  2801 #endif // !PRODUCT
  2803 bool
  2804 G1CollectorPolicy_BestRegionsFirst::choose_collection_set() {
  2805   // Set this here - in case we're not doing young collections.
  2806   double non_young_start_time_sec = os::elapsedTime();
  2808   // The result that this routine will return. This will be set to
  2809   // false if:
  2810   // * we're doing a young or partially young collection and we
  2811   //   have added the youg regions to collection set, or
  2812   // * we add old regions to the collection set.
  2813   bool abandon_collection = true;
  2815   start_recording_regions();
  2817   guarantee(_target_pause_time_ms > -1.0
  2818             NOT_PRODUCT(|| Universe::heap()->gc_cause() == GCCause::_scavenge_alot),
  2819             "_target_pause_time_ms should have been set!");
  2820 #ifndef PRODUCT
  2821   if (_target_pause_time_ms <= -1.0) {
  2822     assert(ScavengeALot && Universe::heap()->gc_cause() == GCCause::_scavenge_alot, "Error");
  2823     _target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
  2825 #endif
  2826   assert(_collection_set == NULL, "Precondition");
  2828   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
  2829   double predicted_pause_time_ms = base_time_ms;
  2831   double target_time_ms = _target_pause_time_ms;
  2832   double time_remaining_ms = target_time_ms - base_time_ms;
  2834   // the 10% and 50% values are arbitrary...
  2835   if (time_remaining_ms < 0.10*target_time_ms) {
  2836     time_remaining_ms = 0.50 * target_time_ms;
  2837     _within_target = false;
  2838   } else {
  2839     _within_target = true;
  2842   // We figure out the number of bytes available for future to-space.
  2843   // For new regions without marking information, we must assume the
  2844   // worst-case of complete survival.  If we have marking information for a
  2845   // region, we can bound the amount of live data.  We can add a number of
  2846   // such regions, as long as the sum of the live data bounds does not
  2847   // exceed the available evacuation space.
  2848   size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
  2850   size_t expansion_bytes =
  2851     _g1->expansion_regions() * HeapRegion::GrainBytes;
  2853   _collection_set_bytes_used_before = 0;
  2854   _collection_set_size = 0;
  2856   // Adjust for expansion and slop.
  2857   max_live_bytes = max_live_bytes + expansion_bytes;
  2859   assert(_g1->regions_accounted_for(), "Region leakage!");
  2861   HeapRegion* hr;
  2862   if (in_young_gc_mode()) {
  2863     double young_start_time_sec = os::elapsedTime();
  2865     if (G1PolicyVerbose > 0) {
  2866       gclog_or_tty->print_cr("Adding %d young regions to the CSet",
  2867                     _g1->young_list()->length());
  2870     _young_cset_length  = 0;
  2871     _last_young_gc_full = full_young_gcs() ? true : false;
  2873     if (_last_young_gc_full)
  2874       ++_full_young_pause_num;
  2875     else
  2876       ++_partial_young_pause_num;
  2878     // The young list is laid with the survivor regions from the previous
  2879     // pause are appended to the RHS of the young list, i.e.
  2880     //   [Newly Young Regions ++ Survivors from last pause].
  2882     hr = _g1->young_list()->first_survivor_region();
  2883     while (hr != NULL) {
  2884       assert(hr->is_survivor(), "badly formed young list");
  2885       hr->set_young();
  2886       hr = hr->get_next_young_region();
  2889     // Clear the fields that point to the survivor list - they are
  2890     // all young now.
  2891     _g1->young_list()->clear_survivors();
  2893     if (_g1->mark_in_progress())
  2894       _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
  2896     _young_cset_length = _inc_cset_young_index;
  2897     _collection_set = _inc_cset_head;
  2898     _collection_set_size = _inc_cset_size;
  2899     _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
  2901     // For young regions in the collection set, we assume the worst
  2902     // case of complete survival
  2903     max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
  2905     time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
  2906     predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
  2908     // The number of recorded young regions is the incremental
  2909     // collection set's current size
  2910     set_recorded_young_regions(_inc_cset_size);
  2911     set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
  2912     set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
  2913 #if PREDICTIONS_VERBOSE
  2914     set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
  2915 #endif // PREDICTIONS_VERBOSE
  2917     if (G1PolicyVerbose > 0) {
  2918       gclog_or_tty->print_cr("  Added " PTR_FORMAT " Young Regions to CS.",
  2919                              _inc_cset_size);
  2920       gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  2921                             max_live_bytes/K);
  2924     assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
  2925     if (_inc_cset_size > 0) {
  2926       assert(_collection_set != NULL, "Invariant");
  2927       abandon_collection = false;
  2930     double young_end_time_sec = os::elapsedTime();
  2931     _recorded_young_cset_choice_time_ms =
  2932       (young_end_time_sec - young_start_time_sec) * 1000.0;
  2934     // We are doing young collections so reset this.
  2935     non_young_start_time_sec = young_end_time_sec;
  2937     // Note we can use either _collection_set_size or
  2938     // _young_cset_length here
  2939     if (_collection_set_size > 0 && _last_young_gc_full) {
  2940       // don't bother adding more regions...
  2941       goto choose_collection_set_end;
  2945   if (!in_young_gc_mode() || !full_young_gcs()) {
  2946     bool should_continue = true;
  2947     NumberSeq seq;
  2948     double avg_prediction = 100000000000000000.0; // something very large
  2950     // Save the current size of the collection set to detect
  2951     // if we actually added any old regions.
  2952     size_t n_young_regions = _collection_set_size;
  2954     do {
  2955       hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
  2956                                                       avg_prediction);
  2957       if (hr != NULL) {
  2958         double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
  2959         time_remaining_ms -= predicted_time_ms;
  2960         predicted_pause_time_ms += predicted_time_ms;
  2961         add_to_collection_set(hr);
  2962         record_non_young_cset_region(hr);
  2963         max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
  2964         if (G1PolicyVerbose > 0) {
  2965           gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  2966                         max_live_bytes/K);
  2968         seq.add(predicted_time_ms);
  2969         avg_prediction = seq.avg() + seq.sd();
  2971       should_continue =
  2972         ( hr != NULL) &&
  2973         ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
  2974           : _collection_set_size < _young_list_fixed_length );
  2975     } while (should_continue);
  2977     if (!adaptive_young_list_length() &&
  2978         _collection_set_size < _young_list_fixed_length)
  2979       _should_revert_to_full_young_gcs  = true;
  2981     if (_collection_set_size > n_young_regions) {
  2982       // We actually added old regions to the collection set
  2983       // so we are not abandoning this collection.
  2984       abandon_collection = false;
  2988 choose_collection_set_end:
  2989   stop_incremental_cset_building();
  2991   count_CS_bytes_used();
  2993   end_recording_regions();
  2995   double non_young_end_time_sec = os::elapsedTime();
  2996   _recorded_non_young_cset_choice_time_ms =
  2997     (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
  2999   return abandon_collection;
  3002 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
  3003   G1CollectorPolicy::record_full_collection_end();
  3004   _collectionSetChooser->updateAfterFullCollection();
  3007 void G1CollectorPolicy_BestRegionsFirst::
  3008 expand_if_possible(size_t numRegions) {
  3009   size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
  3010   _g1->expand(expansion_bytes);
  3013 void G1CollectorPolicy_BestRegionsFirst::
  3014 record_collection_pause_end(bool abandoned) {
  3015   G1CollectorPolicy::record_collection_pause_end(abandoned);
  3016   assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");

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