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

Fri, 16 Apr 2010 08:48:16 -0700

author
apetrusenko
date
Fri, 16 Apr 2010 08:48:16 -0700
changeset 1826
79e419e5ea3b
parent 1823
7666957bc44d
child 1829
1316cec51b4d
permissions
-rw-r--r--

6942253: G1: replace G1ParallelGCAllocBufferSize with YoungPLABSize and OldPLABSize
Summary: Replaces the G1-specific parameter with the existing ones that are used by the other GCs (YoungPLABSize and OldPLABSize)
Reviewed-by: tonyp, johnc

     1 /*
     2  * Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.
     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     4  *
     5  * This code is free software; you can redistribute it and/or modify it
     6  * under the terms of the GNU General Public License version 2 only, as
     7  * published by the Free Software Foundation.
     8  *
     9  * This code is distributed in the hope that it will be useful, but WITHOUT
    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    12  * version 2 for more details (a copy is included in the LICENSE file that
    13  * accompanied this code).
    14  *
    15  * You should have received a copy of the GNU General Public License version
    16  * 2 along with this work; if not, write to the Free Software Foundation,
    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    18  *
    19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
    20  * CA 95054 USA or visit www.sun.com if you need additional information or
    21  * have any questions.
    22  *
    23  */
    25 #include "incls/_precompiled.incl"
    26 #include "incls/_g1CollectorPolicy.cpp.incl"
    28 #define PREDICTIONS_VERBOSE 0
    30 // <NEW PREDICTION>
    32 // Different defaults for different number of GC threads
    33 // They were chosen by running GCOld and SPECjbb on debris with different
    34 //   numbers of GC threads and choosing them based on the results
    36 // all the same
    37 static double rs_length_diff_defaults[] = {
    38   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
    39 };
    41 static double cost_per_card_ms_defaults[] = {
    42   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
    43 };
    45 static double cost_per_scan_only_region_ms_defaults[] = {
    46   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
    47 };
    49 // all the same
    50 static double fully_young_cards_per_entry_ratio_defaults[] = {
    51   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
    52 };
    54 static double cost_per_entry_ms_defaults[] = {
    55   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
    56 };
    58 static double cost_per_byte_ms_defaults[] = {
    59   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
    60 };
    62 // these should be pretty consistent
    63 static double constant_other_time_ms_defaults[] = {
    64   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
    65 };
    68 static double young_other_cost_per_region_ms_defaults[] = {
    69   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
    70 };
    72 static double non_young_other_cost_per_region_ms_defaults[] = {
    73   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
    74 };
    76 // </NEW PREDICTION>
    78 G1CollectorPolicy::G1CollectorPolicy() :
    79   _parallel_gc_threads((ParallelGCThreads > 0) ? ParallelGCThreads : 1),
    80   _n_pauses(0),
    81   _recent_CH_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    82   _recent_G1_strong_roots_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    83   _recent_evac_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    84   _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    85   _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
    86   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
    87   _all_pause_times_ms(new NumberSeq()),
    88   _stop_world_start(0.0),
    89   _all_stop_world_times_ms(new NumberSeq()),
    90   _all_yield_times_ms(new NumberSeq()),
    92   _all_mod_union_times_ms(new NumberSeq()),
    94   _summary(new Summary()),
    95   _abandoned_summary(new AbandonedSummary()),
    97 #ifndef PRODUCT
    98   _cur_clear_ct_time_ms(0.0),
    99   _min_clear_cc_time_ms(-1.0),
   100   _max_clear_cc_time_ms(-1.0),
   101   _cur_clear_cc_time_ms(0.0),
   102   _cum_clear_cc_time_ms(0.0),
   103   _num_cc_clears(0L),
   104 #endif
   106   _region_num_young(0),
   107   _region_num_tenured(0),
   108   _prev_region_num_young(0),
   109   _prev_region_num_tenured(0),
   111   _aux_num(10),
   112   _all_aux_times_ms(new NumberSeq[_aux_num]),
   113   _cur_aux_start_times_ms(new double[_aux_num]),
   114   _cur_aux_times_ms(new double[_aux_num]),
   115   _cur_aux_times_set(new bool[_aux_num]),
   117   _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   118   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   119   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   121   // <NEW PREDICTION>
   123   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   124   _prev_collection_pause_end_ms(0.0),
   125   _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   126   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   127   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   128   _cost_per_scan_only_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   129   _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
   130   _partially_young_cards_per_entry_ratio_seq(
   131                                          new TruncatedSeq(TruncatedSeqLength)),
   132   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   133   _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   134   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   135   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
   136   _cost_per_scan_only_region_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
   137   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   138   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   139   _non_young_other_cost_per_region_ms_seq(
   140                                          new TruncatedSeq(TruncatedSeqLength)),
   142   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   143   _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   144   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
   146   _pause_time_target_ms((double) MaxGCPauseMillis),
   148   // </NEW PREDICTION>
   150   _in_young_gc_mode(false),
   151   _full_young_gcs(true),
   152   _full_young_pause_num(0),
   153   _partial_young_pause_num(0),
   155   _during_marking(false),
   156   _in_marking_window(false),
   157   _in_marking_window_im(false),
   159   _known_garbage_ratio(0.0),
   160   _known_garbage_bytes(0),
   162   _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
   163   _target_pause_time_ms(-1.0),
   165    _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
   167   _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
   168   _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
   170   _recent_avg_pause_time_ratio(0.0),
   171   _num_markings(0),
   172   _n_marks(0),
   173   _n_pauses_at_mark_end(0),
   175   _all_full_gc_times_ms(new NumberSeq()),
   177   // G1PausesBtwnConcMark defaults to -1
   178   // so the hack is to do the cast  QQQ FIXME
   179   _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
   180   _n_marks_since_last_pause(0),
   181   _initiate_conc_mark_if_possible(false),
   182   _during_initial_mark_pause(false),
   183   _should_revert_to_full_young_gcs(false),
   184   _last_full_young_gc(false),
   186   _prev_collection_pause_used_at_end_bytes(0),
   188   _collection_set(NULL),
   189 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
   190 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
   191 #endif // _MSC_VER
   193   _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
   194                                                  G1YoungSurvRateNumRegionsSummary)),
   195   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
   196                                               G1YoungSurvRateNumRegionsSummary)),
   197   // add here any more surv rate groups
   198   _recorded_survivor_regions(0),
   199   _recorded_survivor_head(NULL),
   200   _recorded_survivor_tail(NULL),
   201   _survivors_age_table(true),
   203   _gc_overhead_perc(0.0)
   205 {
   206   // Set up the region size and associated fields. Given that the
   207   // policy is created before the heap, we have to set this up here,
   208   // so it's done as soon as possible.
   209   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
   210   HeapRegionRemSet::setup_remset_size();
   212   // Verify PLAB sizes
   213   const uint region_size = HeapRegion::GrainWords;
   214   if (YoungPLABSize > region_size || OldPLABSize > region_size) {
   215     char buffer[128];
   216     jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
   217                  OldPLABSize > region_size ? "Old" : "Young", region_size);
   218     vm_exit_during_initialization(buffer);
   219   }
   221   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
   222   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
   224   _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
   225   _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
   226   _par_last_scan_only_times_ms = new double[_parallel_gc_threads];
   227   _par_last_scan_only_regions_scanned = new double[_parallel_gc_threads];
   229   _par_last_update_rs_start_times_ms = new double[_parallel_gc_threads];
   230   _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
   231   _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
   233   _par_last_scan_rs_start_times_ms = new double[_parallel_gc_threads];
   234   _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
   235   _par_last_scan_new_refs_times_ms = new double[_parallel_gc_threads];
   237   _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
   239   _par_last_termination_times_ms = new double[_parallel_gc_threads];
   241   // start conservatively
   242   _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
   244   // <NEW PREDICTION>
   246   int index;
   247   if (ParallelGCThreads == 0)
   248     index = 0;
   249   else if (ParallelGCThreads > 8)
   250     index = 7;
   251   else
   252     index = ParallelGCThreads - 1;
   254   _pending_card_diff_seq->add(0.0);
   255   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
   256   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
   257   _cost_per_scan_only_region_ms_seq->add(
   258                                  cost_per_scan_only_region_ms_defaults[index]);
   259   _fully_young_cards_per_entry_ratio_seq->add(
   260                             fully_young_cards_per_entry_ratio_defaults[index]);
   261   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
   262   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
   263   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
   264   _young_other_cost_per_region_ms_seq->add(
   265                                young_other_cost_per_region_ms_defaults[index]);
   266   _non_young_other_cost_per_region_ms_seq->add(
   267                            non_young_other_cost_per_region_ms_defaults[index]);
   269   // </NEW PREDICTION>
   271   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
   272   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
   273   guarantee(max_gc_time < time_slice,
   274             "Max GC time should not be greater than the time slice");
   275   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
   276   _sigma = (double) G1ConfidencePercent / 100.0;
   278   // start conservatively (around 50ms is about right)
   279   _concurrent_mark_init_times_ms->add(0.05);
   280   _concurrent_mark_remark_times_ms->add(0.05);
   281   _concurrent_mark_cleanup_times_ms->add(0.20);
   282   _tenuring_threshold = MaxTenuringThreshold;
   284   // if G1FixedSurvivorSpaceSize is 0 which means the size is not
   285   // fixed, then _max_survivor_regions will be calculated at
   286   // calculate_young_list_target_config during initialization
   287   _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
   289   assert(GCTimeRatio > 0,
   290          "we should have set it to a default value set_g1_gc_flags() "
   291          "if a user set it to 0");
   292   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
   294   initialize_all();
   295 }
   297 // Increment "i", mod "len"
   298 static void inc_mod(int& i, int len) {
   299   i++; if (i == len) i = 0;
   300 }
   302 void G1CollectorPolicy::initialize_flags() {
   303   set_min_alignment(HeapRegion::GrainBytes);
   304   set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
   305   if (SurvivorRatio < 1) {
   306     vm_exit_during_initialization("Invalid survivor ratio specified");
   307   }
   308   CollectorPolicy::initialize_flags();
   309 }
   311 // The easiest way to deal with the parsing of the NewSize /
   312 // MaxNewSize / etc. parameteres is to re-use the code in the
   313 // TwoGenerationCollectorPolicy class. This is similar to what
   314 // ParallelScavenge does with its GenerationSizer class (see
   315 // ParallelScavengeHeap::initialize()). We might change this in the
   316 // future, but it's a good start.
   317 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
   318   size_t size_to_region_num(size_t byte_size) {
   319     return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
   320   }
   322 public:
   323   G1YoungGenSizer() {
   324     initialize_flags();
   325     initialize_size_info();
   326   }
   328   size_t min_young_region_num() {
   329     return size_to_region_num(_min_gen0_size);
   330   }
   331   size_t initial_young_region_num() {
   332     return size_to_region_num(_initial_gen0_size);
   333   }
   334   size_t max_young_region_num() {
   335     return size_to_region_num(_max_gen0_size);
   336   }
   337 };
   339 void G1CollectorPolicy::init() {
   340   // Set aside an initial future to_space.
   341   _g1 = G1CollectedHeap::heap();
   343   assert(Heap_lock->owned_by_self(), "Locking discipline.");
   345   initialize_gc_policy_counters();
   347   if (G1Gen) {
   348     _in_young_gc_mode = true;
   350     G1YoungGenSizer sizer;
   351     size_t initial_region_num = sizer.initial_young_region_num();
   353     if (UseAdaptiveSizePolicy) {
   354       set_adaptive_young_list_length(true);
   355       _young_list_fixed_length = 0;
   356     } else {
   357       set_adaptive_young_list_length(false);
   358       _young_list_fixed_length = initial_region_num;
   359     }
   360      _free_regions_at_end_of_collection = _g1->free_regions();
   361      _scan_only_regions_at_end_of_collection = 0;
   362      calculate_young_list_min_length();
   363      guarantee( _young_list_min_length == 0, "invariant, not enough info" );
   364      calculate_young_list_target_config();
   365    } else {
   366      _young_list_fixed_length = 0;
   367     _in_young_gc_mode = false;
   368   }
   369 }
   371 // Create the jstat counters for the policy.
   372 void G1CollectorPolicy::initialize_gc_policy_counters()
   373 {
   374   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
   375 }
   377 void G1CollectorPolicy::calculate_young_list_min_length() {
   378   _young_list_min_length = 0;
   380   if (!adaptive_young_list_length())
   381     return;
   383   if (_alloc_rate_ms_seq->num() > 3) {
   384     double now_sec = os::elapsedTime();
   385     double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
   386     double alloc_rate_ms = predict_alloc_rate_ms();
   387     int min_regions = (int) ceil(alloc_rate_ms * when_ms);
   388     int current_region_num = (int) _g1->young_list_length();
   389     _young_list_min_length = min_regions + current_region_num;
   390   }
   391 }
   393 void G1CollectorPolicy::calculate_young_list_target_config() {
   394   if (adaptive_young_list_length()) {
   395     size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
   396     calculate_young_list_target_config(rs_lengths);
   397   } else {
   398     if (full_young_gcs())
   399       _young_list_target_length = _young_list_fixed_length;
   400     else
   401       _young_list_target_length = _young_list_fixed_length / 2;
   402     _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);
   403     size_t so_length = calculate_optimal_so_length(_young_list_target_length);
   404     guarantee( so_length < _young_list_target_length, "invariant" );
   405     _young_list_so_prefix_length = so_length;
   406   }
   407   calculate_survivors_policy();
   408 }
   410 // This method calculate the optimal scan-only set for a fixed young
   411 // gen size. I couldn't work out how to reuse the more elaborate one,
   412 // i.e. calculate_young_list_target_config(rs_length), as the loops are
   413 // fundamentally different (the other one finds a config for different
   414 // S-O lengths, whereas here we need to do the opposite).
   415 size_t G1CollectorPolicy::calculate_optimal_so_length(
   416                                                     size_t young_list_length) {
   417   if (!G1UseScanOnlyPrefix)
   418     return 0;
   420   if (_all_pause_times_ms->num() < 3) {
   421     // we won't use a scan-only set at the beginning to allow the rest
   422     // of the predictors to warm up
   423     return 0;
   424   }
   426   if (_cost_per_scan_only_region_ms_seq->num() < 3) {
   427     // then, we'll only set the S-O set to 1 for a little bit of time,
   428     // to get enough information on the scanning cost
   429     return 1;
   430   }
   432   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
   433   size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
   434   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
   435   size_t scanned_cards;
   436   if (full_young_gcs())
   437     scanned_cards = predict_young_card_num(adj_rs_lengths);
   438   else
   439     scanned_cards = predict_non_young_card_num(adj_rs_lengths);
   440   double base_time_ms = predict_base_elapsed_time_ms(pending_cards,
   441                                                      scanned_cards);
   443   size_t so_length = 0;
   444   double max_gc_eff = 0.0;
   445   for (size_t i = 0; i < young_list_length; ++i) {
   446     double gc_eff = 0.0;
   447     double pause_time_ms = 0.0;
   448     predict_gc_eff(young_list_length, i, base_time_ms,
   449                    &gc_eff, &pause_time_ms);
   450     if (gc_eff > max_gc_eff) {
   451       max_gc_eff = gc_eff;
   452       so_length = i;
   453     }
   454   }
   456   // set it to 95% of the optimal to make sure we sample the "area"
   457   // around the optimal length to get up-to-date survival rate data
   458   return so_length * 950 / 1000;
   459 }
   461 // This is a really cool piece of code! It finds the best
   462 // target configuration (young length / scan-only prefix length) so
   463 // that GC efficiency is maximized and that we also meet a pause
   464 // time. It's a triple nested loop. These loops are explained below
   465 // from the inside-out :-)
   466 //
   467 // (a) The innermost loop will try to find the optimal young length
   468 // for a fixed S-O length. It uses a binary search to speed up the
   469 // process. We assume that, for a fixed S-O length, as we add more
   470 // young regions to the CSet, the GC efficiency will only go up (I'll
   471 // skip the proof). So, using a binary search to optimize this process
   472 // makes perfect sense.
   473 //
   474 // (b) The middle loop will fix the S-O length before calling the
   475 // innermost one. It will vary it between two parameters, increasing
   476 // it by a given increment.
   477 //
   478 // (c) The outermost loop will call the middle loop three times.
   479 //   (1) The first time it will explore all possible S-O length values
   480 //   from 0 to as large as it can get, using a coarse increment (to
   481 //   quickly "home in" to where the optimal seems to be).
   482 //   (2) The second time it will explore the values around the optimal
   483 //   that was found by the first iteration using a fine increment.
   484 //   (3) Once the optimal config has been determined by the second
   485 //   iteration, we'll redo the calculation, but setting the S-O length
   486 //   to 95% of the optimal to make sure we sample the "area"
   487 //   around the optimal length to get up-to-date survival rate data
   488 //
   489 // Termination conditions for the iterations are several: the pause
   490 // time is over the limit, we do not have enough to-space, etc.
   492 void G1CollectorPolicy::calculate_young_list_target_config(size_t rs_lengths) {
   493   guarantee( adaptive_young_list_length(), "pre-condition" );
   495   double start_time_sec = os::elapsedTime();
   496   size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
   497   min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
   498   size_t reserve_regions =
   499     (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
   501   if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
   502     // we are in fully-young mode and there are free regions in the heap
   504     double survivor_regions_evac_time =
   505         predict_survivor_regions_evac_time();
   507     size_t min_so_length = 0;
   508     size_t max_so_length = 0;
   510     if (G1UseScanOnlyPrefix) {
   511       if (_all_pause_times_ms->num() < 3) {
   512         // we won't use a scan-only set at the beginning to allow the rest
   513         // of the predictors to warm up
   514         min_so_length = 0;
   515         max_so_length = 0;
   516       } else if (_cost_per_scan_only_region_ms_seq->num() < 3) {
   517         // then, we'll only set the S-O set to 1 for a little bit of time,
   518         // to get enough information on the scanning cost
   519         min_so_length = 1;
   520         max_so_length = 1;
   521       } else if (_in_marking_window || _last_full_young_gc) {
   522         // no S-O prefix during a marking phase either, as at the end
   523         // of the marking phase we'll have to use a very small young
   524         // length target to fill up the rest of the CSet with
   525         // non-young regions and, if we have lots of scan-only regions
   526         // left-over, we will not be able to add any more non-young
   527         // regions.
   528         min_so_length = 0;
   529         max_so_length = 0;
   530       } else {
   531         // this is the common case; we'll never reach the maximum, we
   532         // one of the end conditions will fire well before that
   533         // (hopefully!)
   534         min_so_length = 0;
   535         max_so_length = _free_regions_at_end_of_collection - 1;
   536       }
   537     } else {
   538       // no S-O prefix, as the switch is not set, but we still need to
   539       // do one iteration to calculate the best young target that
   540       // meets the pause time; this way we reuse the same code instead
   541       // of replicating it
   542       min_so_length = 0;
   543       max_so_length = 0;
   544     }
   546     double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
   547     size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
   548     size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
   549     size_t scanned_cards;
   550     if (full_young_gcs())
   551       scanned_cards = predict_young_card_num(adj_rs_lengths);
   552     else
   553       scanned_cards = predict_non_young_card_num(adj_rs_lengths);
   554     // calculate this once, so that we don't have to recalculate it in
   555     // the innermost loop
   556     double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
   557                           + survivor_regions_evac_time;
   558     // the result
   559     size_t final_young_length = 0;
   560     size_t final_so_length = 0;
   561     double final_gc_eff = 0.0;
   562     // we'll also keep track of how many times we go into the inner loop
   563     // this is for profiling reasons
   564     size_t calculations = 0;
   566     // this determines which of the three iterations the outer loop is in
   567     typedef enum {
   568       pass_type_coarse,
   569       pass_type_fine,
   570       pass_type_final
   571     } pass_type_t;
   573     // range of the outer loop's iteration
   574     size_t from_so_length   = min_so_length;
   575     size_t to_so_length     = max_so_length;
   576     guarantee( from_so_length <= to_so_length, "invariant" );
   578     // this will keep the S-O length that's found by the second
   579     // iteration of the outer loop; we'll keep it just in case the third
   580     // iteration fails to find something
   581     size_t fine_so_length   = 0;
   583     // the increment step for the coarse (first) iteration
   584     size_t so_coarse_increments = 5;
   586     // the common case, we'll start with the coarse iteration
   587     pass_type_t pass = pass_type_coarse;
   588     size_t so_length_incr = so_coarse_increments;
   590     if (from_so_length == to_so_length) {
   591       // not point in doing the coarse iteration, we'll go directly into
   592       // the fine one (we essentially trying to find the optimal young
   593       // length for a fixed S-O length).
   594       so_length_incr = 1;
   595       pass = pass_type_final;
   596     } else if (to_so_length - from_so_length < 3 * so_coarse_increments) {
   597       // again, the range is too short so no point in foind the coarse
   598       // iteration either
   599       so_length_incr = 1;
   600       pass = pass_type_fine;
   601     }
   603     bool done = false;
   604     // this is the outermost loop
   605     while (!done) {
   606 #ifdef TRACE_CALC_YOUNG_CONFIG
   607       // leave this in for debugging, just in case
   608       gclog_or_tty->print_cr("searching between " SIZE_FORMAT " and " SIZE_FORMAT
   609                              ", incr " SIZE_FORMAT ", pass %s",
   610                              from_so_length, to_so_length, so_length_incr,
   611                              (pass == pass_type_coarse) ? "coarse" :
   612                              (pass == pass_type_fine) ? "fine" : "final");
   613 #endif // TRACE_CALC_YOUNG_CONFIG
   615       size_t so_length = from_so_length;
   616       size_t init_free_regions =
   617         MAX2((size_t)0,
   618              _free_regions_at_end_of_collection +
   619              _scan_only_regions_at_end_of_collection - reserve_regions);
   621       // this determines whether a configuration was found
   622       bool gc_eff_set = false;
   623       // this is the middle loop
   624       while (so_length <= to_so_length) {
   625         // base time, which excludes region-related time; again we
   626         // calculate it once to avoid recalculating it in the
   627         // innermost loop
   628         double base_time_with_so_ms =
   629                            base_time_ms + predict_scan_only_time_ms(so_length);
   630         // it's already over the pause target, go around
   631         if (base_time_with_so_ms > target_pause_time_ms)
   632           break;
   634         size_t starting_young_length = so_length+1;
   636         // we make sure that the short young length that makes sense
   637         // (one more than the S-O length) is feasible
   638         size_t min_young_length = starting_young_length;
   639         double min_gc_eff;
   640         bool min_ok;
   641         ++calculations;
   642         min_ok = predict_gc_eff(min_young_length, so_length,
   643                                 base_time_with_so_ms,
   644                                 init_free_regions, target_pause_time_ms,
   645                                 &min_gc_eff);
   647         if (min_ok) {
   648           // the shortest young length is indeed feasible; we'll know
   649           // set up the max young length and we'll do a binary search
   650           // between min_young_length and max_young_length
   651           size_t max_young_length = _free_regions_at_end_of_collection - 1;
   652           double max_gc_eff = 0.0;
   653           bool max_ok = false;
   655           // the innermost loop! (finally!)
   656           while (max_young_length > min_young_length) {
   657             // we'll make sure that min_young_length is always at a
   658             // feasible config
   659             guarantee( min_ok, "invariant" );
   661             ++calculations;
   662             max_ok = predict_gc_eff(max_young_length, so_length,
   663                                     base_time_with_so_ms,
   664                                     init_free_regions, target_pause_time_ms,
   665                                     &max_gc_eff);
   667             size_t diff = (max_young_length - min_young_length) / 2;
   668             if (max_ok) {
   669               min_young_length = max_young_length;
   670               min_gc_eff = max_gc_eff;
   671               min_ok = true;
   672             }
   673             max_young_length = min_young_length + diff;
   674           }
   676           // the innermost loop found a config
   677           guarantee( min_ok, "invariant" );
   678           if (min_gc_eff > final_gc_eff) {
   679             // it's the best config so far, so we'll keep it
   680             final_gc_eff = min_gc_eff;
   681             final_young_length = min_young_length;
   682             final_so_length = so_length;
   683             gc_eff_set = true;
   684           }
   685         }
   687         // incremental the fixed S-O length and go around
   688         so_length += so_length_incr;
   689       }
   691       // this is the end of the outermost loop and we need to decide
   692       // what to do during the next iteration
   693       if (pass == pass_type_coarse) {
   694         // we just did the coarse pass (first iteration)
   696         if (!gc_eff_set)
   697           // we didn't find a feasible config so we'll just bail out; of
   698           // course, it might be the case that we missed it; but I'd say
   699           // it's a bit unlikely
   700           done = true;
   701         else {
   702           // We did find a feasible config with optimal GC eff during
   703           // the first pass. So the second pass we'll only consider the
   704           // S-O lengths around that config with a fine increment.
   706           guarantee( so_length_incr == so_coarse_increments, "invariant" );
   707           guarantee( final_so_length >= min_so_length, "invariant" );
   709 #ifdef TRACE_CALC_YOUNG_CONFIG
   710           // leave this in for debugging, just in case
   711           gclog_or_tty->print_cr("  coarse pass: SO length " SIZE_FORMAT,
   712                                  final_so_length);
   713 #endif // TRACE_CALC_YOUNG_CONFIG
   715           from_so_length =
   716             (final_so_length - min_so_length > so_coarse_increments) ?
   717             final_so_length - so_coarse_increments + 1 : min_so_length;
   718           to_so_length =
   719             (max_so_length - final_so_length > so_coarse_increments) ?
   720             final_so_length + so_coarse_increments - 1 : max_so_length;
   722           pass = pass_type_fine;
   723           so_length_incr = 1;
   724         }
   725       } else if (pass == pass_type_fine) {
   726         // we just finished the second pass
   728         if (!gc_eff_set) {
   729           // we didn't find a feasible config (yes, it's possible;
   730           // notice that, sometimes, we go directly into the fine
   731           // iteration and skip the coarse one) so we bail out
   732           done = true;
   733         } else {
   734           // We did find a feasible config with optimal GC eff
   735           guarantee( so_length_incr == 1, "invariant" );
   737           if (final_so_length == 0) {
   738             // The config is of an empty S-O set, so we'll just bail out
   739             done = true;
   740           } else {
   741             // we'll go around once more, setting the S-O length to 95%
   742             // of the optimal
   743             size_t new_so_length = 950 * final_so_length / 1000;
   745 #ifdef TRACE_CALC_YOUNG_CONFIG
   746             // leave this in for debugging, just in case
   747             gclog_or_tty->print_cr("  fine pass: SO length " SIZE_FORMAT
   748                                    ", setting it to " SIZE_FORMAT,
   749                                     final_so_length, new_so_length);
   750 #endif // TRACE_CALC_YOUNG_CONFIG
   752             from_so_length = new_so_length;
   753             to_so_length = new_so_length;
   754             fine_so_length = final_so_length;
   756             pass = pass_type_final;
   757           }
   758         }
   759       } else if (pass == pass_type_final) {
   760         // we just finished the final (third) pass
   762         if (!gc_eff_set)
   763           // we didn't find a feasible config, so we'll just use the one
   764           // we found during the second pass, which we saved
   765           final_so_length = fine_so_length;
   767         // and we're done!
   768         done = true;
   769       } else {
   770         guarantee( false, "should never reach here" );
   771       }
   773       // we now go around the outermost loop
   774     }
   776     // we should have at least one region in the target young length
   777     _young_list_target_length =
   778         MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);
   779     if (final_so_length >= final_young_length)
   780       // and we need to ensure that the S-O length is not greater than
   781       // the target young length (this is being a bit careful)
   782       final_so_length = 0;
   783     _young_list_so_prefix_length = final_so_length;
   784     guarantee( !_in_marking_window || !_last_full_young_gc ||
   785                _young_list_so_prefix_length == 0, "invariant" );
   787     // let's keep an eye of how long we spend on this calculation
   788     // right now, I assume that we'll print it when we need it; we
   789     // should really adde it to the breakdown of a pause
   790     double end_time_sec = os::elapsedTime();
   791     double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
   793 #ifdef TRACE_CALC_YOUNG_CONFIG
   794     // leave this in for debugging, just in case
   795     gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT
   796                            ", SO = " SIZE_FORMAT ", "
   797                            "elapsed %1.2lf ms, calcs: " SIZE_FORMAT " (%s%s) "
   798                            SIZE_FORMAT SIZE_FORMAT,
   799                            target_pause_time_ms,
   800                            _young_list_target_length - _young_list_so_prefix_length,
   801                            _young_list_so_prefix_length,
   802                            elapsed_time_ms,
   803                            calculations,
   804                            full_young_gcs() ? "full" : "partial",
   805                            during_initial_mark_pause() ? " i-m" : "",
   806                            _in_marking_window,
   807                            _in_marking_window_im);
   808 #endif // TRACE_CALC_YOUNG_CONFIG
   810     if (_young_list_target_length < _young_list_min_length) {
   811       // bummer; this means that, if we do a pause when the optimal
   812       // config dictates, we'll violate the pause spacing target (the
   813       // min length was calculate based on the application's current
   814       // alloc rate);
   816       // so, we have to bite the bullet, and allocate the minimum
   817       // number. We'll violate our target, but we just can't meet it.
   819       size_t so_length = 0;
   820       // a note further up explains why we do not want an S-O length
   821       // during marking
   822       if (!_in_marking_window && !_last_full_young_gc)
   823         // but we can still try to see whether we can find an optimal
   824         // S-O length
   825         so_length = calculate_optimal_so_length(_young_list_min_length);
   827 #ifdef TRACE_CALC_YOUNG_CONFIG
   828       // leave this in for debugging, just in case
   829       gclog_or_tty->print_cr("adjusted target length from "
   830                              SIZE_FORMAT " to " SIZE_FORMAT
   831                              ", SO " SIZE_FORMAT,
   832                              _young_list_target_length, _young_list_min_length,
   833                              so_length);
   834 #endif // TRACE_CALC_YOUNG_CONFIG
   836       _young_list_target_length =
   837         MAX2(_young_list_min_length, (size_t)1);
   838       _young_list_so_prefix_length = so_length;
   839     }
   840   } else {
   841     // we are in a partially-young mode or we've run out of regions (due
   842     // to evacuation failure)
   844 #ifdef TRACE_CALC_YOUNG_CONFIG
   845     // leave this in for debugging, just in case
   846     gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
   847                            ", SO " SIZE_FORMAT,
   848                            _young_list_min_length, 0);
   849 #endif // TRACE_CALC_YOUNG_CONFIG
   851     // we'll do the pause as soon as possible and with no S-O prefix
   852     // (see above for the reasons behind the latter)
   853     _young_list_target_length =
   854       MAX2(_young_list_min_length, (size_t) 1);
   855     _young_list_so_prefix_length = 0;
   856   }
   858   _rs_lengths_prediction = rs_lengths;
   859 }
   861 // This is used by: calculate_optimal_so_length(length). It returns
   862 // the GC eff and predicted pause time for a particular config
   863 void
   864 G1CollectorPolicy::predict_gc_eff(size_t young_length,
   865                                   size_t so_length,
   866                                   double base_time_ms,
   867                                   double* ret_gc_eff,
   868                                   double* ret_pause_time_ms) {
   869   double so_time_ms = predict_scan_only_time_ms(so_length);
   870   double accum_surv_rate_adj = 0.0;
   871   if (so_length > 0)
   872     accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
   873   double accum_surv_rate =
   874     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
   875   size_t bytes_to_copy =
   876     (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   877   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   878   double young_other_time_ms =
   879                        predict_young_other_time_ms(young_length - so_length);
   880   double pause_time_ms =
   881                 base_time_ms + so_time_ms + copy_time_ms + young_other_time_ms;
   882   size_t reclaimed_bytes =
   883     (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
   884   double gc_eff = (double) reclaimed_bytes / pause_time_ms;
   886   *ret_gc_eff = gc_eff;
   887   *ret_pause_time_ms = pause_time_ms;
   888 }
   890 // This is used by: calculate_young_list_target_config(rs_length). It
   891 // returns the GC eff of a particular config. It returns false if that
   892 // config violates any of the end conditions of the search in the
   893 // calling method, or true upon success. The end conditions were put
   894 // here since it's called twice and it was best not to replicate them
   895 // in the caller. Also, passing the parameteres avoids having to
   896 // recalculate them in the innermost loop.
   897 bool
   898 G1CollectorPolicy::predict_gc_eff(size_t young_length,
   899                                   size_t so_length,
   900                                   double base_time_with_so_ms,
   901                                   size_t init_free_regions,
   902                                   double target_pause_time_ms,
   903                                   double* ret_gc_eff) {
   904   *ret_gc_eff = 0.0;
   906   if (young_length >= init_free_regions)
   907     // end condition 1: not enough space for the young regions
   908     return false;
   910   double accum_surv_rate_adj = 0.0;
   911   if (so_length > 0)
   912     accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
   913   double accum_surv_rate =
   914     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
   915   size_t bytes_to_copy =
   916     (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   917   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   918   double young_other_time_ms =
   919                        predict_young_other_time_ms(young_length - so_length);
   920   double pause_time_ms =
   921                    base_time_with_so_ms + copy_time_ms + young_other_time_ms;
   923   if (pause_time_ms > target_pause_time_ms)
   924     // end condition 2: over the target pause time
   925     return false;
   927   size_t reclaimed_bytes =
   928     (young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
   929   size_t free_bytes =
   930                  (init_free_regions - young_length) * HeapRegion::GrainBytes;
   932   if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
   933     // end condition 3: out of to-space (conservatively)
   934     return false;
   936   // success!
   937   double gc_eff = (double) reclaimed_bytes / pause_time_ms;
   938   *ret_gc_eff = gc_eff;
   940   return true;
   941 }
   943 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
   944   double survivor_regions_evac_time = 0.0;
   945   for (HeapRegion * r = _recorded_survivor_head;
   946        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
   947        r = r->get_next_young_region()) {
   948     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
   949   }
   950   return survivor_regions_evac_time;
   951 }
   953 void G1CollectorPolicy::check_prediction_validity() {
   954   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
   956   size_t rs_lengths = _g1->young_list_sampled_rs_lengths();
   957   if (rs_lengths > _rs_lengths_prediction) {
   958     // add 10% to avoid having to recalculate often
   959     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
   960     calculate_young_list_target_config(rs_lengths_prediction);
   961   }
   962 }
   964 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
   965                                                bool is_tlab,
   966                                                bool* gc_overhead_limit_was_exceeded) {
   967   guarantee(false, "Not using this policy feature yet.");
   968   return NULL;
   969 }
   971 // This method controls how a collector handles one or more
   972 // of its generations being fully allocated.
   973 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
   974                                                        bool is_tlab) {
   975   guarantee(false, "Not using this policy feature yet.");
   976   return NULL;
   977 }
   980 #ifndef PRODUCT
   981 bool G1CollectorPolicy::verify_young_ages() {
   982   HeapRegion* head = _g1->young_list_first_region();
   983   return
   984     verify_young_ages(head, _short_lived_surv_rate_group);
   985   // also call verify_young_ages on any additional surv rate groups
   986 }
   988 bool
   989 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
   990                                      SurvRateGroup *surv_rate_group) {
   991   guarantee( surv_rate_group != NULL, "pre-condition" );
   993   const char* name = surv_rate_group->name();
   994   bool ret = true;
   995   int prev_age = -1;
   997   for (HeapRegion* curr = head;
   998        curr != NULL;
   999        curr = curr->get_next_young_region()) {
  1000     SurvRateGroup* group = curr->surv_rate_group();
  1001     if (group == NULL && !curr->is_survivor()) {
  1002       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
  1003       ret = false;
  1006     if (surv_rate_group == group) {
  1007       int age = curr->age_in_surv_rate_group();
  1009       if (age < 0) {
  1010         gclog_or_tty->print_cr("## %s: encountered negative age", name);
  1011         ret = false;
  1014       if (age <= prev_age) {
  1015         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
  1016                                "(%d, %d)", name, age, prev_age);
  1017         ret = false;
  1019       prev_age = age;
  1023   return ret;
  1025 #endif // PRODUCT
  1027 void G1CollectorPolicy::record_full_collection_start() {
  1028   _cur_collection_start_sec = os::elapsedTime();
  1029   // Release the future to-space so that it is available for compaction into.
  1030   _g1->set_full_collection();
  1033 void G1CollectorPolicy::record_full_collection_end() {
  1034   // Consider this like a collection pause for the purposes of allocation
  1035   // since last pause.
  1036   double end_sec = os::elapsedTime();
  1037   double full_gc_time_sec = end_sec - _cur_collection_start_sec;
  1038   double full_gc_time_ms = full_gc_time_sec * 1000.0;
  1040   _all_full_gc_times_ms->add(full_gc_time_ms);
  1042   update_recent_gc_times(end_sec, full_gc_time_ms);
  1044   _g1->clear_full_collection();
  1046   // "Nuke" the heuristics that control the fully/partially young GC
  1047   // transitions and make sure we start with fully young GCs after the
  1048   // Full GC.
  1049   set_full_young_gcs(true);
  1050   _last_full_young_gc = false;
  1051   _should_revert_to_full_young_gcs = false;
  1052   clear_initiate_conc_mark_if_possible();
  1053   clear_during_initial_mark_pause();
  1054   _known_garbage_bytes = 0;
  1055   _known_garbage_ratio = 0.0;
  1056   _in_marking_window = false;
  1057   _in_marking_window_im = false;
  1059   _short_lived_surv_rate_group->record_scan_only_prefix(0);
  1060   _short_lived_surv_rate_group->start_adding_regions();
  1061   // also call this on any additional surv rate groups
  1063   record_survivor_regions(0, NULL, NULL);
  1065   _prev_region_num_young   = _region_num_young;
  1066   _prev_region_num_tenured = _region_num_tenured;
  1068   _free_regions_at_end_of_collection = _g1->free_regions();
  1069   _scan_only_regions_at_end_of_collection = 0;
  1070   // Reset survivors SurvRateGroup.
  1071   _survivor_surv_rate_group->reset();
  1072   calculate_young_list_min_length();
  1073   calculate_young_list_target_config();
  1076 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
  1077   _bytes_in_to_space_before_gc += bytes;
  1080 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
  1081   _bytes_in_to_space_after_gc += bytes;
  1084 void G1CollectorPolicy::record_stop_world_start() {
  1085   _stop_world_start = os::elapsedTime();
  1088 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
  1089                                                       size_t start_used) {
  1090   if (PrintGCDetails) {
  1091     gclog_or_tty->stamp(PrintGCTimeStamps);
  1092     gclog_or_tty->print("[GC pause");
  1093     if (in_young_gc_mode())
  1094       gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
  1097   assert(_g1->used_regions() == _g1->recalculate_used_regions(),
  1098          "sanity");
  1099   assert(_g1->used() == _g1->recalculate_used(), "sanity");
  1101   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
  1102   _all_stop_world_times_ms->add(s_w_t_ms);
  1103   _stop_world_start = 0.0;
  1105   _cur_collection_start_sec = start_time_sec;
  1106   _cur_collection_pause_used_at_start_bytes = start_used;
  1107   _cur_collection_pause_used_regions_at_start = _g1->used_regions();
  1108   _pending_cards = _g1->pending_card_num();
  1109   _max_pending_cards = _g1->max_pending_card_num();
  1111   _bytes_in_to_space_before_gc = 0;
  1112   _bytes_in_to_space_after_gc = 0;
  1113   _bytes_in_collection_set_before_gc = 0;
  1115 #ifdef DEBUG
  1116   // initialise these to something well known so that we can spot
  1117   // if they are not set properly
  1119   for (int i = 0; i < _parallel_gc_threads; ++i) {
  1120     _par_last_ext_root_scan_times_ms[i] = -666.0;
  1121     _par_last_mark_stack_scan_times_ms[i] = -666.0;
  1122     _par_last_scan_only_times_ms[i] = -666.0;
  1123     _par_last_scan_only_regions_scanned[i] = -666.0;
  1124     _par_last_update_rs_start_times_ms[i] = -666.0;
  1125     _par_last_update_rs_times_ms[i] = -666.0;
  1126     _par_last_update_rs_processed_buffers[i] = -666.0;
  1127     _par_last_scan_rs_start_times_ms[i] = -666.0;
  1128     _par_last_scan_rs_times_ms[i] = -666.0;
  1129     _par_last_scan_new_refs_times_ms[i] = -666.0;
  1130     _par_last_obj_copy_times_ms[i] = -666.0;
  1131     _par_last_termination_times_ms[i] = -666.0;
  1133 #endif
  1135   for (int i = 0; i < _aux_num; ++i) {
  1136     _cur_aux_times_ms[i] = 0.0;
  1137     _cur_aux_times_set[i] = false;
  1140   _satb_drain_time_set = false;
  1141   _last_satb_drain_processed_buffers = -1;
  1143   if (in_young_gc_mode())
  1144     _last_young_gc_full = false;
  1147   // do that for any other surv rate groups
  1148   _short_lived_surv_rate_group->stop_adding_regions();
  1149   size_t short_lived_so_length = _young_list_so_prefix_length;
  1150   _short_lived_surv_rate_group->record_scan_only_prefix(short_lived_so_length);
  1151   tag_scan_only(short_lived_so_length);
  1152   _survivors_age_table.clear();
  1154   assert( verify_young_ages(), "region age verification" );
  1157 void G1CollectorPolicy::tag_scan_only(size_t short_lived_scan_only_length) {
  1158   // done in a way that it can be extended for other surv rate groups too...
  1160   HeapRegion* head = _g1->young_list_first_region();
  1161   bool finished_short_lived = (short_lived_scan_only_length == 0);
  1163   if (finished_short_lived)
  1164     return;
  1166   for (HeapRegion* curr = head;
  1167        curr != NULL;
  1168        curr = curr->get_next_young_region()) {
  1169     SurvRateGroup* surv_rate_group = curr->surv_rate_group();
  1170     int age = curr->age_in_surv_rate_group();
  1172     if (surv_rate_group == _short_lived_surv_rate_group) {
  1173       if ((size_t)age < short_lived_scan_only_length)
  1174         curr->set_scan_only();
  1175       else
  1176         finished_short_lived = true;
  1180     if (finished_short_lived)
  1181       return;
  1184   guarantee( false, "we should never reach here" );
  1187 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
  1188   _mark_closure_time_ms = mark_closure_time_ms;
  1191 void G1CollectorPolicy::record_concurrent_mark_init_start() {
  1192   _mark_init_start_sec = os::elapsedTime();
  1193   guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
  1196 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
  1197                                                    mark_init_elapsed_time_ms) {
  1198   _during_marking = true;
  1199   assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
  1200   clear_during_initial_mark_pause();
  1201   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
  1204 void G1CollectorPolicy::record_concurrent_mark_init_end() {
  1205   double end_time_sec = os::elapsedTime();
  1206   double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
  1207   _concurrent_mark_init_times_ms->add(elapsed_time_ms);
  1208   record_concurrent_mark_init_end_pre(elapsed_time_ms);
  1210   _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
  1213 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
  1214   _mark_remark_start_sec = os::elapsedTime();
  1215   _during_marking = false;
  1218 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
  1219   double end_time_sec = os::elapsedTime();
  1220   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
  1221   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
  1222   _cur_mark_stop_world_time_ms += elapsed_time_ms;
  1223   _prev_collection_pause_end_ms += elapsed_time_ms;
  1225   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
  1228 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
  1229   _mark_cleanup_start_sec = os::elapsedTime();
  1232 void
  1233 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
  1234                                                       size_t max_live_bytes) {
  1235   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
  1236   record_concurrent_mark_cleanup_end_work2();
  1239 void
  1240 G1CollectorPolicy::
  1241 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
  1242                                          size_t max_live_bytes) {
  1243   if (_n_marks < 2) _n_marks++;
  1244   if (G1PolicyVerbose > 0)
  1245     gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
  1246                            " (of " SIZE_FORMAT " MB heap).",
  1247                            max_live_bytes/M, _g1->capacity()/M);
  1250 // The important thing about this is that it includes "os::elapsedTime".
  1251 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
  1252   double end_time_sec = os::elapsedTime();
  1253   double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
  1254   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
  1255   _cur_mark_stop_world_time_ms += elapsed_time_ms;
  1256   _prev_collection_pause_end_ms += elapsed_time_ms;
  1258   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
  1260   _num_markings++;
  1262   // We did a marking, so reset the "since_last_mark" variables.
  1263   double considerConcMarkCost = 1.0;
  1264   // If there are available processors, concurrent activity is free...
  1265   if (Threads::number_of_non_daemon_threads() * 2 <
  1266       os::active_processor_count()) {
  1267     considerConcMarkCost = 0.0;
  1269   _n_pauses_at_mark_end = _n_pauses;
  1270   _n_marks_since_last_pause++;
  1273 void
  1274 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
  1275   if (in_young_gc_mode()) {
  1276     _should_revert_to_full_young_gcs = false;
  1277     _last_full_young_gc = true;
  1278     _in_marking_window = false;
  1279     if (adaptive_young_list_length())
  1280       calculate_young_list_target_config();
  1284 void G1CollectorPolicy::record_concurrent_pause() {
  1285   if (_stop_world_start > 0.0) {
  1286     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
  1287     _all_yield_times_ms->add(yield_ms);
  1291 void G1CollectorPolicy::record_concurrent_pause_end() {
  1294 void G1CollectorPolicy::record_collection_pause_end_CH_strong_roots() {
  1295   _cur_CH_strong_roots_end_sec = os::elapsedTime();
  1296   _cur_CH_strong_roots_dur_ms =
  1297     (_cur_CH_strong_roots_end_sec - _cur_collection_start_sec) * 1000.0;
  1300 void G1CollectorPolicy::record_collection_pause_end_G1_strong_roots() {
  1301   _cur_G1_strong_roots_end_sec = os::elapsedTime();
  1302   _cur_G1_strong_roots_dur_ms =
  1303     (_cur_G1_strong_roots_end_sec - _cur_CH_strong_roots_end_sec) * 1000.0;
  1306 template<class T>
  1307 T sum_of(T* sum_arr, int start, int n, int N) {
  1308   T sum = (T)0;
  1309   for (int i = 0; i < n; i++) {
  1310     int j = (start + i) % N;
  1311     sum += sum_arr[j];
  1313   return sum;
  1316 void G1CollectorPolicy::print_par_stats (int level,
  1317                                          const char* str,
  1318                                          double* data,
  1319                                          bool summary) {
  1320   double min = data[0], max = data[0];
  1321   double total = 0.0;
  1322   int j;
  1323   for (j = 0; j < level; ++j)
  1324     gclog_or_tty->print("   ");
  1325   gclog_or_tty->print("[%s (ms):", str);
  1326   for (uint i = 0; i < ParallelGCThreads; ++i) {
  1327     double val = data[i];
  1328     if (val < min)
  1329       min = val;
  1330     if (val > max)
  1331       max = val;
  1332     total += val;
  1333     gclog_or_tty->print("  %3.1lf", val);
  1335   if (summary) {
  1336     gclog_or_tty->print_cr("");
  1337     double avg = total / (double) ParallelGCThreads;
  1338     gclog_or_tty->print(" ");
  1339     for (j = 0; j < level; ++j)
  1340       gclog_or_tty->print("   ");
  1341     gclog_or_tty->print("Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf",
  1342                         avg, min, max);
  1344   gclog_or_tty->print_cr("]");
  1347 void G1CollectorPolicy::print_par_buffers (int level,
  1348                                          const char* str,
  1349                                          double* data,
  1350                                          bool summary) {
  1351   double min = data[0], max = data[0];
  1352   double total = 0.0;
  1353   int j;
  1354   for (j = 0; j < level; ++j)
  1355     gclog_or_tty->print("   ");
  1356   gclog_or_tty->print("[%s :", str);
  1357   for (uint i = 0; i < ParallelGCThreads; ++i) {
  1358     double val = data[i];
  1359     if (val < min)
  1360       min = val;
  1361     if (val > max)
  1362       max = val;
  1363     total += val;
  1364     gclog_or_tty->print(" %d", (int) val);
  1366   if (summary) {
  1367     gclog_or_tty->print_cr("");
  1368     double avg = total / (double) ParallelGCThreads;
  1369     gclog_or_tty->print(" ");
  1370     for (j = 0; j < level; ++j)
  1371       gclog_or_tty->print("   ");
  1372     gclog_or_tty->print("Sum: %d, Avg: %d, Min: %d, Max: %d",
  1373                (int)total, (int)avg, (int)min, (int)max);
  1375   gclog_or_tty->print_cr("]");
  1378 void G1CollectorPolicy::print_stats (int level,
  1379                                      const char* str,
  1380                                      double value) {
  1381   for (int j = 0; j < level; ++j)
  1382     gclog_or_tty->print("   ");
  1383   gclog_or_tty->print_cr("[%s: %5.1lf ms]", str, value);
  1386 void G1CollectorPolicy::print_stats (int level,
  1387                                      const char* str,
  1388                                      int value) {
  1389   for (int j = 0; j < level; ++j)
  1390     gclog_or_tty->print("   ");
  1391   gclog_or_tty->print_cr("[%s: %d]", str, value);
  1394 double G1CollectorPolicy::avg_value (double* data) {
  1395   if (ParallelGCThreads > 0) {
  1396     double ret = 0.0;
  1397     for (uint i = 0; i < ParallelGCThreads; ++i)
  1398       ret += data[i];
  1399     return ret / (double) ParallelGCThreads;
  1400   } else {
  1401     return data[0];
  1405 double G1CollectorPolicy::max_value (double* data) {
  1406   if (ParallelGCThreads > 0) {
  1407     double ret = data[0];
  1408     for (uint i = 1; i < ParallelGCThreads; ++i)
  1409       if (data[i] > ret)
  1410         ret = data[i];
  1411     return ret;
  1412   } else {
  1413     return data[0];
  1417 double G1CollectorPolicy::sum_of_values (double* data) {
  1418   if (ParallelGCThreads > 0) {
  1419     double sum = 0.0;
  1420     for (uint i = 0; i < ParallelGCThreads; i++)
  1421       sum += data[i];
  1422     return sum;
  1423   } else {
  1424     return data[0];
  1428 double G1CollectorPolicy::max_sum (double* data1,
  1429                                    double* data2) {
  1430   double ret = data1[0] + data2[0];
  1432   if (ParallelGCThreads > 0) {
  1433     for (uint i = 1; i < ParallelGCThreads; ++i) {
  1434       double data = data1[i] + data2[i];
  1435       if (data > ret)
  1436         ret = data;
  1439   return ret;
  1442 // Anything below that is considered to be zero
  1443 #define MIN_TIMER_GRANULARITY 0.0000001
  1445 void G1CollectorPolicy::record_collection_pause_end(bool abandoned) {
  1446   double end_time_sec = os::elapsedTime();
  1447   double elapsed_ms = _last_pause_time_ms;
  1448   bool parallel = ParallelGCThreads > 0;
  1449   double evac_ms = (end_time_sec - _cur_G1_strong_roots_end_sec) * 1000.0;
  1450   size_t rs_size =
  1451     _cur_collection_pause_used_regions_at_start - collection_set_size();
  1452   size_t cur_used_bytes = _g1->used();
  1453   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
  1454   bool last_pause_included_initial_mark = false;
  1455   bool update_stats = !abandoned && !_g1->evacuation_failed();
  1457 #ifndef PRODUCT
  1458   if (G1YoungSurvRateVerbose) {
  1459     gclog_or_tty->print_cr("");
  1460     _short_lived_surv_rate_group->print();
  1461     // do that for any other surv rate groups too
  1463 #endif // PRODUCT
  1465   if (in_young_gc_mode()) {
  1466     last_pause_included_initial_mark = during_initial_mark_pause();
  1467     if (last_pause_included_initial_mark)
  1468       record_concurrent_mark_init_end_pre(0.0);
  1470     size_t min_used_targ =
  1471       (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
  1474     if (!_g1->mark_in_progress() && !_last_full_young_gc) {
  1475       assert(!last_pause_included_initial_mark, "invariant");
  1476       if (cur_used_bytes > min_used_targ &&
  1477           cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
  1478         assert(!during_initial_mark_pause(), "we should not see this here");
  1480         // Note: this might have already been set, if during the last
  1481         // pause we decided to start a cycle but at the beginning of
  1482         // this pause we decided to postpone it. That's OK.
  1483         set_initiate_conc_mark_if_possible();
  1487     _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
  1490   _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
  1491                           end_time_sec, false);
  1493   guarantee(_cur_collection_pause_used_regions_at_start >=
  1494             collection_set_size(),
  1495             "Negative RS size?");
  1497   // This assert is exempted when we're doing parallel collection pauses,
  1498   // because the fragmentation caused by the parallel GC allocation buffers
  1499   // can lead to more memory being used during collection than was used
  1500   // before. Best leave this out until the fragmentation problem is fixed.
  1501   // Pauses in which evacuation failed can also lead to negative
  1502   // collections, since no space is reclaimed from a region containing an
  1503   // object whose evacuation failed.
  1504   // Further, we're now always doing parallel collection.  But I'm still
  1505   // leaving this here as a placeholder for a more precise assertion later.
  1506   // (DLD, 10/05.)
  1507   assert((true || parallel) // Always using GC LABs now.
  1508          || _g1->evacuation_failed()
  1509          || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
  1510          "Negative collection");
  1512   size_t freed_bytes =
  1513     _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
  1514   size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
  1515   double survival_fraction =
  1516     (double)surviving_bytes/
  1517     (double)_collection_set_bytes_used_before;
  1519   _n_pauses++;
  1521   if (update_stats) {
  1522     _recent_CH_strong_roots_times_ms->add(_cur_CH_strong_roots_dur_ms);
  1523     _recent_G1_strong_roots_times_ms->add(_cur_G1_strong_roots_dur_ms);
  1524     _recent_evac_times_ms->add(evac_ms);
  1525     _recent_pause_times_ms->add(elapsed_ms);
  1527     _recent_rs_sizes->add(rs_size);
  1529     // We exempt parallel collection from this check because Alloc Buffer
  1530     // fragmentation can produce negative collections.  Same with evac
  1531     // failure.
  1532     // Further, we're now always doing parallel collection.  But I'm still
  1533     // leaving this here as a placeholder for a more precise assertion later.
  1534     // (DLD, 10/05.
  1535     assert((true || parallel)
  1536            || _g1->evacuation_failed()
  1537            || surviving_bytes <= _collection_set_bytes_used_before,
  1538            "Or else negative collection!");
  1539     _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
  1540     _recent_CS_bytes_surviving->add(surviving_bytes);
  1542     // this is where we update the allocation rate of the application
  1543     double app_time_ms =
  1544       (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
  1545     if (app_time_ms < MIN_TIMER_GRANULARITY) {
  1546       // This usually happens due to the timer not having the required
  1547       // granularity. Some Linuxes are the usual culprits.
  1548       // We'll just set it to something (arbitrarily) small.
  1549       app_time_ms = 1.0;
  1551     size_t regions_allocated =
  1552       (_region_num_young - _prev_region_num_young) +
  1553       (_region_num_tenured - _prev_region_num_tenured);
  1554     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
  1555     _alloc_rate_ms_seq->add(alloc_rate_ms);
  1556     _prev_region_num_young   = _region_num_young;
  1557     _prev_region_num_tenured = _region_num_tenured;
  1559     double interval_ms =
  1560       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
  1561     update_recent_gc_times(end_time_sec, elapsed_ms);
  1562     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
  1563     if (recent_avg_pause_time_ratio() < 0.0 ||
  1564         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
  1565 #ifndef PRODUCT
  1566       // Dump info to allow post-facto debugging
  1567       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
  1568       gclog_or_tty->print_cr("-------------------------------------------");
  1569       gclog_or_tty->print_cr("Recent GC Times (ms):");
  1570       _recent_gc_times_ms->dump();
  1571       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
  1572       _recent_prev_end_times_for_all_gcs_sec->dump();
  1573       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
  1574                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
  1575       // In debug mode, terminate the JVM if the user wants to debug at this point.
  1576       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
  1577 #endif  // !PRODUCT
  1578       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
  1579       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
  1580       if (_recent_avg_pause_time_ratio < 0.0) {
  1581         _recent_avg_pause_time_ratio = 0.0;
  1582       } else {
  1583         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
  1584         _recent_avg_pause_time_ratio = 1.0;
  1589   if (G1PolicyVerbose > 1) {
  1590     gclog_or_tty->print_cr("   Recording collection pause(%d)", _n_pauses);
  1593   PauseSummary* summary;
  1594   if (abandoned) {
  1595     summary = _abandoned_summary;
  1596   } else {
  1597     summary = _summary;
  1600   double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
  1601   double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
  1602   double scan_only_time = avg_value(_par_last_scan_only_times_ms);
  1603   double scan_only_regions_scanned =
  1604     sum_of_values(_par_last_scan_only_regions_scanned);
  1605   double update_rs_time = avg_value(_par_last_update_rs_times_ms);
  1606   double update_rs_processed_buffers =
  1607     sum_of_values(_par_last_update_rs_processed_buffers);
  1608   double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
  1609   double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
  1610   double termination_time = avg_value(_par_last_termination_times_ms);
  1612   double parallel_other_time = _cur_collection_par_time_ms -
  1613     (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
  1614      scan_only_time + scan_rs_time + obj_copy_time + termination_time);
  1615   if (update_stats) {
  1616     MainBodySummary* body_summary = summary->main_body_summary();
  1617     guarantee(body_summary != NULL, "should not be null!");
  1619     if (_satb_drain_time_set)
  1620       body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
  1621     else
  1622       body_summary->record_satb_drain_time_ms(0.0);
  1623     body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
  1624     body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
  1625     body_summary->record_scan_only_time_ms(scan_only_time);
  1626     body_summary->record_update_rs_time_ms(update_rs_time);
  1627     body_summary->record_scan_rs_time_ms(scan_rs_time);
  1628     body_summary->record_obj_copy_time_ms(obj_copy_time);
  1629     if (parallel) {
  1630       body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
  1631       body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
  1632       body_summary->record_termination_time_ms(termination_time);
  1633       body_summary->record_parallel_other_time_ms(parallel_other_time);
  1635     body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
  1638   if (G1PolicyVerbose > 1) {
  1639     gclog_or_tty->print_cr("      ET: %10.6f ms           (avg: %10.6f ms)\n"
  1640                            "        CH Strong: %10.6f ms    (avg: %10.6f ms)\n"
  1641                            "        G1 Strong: %10.6f ms    (avg: %10.6f ms)\n"
  1642                            "        Evac:      %10.6f ms    (avg: %10.6f ms)\n"
  1643                            "       ET-RS:  %10.6f ms      (avg: %10.6f ms)\n"
  1644                            "      |RS|: " SIZE_FORMAT,
  1645                            elapsed_ms, recent_avg_time_for_pauses_ms(),
  1646                            _cur_CH_strong_roots_dur_ms, recent_avg_time_for_CH_strong_ms(),
  1647                            _cur_G1_strong_roots_dur_ms, recent_avg_time_for_G1_strong_ms(),
  1648                            evac_ms, recent_avg_time_for_evac_ms(),
  1649                            scan_rs_time,
  1650                            recent_avg_time_for_pauses_ms() -
  1651                            recent_avg_time_for_G1_strong_ms(),
  1652                            rs_size);
  1654     gclog_or_tty->print_cr("       Used at start: " SIZE_FORMAT"K"
  1655                            "       At end " SIZE_FORMAT "K\n"
  1656                            "       garbage      : " SIZE_FORMAT "K"
  1657                            "       of     " SIZE_FORMAT "K\n"
  1658                            "       survival     : %6.2f%%  (%6.2f%% avg)",
  1659                            _cur_collection_pause_used_at_start_bytes/K,
  1660                            _g1->used()/K, freed_bytes/K,
  1661                            _collection_set_bytes_used_before/K,
  1662                            survival_fraction*100.0,
  1663                            recent_avg_survival_fraction()*100.0);
  1664     gclog_or_tty->print_cr("       Recent %% gc pause time: %6.2f",
  1665                            recent_avg_pause_time_ratio() * 100.0);
  1668   double other_time_ms = elapsed_ms;
  1670   if (!abandoned) {
  1671     if (_satb_drain_time_set)
  1672       other_time_ms -= _cur_satb_drain_time_ms;
  1674     if (parallel)
  1675       other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
  1676     else
  1677       other_time_ms -=
  1678         update_rs_time +
  1679         ext_root_scan_time + mark_stack_scan_time + scan_only_time +
  1680         scan_rs_time + obj_copy_time;
  1683   if (PrintGCDetails) {
  1684     gclog_or_tty->print_cr("%s%s, %1.8lf secs]",
  1685                            abandoned ? " (abandoned)" : "",
  1686                            (last_pause_included_initial_mark) ? " (initial-mark)" : "",
  1687                            elapsed_ms / 1000.0);
  1689     if (!abandoned) {
  1690       if (_satb_drain_time_set) {
  1691         print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
  1693       if (_last_satb_drain_processed_buffers >= 0) {
  1694         print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
  1696       if (parallel) {
  1697         print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
  1698         print_par_stats(2, "Update RS (Start)", _par_last_update_rs_start_times_ms, false);
  1699         print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
  1700         print_par_buffers(3, "Processed Buffers",
  1701                           _par_last_update_rs_processed_buffers, true);
  1702         print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
  1703         print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
  1704         print_par_stats(2, "Scan-Only Scanning", _par_last_scan_only_times_ms);
  1705         print_par_buffers(3, "Scan-Only Regions",
  1706                           _par_last_scan_only_regions_scanned, true);
  1707         print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
  1708         print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
  1709         print_par_stats(2, "Termination", _par_last_termination_times_ms);
  1710         print_stats(2, "Other", parallel_other_time);
  1711         print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
  1712       } else {
  1713         print_stats(1, "Update RS", update_rs_time);
  1714         print_stats(2, "Processed Buffers",
  1715                     (int)update_rs_processed_buffers);
  1716         print_stats(1, "Ext Root Scanning", ext_root_scan_time);
  1717         print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
  1718         print_stats(1, "Scan-Only Scanning", scan_only_time);
  1719         print_stats(1, "Scan RS", scan_rs_time);
  1720         print_stats(1, "Object Copying", obj_copy_time);
  1723 #ifndef PRODUCT
  1724     print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
  1725     print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
  1726     print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
  1727     print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
  1728     if (_num_cc_clears > 0) {
  1729       print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
  1731 #endif
  1732     print_stats(1, "Other", other_time_ms);
  1733     for (int i = 0; i < _aux_num; ++i) {
  1734       if (_cur_aux_times_set[i]) {
  1735         char buffer[96];
  1736         sprintf(buffer, "Aux%d", i);
  1737         print_stats(1, buffer, _cur_aux_times_ms[i]);
  1741   if (PrintGCDetails)
  1742     gclog_or_tty->print("   [");
  1743   if (PrintGC || PrintGCDetails)
  1744     _g1->print_size_transition(gclog_or_tty,
  1745                                _cur_collection_pause_used_at_start_bytes,
  1746                                _g1->used(), _g1->capacity());
  1747   if (PrintGCDetails)
  1748     gclog_or_tty->print_cr("]");
  1750   _all_pause_times_ms->add(elapsed_ms);
  1751   if (update_stats) {
  1752     summary->record_total_time_ms(elapsed_ms);
  1753     summary->record_other_time_ms(other_time_ms);
  1755   for (int i = 0; i < _aux_num; ++i)
  1756     if (_cur_aux_times_set[i])
  1757       _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
  1759   // Reset marks-between-pauses counter.
  1760   _n_marks_since_last_pause = 0;
  1762   // Update the efficiency-since-mark vars.
  1763   double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
  1764   if (elapsed_ms < MIN_TIMER_GRANULARITY) {
  1765     // This usually happens due to the timer not having the required
  1766     // granularity. Some Linuxes are the usual culprits.
  1767     // We'll just set it to something (arbitrarily) small.
  1768     proc_ms = 1.0;
  1770   double cur_efficiency = (double) freed_bytes / proc_ms;
  1772   bool new_in_marking_window = _in_marking_window;
  1773   bool new_in_marking_window_im = false;
  1774   if (during_initial_mark_pause()) {
  1775     new_in_marking_window = true;
  1776     new_in_marking_window_im = true;
  1779   if (in_young_gc_mode()) {
  1780     if (_last_full_young_gc) {
  1781       set_full_young_gcs(false);
  1782       _last_full_young_gc = false;
  1785     if ( !_last_young_gc_full ) {
  1786       if ( _should_revert_to_full_young_gcs ||
  1787            _known_garbage_ratio < 0.05 ||
  1788            (adaptive_young_list_length() &&
  1789            (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
  1790         set_full_young_gcs(true);
  1793     _should_revert_to_full_young_gcs = false;
  1795     if (_last_young_gc_full && !_during_marking)
  1796       _young_gc_eff_seq->add(cur_efficiency);
  1799   _short_lived_surv_rate_group->start_adding_regions();
  1800   // do that for any other surv rate groupsx
  1802   // <NEW PREDICTION>
  1804   if (update_stats) {
  1805     double pause_time_ms = elapsed_ms;
  1807     size_t diff = 0;
  1808     if (_max_pending_cards >= _pending_cards)
  1809       diff = _max_pending_cards - _pending_cards;
  1810     _pending_card_diff_seq->add((double) diff);
  1812     double cost_per_card_ms = 0.0;
  1813     if (_pending_cards > 0) {
  1814       cost_per_card_ms = update_rs_time / (double) _pending_cards;
  1815       _cost_per_card_ms_seq->add(cost_per_card_ms);
  1818     double cost_per_scan_only_region_ms = 0.0;
  1819     if (scan_only_regions_scanned > 0.0) {
  1820       cost_per_scan_only_region_ms =
  1821         scan_only_time / scan_only_regions_scanned;
  1822       if (_in_marking_window_im)
  1823         _cost_per_scan_only_region_ms_during_cm_seq->add(cost_per_scan_only_region_ms);
  1824       else
  1825         _cost_per_scan_only_region_ms_seq->add(cost_per_scan_only_region_ms);
  1828     size_t cards_scanned = _g1->cards_scanned();
  1830     double cost_per_entry_ms = 0.0;
  1831     if (cards_scanned > 10) {
  1832       cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
  1833       if (_last_young_gc_full)
  1834         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1835       else
  1836         _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1839     if (_max_rs_lengths > 0) {
  1840       double cards_per_entry_ratio =
  1841         (double) cards_scanned / (double) _max_rs_lengths;
  1842       if (_last_young_gc_full)
  1843         _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1844       else
  1845         _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1848     size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
  1849     if (rs_length_diff >= 0)
  1850       _rs_length_diff_seq->add((double) rs_length_diff);
  1852     size_t copied_bytes = surviving_bytes;
  1853     double cost_per_byte_ms = 0.0;
  1854     if (copied_bytes > 0) {
  1855       cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
  1856       if (_in_marking_window)
  1857         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
  1858       else
  1859         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
  1862     double all_other_time_ms = pause_time_ms -
  1863       (update_rs_time + scan_only_time + scan_rs_time + obj_copy_time +
  1864        _mark_closure_time_ms + termination_time);
  1866     double young_other_time_ms = 0.0;
  1867     if (_recorded_young_regions > 0) {
  1868       young_other_time_ms =
  1869         _recorded_young_cset_choice_time_ms +
  1870         _recorded_young_free_cset_time_ms;
  1871       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
  1872                                              (double) _recorded_young_regions);
  1874     double non_young_other_time_ms = 0.0;
  1875     if (_recorded_non_young_regions > 0) {
  1876       non_young_other_time_ms =
  1877         _recorded_non_young_cset_choice_time_ms +
  1878         _recorded_non_young_free_cset_time_ms;
  1880       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
  1881                                          (double) _recorded_non_young_regions);
  1884     double constant_other_time_ms = all_other_time_ms -
  1885       (young_other_time_ms + non_young_other_time_ms);
  1886     _constant_other_time_ms_seq->add(constant_other_time_ms);
  1888     double survival_ratio = 0.0;
  1889     if (_bytes_in_collection_set_before_gc > 0) {
  1890       survival_ratio = (double) bytes_in_to_space_during_gc() /
  1891         (double) _bytes_in_collection_set_before_gc;
  1894     _pending_cards_seq->add((double) _pending_cards);
  1895     _scanned_cards_seq->add((double) cards_scanned);
  1896     _rs_lengths_seq->add((double) _max_rs_lengths);
  1898     double expensive_region_limit_ms =
  1899       (double) MaxGCPauseMillis - predict_constant_other_time_ms();
  1900     if (expensive_region_limit_ms < 0.0) {
  1901       // this means that the other time was predicted to be longer than
  1902       // than the max pause time
  1903       expensive_region_limit_ms = (double) MaxGCPauseMillis;
  1905     _expensive_region_limit_ms = expensive_region_limit_ms;
  1907     if (PREDICTIONS_VERBOSE) {
  1908       gclog_or_tty->print_cr("");
  1909       gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
  1910                     "REGIONS %d %d %d %d "
  1911                     "PENDING_CARDS %d %d "
  1912                     "CARDS_SCANNED %d %d "
  1913                     "RS_LENGTHS %d %d "
  1914                     "SCAN_ONLY_SCAN %1.6lf %1.6lf "
  1915                     "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
  1916                     "SURVIVAL_RATIO %1.6lf %1.6lf "
  1917                     "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
  1918                     "OTHER_YOUNG %1.6lf %1.6lf "
  1919                     "OTHER_NON_YOUNG %1.6lf %1.6lf "
  1920                     "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
  1921                     "ELAPSED %1.6lf %1.6lf ",
  1922                     _cur_collection_start_sec,
  1923                     (!_last_young_gc_full) ? 2 :
  1924                     (last_pause_included_initial_mark) ? 1 : 0,
  1925                     _recorded_region_num,
  1926                     _recorded_young_regions,
  1927                     _recorded_scan_only_regions,
  1928                     _recorded_non_young_regions,
  1929                     _predicted_pending_cards, _pending_cards,
  1930                     _predicted_cards_scanned, cards_scanned,
  1931                     _predicted_rs_lengths, _max_rs_lengths,
  1932                     _predicted_scan_only_scan_time_ms, scan_only_time,
  1933                     _predicted_rs_update_time_ms, update_rs_time,
  1934                     _predicted_rs_scan_time_ms, scan_rs_time,
  1935                     _predicted_survival_ratio, survival_ratio,
  1936                     _predicted_object_copy_time_ms, obj_copy_time,
  1937                     _predicted_constant_other_time_ms, constant_other_time_ms,
  1938                     _predicted_young_other_time_ms, young_other_time_ms,
  1939                     _predicted_non_young_other_time_ms,
  1940                     non_young_other_time_ms,
  1941                     _vtime_diff_ms, termination_time,
  1942                     _predicted_pause_time_ms, elapsed_ms);
  1945     if (G1PolicyVerbose > 0) {
  1946       gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
  1947                     _predicted_pause_time_ms,
  1948                     (_within_target) ? "within" : "outside",
  1949                     elapsed_ms);
  1954   _in_marking_window = new_in_marking_window;
  1955   _in_marking_window_im = new_in_marking_window_im;
  1956   _free_regions_at_end_of_collection = _g1->free_regions();
  1957   _scan_only_regions_at_end_of_collection = _g1->young_list_length();
  1958   calculate_young_list_min_length();
  1959   calculate_young_list_target_config();
  1961   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
  1962   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
  1963   adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
  1965   // </NEW PREDICTION>
  1967   _target_pause_time_ms = -1.0;
  1970 // <NEW PREDICTION>
  1972 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
  1973                                                      double update_rs_processed_buffers,
  1974                                                      double goal_ms) {
  1975   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  1976   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
  1978   if (G1UseAdaptiveConcRefinement) {
  1979     const int k_gy = 3, k_gr = 6;
  1980     const double inc_k = 1.1, dec_k = 0.9;
  1982     int g = cg1r->green_zone();
  1983     if (update_rs_time > goal_ms) {
  1984       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
  1985     } else {
  1986       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
  1987         g = (int)MAX2(g * inc_k, g + 1.0);
  1990     // Change the refinement threads params
  1991     cg1r->set_green_zone(g);
  1992     cg1r->set_yellow_zone(g * k_gy);
  1993     cg1r->set_red_zone(g * k_gr);
  1994     cg1r->reinitialize_threads();
  1996     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
  1997     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
  1998                                     cg1r->yellow_zone());
  1999     // Change the barrier params
  2000     dcqs.set_process_completed_threshold(processing_threshold);
  2001     dcqs.set_max_completed_queue(cg1r->red_zone());
  2004   int curr_queue_size = dcqs.completed_buffers_num();
  2005   if (curr_queue_size >= cg1r->yellow_zone()) {
  2006     dcqs.set_completed_queue_padding(curr_queue_size);
  2007   } else {
  2008     dcqs.set_completed_queue_padding(0);
  2010   dcqs.notify_if_necessary();
  2013 double
  2014 G1CollectorPolicy::
  2015 predict_young_collection_elapsed_time_ms(size_t adjustment) {
  2016   guarantee( adjustment == 0 || adjustment == 1, "invariant" );
  2018   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  2019   size_t young_num = g1h->young_list_length();
  2020   if (young_num == 0)
  2021     return 0.0;
  2023   young_num += adjustment;
  2024   size_t pending_cards = predict_pending_cards();
  2025   size_t rs_lengths = g1h->young_list_sampled_rs_lengths() +
  2026                       predict_rs_length_diff();
  2027   size_t card_num;
  2028   if (full_young_gcs())
  2029     card_num = predict_young_card_num(rs_lengths);
  2030   else
  2031     card_num = predict_non_young_card_num(rs_lengths);
  2032   size_t young_byte_size = young_num * HeapRegion::GrainBytes;
  2033   double accum_yg_surv_rate =
  2034     _short_lived_surv_rate_group->accum_surv_rate(adjustment);
  2036   size_t bytes_to_copy =
  2037     (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
  2039   return
  2040     predict_rs_update_time_ms(pending_cards) +
  2041     predict_rs_scan_time_ms(card_num) +
  2042     predict_object_copy_time_ms(bytes_to_copy) +
  2043     predict_young_other_time_ms(young_num) +
  2044     predict_constant_other_time_ms();
  2047 double
  2048 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
  2049   size_t rs_length = predict_rs_length_diff();
  2050   size_t card_num;
  2051   if (full_young_gcs())
  2052     card_num = predict_young_card_num(rs_length);
  2053   else
  2054     card_num = predict_non_young_card_num(rs_length);
  2055   return predict_base_elapsed_time_ms(pending_cards, card_num);
  2058 double
  2059 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
  2060                                                 size_t scanned_cards) {
  2061   return
  2062     predict_rs_update_time_ms(pending_cards) +
  2063     predict_rs_scan_time_ms(scanned_cards) +
  2064     predict_constant_other_time_ms();
  2067 double
  2068 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
  2069                                                   bool young) {
  2070   size_t rs_length = hr->rem_set()->occupied();
  2071   size_t card_num;
  2072   if (full_young_gcs())
  2073     card_num = predict_young_card_num(rs_length);
  2074   else
  2075     card_num = predict_non_young_card_num(rs_length);
  2076   size_t bytes_to_copy = predict_bytes_to_copy(hr);
  2078   double region_elapsed_time_ms =
  2079     predict_rs_scan_time_ms(card_num) +
  2080     predict_object_copy_time_ms(bytes_to_copy);
  2082   if (young)
  2083     region_elapsed_time_ms += predict_young_other_time_ms(1);
  2084   else
  2085     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
  2087   return region_elapsed_time_ms;
  2090 size_t
  2091 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
  2092   size_t bytes_to_copy;
  2093   if (hr->is_marked())
  2094     bytes_to_copy = hr->max_live_bytes();
  2095   else {
  2096     guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
  2097                "invariant" );
  2098     int age = hr->age_in_surv_rate_group();
  2099     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
  2100     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
  2103   return bytes_to_copy;
  2106 void
  2107 G1CollectorPolicy::start_recording_regions() {
  2108   _recorded_rs_lengths            = 0;
  2109   _recorded_scan_only_regions     = 0;
  2110   _recorded_young_regions         = 0;
  2111   _recorded_non_young_regions     = 0;
  2113 #if PREDICTIONS_VERBOSE
  2114   _predicted_rs_lengths           = 0;
  2115   _predicted_cards_scanned        = 0;
  2117   _recorded_marked_bytes          = 0;
  2118   _recorded_young_bytes           = 0;
  2119   _predicted_bytes_to_copy        = 0;
  2120 #endif // PREDICTIONS_VERBOSE
  2123 void
  2124 G1CollectorPolicy::record_cset_region(HeapRegion* hr, bool young) {
  2125   if (young) {
  2126     ++_recorded_young_regions;
  2127   } else {
  2128     ++_recorded_non_young_regions;
  2130 #if PREDICTIONS_VERBOSE
  2131   if (young) {
  2132     _recorded_young_bytes += hr->used();
  2133   } else {
  2134     _recorded_marked_bytes += hr->max_live_bytes();
  2136   _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
  2137 #endif // PREDICTIONS_VERBOSE
  2139   size_t rs_length = hr->rem_set()->occupied();
  2140   _recorded_rs_lengths += rs_length;
  2143 void
  2144 G1CollectorPolicy::record_scan_only_regions(size_t scan_only_length) {
  2145   _recorded_scan_only_regions = scan_only_length;
  2148 void
  2149 G1CollectorPolicy::end_recording_regions() {
  2150 #if PREDICTIONS_VERBOSE
  2151   _predicted_pending_cards = predict_pending_cards();
  2152   _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
  2153   if (full_young_gcs())
  2154     _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
  2155   else
  2156     _predicted_cards_scanned +=
  2157       predict_non_young_card_num(_predicted_rs_lengths);
  2158   _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
  2160   _predicted_scan_only_scan_time_ms =
  2161     predict_scan_only_time_ms(_recorded_scan_only_regions);
  2162   _predicted_rs_update_time_ms =
  2163     predict_rs_update_time_ms(_g1->pending_card_num());
  2164   _predicted_rs_scan_time_ms =
  2165     predict_rs_scan_time_ms(_predicted_cards_scanned);
  2166   _predicted_object_copy_time_ms =
  2167     predict_object_copy_time_ms(_predicted_bytes_to_copy);
  2168   _predicted_constant_other_time_ms =
  2169     predict_constant_other_time_ms();
  2170   _predicted_young_other_time_ms =
  2171     predict_young_other_time_ms(_recorded_young_regions);
  2172   _predicted_non_young_other_time_ms =
  2173     predict_non_young_other_time_ms(_recorded_non_young_regions);
  2175   _predicted_pause_time_ms =
  2176     _predicted_scan_only_scan_time_ms +
  2177     _predicted_rs_update_time_ms +
  2178     _predicted_rs_scan_time_ms +
  2179     _predicted_object_copy_time_ms +
  2180     _predicted_constant_other_time_ms +
  2181     _predicted_young_other_time_ms +
  2182     _predicted_non_young_other_time_ms;
  2183 #endif // PREDICTIONS_VERBOSE
  2186 void G1CollectorPolicy::check_if_region_is_too_expensive(double
  2187                                                            predicted_time_ms) {
  2188   // I don't think we need to do this when in young GC mode since
  2189   // marking will be initiated next time we hit the soft limit anyway...
  2190   if (predicted_time_ms > _expensive_region_limit_ms) {
  2191     if (!in_young_gc_mode()) {
  2192         set_full_young_gcs(true);
  2193         // We might want to do something different here. However,
  2194         // right now we don't support the non-generational G1 mode
  2195         // (and in fact we are planning to remove the associated code,
  2196         // see CR 6814390). So, let's leave it as is and this will be
  2197         // removed some time in the future
  2198         ShouldNotReachHere();
  2199         set_during_initial_mark_pause();
  2200     } else
  2201       // no point in doing another partial one
  2202       _should_revert_to_full_young_gcs = true;
  2206 // </NEW PREDICTION>
  2209 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
  2210                                                double elapsed_ms) {
  2211   _recent_gc_times_ms->add(elapsed_ms);
  2212   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
  2213   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
  2216 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
  2217   if (_recent_pause_times_ms->num() == 0) return (double) MaxGCPauseMillis;
  2218   else return _recent_pause_times_ms->avg();
  2221 double G1CollectorPolicy::recent_avg_time_for_CH_strong_ms() {
  2222   if (_recent_CH_strong_roots_times_ms->num() == 0)
  2223     return (double)MaxGCPauseMillis/3.0;
  2224   else return _recent_CH_strong_roots_times_ms->avg();
  2227 double G1CollectorPolicy::recent_avg_time_for_G1_strong_ms() {
  2228   if (_recent_G1_strong_roots_times_ms->num() == 0)
  2229     return (double)MaxGCPauseMillis/3.0;
  2230   else return _recent_G1_strong_roots_times_ms->avg();
  2233 double G1CollectorPolicy::recent_avg_time_for_evac_ms() {
  2234   if (_recent_evac_times_ms->num() == 0) return (double)MaxGCPauseMillis/3.0;
  2235   else return _recent_evac_times_ms->avg();
  2238 int G1CollectorPolicy::number_of_recent_gcs() {
  2239   assert(_recent_CH_strong_roots_times_ms->num() ==
  2240          _recent_G1_strong_roots_times_ms->num(), "Sequence out of sync");
  2241   assert(_recent_G1_strong_roots_times_ms->num() ==
  2242          _recent_evac_times_ms->num(), "Sequence out of sync");
  2243   assert(_recent_evac_times_ms->num() ==
  2244          _recent_pause_times_ms->num(), "Sequence out of sync");
  2245   assert(_recent_pause_times_ms->num() ==
  2246          _recent_CS_bytes_used_before->num(), "Sequence out of sync");
  2247   assert(_recent_CS_bytes_used_before->num() ==
  2248          _recent_CS_bytes_surviving->num(), "Sequence out of sync");
  2249   return _recent_pause_times_ms->num();
  2252 double G1CollectorPolicy::recent_avg_survival_fraction() {
  2253   return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
  2254                                            _recent_CS_bytes_used_before);
  2257 double G1CollectorPolicy::last_survival_fraction() {
  2258   return last_survival_fraction_work(_recent_CS_bytes_surviving,
  2259                                      _recent_CS_bytes_used_before);
  2262 double
  2263 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
  2264                                                      TruncatedSeq* before) {
  2265   assert(surviving->num() == before->num(), "Sequence out of sync");
  2266   if (before->sum() > 0.0) {
  2267       double recent_survival_rate = surviving->sum() / before->sum();
  2268       // We exempt parallel collection from this check because Alloc Buffer
  2269       // fragmentation can produce negative collections.
  2270       // Further, we're now always doing parallel collection.  But I'm still
  2271       // leaving this here as a placeholder for a more precise assertion later.
  2272       // (DLD, 10/05.)
  2273       assert((true || ParallelGCThreads > 0) ||
  2274              _g1->evacuation_failed() ||
  2275              recent_survival_rate <= 1.0, "Or bad frac");
  2276       return recent_survival_rate;
  2277   } else {
  2278     return 1.0; // Be conservative.
  2282 double
  2283 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
  2284                                                TruncatedSeq* before) {
  2285   assert(surviving->num() == before->num(), "Sequence out of sync");
  2286   if (surviving->num() > 0 && before->last() > 0.0) {
  2287     double last_survival_rate = surviving->last() / before->last();
  2288     // We exempt parallel collection from this check because Alloc Buffer
  2289     // fragmentation can produce negative collections.
  2290     // Further, we're now always doing parallel collection.  But I'm still
  2291     // leaving this here as a placeholder for a more precise assertion later.
  2292     // (DLD, 10/05.)
  2293     assert((true || ParallelGCThreads > 0) ||
  2294            last_survival_rate <= 1.0, "Or bad frac");
  2295     return last_survival_rate;
  2296   } else {
  2297     return 1.0;
  2301 static const int survival_min_obs = 5;
  2302 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
  2303 static const double min_survival_rate = 0.1;
  2305 double
  2306 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
  2307                                                            double latest) {
  2308   double res = avg;
  2309   if (number_of_recent_gcs() < survival_min_obs) {
  2310     res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
  2312   res = MAX2(res, latest);
  2313   res = MAX2(res, min_survival_rate);
  2314   // In the parallel case, LAB fragmentation can produce "negative
  2315   // collections"; so can evac failure.  Cap at 1.0
  2316   res = MIN2(res, 1.0);
  2317   return res;
  2320 size_t G1CollectorPolicy::expansion_amount() {
  2321   if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
  2322     // We will double the existing space, or take
  2323     // G1ExpandByPercentOfAvailable % of the available expansion
  2324     // space, whichever is smaller, bounded below by a minimum
  2325     // expansion (unless that's all that's left.)
  2326     const size_t min_expand_bytes = 1*M;
  2327     size_t reserved_bytes = _g1->g1_reserved_obj_bytes();
  2328     size_t committed_bytes = _g1->capacity();
  2329     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
  2330     size_t expand_bytes;
  2331     size_t expand_bytes_via_pct =
  2332       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
  2333     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
  2334     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
  2335     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
  2336     if (G1PolicyVerbose > 1) {
  2337       gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
  2338                  "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
  2339                  "                   Answer = %d.\n",
  2340                  recent_avg_pause_time_ratio(),
  2341                  byte_size_in_proper_unit(committed_bytes),
  2342                  proper_unit_for_byte_size(committed_bytes),
  2343                  byte_size_in_proper_unit(uncommitted_bytes),
  2344                  proper_unit_for_byte_size(uncommitted_bytes),
  2345                  byte_size_in_proper_unit(expand_bytes_via_pct),
  2346                  proper_unit_for_byte_size(expand_bytes_via_pct),
  2347                  byte_size_in_proper_unit(expand_bytes),
  2348                  proper_unit_for_byte_size(expand_bytes));
  2350     return expand_bytes;
  2351   } else {
  2352     return 0;
  2356 void G1CollectorPolicy::note_start_of_mark_thread() {
  2357   _mark_thread_startup_sec = os::elapsedTime();
  2360 class CountCSClosure: public HeapRegionClosure {
  2361   G1CollectorPolicy* _g1_policy;
  2362 public:
  2363   CountCSClosure(G1CollectorPolicy* g1_policy) :
  2364     _g1_policy(g1_policy) {}
  2365   bool doHeapRegion(HeapRegion* r) {
  2366     _g1_policy->_bytes_in_collection_set_before_gc += r->used();
  2367     return false;
  2369 };
  2371 void G1CollectorPolicy::count_CS_bytes_used() {
  2372   CountCSClosure cs_closure(this);
  2373   _g1->collection_set_iterate(&cs_closure);
  2376 static void print_indent(int level) {
  2377   for (int j = 0; j < level+1; ++j)
  2378     gclog_or_tty->print("   ");
  2381 void G1CollectorPolicy::print_summary (int level,
  2382                                        const char* str,
  2383                                        NumberSeq* seq) const {
  2384   double sum = seq->sum();
  2385   print_indent(level);
  2386   gclog_or_tty->print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
  2387                 str, sum / 1000.0, seq->avg());
  2390 void G1CollectorPolicy::print_summary_sd (int level,
  2391                                           const char* str,
  2392                                           NumberSeq* seq) const {
  2393   print_summary(level, str, seq);
  2394   print_indent(level + 5);
  2395   gclog_or_tty->print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
  2396                 seq->num(), seq->sd(), seq->maximum());
  2399 void G1CollectorPolicy::check_other_times(int level,
  2400                                         NumberSeq* other_times_ms,
  2401                                         NumberSeq* calc_other_times_ms) const {
  2402   bool should_print = false;
  2404   double max_sum = MAX2(fabs(other_times_ms->sum()),
  2405                         fabs(calc_other_times_ms->sum()));
  2406   double min_sum = MIN2(fabs(other_times_ms->sum()),
  2407                         fabs(calc_other_times_ms->sum()));
  2408   double sum_ratio = max_sum / min_sum;
  2409   if (sum_ratio > 1.1) {
  2410     should_print = true;
  2411     print_indent(level + 1);
  2412     gclog_or_tty->print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
  2415   double max_avg = MAX2(fabs(other_times_ms->avg()),
  2416                         fabs(calc_other_times_ms->avg()));
  2417   double min_avg = MIN2(fabs(other_times_ms->avg()),
  2418                         fabs(calc_other_times_ms->avg()));
  2419   double avg_ratio = max_avg / min_avg;
  2420   if (avg_ratio > 1.1) {
  2421     should_print = true;
  2422     print_indent(level + 1);
  2423     gclog_or_tty->print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
  2426   if (other_times_ms->sum() < -0.01) {
  2427     print_indent(level + 1);
  2428     gclog_or_tty->print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
  2431   if (other_times_ms->avg() < -0.01) {
  2432     print_indent(level + 1);
  2433     gclog_or_tty->print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
  2436   if (calc_other_times_ms->sum() < -0.01) {
  2437     should_print = true;
  2438     print_indent(level + 1);
  2439     gclog_or_tty->print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
  2442   if (calc_other_times_ms->avg() < -0.01) {
  2443     should_print = true;
  2444     print_indent(level + 1);
  2445     gclog_or_tty->print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
  2448   if (should_print)
  2449     print_summary(level, "Other(Calc)", calc_other_times_ms);
  2452 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
  2453   bool parallel = ParallelGCThreads > 0;
  2454   MainBodySummary*    body_summary = summary->main_body_summary();
  2455   if (summary->get_total_seq()->num() > 0) {
  2456     print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
  2457     if (body_summary != NULL) {
  2458       print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
  2459       if (parallel) {
  2460         print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
  2461         print_summary(2, "Update RS", body_summary->get_update_rs_seq());
  2462         print_summary(2, "Ext Root Scanning",
  2463                       body_summary->get_ext_root_scan_seq());
  2464         print_summary(2, "Mark Stack Scanning",
  2465                       body_summary->get_mark_stack_scan_seq());
  2466         print_summary(2, "Scan-Only Scanning",
  2467                       body_summary->get_scan_only_seq());
  2468         print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
  2469         print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
  2470         print_summary(2, "Termination", body_summary->get_termination_seq());
  2471         print_summary(2, "Other", body_summary->get_parallel_other_seq());
  2473           NumberSeq* other_parts[] = {
  2474             body_summary->get_update_rs_seq(),
  2475             body_summary->get_ext_root_scan_seq(),
  2476             body_summary->get_mark_stack_scan_seq(),
  2477             body_summary->get_scan_only_seq(),
  2478             body_summary->get_scan_rs_seq(),
  2479             body_summary->get_obj_copy_seq(),
  2480             body_summary->get_termination_seq()
  2481           };
  2482           NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
  2483                                         7, other_parts);
  2484           check_other_times(2, body_summary->get_parallel_other_seq(),
  2485                             &calc_other_times_ms);
  2487         print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
  2488         print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
  2489       } else {
  2490         print_summary(1, "Update RS", body_summary->get_update_rs_seq());
  2491         print_summary(1, "Ext Root Scanning",
  2492                       body_summary->get_ext_root_scan_seq());
  2493         print_summary(1, "Mark Stack Scanning",
  2494                       body_summary->get_mark_stack_scan_seq());
  2495         print_summary(1, "Scan-Only Scanning",
  2496                       body_summary->get_scan_only_seq());
  2497         print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
  2498         print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
  2501     print_summary(1, "Other", summary->get_other_seq());
  2503       NumberSeq calc_other_times_ms;
  2504       if (body_summary != NULL) {
  2505         // not abandoned
  2506         if (parallel) {
  2507           // parallel
  2508           NumberSeq* other_parts[] = {
  2509             body_summary->get_satb_drain_seq(),
  2510             body_summary->get_parallel_seq(),
  2511             body_summary->get_clear_ct_seq()
  2512           };
  2513           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2514                                           3, other_parts);
  2515         } else {
  2516           // serial
  2517           NumberSeq* other_parts[] = {
  2518             body_summary->get_satb_drain_seq(),
  2519             body_summary->get_update_rs_seq(),
  2520             body_summary->get_ext_root_scan_seq(),
  2521             body_summary->get_mark_stack_scan_seq(),
  2522             body_summary->get_scan_only_seq(),
  2523             body_summary->get_scan_rs_seq(),
  2524             body_summary->get_obj_copy_seq()
  2525           };
  2526           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2527                                           7, other_parts);
  2529       } else {
  2530         // abandoned
  2531         calc_other_times_ms = NumberSeq();
  2533       check_other_times(1,  summary->get_other_seq(), &calc_other_times_ms);
  2535   } else {
  2536     print_indent(0);
  2537     gclog_or_tty->print_cr("none");
  2539   gclog_or_tty->print_cr("");
  2542 void
  2543 G1CollectorPolicy::print_abandoned_summary(PauseSummary* summary) const {
  2544   bool printed = false;
  2545   if (summary->get_total_seq()->num() > 0) {
  2546     printed = true;
  2547     print_summary(summary);
  2549   if (!printed) {
  2550     print_indent(0);
  2551     gclog_or_tty->print_cr("none");
  2552     gclog_or_tty->print_cr("");
  2556 void G1CollectorPolicy::print_tracing_info() const {
  2557   if (TraceGen0Time) {
  2558     gclog_or_tty->print_cr("ALL PAUSES");
  2559     print_summary_sd(0, "Total", _all_pause_times_ms);
  2560     gclog_or_tty->print_cr("");
  2561     gclog_or_tty->print_cr("");
  2562     gclog_or_tty->print_cr("   Full Young GC Pauses:    %8d", _full_young_pause_num);
  2563     gclog_or_tty->print_cr("   Partial Young GC Pauses: %8d", _partial_young_pause_num);
  2564     gclog_or_tty->print_cr("");
  2566     gclog_or_tty->print_cr("EVACUATION PAUSES");
  2567     print_summary(_summary);
  2569     gclog_or_tty->print_cr("ABANDONED PAUSES");
  2570     print_abandoned_summary(_abandoned_summary);
  2572     gclog_or_tty->print_cr("MISC");
  2573     print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
  2574     print_summary_sd(0, "Yields", _all_yield_times_ms);
  2575     for (int i = 0; i < _aux_num; ++i) {
  2576       if (_all_aux_times_ms[i].num() > 0) {
  2577         char buffer[96];
  2578         sprintf(buffer, "Aux%d", i);
  2579         print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
  2583     size_t all_region_num = _region_num_young + _region_num_tenured;
  2584     gclog_or_tty->print_cr("   New Regions %8d, Young %8d (%6.2lf%%), "
  2585                "Tenured %8d (%6.2lf%%)",
  2586                all_region_num,
  2587                _region_num_young,
  2588                (double) _region_num_young / (double) all_region_num * 100.0,
  2589                _region_num_tenured,
  2590                (double) _region_num_tenured / (double) all_region_num * 100.0);
  2592   if (TraceGen1Time) {
  2593     if (_all_full_gc_times_ms->num() > 0) {
  2594       gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
  2595                  _all_full_gc_times_ms->num(),
  2596                  _all_full_gc_times_ms->sum() / 1000.0);
  2597       gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
  2598       gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
  2599                     _all_full_gc_times_ms->sd(),
  2600                     _all_full_gc_times_ms->maximum());
  2605 void G1CollectorPolicy::print_yg_surv_rate_info() const {
  2606 #ifndef PRODUCT
  2607   _short_lived_surv_rate_group->print_surv_rate_summary();
  2608   // add this call for any other surv rate groups
  2609 #endif // PRODUCT
  2612 bool
  2613 G1CollectorPolicy::should_add_next_region_to_young_list() {
  2614   assert(in_young_gc_mode(), "should be in young GC mode");
  2615   bool ret;
  2616   size_t young_list_length = _g1->young_list_length();
  2617   size_t young_list_max_length = _young_list_target_length;
  2618   if (G1FixedEdenSize) {
  2619     young_list_max_length -= _max_survivor_regions;
  2621   if (young_list_length < young_list_max_length) {
  2622     ret = true;
  2623     ++_region_num_young;
  2624   } else {
  2625     ret = false;
  2626     ++_region_num_tenured;
  2629   return ret;
  2632 #ifndef PRODUCT
  2633 // for debugging, bit of a hack...
  2634 static char*
  2635 region_num_to_mbs(int length) {
  2636   static char buffer[64];
  2637   double bytes = (double) (length * HeapRegion::GrainBytes);
  2638   double mbs = bytes / (double) (1024 * 1024);
  2639   sprintf(buffer, "%7.2lfMB", mbs);
  2640   return buffer;
  2642 #endif // PRODUCT
  2644 size_t G1CollectorPolicy::max_regions(int purpose) {
  2645   switch (purpose) {
  2646     case GCAllocForSurvived:
  2647       return _max_survivor_regions;
  2648     case GCAllocForTenured:
  2649       return REGIONS_UNLIMITED;
  2650     default:
  2651       ShouldNotReachHere();
  2652       return REGIONS_UNLIMITED;
  2653   };
  2656 // Calculates survivor space parameters.
  2657 void G1CollectorPolicy::calculate_survivors_policy()
  2659   if (G1FixedSurvivorSpaceSize == 0) {
  2660     _max_survivor_regions = _young_list_target_length / SurvivorRatio;
  2661   } else {
  2662     _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
  2665   if (G1FixedTenuringThreshold) {
  2666     _tenuring_threshold = MaxTenuringThreshold;
  2667   } else {
  2668     _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
  2669         HeapRegion::GrainWords * _max_survivor_regions);
  2673 bool
  2674 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t
  2675                                                                word_size) {
  2676   assert(_g1->regions_accounted_for(), "Region leakage!");
  2677   double max_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
  2679   size_t young_list_length = _g1->young_list_length();
  2680   size_t young_list_max_length = _young_list_target_length;
  2681   if (G1FixedEdenSize) {
  2682     young_list_max_length -= _max_survivor_regions;
  2684   bool reached_target_length = young_list_length >= young_list_max_length;
  2686   if (in_young_gc_mode()) {
  2687     if (reached_target_length) {
  2688       assert( young_list_length > 0 && _g1->young_list_length() > 0,
  2689               "invariant" );
  2690       _target_pause_time_ms = max_pause_time_ms;
  2691       return true;
  2693   } else {
  2694     guarantee( false, "should not reach here" );
  2697   return false;
  2700 #ifndef PRODUCT
  2701 class HRSortIndexIsOKClosure: public HeapRegionClosure {
  2702   CollectionSetChooser* _chooser;
  2703 public:
  2704   HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
  2705     _chooser(chooser) {}
  2707   bool doHeapRegion(HeapRegion* r) {
  2708     if (!r->continuesHumongous()) {
  2709       assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
  2711     return false;
  2713 };
  2715 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
  2716   HRSortIndexIsOKClosure cl(_collectionSetChooser);
  2717   _g1->heap_region_iterate(&cl);
  2718   return true;
  2720 #endif
  2722 void
  2723 G1CollectorPolicy::decide_on_conc_mark_initiation() {
  2724   // We are about to decide on whether this pause will be an
  2725   // initial-mark pause.
  2727   // First, during_initial_mark_pause() should not be already set. We
  2728   // will set it here if we have to. However, it should be cleared by
  2729   // the end of the pause (it's only set for the duration of an
  2730   // initial-mark pause).
  2731   assert(!during_initial_mark_pause(), "pre-condition");
  2733   if (initiate_conc_mark_if_possible()) {
  2734     // We had noticed on a previous pause that the heap occupancy has
  2735     // gone over the initiating threshold and we should start a
  2736     // concurrent marking cycle. So we might initiate one.
  2738     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
  2739     if (!during_cycle) {
  2740       // The concurrent marking thread is not "during a cycle", i.e.,
  2741       // it has completed the last one. So we can go ahead and
  2742       // initiate a new cycle.
  2744       set_during_initial_mark_pause();
  2746       // And we can now clear initiate_conc_mark_if_possible() as
  2747       // we've already acted on it.
  2748       clear_initiate_conc_mark_if_possible();
  2749     } else {
  2750       // The concurrent marking thread is still finishing up the
  2751       // previous cycle. If we start one right now the two cycles
  2752       // overlap. In particular, the concurrent marking thread might
  2753       // be in the process of clearing the next marking bitmap (which
  2754       // we will use for the next cycle if we start one). Starting a
  2755       // cycle now will be bad given that parts of the marking
  2756       // information might get cleared by the marking thread. And we
  2757       // cannot wait for the marking thread to finish the cycle as it
  2758       // periodically yields while clearing the next marking bitmap
  2759       // and, if it's in a yield point, it's waiting for us to
  2760       // finish. So, at this point we will not start a cycle and we'll
  2761       // let the concurrent marking thread complete the last one.
  2766 void
  2767 G1CollectorPolicy_BestRegionsFirst::
  2768 record_collection_pause_start(double start_time_sec, size_t start_used) {
  2769   G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
  2772 class NextNonCSElemFinder: public HeapRegionClosure {
  2773   HeapRegion* _res;
  2774 public:
  2775   NextNonCSElemFinder(): _res(NULL) {}
  2776   bool doHeapRegion(HeapRegion* r) {
  2777     if (!r->in_collection_set()) {
  2778       _res = r;
  2779       return true;
  2780     } else {
  2781       return false;
  2784   HeapRegion* res() { return _res; }
  2785 };
  2787 class KnownGarbageClosure: public HeapRegionClosure {
  2788   CollectionSetChooser* _hrSorted;
  2790 public:
  2791   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
  2792     _hrSorted(hrSorted)
  2793   {}
  2795   bool doHeapRegion(HeapRegion* r) {
  2796     // We only include humongous regions in collection
  2797     // sets when concurrent mark shows that their contained object is
  2798     // unreachable.
  2800     // Do we have any marking information for this region?
  2801     if (r->is_marked()) {
  2802       // We don't include humongous regions in collection
  2803       // sets because we collect them immediately at the end of a marking
  2804       // cycle.  We also don't include young regions because we *must*
  2805       // include them in the next collection pause.
  2806       if (!r->isHumongous() && !r->is_young()) {
  2807         _hrSorted->addMarkedHeapRegion(r);
  2810     return false;
  2812 };
  2814 class ParKnownGarbageHRClosure: public HeapRegionClosure {
  2815   CollectionSetChooser* _hrSorted;
  2816   jint _marked_regions_added;
  2817   jint _chunk_size;
  2818   jint _cur_chunk_idx;
  2819   jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
  2820   int _worker;
  2821   int _invokes;
  2823   void get_new_chunk() {
  2824     _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
  2825     _cur_chunk_end = _cur_chunk_idx + _chunk_size;
  2827   void add_region(HeapRegion* r) {
  2828     if (_cur_chunk_idx == _cur_chunk_end) {
  2829       get_new_chunk();
  2831     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
  2832     _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
  2833     _marked_regions_added++;
  2834     _cur_chunk_idx++;
  2837 public:
  2838   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
  2839                            jint chunk_size,
  2840                            int worker) :
  2841     _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
  2842     _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
  2843     _invokes(0)
  2844   {}
  2846   bool doHeapRegion(HeapRegion* r) {
  2847     // We only include humongous regions in collection
  2848     // sets when concurrent mark shows that their contained object is
  2849     // unreachable.
  2850     _invokes++;
  2852     // Do we have any marking information for this region?
  2853     if (r->is_marked()) {
  2854       // We don't include humongous regions in collection
  2855       // sets because we collect them immediately at the end of a marking
  2856       // cycle.
  2857       // We also do not include young regions in collection sets
  2858       if (!r->isHumongous() && !r->is_young()) {
  2859         add_region(r);
  2862     return false;
  2864   jint marked_regions_added() { return _marked_regions_added; }
  2865   int invokes() { return _invokes; }
  2866 };
  2868 class ParKnownGarbageTask: public AbstractGangTask {
  2869   CollectionSetChooser* _hrSorted;
  2870   jint _chunk_size;
  2871   G1CollectedHeap* _g1;
  2872 public:
  2873   ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
  2874     AbstractGangTask("ParKnownGarbageTask"),
  2875     _hrSorted(hrSorted), _chunk_size(chunk_size),
  2876     _g1(G1CollectedHeap::heap())
  2877   {}
  2879   void work(int i) {
  2880     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
  2881     // Back to zero for the claim value.
  2882     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
  2883                                          HeapRegion::InitialClaimValue);
  2884     jint regions_added = parKnownGarbageCl.marked_regions_added();
  2885     _hrSorted->incNumMarkedHeapRegions(regions_added);
  2886     if (G1PrintParCleanupStats) {
  2887       gclog_or_tty->print("     Thread %d called %d times, added %d regions to list.\n",
  2888                  i, parKnownGarbageCl.invokes(), regions_added);
  2891 };
  2893 void
  2894 G1CollectorPolicy_BestRegionsFirst::
  2895 record_concurrent_mark_cleanup_end(size_t freed_bytes,
  2896                                    size_t max_live_bytes) {
  2897   double start;
  2898   if (G1PrintParCleanupStats) start = os::elapsedTime();
  2899   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
  2901   _collectionSetChooser->clearMarkedHeapRegions();
  2902   double clear_marked_end;
  2903   if (G1PrintParCleanupStats) {
  2904     clear_marked_end = os::elapsedTime();
  2905     gclog_or_tty->print_cr("  clear marked regions + work1: %8.3f ms.",
  2906                   (clear_marked_end - start)*1000.0);
  2908   if (ParallelGCThreads > 0) {
  2909     const size_t OverpartitionFactor = 4;
  2910     const size_t MinChunkSize = 8;
  2911     const size_t ChunkSize =
  2912       MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
  2913            MinChunkSize);
  2914     _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
  2915                                                              ChunkSize);
  2916     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
  2917                                             (int) ChunkSize);
  2918     _g1->workers()->run_task(&parKnownGarbageTask);
  2920     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
  2921            "sanity check");
  2922   } else {
  2923     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
  2924     _g1->heap_region_iterate(&knownGarbagecl);
  2926   double known_garbage_end;
  2927   if (G1PrintParCleanupStats) {
  2928     known_garbage_end = os::elapsedTime();
  2929     gclog_or_tty->print_cr("  compute known garbage: %8.3f ms.",
  2930                   (known_garbage_end - clear_marked_end)*1000.0);
  2932   _collectionSetChooser->sortMarkedHeapRegions();
  2933   double sort_end;
  2934   if (G1PrintParCleanupStats) {
  2935     sort_end = os::elapsedTime();
  2936     gclog_or_tty->print_cr("  sorting: %8.3f ms.",
  2937                   (sort_end - known_garbage_end)*1000.0);
  2940   record_concurrent_mark_cleanup_end_work2();
  2941   double work2_end;
  2942   if (G1PrintParCleanupStats) {
  2943     work2_end = os::elapsedTime();
  2944     gclog_or_tty->print_cr("  work2: %8.3f ms.",
  2945                   (work2_end - sort_end)*1000.0);
  2949 // Add the heap region to the collection set and return the conservative
  2950 // estimate of the number of live bytes.
  2951 void G1CollectorPolicy::
  2952 add_to_collection_set(HeapRegion* hr) {
  2953   if (G1PrintHeapRegions) {
  2954     gclog_or_tty->print_cr("added region to cset "
  2955                            "%d:["PTR_FORMAT", "PTR_FORMAT"], "
  2956                            "top "PTR_FORMAT", %s",
  2957                            hr->hrs_index(), hr->bottom(), hr->end(),
  2958                            hr->top(), hr->is_young() ? "YOUNG" : "NOT_YOUNG");
  2961   if (_g1->mark_in_progress())
  2962     _g1->concurrent_mark()->registerCSetRegion(hr);
  2964   assert(!hr->in_collection_set(),
  2965               "should not already be in the CSet");
  2966   hr->set_in_collection_set(true);
  2967   hr->set_next_in_collection_set(_collection_set);
  2968   _collection_set = hr;
  2969   _collection_set_size++;
  2970   _collection_set_bytes_used_before += hr->used();
  2971   _g1->register_region_with_in_cset_fast_test(hr);
  2974 void
  2975 G1CollectorPolicy_BestRegionsFirst::
  2976 choose_collection_set() {
  2977   double non_young_start_time_sec;
  2978   start_recording_regions();
  2980   guarantee(_target_pause_time_ms > -1.0
  2981             NOT_PRODUCT(|| Universe::heap()->gc_cause() == GCCause::_scavenge_alot),
  2982             "_target_pause_time_ms should have been set!");
  2983 #ifndef PRODUCT
  2984   if (_target_pause_time_ms <= -1.0) {
  2985     assert(ScavengeALot && Universe::heap()->gc_cause() == GCCause::_scavenge_alot, "Error");
  2986     _target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
  2988 #endif
  2989   assert(_collection_set == NULL, "Precondition");
  2991   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
  2992   double predicted_pause_time_ms = base_time_ms;
  2994   double target_time_ms = _target_pause_time_ms;
  2995   double time_remaining_ms = target_time_ms - base_time_ms;
  2997   // the 10% and 50% values are arbitrary...
  2998   if (time_remaining_ms < 0.10*target_time_ms) {
  2999     time_remaining_ms = 0.50 * target_time_ms;
  3000     _within_target = false;
  3001   } else {
  3002     _within_target = true;
  3005   // We figure out the number of bytes available for future to-space.
  3006   // For new regions without marking information, we must assume the
  3007   // worst-case of complete survival.  If we have marking information for a
  3008   // region, we can bound the amount of live data.  We can add a number of
  3009   // such regions, as long as the sum of the live data bounds does not
  3010   // exceed the available evacuation space.
  3011   size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
  3013   size_t expansion_bytes =
  3014     _g1->expansion_regions() * HeapRegion::GrainBytes;
  3016   _collection_set_bytes_used_before = 0;
  3017   _collection_set_size = 0;
  3019   // Adjust for expansion and slop.
  3020   max_live_bytes = max_live_bytes + expansion_bytes;
  3022   assert(_g1->regions_accounted_for(), "Region leakage!");
  3024   HeapRegion* hr;
  3025   if (in_young_gc_mode()) {
  3026     double young_start_time_sec = os::elapsedTime();
  3028     if (G1PolicyVerbose > 0) {
  3029       gclog_or_tty->print_cr("Adding %d young regions to the CSet",
  3030                     _g1->young_list_length());
  3032     _young_cset_length  = 0;
  3033     _last_young_gc_full = full_young_gcs() ? true : false;
  3034     if (_last_young_gc_full)
  3035       ++_full_young_pause_num;
  3036     else
  3037       ++_partial_young_pause_num;
  3038     hr = _g1->pop_region_from_young_list();
  3039     while (hr != NULL) {
  3041       assert( hr->young_index_in_cset() == -1, "invariant" );
  3042       assert( hr->age_in_surv_rate_group() != -1, "invariant" );
  3043       hr->set_young_index_in_cset((int) _young_cset_length);
  3045       ++_young_cset_length;
  3046       double predicted_time_ms = predict_region_elapsed_time_ms(hr, true);
  3047       time_remaining_ms -= predicted_time_ms;
  3048       predicted_pause_time_ms += predicted_time_ms;
  3049       assert(!hr->in_collection_set(), "invariant");
  3050       add_to_collection_set(hr);
  3051       record_cset_region(hr, true);
  3052       max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
  3053       if (G1PolicyVerbose > 0) {
  3054         gclog_or_tty->print_cr("  Added [" PTR_FORMAT ", " PTR_FORMAT") to CS.",
  3055                       hr->bottom(), hr->end());
  3056         gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  3057                       max_live_bytes/K);
  3059       hr = _g1->pop_region_from_young_list();
  3062     record_scan_only_regions(_g1->young_list_scan_only_length());
  3064     double young_end_time_sec = os::elapsedTime();
  3065     _recorded_young_cset_choice_time_ms =
  3066       (young_end_time_sec - young_start_time_sec) * 1000.0;
  3068     non_young_start_time_sec = os::elapsedTime();
  3070     if (_young_cset_length > 0 && _last_young_gc_full) {
  3071       // don't bother adding more regions...
  3072       goto choose_collection_set_end;
  3076   if (!in_young_gc_mode() || !full_young_gcs()) {
  3077     bool should_continue = true;
  3078     NumberSeq seq;
  3079     double avg_prediction = 100000000000000000.0; // something very large
  3080     do {
  3081       hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
  3082                                                       avg_prediction);
  3083       if (hr != NULL) {
  3084         double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
  3085         time_remaining_ms -= predicted_time_ms;
  3086         predicted_pause_time_ms += predicted_time_ms;
  3087         add_to_collection_set(hr);
  3088         record_cset_region(hr, false);
  3089         max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
  3090         if (G1PolicyVerbose > 0) {
  3091           gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  3092                         max_live_bytes/K);
  3094         seq.add(predicted_time_ms);
  3095         avg_prediction = seq.avg() + seq.sd();
  3097       should_continue =
  3098         ( hr != NULL) &&
  3099         ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
  3100           : _collection_set_size < _young_list_fixed_length );
  3101     } while (should_continue);
  3103     if (!adaptive_young_list_length() &&
  3104         _collection_set_size < _young_list_fixed_length)
  3105       _should_revert_to_full_young_gcs  = true;
  3108 choose_collection_set_end:
  3109   count_CS_bytes_used();
  3111   end_recording_regions();
  3113   double non_young_end_time_sec = os::elapsedTime();
  3114   _recorded_non_young_cset_choice_time_ms =
  3115     (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
  3118 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
  3119   G1CollectorPolicy::record_full_collection_end();
  3120   _collectionSetChooser->updateAfterFullCollection();
  3123 void G1CollectorPolicy_BestRegionsFirst::
  3124 expand_if_possible(size_t numRegions) {
  3125   size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
  3126   _g1->expand(expansion_bytes);
  3129 void G1CollectorPolicy_BestRegionsFirst::
  3130 record_collection_pause_end(bool abandoned) {
  3131   G1CollectorPolicy::record_collection_pause_end(abandoned);
  3132   assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");

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