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

Mon, 01 Aug 2011 10:04:28 -0700

author
johnc
date
Mon, 01 Aug 2011 10:04:28 -0700
changeset 3021
14a2fd14c0db
parent 2975
5f6f2615433a
child 3028
f44782f04dd4
permissions
-rw-r--r--

7068240: G1: Long "parallel other time" and "ext root scanning" when running specific benchmark
Summary: In root processing, move the scanning of the reference processor's discovered lists to before RSet updating and scanning. When scanning the reference processor's discovered lists, use a buffering closure so that the time spent copying any reference object is correctly attributed. Also removed a couple of unused and irrelevant timers.
Reviewed-by: ysr, jmasa

     1 /*
     2  * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     4  *
     5  * This code is free software; you can redistribute it and/or modify it
     6  * under the terms of the GNU General Public License version 2 only, as
     7  * published by the Free Software Foundation.
     8  *
     9  * This code is distributed in the hope that it will be useful, but WITHOUT
    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    12  * version 2 for more details (a copy is included in the LICENSE file that
    13  * accompanied this code).
    14  *
    15  * You should have received a copy of the GNU General Public License version
    16  * 2 along with this work; if not, write to the Free Software Foundation,
    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    18  *
    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
    20  * or visit www.oracle.com if you need additional information or have any
    21  * questions.
    22  *
    23  */
    25 #include "precompiled.hpp"
    26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
    27 #include "gc_implementation/g1/concurrentMark.hpp"
    28 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
    29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
    30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
    31 #include "gc_implementation/g1/heapRegionRemSet.hpp"
    32 #include "gc_implementation/shared/gcPolicyCounters.hpp"
    33 #include "runtime/arguments.hpp"
    34 #include "runtime/java.hpp"
    35 #include "runtime/mutexLocker.hpp"
    36 #include "utilities/debug.hpp"
    38 #define PREDICTIONS_VERBOSE 0
    40 // <NEW PREDICTION>
    42 // Different defaults for different number of GC threads
    43 // They were chosen by running GCOld and SPECjbb on debris with different
    44 //   numbers of GC threads and choosing them based on the results
    46 // all the same
    47 static double rs_length_diff_defaults[] = {
    48   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
    49 };
    51 static double cost_per_card_ms_defaults[] = {
    52   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
    53 };
    55 // all the same
    56 static double fully_young_cards_per_entry_ratio_defaults[] = {
    57   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
    58 };
    60 static double cost_per_entry_ms_defaults[] = {
    61   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
    62 };
    64 static double cost_per_byte_ms_defaults[] = {
    65   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
    66 };
    68 // these should be pretty consistent
    69 static double constant_other_time_ms_defaults[] = {
    70   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
    71 };
    74 static double young_other_cost_per_region_ms_defaults[] = {
    75   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
    76 };
    78 static double non_young_other_cost_per_region_ms_defaults[] = {
    79   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
    80 };
    82 // </NEW PREDICTION>
    84 // Help class for avoiding interleaved logging
    85 class LineBuffer: public StackObj {
    87 private:
    88   static const int BUFFER_LEN = 1024;
    89   static const int INDENT_CHARS = 3;
    90   char _buffer[BUFFER_LEN];
    91   int _indent_level;
    92   int _cur;
    94   void vappend(const char* format, va_list ap) {
    95     int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
    96     if (res != -1) {
    97       _cur += res;
    98     } else {
    99       DEBUG_ONLY(warning("buffer too small in LineBuffer");)
   100       _buffer[BUFFER_LEN -1] = 0;
   101       _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
   102     }
   103   }
   105 public:
   106   explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
   107     for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
   108       _buffer[_cur] = ' ';
   109     }
   110   }
   112 #ifndef PRODUCT
   113   ~LineBuffer() {
   114     assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
   115   }
   116 #endif
   118   void append(const char* format, ...) {
   119     va_list ap;
   120     va_start(ap, format);
   121     vappend(format, ap);
   122     va_end(ap);
   123   }
   125   void append_and_print_cr(const char* format, ...) {
   126     va_list ap;
   127     va_start(ap, format);
   128     vappend(format, ap);
   129     va_end(ap);
   130     gclog_or_tty->print_cr("%s", _buffer);
   131     _cur = _indent_level * INDENT_CHARS;
   132   }
   133 };
   135 G1CollectorPolicy::G1CollectorPolicy() :
   136   _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
   137                         ? ParallelGCThreads : 1),
   139   _n_pauses(0),
   140   _recent_rs_scan_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   141   _recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   142   _recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
   143   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   144   _all_pause_times_ms(new NumberSeq()),
   145   _stop_world_start(0.0),
   146   _all_stop_world_times_ms(new NumberSeq()),
   147   _all_yield_times_ms(new NumberSeq()),
   149   _all_mod_union_times_ms(new NumberSeq()),
   151   _summary(new Summary()),
   153 #ifndef PRODUCT
   154   _cur_clear_ct_time_ms(0.0),
   155   _min_clear_cc_time_ms(-1.0),
   156   _max_clear_cc_time_ms(-1.0),
   157   _cur_clear_cc_time_ms(0.0),
   158   _cum_clear_cc_time_ms(0.0),
   159   _num_cc_clears(0L),
   160 #endif
   162   _region_num_young(0),
   163   _region_num_tenured(0),
   164   _prev_region_num_young(0),
   165   _prev_region_num_tenured(0),
   167   _aux_num(10),
   168   _all_aux_times_ms(new NumberSeq[_aux_num]),
   169   _cur_aux_start_times_ms(new double[_aux_num]),
   170   _cur_aux_times_ms(new double[_aux_num]),
   171   _cur_aux_times_set(new bool[_aux_num]),
   173   _concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   174   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   175   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   177   // <NEW PREDICTION>
   179   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   180   _prev_collection_pause_end_ms(0.0),
   181   _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   182   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   183   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   184   _fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
   185   _partially_young_cards_per_entry_ratio_seq(
   186                                          new TruncatedSeq(TruncatedSeqLength)),
   187   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   188   _partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   189   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   190   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
   191   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   192   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   193   _non_young_other_cost_per_region_ms_seq(
   194                                          new TruncatedSeq(TruncatedSeqLength)),
   196   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   197   _scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   198   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
   200   _pause_time_target_ms((double) MaxGCPauseMillis),
   202   // </NEW PREDICTION>
   204   _in_young_gc_mode(false),
   205   _full_young_gcs(true),
   206   _full_young_pause_num(0),
   207   _partial_young_pause_num(0),
   209   _during_marking(false),
   210   _in_marking_window(false),
   211   _in_marking_window_im(false),
   213   _known_garbage_ratio(0.0),
   214   _known_garbage_bytes(0),
   216   _young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
   218    _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
   220   _recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
   221   _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
   223   _recent_avg_pause_time_ratio(0.0),
   224   _num_markings(0),
   225   _n_marks(0),
   226   _n_pauses_at_mark_end(0),
   228   _all_full_gc_times_ms(new NumberSeq()),
   230   // G1PausesBtwnConcMark defaults to -1
   231   // so the hack is to do the cast  QQQ FIXME
   232   _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
   233   _n_marks_since_last_pause(0),
   234   _initiate_conc_mark_if_possible(false),
   235   _during_initial_mark_pause(false),
   236   _should_revert_to_full_young_gcs(false),
   237   _last_full_young_gc(false),
   239   _eden_bytes_before_gc(0),
   240   _survivor_bytes_before_gc(0),
   241   _capacity_before_gc(0),
   243   _prev_collection_pause_used_at_end_bytes(0),
   245   _collection_set(NULL),
   246   _collection_set_size(0),
   247   _collection_set_bytes_used_before(0),
   249   // Incremental CSet attributes
   250   _inc_cset_build_state(Inactive),
   251   _inc_cset_head(NULL),
   252   _inc_cset_tail(NULL),
   253   _inc_cset_size(0),
   254   _inc_cset_young_index(0),
   255   _inc_cset_bytes_used_before(0),
   256   _inc_cset_max_finger(NULL),
   257   _inc_cset_recorded_young_bytes(0),
   258   _inc_cset_recorded_rs_lengths(0),
   259   _inc_cset_predicted_elapsed_time_ms(0.0),
   260   _inc_cset_predicted_bytes_to_copy(0),
   262 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
   263 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
   264 #endif // _MSC_VER
   266   _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
   267                                                  G1YoungSurvRateNumRegionsSummary)),
   268   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
   269                                               G1YoungSurvRateNumRegionsSummary)),
   270   // add here any more surv rate groups
   271   _recorded_survivor_regions(0),
   272   _recorded_survivor_head(NULL),
   273   _recorded_survivor_tail(NULL),
   274   _survivors_age_table(true),
   276   _gc_overhead_perc(0.0)
   278 {
   279   // Set up the region size and associated fields. Given that the
   280   // policy is created before the heap, we have to set this up here,
   281   // so it's done as soon as possible.
   282   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
   283   HeapRegionRemSet::setup_remset_size();
   285   // Verify PLAB sizes
   286   const uint region_size = HeapRegion::GrainWords;
   287   if (YoungPLABSize > region_size || OldPLABSize > region_size) {
   288     char buffer[128];
   289     jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
   290                  OldPLABSize > region_size ? "Old" : "Young", region_size);
   291     vm_exit_during_initialization(buffer);
   292   }
   294   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
   295   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
   297   _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
   298   _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
   299   _par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
   301   _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
   302   _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
   304   _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
   306   _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
   308   _par_last_termination_times_ms = new double[_parallel_gc_threads];
   309   _par_last_termination_attempts = new double[_parallel_gc_threads];
   310   _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
   311   _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
   313   // start conservatively
   314   _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
   316   // <NEW PREDICTION>
   318   int index;
   319   if (ParallelGCThreads == 0)
   320     index = 0;
   321   else if (ParallelGCThreads > 8)
   322     index = 7;
   323   else
   324     index = ParallelGCThreads - 1;
   326   _pending_card_diff_seq->add(0.0);
   327   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
   328   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
   329   _fully_young_cards_per_entry_ratio_seq->add(
   330                             fully_young_cards_per_entry_ratio_defaults[index]);
   331   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
   332   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
   333   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
   334   _young_other_cost_per_region_ms_seq->add(
   335                                young_other_cost_per_region_ms_defaults[index]);
   336   _non_young_other_cost_per_region_ms_seq->add(
   337                            non_young_other_cost_per_region_ms_defaults[index]);
   339   // </NEW PREDICTION>
   341   // Below, we might need to calculate the pause time target based on
   342   // the pause interval. When we do so we are going to give G1 maximum
   343   // flexibility and allow it to do pauses when it needs to. So, we'll
   344   // arrange that the pause interval to be pause time target + 1 to
   345   // ensure that a) the pause time target is maximized with respect to
   346   // the pause interval and b) we maintain the invariant that pause
   347   // time target < pause interval. If the user does not want this
   348   // maximum flexibility, they will have to set the pause interval
   349   // explicitly.
   351   // First make sure that, if either parameter is set, its value is
   352   // reasonable.
   353   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
   354     if (MaxGCPauseMillis < 1) {
   355       vm_exit_during_initialization("MaxGCPauseMillis should be "
   356                                     "greater than 0");
   357     }
   358   }
   359   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
   360     if (GCPauseIntervalMillis < 1) {
   361       vm_exit_during_initialization("GCPauseIntervalMillis should be "
   362                                     "greater than 0");
   363     }
   364   }
   366   // Then, if the pause time target parameter was not set, set it to
   367   // the default value.
   368   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
   369     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
   370       // The default pause time target in G1 is 200ms
   371       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
   372     } else {
   373       // We do not allow the pause interval to be set without the
   374       // pause time target
   375       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
   376                                     "without setting MaxGCPauseMillis");
   377     }
   378   }
   380   // Then, if the interval parameter was not set, set it according to
   381   // the pause time target (this will also deal with the case when the
   382   // pause time target is the default value).
   383   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
   384     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
   385   }
   387   // Finally, make sure that the two parameters are consistent.
   388   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
   389     char buffer[256];
   390     jio_snprintf(buffer, 256,
   391                  "MaxGCPauseMillis (%u) should be less than "
   392                  "GCPauseIntervalMillis (%u)",
   393                  MaxGCPauseMillis, GCPauseIntervalMillis);
   394     vm_exit_during_initialization(buffer);
   395   }
   397   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
   398   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
   399   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
   400   _sigma = (double) G1ConfidencePercent / 100.0;
   402   // start conservatively (around 50ms is about right)
   403   _concurrent_mark_init_times_ms->add(0.05);
   404   _concurrent_mark_remark_times_ms->add(0.05);
   405   _concurrent_mark_cleanup_times_ms->add(0.20);
   406   _tenuring_threshold = MaxTenuringThreshold;
   408   // if G1FixedSurvivorSpaceSize is 0 which means the size is not
   409   // fixed, then _max_survivor_regions will be calculated at
   410   // calculate_young_list_target_length during initialization
   411   _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
   413   assert(GCTimeRatio > 0,
   414          "we should have set it to a default value set_g1_gc_flags() "
   415          "if a user set it to 0");
   416   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
   418   initialize_all();
   419 }
   421 // Increment "i", mod "len"
   422 static void inc_mod(int& i, int len) {
   423   i++; if (i == len) i = 0;
   424 }
   426 void G1CollectorPolicy::initialize_flags() {
   427   set_min_alignment(HeapRegion::GrainBytes);
   428   set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
   429   if (SurvivorRatio < 1) {
   430     vm_exit_during_initialization("Invalid survivor ratio specified");
   431   }
   432   CollectorPolicy::initialize_flags();
   433 }
   435 // The easiest way to deal with the parsing of the NewSize /
   436 // MaxNewSize / etc. parameteres is to re-use the code in the
   437 // TwoGenerationCollectorPolicy class. This is similar to what
   438 // ParallelScavenge does with its GenerationSizer class (see
   439 // ParallelScavengeHeap::initialize()). We might change this in the
   440 // future, but it's a good start.
   441 class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
   442   size_t size_to_region_num(size_t byte_size) {
   443     return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
   444   }
   446 public:
   447   G1YoungGenSizer() {
   448     initialize_flags();
   449     initialize_size_info();
   450   }
   452   size_t min_young_region_num() {
   453     return size_to_region_num(_min_gen0_size);
   454   }
   455   size_t initial_young_region_num() {
   456     return size_to_region_num(_initial_gen0_size);
   457   }
   458   size_t max_young_region_num() {
   459     return size_to_region_num(_max_gen0_size);
   460   }
   461 };
   463 void G1CollectorPolicy::init() {
   464   // Set aside an initial future to_space.
   465   _g1 = G1CollectedHeap::heap();
   467   assert(Heap_lock->owned_by_self(), "Locking discipline.");
   469   initialize_gc_policy_counters();
   471   if (G1Gen) {
   472     _in_young_gc_mode = true;
   474     G1YoungGenSizer sizer;
   475     size_t initial_region_num = sizer.initial_young_region_num();
   477     if (UseAdaptiveSizePolicy) {
   478       set_adaptive_young_list_length(true);
   479       _young_list_fixed_length = 0;
   480     } else {
   481       set_adaptive_young_list_length(false);
   482       _young_list_fixed_length = initial_region_num;
   483     }
   484     _free_regions_at_end_of_collection = _g1->free_regions();
   485     calculate_young_list_min_length();
   486     guarantee( _young_list_min_length == 0, "invariant, not enough info" );
   487     calculate_young_list_target_length();
   488   } else {
   489      _young_list_fixed_length = 0;
   490     _in_young_gc_mode = false;
   491   }
   493   // We may immediately start allocating regions and placing them on the
   494   // collection set list. Initialize the per-collection set info
   495   start_incremental_cset_building();
   496 }
   498 // Create the jstat counters for the policy.
   499 void G1CollectorPolicy::initialize_gc_policy_counters()
   500 {
   501   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
   502 }
   504 void G1CollectorPolicy::calculate_young_list_min_length() {
   505   _young_list_min_length = 0;
   507   if (!adaptive_young_list_length())
   508     return;
   510   if (_alloc_rate_ms_seq->num() > 3) {
   511     double now_sec = os::elapsedTime();
   512     double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
   513     double alloc_rate_ms = predict_alloc_rate_ms();
   514     size_t min_regions = (size_t) ceil(alloc_rate_ms * when_ms);
   515     size_t current_region_num = _g1->young_list()->length();
   516     _young_list_min_length = min_regions + current_region_num;
   517   }
   518 }
   520 void G1CollectorPolicy::calculate_young_list_target_length() {
   521   if (adaptive_young_list_length()) {
   522     size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
   523     calculate_young_list_target_length(rs_lengths);
   524   } else {
   525     if (full_young_gcs())
   526       _young_list_target_length = _young_list_fixed_length;
   527     else
   528       _young_list_target_length = _young_list_fixed_length / 2;
   529   }
   531   // Make sure we allow the application to allocate at least one
   532   // region before we need to do a collection again.
   533   size_t min_length = _g1->young_list()->length() + 1;
   534   _young_list_target_length = MAX2(_young_list_target_length, min_length);
   535   calculate_max_gc_locker_expansion();
   536   calculate_survivors_policy();
   537 }
   539 void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
   540   guarantee( adaptive_young_list_length(), "pre-condition" );
   541   guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
   543   double start_time_sec = os::elapsedTime();
   544   size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
   545   min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
   546   size_t reserve_regions =
   547     (size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
   549   if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
   550     // we are in fully-young mode and there are free regions in the heap
   552     double survivor_regions_evac_time =
   553         predict_survivor_regions_evac_time();
   555     double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
   556     size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
   557     size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
   558     size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
   559     double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
   560                           + survivor_regions_evac_time;
   562     // the result
   563     size_t final_young_length = 0;
   565     size_t init_free_regions =
   566       MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
   568     // if we're still under the pause target...
   569     if (base_time_ms <= target_pause_time_ms) {
   570       // We make sure that the shortest young length that makes sense
   571       // fits within the target pause time.
   572       size_t min_young_length = 1;
   574       if (predict_will_fit(min_young_length, base_time_ms,
   575                                      init_free_regions, target_pause_time_ms)) {
   576         // The shortest young length will fit within the target pause time;
   577         // we'll now check whether the absolute maximum number of young
   578         // regions will fit in the target pause time. If not, we'll do
   579         // a binary search between min_young_length and max_young_length
   580         size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
   581         size_t max_young_length = abs_max_young_length;
   583         if (max_young_length > min_young_length) {
   584           // Let's check if the initial max young length will fit within the
   585           // target pause. If so then there is no need to search for a maximal
   586           // young length - we'll return the initial maximum
   588           if (predict_will_fit(max_young_length, base_time_ms,
   589                                 init_free_regions, target_pause_time_ms)) {
   590             // The maximum young length will satisfy the target pause time.
   591             // We are done so set min young length to this maximum length.
   592             // The code after the loop will then set final_young_length using
   593             // the value cached in the minimum length.
   594             min_young_length = max_young_length;
   595           } else {
   596             // The maximum possible number of young regions will not fit within
   597             // the target pause time so let's search....
   599             size_t diff = (max_young_length - min_young_length) / 2;
   600             max_young_length = min_young_length + diff;
   602             while (max_young_length > min_young_length) {
   603               if (predict_will_fit(max_young_length, base_time_ms,
   604                                         init_free_regions, target_pause_time_ms)) {
   606                 // The current max young length will fit within the target
   607                 // pause time. Note we do not exit the loop here. By setting
   608                 // min = max, and then increasing the max below means that
   609                 // we will continue searching for an upper bound in the
   610                 // range [max..max+diff]
   611                 min_young_length = max_young_length;
   612               }
   613               diff = (max_young_length - min_young_length) / 2;
   614               max_young_length = min_young_length + diff;
   615             }
   616             // the above loop found a maximal young length that will fit
   617             // within the target pause time.
   618           }
   619           assert(min_young_length <= abs_max_young_length, "just checking");
   620         }
   621         final_young_length = min_young_length;
   622       }
   623     }
   624     // and we're done!
   626     // we should have at least one region in the target young length
   627     _young_list_target_length =
   628                               final_young_length + _recorded_survivor_regions;
   630     // let's keep an eye of how long we spend on this calculation
   631     // right now, I assume that we'll print it when we need it; we
   632     // should really adde it to the breakdown of a pause
   633     double end_time_sec = os::elapsedTime();
   634     double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
   636 #ifdef TRACE_CALC_YOUNG_LENGTH
   637     // leave this in for debugging, just in case
   638     gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
   639                            "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
   640                            target_pause_time_ms,
   641                            _young_list_target_length
   642                            elapsed_time_ms,
   643                            full_young_gcs() ? "full" : "partial",
   644                            during_initial_mark_pause() ? " i-m" : "",
   645                            _in_marking_window,
   646                            _in_marking_window_im);
   647 #endif // TRACE_CALC_YOUNG_LENGTH
   649     if (_young_list_target_length < _young_list_min_length) {
   650       // bummer; this means that, if we do a pause when the maximal
   651       // length dictates, we'll violate the pause spacing target (the
   652       // min length was calculate based on the application's current
   653       // alloc rate);
   655       // so, we have to bite the bullet, and allocate the minimum
   656       // number. We'll violate our target, but we just can't meet it.
   658 #ifdef TRACE_CALC_YOUNG_LENGTH
   659       // leave this in for debugging, just in case
   660       gclog_or_tty->print_cr("adjusted target length from "
   661                              SIZE_FORMAT " to " SIZE_FORMAT,
   662                              _young_list_target_length, _young_list_min_length);
   663 #endif // TRACE_CALC_YOUNG_LENGTH
   665       _young_list_target_length = _young_list_min_length;
   666     }
   667   } else {
   668     // we are in a partially-young mode or we've run out of regions (due
   669     // to evacuation failure)
   671 #ifdef TRACE_CALC_YOUNG_LENGTH
   672     // leave this in for debugging, just in case
   673     gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
   674                            _young_list_min_length);
   675 #endif // TRACE_CALC_YOUNG_LENGTH
   676     // we'll do the pause as soon as possible by choosing the minimum
   677     _young_list_target_length = _young_list_min_length;
   678   }
   680   _rs_lengths_prediction = rs_lengths;
   681 }
   683 // This is used by: calculate_young_list_target_length(rs_length). It
   684 // returns true iff:
   685 //   the predicted pause time for the given young list will not overflow
   686 //   the target pause time
   687 // and:
   688 //   the predicted amount of surviving data will not overflow the
   689 //   the amount of free space available for survivor regions.
   690 //
   691 bool
   692 G1CollectorPolicy::predict_will_fit(size_t young_length,
   693                                     double base_time_ms,
   694                                     size_t init_free_regions,
   695                                     double target_pause_time_ms) {
   697   if (young_length >= init_free_regions)
   698     // end condition 1: not enough space for the young regions
   699     return false;
   701   double accum_surv_rate_adj = 0.0;
   702   double accum_surv_rate =
   703     accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
   705   size_t bytes_to_copy =
   706     (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   708   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   710   double young_other_time_ms =
   711                        predict_young_other_time_ms(young_length);
   713   double pause_time_ms =
   714                    base_time_ms + copy_time_ms + young_other_time_ms;
   716   if (pause_time_ms > target_pause_time_ms)
   717     // end condition 2: over the target pause time
   718     return false;
   720   size_t free_bytes =
   721                  (init_free_regions - young_length) * HeapRegion::GrainBytes;
   723   if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
   724     // end condition 3: out of to-space (conservatively)
   725     return false;
   727   // success!
   728   return true;
   729 }
   731 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
   732   double survivor_regions_evac_time = 0.0;
   733   for (HeapRegion * r = _recorded_survivor_head;
   734        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
   735        r = r->get_next_young_region()) {
   736     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
   737   }
   738   return survivor_regions_evac_time;
   739 }
   741 void G1CollectorPolicy::check_prediction_validity() {
   742   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
   744   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
   745   if (rs_lengths > _rs_lengths_prediction) {
   746     // add 10% to avoid having to recalculate often
   747     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
   748     calculate_young_list_target_length(rs_lengths_prediction);
   749   }
   750 }
   752 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
   753                                                bool is_tlab,
   754                                                bool* gc_overhead_limit_was_exceeded) {
   755   guarantee(false, "Not using this policy feature yet.");
   756   return NULL;
   757 }
   759 // This method controls how a collector handles one or more
   760 // of its generations being fully allocated.
   761 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
   762                                                        bool is_tlab) {
   763   guarantee(false, "Not using this policy feature yet.");
   764   return NULL;
   765 }
   768 #ifndef PRODUCT
   769 bool G1CollectorPolicy::verify_young_ages() {
   770   HeapRegion* head = _g1->young_list()->first_region();
   771   return
   772     verify_young_ages(head, _short_lived_surv_rate_group);
   773   // also call verify_young_ages on any additional surv rate groups
   774 }
   776 bool
   777 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
   778                                      SurvRateGroup *surv_rate_group) {
   779   guarantee( surv_rate_group != NULL, "pre-condition" );
   781   const char* name = surv_rate_group->name();
   782   bool ret = true;
   783   int prev_age = -1;
   785   for (HeapRegion* curr = head;
   786        curr != NULL;
   787        curr = curr->get_next_young_region()) {
   788     SurvRateGroup* group = curr->surv_rate_group();
   789     if (group == NULL && !curr->is_survivor()) {
   790       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
   791       ret = false;
   792     }
   794     if (surv_rate_group == group) {
   795       int age = curr->age_in_surv_rate_group();
   797       if (age < 0) {
   798         gclog_or_tty->print_cr("## %s: encountered negative age", name);
   799         ret = false;
   800       }
   802       if (age <= prev_age) {
   803         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
   804                                "(%d, %d)", name, age, prev_age);
   805         ret = false;
   806       }
   807       prev_age = age;
   808     }
   809   }
   811   return ret;
   812 }
   813 #endif // PRODUCT
   815 void G1CollectorPolicy::record_full_collection_start() {
   816   _cur_collection_start_sec = os::elapsedTime();
   817   // Release the future to-space so that it is available for compaction into.
   818   _g1->set_full_collection();
   819 }
   821 void G1CollectorPolicy::record_full_collection_end() {
   822   // Consider this like a collection pause for the purposes of allocation
   823   // since last pause.
   824   double end_sec = os::elapsedTime();
   825   double full_gc_time_sec = end_sec - _cur_collection_start_sec;
   826   double full_gc_time_ms = full_gc_time_sec * 1000.0;
   828   _all_full_gc_times_ms->add(full_gc_time_ms);
   830   update_recent_gc_times(end_sec, full_gc_time_ms);
   832   _g1->clear_full_collection();
   834   // "Nuke" the heuristics that control the fully/partially young GC
   835   // transitions and make sure we start with fully young GCs after the
   836   // Full GC.
   837   set_full_young_gcs(true);
   838   _last_full_young_gc = false;
   839   _should_revert_to_full_young_gcs = false;
   840   clear_initiate_conc_mark_if_possible();
   841   clear_during_initial_mark_pause();
   842   _known_garbage_bytes = 0;
   843   _known_garbage_ratio = 0.0;
   844   _in_marking_window = false;
   845   _in_marking_window_im = false;
   847   _short_lived_surv_rate_group->start_adding_regions();
   848   // also call this on any additional surv rate groups
   850   record_survivor_regions(0, NULL, NULL);
   852   _prev_region_num_young   = _region_num_young;
   853   _prev_region_num_tenured = _region_num_tenured;
   855   _free_regions_at_end_of_collection = _g1->free_regions();
   856   // Reset survivors SurvRateGroup.
   857   _survivor_surv_rate_group->reset();
   858   calculate_young_list_min_length();
   859   calculate_young_list_target_length();
   860 }
   862 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
   863   _bytes_in_to_space_before_gc += bytes;
   864 }
   866 void G1CollectorPolicy::record_after_bytes(size_t bytes) {
   867   _bytes_in_to_space_after_gc += bytes;
   868 }
   870 void G1CollectorPolicy::record_stop_world_start() {
   871   _stop_world_start = os::elapsedTime();
   872 }
   874 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
   875                                                       size_t start_used) {
   876   if (PrintGCDetails) {
   877     gclog_or_tty->stamp(PrintGCTimeStamps);
   878     gclog_or_tty->print("[GC pause");
   879     if (in_young_gc_mode())
   880       gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
   881   }
   883   assert(_g1->used() == _g1->recalculate_used(),
   884          err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
   885                  _g1->used(), _g1->recalculate_used()));
   887   double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
   888   _all_stop_world_times_ms->add(s_w_t_ms);
   889   _stop_world_start = 0.0;
   891   _cur_collection_start_sec = start_time_sec;
   892   _cur_collection_pause_used_at_start_bytes = start_used;
   893   _cur_collection_pause_used_regions_at_start = _g1->used_regions();
   894   _pending_cards = _g1->pending_card_num();
   895   _max_pending_cards = _g1->max_pending_card_num();
   897   _bytes_in_to_space_before_gc = 0;
   898   _bytes_in_to_space_after_gc = 0;
   899   _bytes_in_collection_set_before_gc = 0;
   901   YoungList* young_list = _g1->young_list();
   902   _eden_bytes_before_gc = young_list->eden_used_bytes();
   903   _survivor_bytes_before_gc = young_list->survivor_used_bytes();
   904   _capacity_before_gc = _g1->capacity();
   906 #ifdef DEBUG
   907   // initialise these to something well known so that we can spot
   908   // if they are not set properly
   910   for (int i = 0; i < _parallel_gc_threads; ++i) {
   911     _par_last_gc_worker_start_times_ms[i] = -1234.0;
   912     _par_last_ext_root_scan_times_ms[i] = -1234.0;
   913     _par_last_mark_stack_scan_times_ms[i] = -1234.0;
   914     _par_last_update_rs_times_ms[i] = -1234.0;
   915     _par_last_update_rs_processed_buffers[i] = -1234.0;
   916     _par_last_scan_rs_times_ms[i] = -1234.0;
   917     _par_last_obj_copy_times_ms[i] = -1234.0;
   918     _par_last_termination_times_ms[i] = -1234.0;
   919     _par_last_termination_attempts[i] = -1234.0;
   920     _par_last_gc_worker_end_times_ms[i] = -1234.0;
   921     _par_last_gc_worker_times_ms[i] = -1234.0;
   922   }
   923 #endif
   925   for (int i = 0; i < _aux_num; ++i) {
   926     _cur_aux_times_ms[i] = 0.0;
   927     _cur_aux_times_set[i] = false;
   928   }
   930   _satb_drain_time_set = false;
   931   _last_satb_drain_processed_buffers = -1;
   933   if (in_young_gc_mode())
   934     _last_young_gc_full = false;
   936   // do that for any other surv rate groups
   937   _short_lived_surv_rate_group->stop_adding_regions();
   938   _survivors_age_table.clear();
   940   assert( verify_young_ages(), "region age verification" );
   941 }
   943 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
   944   _mark_closure_time_ms = mark_closure_time_ms;
   945 }
   947 void G1CollectorPolicy::record_concurrent_mark_init_start() {
   948   _mark_init_start_sec = os::elapsedTime();
   949   guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
   950 }
   952 void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
   953                                                    mark_init_elapsed_time_ms) {
   954   _during_marking = true;
   955   assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
   956   clear_during_initial_mark_pause();
   957   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
   958 }
   960 void G1CollectorPolicy::record_concurrent_mark_init_end() {
   961   double end_time_sec = os::elapsedTime();
   962   double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
   963   _concurrent_mark_init_times_ms->add(elapsed_time_ms);
   964   record_concurrent_mark_init_end_pre(elapsed_time_ms);
   966   _mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
   967 }
   969 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
   970   _mark_remark_start_sec = os::elapsedTime();
   971   _during_marking = false;
   972 }
   974 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
   975   double end_time_sec = os::elapsedTime();
   976   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
   977   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
   978   _cur_mark_stop_world_time_ms += elapsed_time_ms;
   979   _prev_collection_pause_end_ms += elapsed_time_ms;
   981   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
   982 }
   984 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
   985   _mark_cleanup_start_sec = os::elapsedTime();
   986 }
   988 void
   989 G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
   990                                                       size_t max_live_bytes) {
   991   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
   992   record_concurrent_mark_cleanup_end_work2();
   993 }
   995 void
   996 G1CollectorPolicy::
   997 record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
   998                                          size_t max_live_bytes) {
   999   if (_n_marks < 2) _n_marks++;
  1000   if (G1PolicyVerbose > 0)
  1001     gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
  1002                            " (of " SIZE_FORMAT " MB heap).",
  1003                            max_live_bytes/M, _g1->capacity()/M);
  1006 // The important thing about this is that it includes "os::elapsedTime".
  1007 void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
  1008   double end_time_sec = os::elapsedTime();
  1009   double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
  1010   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
  1011   _cur_mark_stop_world_time_ms += elapsed_time_ms;
  1012   _prev_collection_pause_end_ms += elapsed_time_ms;
  1014   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
  1016   _num_markings++;
  1018   // We did a marking, so reset the "since_last_mark" variables.
  1019   double considerConcMarkCost = 1.0;
  1020   // If there are available processors, concurrent activity is free...
  1021   if (Threads::number_of_non_daemon_threads() * 2 <
  1022       os::active_processor_count()) {
  1023     considerConcMarkCost = 0.0;
  1025   _n_pauses_at_mark_end = _n_pauses;
  1026   _n_marks_since_last_pause++;
  1029 void
  1030 G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
  1031   if (in_young_gc_mode()) {
  1032     _should_revert_to_full_young_gcs = false;
  1033     _last_full_young_gc = true;
  1034     _in_marking_window = false;
  1035     if (adaptive_young_list_length())
  1036       calculate_young_list_target_length();
  1040 void G1CollectorPolicy::record_concurrent_pause() {
  1041   if (_stop_world_start > 0.0) {
  1042     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
  1043     _all_yield_times_ms->add(yield_ms);
  1047 void G1CollectorPolicy::record_concurrent_pause_end() {
  1050 template<class T>
  1051 T sum_of(T* sum_arr, int start, int n, int N) {
  1052   T sum = (T)0;
  1053   for (int i = 0; i < n; i++) {
  1054     int j = (start + i) % N;
  1055     sum += sum_arr[j];
  1057   return sum;
  1060 void G1CollectorPolicy::print_par_stats(int level,
  1061                                         const char* str,
  1062                                         double* data) {
  1063   double min = data[0], max = data[0];
  1064   double total = 0.0;
  1065   LineBuffer buf(level);
  1066   buf.append("[%s (ms):", str);
  1067   for (uint i = 0; i < ParallelGCThreads; ++i) {
  1068     double val = data[i];
  1069     if (val < min)
  1070       min = val;
  1071     if (val > max)
  1072       max = val;
  1073     total += val;
  1074     buf.append("  %3.1lf", val);
  1076   buf.append_and_print_cr("");
  1077   double avg = total / (double) ParallelGCThreads;
  1078   buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",
  1079     avg, min, max, max - min);
  1082 void G1CollectorPolicy::print_par_sizes(int level,
  1083                                         const char* str,
  1084                                         double* data) {
  1085   double min = data[0], max = data[0];
  1086   double total = 0.0;
  1087   LineBuffer buf(level);
  1088   buf.append("[%s :", str);
  1089   for (uint i = 0; i < ParallelGCThreads; ++i) {
  1090     double val = data[i];
  1091     if (val < min)
  1092       min = val;
  1093     if (val > max)
  1094       max = val;
  1095     total += val;
  1096     buf.append(" %d", (int) val);
  1098   buf.append_and_print_cr("");
  1099   double avg = total / (double) ParallelGCThreads;
  1100   buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
  1101     (int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
  1104 void G1CollectorPolicy::print_stats (int level,
  1105                                      const char* str,
  1106                                      double value) {
  1107   LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
  1110 void G1CollectorPolicy::print_stats (int level,
  1111                                      const char* str,
  1112                                      int value) {
  1113   LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
  1116 double G1CollectorPolicy::avg_value (double* data) {
  1117   if (G1CollectedHeap::use_parallel_gc_threads()) {
  1118     double ret = 0.0;
  1119     for (uint i = 0; i < ParallelGCThreads; ++i)
  1120       ret += data[i];
  1121     return ret / (double) ParallelGCThreads;
  1122   } else {
  1123     return data[0];
  1127 double G1CollectorPolicy::max_value (double* data) {
  1128   if (G1CollectedHeap::use_parallel_gc_threads()) {
  1129     double ret = data[0];
  1130     for (uint i = 1; i < ParallelGCThreads; ++i)
  1131       if (data[i] > ret)
  1132         ret = data[i];
  1133     return ret;
  1134   } else {
  1135     return data[0];
  1139 double G1CollectorPolicy::sum_of_values (double* data) {
  1140   if (G1CollectedHeap::use_parallel_gc_threads()) {
  1141     double sum = 0.0;
  1142     for (uint i = 0; i < ParallelGCThreads; i++)
  1143       sum += data[i];
  1144     return sum;
  1145   } else {
  1146     return data[0];
  1150 double G1CollectorPolicy::max_sum (double* data1,
  1151                                    double* data2) {
  1152   double ret = data1[0] + data2[0];
  1154   if (G1CollectedHeap::use_parallel_gc_threads()) {
  1155     for (uint i = 1; i < ParallelGCThreads; ++i) {
  1156       double data = data1[i] + data2[i];
  1157       if (data > ret)
  1158         ret = data;
  1161   return ret;
  1164 // Anything below that is considered to be zero
  1165 #define MIN_TIMER_GRANULARITY 0.0000001
  1167 void G1CollectorPolicy::record_collection_pause_end() {
  1168   double end_time_sec = os::elapsedTime();
  1169   double elapsed_ms = _last_pause_time_ms;
  1170   bool parallel = G1CollectedHeap::use_parallel_gc_threads();
  1171   size_t rs_size =
  1172     _cur_collection_pause_used_regions_at_start - collection_set_size();
  1173   size_t cur_used_bytes = _g1->used();
  1174   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
  1175   bool last_pause_included_initial_mark = false;
  1176   bool update_stats = !_g1->evacuation_failed();
  1178 #ifndef PRODUCT
  1179   if (G1YoungSurvRateVerbose) {
  1180     gclog_or_tty->print_cr("");
  1181     _short_lived_surv_rate_group->print();
  1182     // do that for any other surv rate groups too
  1184 #endif // PRODUCT
  1186   if (in_young_gc_mode()) {
  1187     last_pause_included_initial_mark = during_initial_mark_pause();
  1188     if (last_pause_included_initial_mark)
  1189       record_concurrent_mark_init_end_pre(0.0);
  1191     size_t min_used_targ =
  1192       (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
  1195     if (!_g1->mark_in_progress() && !_last_full_young_gc) {
  1196       assert(!last_pause_included_initial_mark, "invariant");
  1197       if (cur_used_bytes > min_used_targ &&
  1198           cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
  1199         assert(!during_initial_mark_pause(), "we should not see this here");
  1201         // Note: this might have already been set, if during the last
  1202         // pause we decided to start a cycle but at the beginning of
  1203         // this pause we decided to postpone it. That's OK.
  1204         set_initiate_conc_mark_if_possible();
  1208     _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
  1211   _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
  1212                           end_time_sec, false);
  1214   guarantee(_cur_collection_pause_used_regions_at_start >=
  1215             collection_set_size(),
  1216             "Negative RS size?");
  1218   // This assert is exempted when we're doing parallel collection pauses,
  1219   // because the fragmentation caused by the parallel GC allocation buffers
  1220   // can lead to more memory being used during collection than was used
  1221   // before. Best leave this out until the fragmentation problem is fixed.
  1222   // Pauses in which evacuation failed can also lead to negative
  1223   // collections, since no space is reclaimed from a region containing an
  1224   // object whose evacuation failed.
  1225   // Further, we're now always doing parallel collection.  But I'm still
  1226   // leaving this here as a placeholder for a more precise assertion later.
  1227   // (DLD, 10/05.)
  1228   assert((true || parallel) // Always using GC LABs now.
  1229          || _g1->evacuation_failed()
  1230          || _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
  1231          "Negative collection");
  1233   size_t freed_bytes =
  1234     _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
  1235   size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
  1237   double survival_fraction =
  1238     (double)surviving_bytes/
  1239     (double)_collection_set_bytes_used_before;
  1241   _n_pauses++;
  1243   double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
  1244   double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
  1245   double update_rs_time = avg_value(_par_last_update_rs_times_ms);
  1246   double update_rs_processed_buffers =
  1247     sum_of_values(_par_last_update_rs_processed_buffers);
  1248   double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
  1249   double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
  1250   double termination_time = avg_value(_par_last_termination_times_ms);
  1252   double parallel_known_time = update_rs_time +
  1253                                ext_root_scan_time +
  1254                                mark_stack_scan_time +
  1255                                scan_rs_time +
  1256                                obj_copy_time +
  1257                                termination_time;
  1259   double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
  1261   PauseSummary* summary = _summary;
  1263   if (update_stats) {
  1264     _recent_rs_scan_times_ms->add(scan_rs_time);
  1265     _recent_pause_times_ms->add(elapsed_ms);
  1266     _recent_rs_sizes->add(rs_size);
  1268     MainBodySummary* body_summary = summary->main_body_summary();
  1269     guarantee(body_summary != NULL, "should not be null!");
  1271     if (_satb_drain_time_set)
  1272       body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
  1273     else
  1274       body_summary->record_satb_drain_time_ms(0.0);
  1276     body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
  1277     body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
  1278     body_summary->record_update_rs_time_ms(update_rs_time);
  1279     body_summary->record_scan_rs_time_ms(scan_rs_time);
  1280     body_summary->record_obj_copy_time_ms(obj_copy_time);
  1281     if (parallel) {
  1282       body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
  1283       body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
  1284       body_summary->record_termination_time_ms(termination_time);
  1285       body_summary->record_parallel_other_time_ms(parallel_other_time);
  1287     body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
  1289     // We exempt parallel collection from this check because Alloc Buffer
  1290     // fragmentation can produce negative collections.  Same with evac
  1291     // failure.
  1292     // Further, we're now always doing parallel collection.  But I'm still
  1293     // leaving this here as a placeholder for a more precise assertion later.
  1294     // (DLD, 10/05.
  1295     assert((true || parallel)
  1296            || _g1->evacuation_failed()
  1297            || surviving_bytes <= _collection_set_bytes_used_before,
  1298            "Or else negative collection!");
  1299     _recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
  1300     _recent_CS_bytes_surviving->add(surviving_bytes);
  1302     // this is where we update the allocation rate of the application
  1303     double app_time_ms =
  1304       (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
  1305     if (app_time_ms < MIN_TIMER_GRANULARITY) {
  1306       // This usually happens due to the timer not having the required
  1307       // granularity. Some Linuxes are the usual culprits.
  1308       // We'll just set it to something (arbitrarily) small.
  1309       app_time_ms = 1.0;
  1311     size_t regions_allocated =
  1312       (_region_num_young - _prev_region_num_young) +
  1313       (_region_num_tenured - _prev_region_num_tenured);
  1314     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
  1315     _alloc_rate_ms_seq->add(alloc_rate_ms);
  1316     _prev_region_num_young   = _region_num_young;
  1317     _prev_region_num_tenured = _region_num_tenured;
  1319     double interval_ms =
  1320       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
  1321     update_recent_gc_times(end_time_sec, elapsed_ms);
  1322     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
  1323     if (recent_avg_pause_time_ratio() < 0.0 ||
  1324         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
  1325 #ifndef PRODUCT
  1326       // Dump info to allow post-facto debugging
  1327       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
  1328       gclog_or_tty->print_cr("-------------------------------------------");
  1329       gclog_or_tty->print_cr("Recent GC Times (ms):");
  1330       _recent_gc_times_ms->dump();
  1331       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
  1332       _recent_prev_end_times_for_all_gcs_sec->dump();
  1333       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
  1334                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
  1335       // In debug mode, terminate the JVM if the user wants to debug at this point.
  1336       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
  1337 #endif  // !PRODUCT
  1338       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
  1339       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
  1340       if (_recent_avg_pause_time_ratio < 0.0) {
  1341         _recent_avg_pause_time_ratio = 0.0;
  1342       } else {
  1343         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
  1344         _recent_avg_pause_time_ratio = 1.0;
  1349   if (G1PolicyVerbose > 1) {
  1350     gclog_or_tty->print_cr("   Recording collection pause(%d)", _n_pauses);
  1353   if (G1PolicyVerbose > 1) {
  1354     gclog_or_tty->print_cr("      ET: %10.6f ms           (avg: %10.6f ms)\n"
  1355                            "       ET-RS:  %10.6f ms      (avg: %10.6f ms)\n"
  1356                            "      |RS|: " SIZE_FORMAT,
  1357                            elapsed_ms, recent_avg_time_for_pauses_ms(),
  1358                            scan_rs_time, recent_avg_time_for_rs_scan_ms(),
  1359                            rs_size);
  1361     gclog_or_tty->print_cr("       Used at start: " SIZE_FORMAT"K"
  1362                            "       At end " SIZE_FORMAT "K\n"
  1363                            "       garbage      : " SIZE_FORMAT "K"
  1364                            "       of     " SIZE_FORMAT "K\n"
  1365                            "       survival     : %6.2f%%  (%6.2f%% avg)",
  1366                            _cur_collection_pause_used_at_start_bytes/K,
  1367                            _g1->used()/K, freed_bytes/K,
  1368                            _collection_set_bytes_used_before/K,
  1369                            survival_fraction*100.0,
  1370                            recent_avg_survival_fraction()*100.0);
  1371     gclog_or_tty->print_cr("       Recent %% gc pause time: %6.2f",
  1372                            recent_avg_pause_time_ratio() * 100.0);
  1375   double other_time_ms = elapsed_ms;
  1377   if (_satb_drain_time_set) {
  1378     other_time_ms -= _cur_satb_drain_time_ms;
  1381   if (parallel) {
  1382     other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
  1383   } else {
  1384     other_time_ms -=
  1385       update_rs_time +
  1386       ext_root_scan_time + mark_stack_scan_time +
  1387       scan_rs_time + obj_copy_time;
  1390   if (PrintGCDetails) {
  1391     gclog_or_tty->print_cr("%s, %1.8lf secs]",
  1392                            (last_pause_included_initial_mark) ? " (initial-mark)" : "",
  1393                            elapsed_ms / 1000.0);
  1395     if (_satb_drain_time_set) {
  1396       print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
  1398     if (_last_satb_drain_processed_buffers >= 0) {
  1399       print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
  1401     if (parallel) {
  1402       print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
  1403       print_par_stats(2, "GC Worker Start Time", _par_last_gc_worker_start_times_ms);
  1404       print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
  1405       print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
  1406       print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
  1407       print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
  1408       print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
  1409       print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
  1410       print_par_stats(2, "Termination", _par_last_termination_times_ms);
  1411       print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
  1412       print_par_stats(2, "GC Worker End Time", _par_last_gc_worker_end_times_ms);
  1414       for (int i = 0; i < _parallel_gc_threads; i++) {
  1415         _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];
  1417       print_par_stats(2, "GC Worker Times", _par_last_gc_worker_times_ms);
  1419       print_stats(2, "Parallel Other", parallel_other_time);
  1420       print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
  1421     } else {
  1422       print_stats(1, "Update RS", update_rs_time);
  1423       print_stats(2, "Processed Buffers",
  1424                   (int)update_rs_processed_buffers);
  1425       print_stats(1, "Ext Root Scanning", ext_root_scan_time);
  1426       print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
  1427       print_stats(1, "Scan RS", scan_rs_time);
  1428       print_stats(1, "Object Copying", obj_copy_time);
  1430 #ifndef PRODUCT
  1431     print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
  1432     print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
  1433     print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
  1434     print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
  1435     if (_num_cc_clears > 0) {
  1436       print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
  1438 #endif
  1439     print_stats(1, "Other", other_time_ms);
  1440     print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
  1442     for (int i = 0; i < _aux_num; ++i) {
  1443       if (_cur_aux_times_set[i]) {
  1444         char buffer[96];
  1445         sprintf(buffer, "Aux%d", i);
  1446         print_stats(1, buffer, _cur_aux_times_ms[i]);
  1451   _all_pause_times_ms->add(elapsed_ms);
  1452   if (update_stats) {
  1453     summary->record_total_time_ms(elapsed_ms);
  1454     summary->record_other_time_ms(other_time_ms);
  1456   for (int i = 0; i < _aux_num; ++i)
  1457     if (_cur_aux_times_set[i])
  1458       _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
  1460   // Reset marks-between-pauses counter.
  1461   _n_marks_since_last_pause = 0;
  1463   // Update the efficiency-since-mark vars.
  1464   double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
  1465   if (elapsed_ms < MIN_TIMER_GRANULARITY) {
  1466     // This usually happens due to the timer not having the required
  1467     // granularity. Some Linuxes are the usual culprits.
  1468     // We'll just set it to something (arbitrarily) small.
  1469     proc_ms = 1.0;
  1471   double cur_efficiency = (double) freed_bytes / proc_ms;
  1473   bool new_in_marking_window = _in_marking_window;
  1474   bool new_in_marking_window_im = false;
  1475   if (during_initial_mark_pause()) {
  1476     new_in_marking_window = true;
  1477     new_in_marking_window_im = true;
  1480   if (in_young_gc_mode()) {
  1481     if (_last_full_young_gc) {
  1482       set_full_young_gcs(false);
  1483       _last_full_young_gc = false;
  1486     if ( !_last_young_gc_full ) {
  1487       if ( _should_revert_to_full_young_gcs ||
  1488            _known_garbage_ratio < 0.05 ||
  1489            (adaptive_young_list_length() &&
  1490            (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
  1491         set_full_young_gcs(true);
  1494     _should_revert_to_full_young_gcs = false;
  1496     if (_last_young_gc_full && !_during_marking)
  1497       _young_gc_eff_seq->add(cur_efficiency);
  1500   _short_lived_surv_rate_group->start_adding_regions();
  1501   // do that for any other surv rate groupsx
  1503   // <NEW PREDICTION>
  1505   if (update_stats) {
  1506     double pause_time_ms = elapsed_ms;
  1508     size_t diff = 0;
  1509     if (_max_pending_cards >= _pending_cards)
  1510       diff = _max_pending_cards - _pending_cards;
  1511     _pending_card_diff_seq->add((double) diff);
  1513     double cost_per_card_ms = 0.0;
  1514     if (_pending_cards > 0) {
  1515       cost_per_card_ms = update_rs_time / (double) _pending_cards;
  1516       _cost_per_card_ms_seq->add(cost_per_card_ms);
  1519     size_t cards_scanned = _g1->cards_scanned();
  1521     double cost_per_entry_ms = 0.0;
  1522     if (cards_scanned > 10) {
  1523       cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
  1524       if (_last_young_gc_full)
  1525         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1526       else
  1527         _partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1530     if (_max_rs_lengths > 0) {
  1531       double cards_per_entry_ratio =
  1532         (double) cards_scanned / (double) _max_rs_lengths;
  1533       if (_last_young_gc_full)
  1534         _fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1535       else
  1536         _partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1539     size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
  1540     if (rs_length_diff >= 0)
  1541       _rs_length_diff_seq->add((double) rs_length_diff);
  1543     size_t copied_bytes = surviving_bytes;
  1544     double cost_per_byte_ms = 0.0;
  1545     if (copied_bytes > 0) {
  1546       cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
  1547       if (_in_marking_window)
  1548         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
  1549       else
  1550         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
  1553     double all_other_time_ms = pause_time_ms -
  1554       (update_rs_time + scan_rs_time + obj_copy_time +
  1555        _mark_closure_time_ms + termination_time);
  1557     double young_other_time_ms = 0.0;
  1558     if (_recorded_young_regions > 0) {
  1559       young_other_time_ms =
  1560         _recorded_young_cset_choice_time_ms +
  1561         _recorded_young_free_cset_time_ms;
  1562       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
  1563                                              (double) _recorded_young_regions);
  1565     double non_young_other_time_ms = 0.0;
  1566     if (_recorded_non_young_regions > 0) {
  1567       non_young_other_time_ms =
  1568         _recorded_non_young_cset_choice_time_ms +
  1569         _recorded_non_young_free_cset_time_ms;
  1571       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
  1572                                          (double) _recorded_non_young_regions);
  1575     double constant_other_time_ms = all_other_time_ms -
  1576       (young_other_time_ms + non_young_other_time_ms);
  1577     _constant_other_time_ms_seq->add(constant_other_time_ms);
  1579     double survival_ratio = 0.0;
  1580     if (_bytes_in_collection_set_before_gc > 0) {
  1581       survival_ratio = (double) bytes_in_to_space_during_gc() /
  1582         (double) _bytes_in_collection_set_before_gc;
  1585     _pending_cards_seq->add((double) _pending_cards);
  1586     _scanned_cards_seq->add((double) cards_scanned);
  1587     _rs_lengths_seq->add((double) _max_rs_lengths);
  1589     double expensive_region_limit_ms =
  1590       (double) MaxGCPauseMillis - predict_constant_other_time_ms();
  1591     if (expensive_region_limit_ms < 0.0) {
  1592       // this means that the other time was predicted to be longer than
  1593       // than the max pause time
  1594       expensive_region_limit_ms = (double) MaxGCPauseMillis;
  1596     _expensive_region_limit_ms = expensive_region_limit_ms;
  1598     if (PREDICTIONS_VERBOSE) {
  1599       gclog_or_tty->print_cr("");
  1600       gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
  1601                     "REGIONS %d %d %d "
  1602                     "PENDING_CARDS %d %d "
  1603                     "CARDS_SCANNED %d %d "
  1604                     "RS_LENGTHS %d %d "
  1605                     "RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
  1606                     "SURVIVAL_RATIO %1.6lf %1.6lf "
  1607                     "OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
  1608                     "OTHER_YOUNG %1.6lf %1.6lf "
  1609                     "OTHER_NON_YOUNG %1.6lf %1.6lf "
  1610                     "VTIME_DIFF %1.6lf TERMINATION %1.6lf "
  1611                     "ELAPSED %1.6lf %1.6lf ",
  1612                     _cur_collection_start_sec,
  1613                     (!_last_young_gc_full) ? 2 :
  1614                     (last_pause_included_initial_mark) ? 1 : 0,
  1615                     _recorded_region_num,
  1616                     _recorded_young_regions,
  1617                     _recorded_non_young_regions,
  1618                     _predicted_pending_cards, _pending_cards,
  1619                     _predicted_cards_scanned, cards_scanned,
  1620                     _predicted_rs_lengths, _max_rs_lengths,
  1621                     _predicted_rs_update_time_ms, update_rs_time,
  1622                     _predicted_rs_scan_time_ms, scan_rs_time,
  1623                     _predicted_survival_ratio, survival_ratio,
  1624                     _predicted_object_copy_time_ms, obj_copy_time,
  1625                     _predicted_constant_other_time_ms, constant_other_time_ms,
  1626                     _predicted_young_other_time_ms, young_other_time_ms,
  1627                     _predicted_non_young_other_time_ms,
  1628                     non_young_other_time_ms,
  1629                     _vtime_diff_ms, termination_time,
  1630                     _predicted_pause_time_ms, elapsed_ms);
  1633     if (G1PolicyVerbose > 0) {
  1634       gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
  1635                     _predicted_pause_time_ms,
  1636                     (_within_target) ? "within" : "outside",
  1637                     elapsed_ms);
  1642   _in_marking_window = new_in_marking_window;
  1643   _in_marking_window_im = new_in_marking_window_im;
  1644   _free_regions_at_end_of_collection = _g1->free_regions();
  1645   calculate_young_list_min_length();
  1646   calculate_young_list_target_length();
  1648   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
  1649   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
  1650   adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
  1651   // </NEW PREDICTION>
  1654 #define EXT_SIZE_FORMAT "%d%s"
  1655 #define EXT_SIZE_PARAMS(bytes)                                  \
  1656   byte_size_in_proper_unit((bytes)),                            \
  1657   proper_unit_for_byte_size((bytes))
  1659 void G1CollectorPolicy::print_heap_transition() {
  1660   if (PrintGCDetails) {
  1661     YoungList* young_list = _g1->young_list();
  1662     size_t eden_bytes = young_list->eden_used_bytes();
  1663     size_t survivor_bytes = young_list->survivor_used_bytes();
  1664     size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
  1665     size_t used = _g1->used();
  1666     size_t capacity = _g1->capacity();
  1668     gclog_or_tty->print_cr(
  1669          "   [Eden: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
  1670              "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
  1671              "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
  1672                      EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
  1673              EXT_SIZE_PARAMS(_eden_bytes_before_gc),
  1674                EXT_SIZE_PARAMS(eden_bytes),
  1675              EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
  1676                EXT_SIZE_PARAMS(survivor_bytes),
  1677              EXT_SIZE_PARAMS(used_before_gc),
  1678              EXT_SIZE_PARAMS(_capacity_before_gc),
  1679                EXT_SIZE_PARAMS(used),
  1680                EXT_SIZE_PARAMS(capacity));
  1681   } else if (PrintGC) {
  1682     _g1->print_size_transition(gclog_or_tty,
  1683                                _cur_collection_pause_used_at_start_bytes,
  1684                                _g1->used(), _g1->capacity());
  1688 // <NEW PREDICTION>
  1690 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
  1691                                                      double update_rs_processed_buffers,
  1692                                                      double goal_ms) {
  1693   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  1694   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
  1696   if (G1UseAdaptiveConcRefinement) {
  1697     const int k_gy = 3, k_gr = 6;
  1698     const double inc_k = 1.1, dec_k = 0.9;
  1700     int g = cg1r->green_zone();
  1701     if (update_rs_time > goal_ms) {
  1702       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
  1703     } else {
  1704       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
  1705         g = (int)MAX2(g * inc_k, g + 1.0);
  1708     // Change the refinement threads params
  1709     cg1r->set_green_zone(g);
  1710     cg1r->set_yellow_zone(g * k_gy);
  1711     cg1r->set_red_zone(g * k_gr);
  1712     cg1r->reinitialize_threads();
  1714     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
  1715     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
  1716                                     cg1r->yellow_zone());
  1717     // Change the barrier params
  1718     dcqs.set_process_completed_threshold(processing_threshold);
  1719     dcqs.set_max_completed_queue(cg1r->red_zone());
  1722   int curr_queue_size = dcqs.completed_buffers_num();
  1723   if (curr_queue_size >= cg1r->yellow_zone()) {
  1724     dcqs.set_completed_queue_padding(curr_queue_size);
  1725   } else {
  1726     dcqs.set_completed_queue_padding(0);
  1728   dcqs.notify_if_necessary();
  1731 double
  1732 G1CollectorPolicy::
  1733 predict_young_collection_elapsed_time_ms(size_t adjustment) {
  1734   guarantee( adjustment == 0 || adjustment == 1, "invariant" );
  1736   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  1737   size_t young_num = g1h->young_list()->length();
  1738   if (young_num == 0)
  1739     return 0.0;
  1741   young_num += adjustment;
  1742   size_t pending_cards = predict_pending_cards();
  1743   size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
  1744                       predict_rs_length_diff();
  1745   size_t card_num;
  1746   if (full_young_gcs())
  1747     card_num = predict_young_card_num(rs_lengths);
  1748   else
  1749     card_num = predict_non_young_card_num(rs_lengths);
  1750   size_t young_byte_size = young_num * HeapRegion::GrainBytes;
  1751   double accum_yg_surv_rate =
  1752     _short_lived_surv_rate_group->accum_surv_rate(adjustment);
  1754   size_t bytes_to_copy =
  1755     (size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
  1757   return
  1758     predict_rs_update_time_ms(pending_cards) +
  1759     predict_rs_scan_time_ms(card_num) +
  1760     predict_object_copy_time_ms(bytes_to_copy) +
  1761     predict_young_other_time_ms(young_num) +
  1762     predict_constant_other_time_ms();
  1765 double
  1766 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
  1767   size_t rs_length = predict_rs_length_diff();
  1768   size_t card_num;
  1769   if (full_young_gcs())
  1770     card_num = predict_young_card_num(rs_length);
  1771   else
  1772     card_num = predict_non_young_card_num(rs_length);
  1773   return predict_base_elapsed_time_ms(pending_cards, card_num);
  1776 double
  1777 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
  1778                                                 size_t scanned_cards) {
  1779   return
  1780     predict_rs_update_time_ms(pending_cards) +
  1781     predict_rs_scan_time_ms(scanned_cards) +
  1782     predict_constant_other_time_ms();
  1785 double
  1786 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
  1787                                                   bool young) {
  1788   size_t rs_length = hr->rem_set()->occupied();
  1789   size_t card_num;
  1790   if (full_young_gcs())
  1791     card_num = predict_young_card_num(rs_length);
  1792   else
  1793     card_num = predict_non_young_card_num(rs_length);
  1794   size_t bytes_to_copy = predict_bytes_to_copy(hr);
  1796   double region_elapsed_time_ms =
  1797     predict_rs_scan_time_ms(card_num) +
  1798     predict_object_copy_time_ms(bytes_to_copy);
  1800   if (young)
  1801     region_elapsed_time_ms += predict_young_other_time_ms(1);
  1802   else
  1803     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
  1805   return region_elapsed_time_ms;
  1808 size_t
  1809 G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
  1810   size_t bytes_to_copy;
  1811   if (hr->is_marked())
  1812     bytes_to_copy = hr->max_live_bytes();
  1813   else {
  1814     guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
  1815                "invariant" );
  1816     int age = hr->age_in_surv_rate_group();
  1817     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
  1818     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
  1821   return bytes_to_copy;
  1824 void
  1825 G1CollectorPolicy::start_recording_regions() {
  1826   _recorded_rs_lengths            = 0;
  1827   _recorded_young_regions         = 0;
  1828   _recorded_non_young_regions     = 0;
  1830 #if PREDICTIONS_VERBOSE
  1831   _recorded_marked_bytes          = 0;
  1832   _recorded_young_bytes           = 0;
  1833   _predicted_bytes_to_copy        = 0;
  1834   _predicted_rs_lengths           = 0;
  1835   _predicted_cards_scanned        = 0;
  1836 #endif // PREDICTIONS_VERBOSE
  1839 void
  1840 G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
  1841 #if PREDICTIONS_VERBOSE
  1842   if (!young) {
  1843     _recorded_marked_bytes += hr->max_live_bytes();
  1845   _predicted_bytes_to_copy += predict_bytes_to_copy(hr);
  1846 #endif // PREDICTIONS_VERBOSE
  1848   size_t rs_length = hr->rem_set()->occupied();
  1849   _recorded_rs_lengths += rs_length;
  1852 void
  1853 G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
  1854   assert(!hr->is_young(), "should not call this");
  1855   ++_recorded_non_young_regions;
  1856   record_cset_region_info(hr, false);
  1859 void
  1860 G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
  1861   _recorded_young_regions = n_regions;
  1864 void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
  1865 #if PREDICTIONS_VERBOSE
  1866   _recorded_young_bytes = bytes;
  1867 #endif // PREDICTIONS_VERBOSE
  1870 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
  1871   _recorded_rs_lengths = rs_lengths;
  1874 void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
  1875   _predicted_bytes_to_copy = bytes;
  1878 void
  1879 G1CollectorPolicy::end_recording_regions() {
  1880   // The _predicted_pause_time_ms field is referenced in code
  1881   // not under PREDICTIONS_VERBOSE. Let's initialize it.
  1882   _predicted_pause_time_ms = -1.0;
  1884 #if PREDICTIONS_VERBOSE
  1885   _predicted_pending_cards = predict_pending_cards();
  1886   _predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
  1887   if (full_young_gcs())
  1888     _predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
  1889   else
  1890     _predicted_cards_scanned +=
  1891       predict_non_young_card_num(_predicted_rs_lengths);
  1892   _recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
  1894   _predicted_rs_update_time_ms =
  1895     predict_rs_update_time_ms(_g1->pending_card_num());
  1896   _predicted_rs_scan_time_ms =
  1897     predict_rs_scan_time_ms(_predicted_cards_scanned);
  1898   _predicted_object_copy_time_ms =
  1899     predict_object_copy_time_ms(_predicted_bytes_to_copy);
  1900   _predicted_constant_other_time_ms =
  1901     predict_constant_other_time_ms();
  1902   _predicted_young_other_time_ms =
  1903     predict_young_other_time_ms(_recorded_young_regions);
  1904   _predicted_non_young_other_time_ms =
  1905     predict_non_young_other_time_ms(_recorded_non_young_regions);
  1907   _predicted_pause_time_ms =
  1908     _predicted_rs_update_time_ms +
  1909     _predicted_rs_scan_time_ms +
  1910     _predicted_object_copy_time_ms +
  1911     _predicted_constant_other_time_ms +
  1912     _predicted_young_other_time_ms +
  1913     _predicted_non_young_other_time_ms;
  1914 #endif // PREDICTIONS_VERBOSE
  1917 void G1CollectorPolicy::check_if_region_is_too_expensive(double
  1918                                                            predicted_time_ms) {
  1919   // I don't think we need to do this when in young GC mode since
  1920   // marking will be initiated next time we hit the soft limit anyway...
  1921   if (predicted_time_ms > _expensive_region_limit_ms) {
  1922     if (!in_young_gc_mode()) {
  1923         set_full_young_gcs(true);
  1924         // We might want to do something different here. However,
  1925         // right now we don't support the non-generational G1 mode
  1926         // (and in fact we are planning to remove the associated code,
  1927         // see CR 6814390). So, let's leave it as is and this will be
  1928         // removed some time in the future
  1929         ShouldNotReachHere();
  1930         set_during_initial_mark_pause();
  1931     } else
  1932       // no point in doing another partial one
  1933       _should_revert_to_full_young_gcs = true;
  1937 // </NEW PREDICTION>
  1940 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
  1941                                                double elapsed_ms) {
  1942   _recent_gc_times_ms->add(elapsed_ms);
  1943   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
  1944   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
  1947 double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
  1948   if (_recent_pause_times_ms->num() == 0) {
  1949     return (double) MaxGCPauseMillis;
  1951   return _recent_pause_times_ms->avg();
  1954 double G1CollectorPolicy::recent_avg_time_for_rs_scan_ms() {
  1955   if (_recent_rs_scan_times_ms->num() == 0) {
  1956     return (double)MaxGCPauseMillis/3.0;
  1958   return _recent_rs_scan_times_ms->avg();
  1961 int G1CollectorPolicy::number_of_recent_gcs() {
  1962   assert(_recent_rs_scan_times_ms->num() ==
  1963          _recent_pause_times_ms->num(), "Sequence out of sync");
  1964   assert(_recent_pause_times_ms->num() ==
  1965          _recent_CS_bytes_used_before->num(), "Sequence out of sync");
  1966   assert(_recent_CS_bytes_used_before->num() ==
  1967          _recent_CS_bytes_surviving->num(), "Sequence out of sync");
  1969   return _recent_pause_times_ms->num();
  1972 double G1CollectorPolicy::recent_avg_survival_fraction() {
  1973   return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
  1974                                            _recent_CS_bytes_used_before);
  1977 double G1CollectorPolicy::last_survival_fraction() {
  1978   return last_survival_fraction_work(_recent_CS_bytes_surviving,
  1979                                      _recent_CS_bytes_used_before);
  1982 double
  1983 G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
  1984                                                      TruncatedSeq* before) {
  1985   assert(surviving->num() == before->num(), "Sequence out of sync");
  1986   if (before->sum() > 0.0) {
  1987       double recent_survival_rate = surviving->sum() / before->sum();
  1988       // We exempt parallel collection from this check because Alloc Buffer
  1989       // fragmentation can produce negative collections.
  1990       // Further, we're now always doing parallel collection.  But I'm still
  1991       // leaving this here as a placeholder for a more precise assertion later.
  1992       // (DLD, 10/05.)
  1993       assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
  1994              _g1->evacuation_failed() ||
  1995              recent_survival_rate <= 1.0, "Or bad frac");
  1996       return recent_survival_rate;
  1997   } else {
  1998     return 1.0; // Be conservative.
  2002 double
  2003 G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
  2004                                                TruncatedSeq* before) {
  2005   assert(surviving->num() == before->num(), "Sequence out of sync");
  2006   if (surviving->num() > 0 && before->last() > 0.0) {
  2007     double last_survival_rate = surviving->last() / before->last();
  2008     // We exempt parallel collection from this check because Alloc Buffer
  2009     // fragmentation can produce negative collections.
  2010     // Further, we're now always doing parallel collection.  But I'm still
  2011     // leaving this here as a placeholder for a more precise assertion later.
  2012     // (DLD, 10/05.)
  2013     assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
  2014            last_survival_rate <= 1.0, "Or bad frac");
  2015     return last_survival_rate;
  2016   } else {
  2017     return 1.0;
  2021 static const int survival_min_obs = 5;
  2022 static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
  2023 static const double min_survival_rate = 0.1;
  2025 double
  2026 G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
  2027                                                            double latest) {
  2028   double res = avg;
  2029   if (number_of_recent_gcs() < survival_min_obs) {
  2030     res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
  2032   res = MAX2(res, latest);
  2033   res = MAX2(res, min_survival_rate);
  2034   // In the parallel case, LAB fragmentation can produce "negative
  2035   // collections"; so can evac failure.  Cap at 1.0
  2036   res = MIN2(res, 1.0);
  2037   return res;
  2040 size_t G1CollectorPolicy::expansion_amount() {
  2041   if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
  2042     // We will double the existing space, or take
  2043     // G1ExpandByPercentOfAvailable % of the available expansion
  2044     // space, whichever is smaller, bounded below by a minimum
  2045     // expansion (unless that's all that's left.)
  2046     const size_t min_expand_bytes = 1*M;
  2047     size_t reserved_bytes = _g1->max_capacity();
  2048     size_t committed_bytes = _g1->capacity();
  2049     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
  2050     size_t expand_bytes;
  2051     size_t expand_bytes_via_pct =
  2052       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
  2053     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
  2054     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
  2055     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
  2056     if (G1PolicyVerbose > 1) {
  2057       gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
  2058                  "committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
  2059                  "                   Answer = %d.\n",
  2060                  recent_avg_pause_time_ratio(),
  2061                  byte_size_in_proper_unit(committed_bytes),
  2062                  proper_unit_for_byte_size(committed_bytes),
  2063                  byte_size_in_proper_unit(uncommitted_bytes),
  2064                  proper_unit_for_byte_size(uncommitted_bytes),
  2065                  byte_size_in_proper_unit(expand_bytes_via_pct),
  2066                  proper_unit_for_byte_size(expand_bytes_via_pct),
  2067                  byte_size_in_proper_unit(expand_bytes),
  2068                  proper_unit_for_byte_size(expand_bytes));
  2070     return expand_bytes;
  2071   } else {
  2072     return 0;
  2076 void G1CollectorPolicy::note_start_of_mark_thread() {
  2077   _mark_thread_startup_sec = os::elapsedTime();
  2080 class CountCSClosure: public HeapRegionClosure {
  2081   G1CollectorPolicy* _g1_policy;
  2082 public:
  2083   CountCSClosure(G1CollectorPolicy* g1_policy) :
  2084     _g1_policy(g1_policy) {}
  2085   bool doHeapRegion(HeapRegion* r) {
  2086     _g1_policy->_bytes_in_collection_set_before_gc += r->used();
  2087     return false;
  2089 };
  2091 void G1CollectorPolicy::count_CS_bytes_used() {
  2092   CountCSClosure cs_closure(this);
  2093   _g1->collection_set_iterate(&cs_closure);
  2096 void G1CollectorPolicy::print_summary (int level,
  2097                                        const char* str,
  2098                                        NumberSeq* seq) const {
  2099   double sum = seq->sum();
  2100   LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
  2101                 str, sum / 1000.0, seq->avg());
  2104 void G1CollectorPolicy::print_summary_sd (int level,
  2105                                           const char* str,
  2106                                           NumberSeq* seq) const {
  2107   print_summary(level, str, seq);
  2108   LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
  2109                 seq->num(), seq->sd(), seq->maximum());
  2112 void G1CollectorPolicy::check_other_times(int level,
  2113                                         NumberSeq* other_times_ms,
  2114                                         NumberSeq* calc_other_times_ms) const {
  2115   bool should_print = false;
  2116   LineBuffer buf(level + 2);
  2118   double max_sum = MAX2(fabs(other_times_ms->sum()),
  2119                         fabs(calc_other_times_ms->sum()));
  2120   double min_sum = MIN2(fabs(other_times_ms->sum()),
  2121                         fabs(calc_other_times_ms->sum()));
  2122   double sum_ratio = max_sum / min_sum;
  2123   if (sum_ratio > 1.1) {
  2124     should_print = true;
  2125     buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
  2128   double max_avg = MAX2(fabs(other_times_ms->avg()),
  2129                         fabs(calc_other_times_ms->avg()));
  2130   double min_avg = MIN2(fabs(other_times_ms->avg()),
  2131                         fabs(calc_other_times_ms->avg()));
  2132   double avg_ratio = max_avg / min_avg;
  2133   if (avg_ratio > 1.1) {
  2134     should_print = true;
  2135     buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
  2138   if (other_times_ms->sum() < -0.01) {
  2139     buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
  2142   if (other_times_ms->avg() < -0.01) {
  2143     buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
  2146   if (calc_other_times_ms->sum() < -0.01) {
  2147     should_print = true;
  2148     buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
  2151   if (calc_other_times_ms->avg() < -0.01) {
  2152     should_print = true;
  2153     buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
  2156   if (should_print)
  2157     print_summary(level, "Other(Calc)", calc_other_times_ms);
  2160 void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
  2161   bool parallel = G1CollectedHeap::use_parallel_gc_threads();
  2162   MainBodySummary*    body_summary = summary->main_body_summary();
  2163   if (summary->get_total_seq()->num() > 0) {
  2164     print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
  2165     if (body_summary != NULL) {
  2166       print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
  2167       if (parallel) {
  2168         print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
  2169         print_summary(2, "Update RS", body_summary->get_update_rs_seq());
  2170         print_summary(2, "Ext Root Scanning",
  2171                       body_summary->get_ext_root_scan_seq());
  2172         print_summary(2, "Mark Stack Scanning",
  2173                       body_summary->get_mark_stack_scan_seq());
  2174         print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
  2175         print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
  2176         print_summary(2, "Termination", body_summary->get_termination_seq());
  2177         print_summary(2, "Other", body_summary->get_parallel_other_seq());
  2179           NumberSeq* other_parts[] = {
  2180             body_summary->get_update_rs_seq(),
  2181             body_summary->get_ext_root_scan_seq(),
  2182             body_summary->get_mark_stack_scan_seq(),
  2183             body_summary->get_scan_rs_seq(),
  2184             body_summary->get_obj_copy_seq(),
  2185             body_summary->get_termination_seq()
  2186           };
  2187           NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
  2188                                         6, other_parts);
  2189           check_other_times(2, body_summary->get_parallel_other_seq(),
  2190                             &calc_other_times_ms);
  2192         print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
  2193         print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
  2194       } else {
  2195         print_summary(1, "Update RS", body_summary->get_update_rs_seq());
  2196         print_summary(1, "Ext Root Scanning",
  2197                       body_summary->get_ext_root_scan_seq());
  2198         print_summary(1, "Mark Stack Scanning",
  2199                       body_summary->get_mark_stack_scan_seq());
  2200         print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
  2201         print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
  2204     print_summary(1, "Other", summary->get_other_seq());
  2206       if (body_summary != NULL) {
  2207         NumberSeq calc_other_times_ms;
  2208         if (parallel) {
  2209           // parallel
  2210           NumberSeq* other_parts[] = {
  2211             body_summary->get_satb_drain_seq(),
  2212             body_summary->get_parallel_seq(),
  2213             body_summary->get_clear_ct_seq()
  2214           };
  2215           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2216                                                 3, other_parts);
  2217         } else {
  2218           // serial
  2219           NumberSeq* other_parts[] = {
  2220             body_summary->get_satb_drain_seq(),
  2221             body_summary->get_update_rs_seq(),
  2222             body_summary->get_ext_root_scan_seq(),
  2223             body_summary->get_mark_stack_scan_seq(),
  2224             body_summary->get_scan_rs_seq(),
  2225             body_summary->get_obj_copy_seq()
  2226           };
  2227           calc_other_times_ms = NumberSeq(summary->get_total_seq(),
  2228                                                 6, other_parts);
  2230         check_other_times(1,  summary->get_other_seq(), &calc_other_times_ms);
  2233   } else {
  2234     LineBuffer(1).append_and_print_cr("none");
  2236   LineBuffer(0).append_and_print_cr("");
  2239 void G1CollectorPolicy::print_tracing_info() const {
  2240   if (TraceGen0Time) {
  2241     gclog_or_tty->print_cr("ALL PAUSES");
  2242     print_summary_sd(0, "Total", _all_pause_times_ms);
  2243     gclog_or_tty->print_cr("");
  2244     gclog_or_tty->print_cr("");
  2245     gclog_or_tty->print_cr("   Full Young GC Pauses:    %8d", _full_young_pause_num);
  2246     gclog_or_tty->print_cr("   Partial Young GC Pauses: %8d", _partial_young_pause_num);
  2247     gclog_or_tty->print_cr("");
  2249     gclog_or_tty->print_cr("EVACUATION PAUSES");
  2250     print_summary(_summary);
  2252     gclog_or_tty->print_cr("MISC");
  2253     print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
  2254     print_summary_sd(0, "Yields", _all_yield_times_ms);
  2255     for (int i = 0; i < _aux_num; ++i) {
  2256       if (_all_aux_times_ms[i].num() > 0) {
  2257         char buffer[96];
  2258         sprintf(buffer, "Aux%d", i);
  2259         print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
  2263     size_t all_region_num = _region_num_young + _region_num_tenured;
  2264     gclog_or_tty->print_cr("   New Regions %8d, Young %8d (%6.2lf%%), "
  2265                "Tenured %8d (%6.2lf%%)",
  2266                all_region_num,
  2267                _region_num_young,
  2268                (double) _region_num_young / (double) all_region_num * 100.0,
  2269                _region_num_tenured,
  2270                (double) _region_num_tenured / (double) all_region_num * 100.0);
  2272   if (TraceGen1Time) {
  2273     if (_all_full_gc_times_ms->num() > 0) {
  2274       gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
  2275                  _all_full_gc_times_ms->num(),
  2276                  _all_full_gc_times_ms->sum() / 1000.0);
  2277       gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
  2278       gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
  2279                     _all_full_gc_times_ms->sd(),
  2280                     _all_full_gc_times_ms->maximum());
  2285 void G1CollectorPolicy::print_yg_surv_rate_info() const {
  2286 #ifndef PRODUCT
  2287   _short_lived_surv_rate_group->print_surv_rate_summary();
  2288   // add this call for any other surv rate groups
  2289 #endif // PRODUCT
  2292 void
  2293 G1CollectorPolicy::update_region_num(bool young) {
  2294   if (young) {
  2295     ++_region_num_young;
  2296   } else {
  2297     ++_region_num_tenured;
  2301 #ifndef PRODUCT
  2302 // for debugging, bit of a hack...
  2303 static char*
  2304 region_num_to_mbs(int length) {
  2305   static char buffer[64];
  2306   double bytes = (double) (length * HeapRegion::GrainBytes);
  2307   double mbs = bytes / (double) (1024 * 1024);
  2308   sprintf(buffer, "%7.2lfMB", mbs);
  2309   return buffer;
  2311 #endif // PRODUCT
  2313 size_t G1CollectorPolicy::max_regions(int purpose) {
  2314   switch (purpose) {
  2315     case GCAllocForSurvived:
  2316       return _max_survivor_regions;
  2317     case GCAllocForTenured:
  2318       return REGIONS_UNLIMITED;
  2319     default:
  2320       ShouldNotReachHere();
  2321       return REGIONS_UNLIMITED;
  2322   };
  2325 void G1CollectorPolicy::calculate_max_gc_locker_expansion() {
  2326   size_t expansion_region_num = 0;
  2327   if (GCLockerEdenExpansionPercent > 0) {
  2328     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
  2329     double expansion_region_num_d = perc * (double) _young_list_target_length;
  2330     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
  2331     // less than 1.0) we'll get 1.
  2332     expansion_region_num = (size_t) ceil(expansion_region_num_d);
  2333   } else {
  2334     assert(expansion_region_num == 0, "sanity");
  2336   _young_list_max_length = _young_list_target_length + expansion_region_num;
  2337   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
  2340 // Calculates survivor space parameters.
  2341 void G1CollectorPolicy::calculate_survivors_policy()
  2343   if (G1FixedSurvivorSpaceSize == 0) {
  2344     _max_survivor_regions = _young_list_target_length / SurvivorRatio;
  2345   } else {
  2346     _max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
  2349   if (G1FixedTenuringThreshold) {
  2350     _tenuring_threshold = MaxTenuringThreshold;
  2351   } else {
  2352     _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
  2353         HeapRegion::GrainWords * _max_survivor_regions);
  2357 #ifndef PRODUCT
  2358 class HRSortIndexIsOKClosure: public HeapRegionClosure {
  2359   CollectionSetChooser* _chooser;
  2360 public:
  2361   HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
  2362     _chooser(chooser) {}
  2364   bool doHeapRegion(HeapRegion* r) {
  2365     if (!r->continuesHumongous()) {
  2366       assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
  2368     return false;
  2370 };
  2372 bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
  2373   HRSortIndexIsOKClosure cl(_collectionSetChooser);
  2374   _g1->heap_region_iterate(&cl);
  2375   return true;
  2377 #endif
  2379 bool
  2380 G1CollectorPolicy::force_initial_mark_if_outside_cycle() {
  2381   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
  2382   if (!during_cycle) {
  2383     set_initiate_conc_mark_if_possible();
  2384     return true;
  2385   } else {
  2386     return false;
  2390 void
  2391 G1CollectorPolicy::decide_on_conc_mark_initiation() {
  2392   // We are about to decide on whether this pause will be an
  2393   // initial-mark pause.
  2395   // First, during_initial_mark_pause() should not be already set. We
  2396   // will set it here if we have to. However, it should be cleared by
  2397   // the end of the pause (it's only set for the duration of an
  2398   // initial-mark pause).
  2399   assert(!during_initial_mark_pause(), "pre-condition");
  2401   if (initiate_conc_mark_if_possible()) {
  2402     // We had noticed on a previous pause that the heap occupancy has
  2403     // gone over the initiating threshold and we should start a
  2404     // concurrent marking cycle. So we might initiate one.
  2406     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
  2407     if (!during_cycle) {
  2408       // The concurrent marking thread is not "during a cycle", i.e.,
  2409       // it has completed the last one. So we can go ahead and
  2410       // initiate a new cycle.
  2412       set_during_initial_mark_pause();
  2414       // And we can now clear initiate_conc_mark_if_possible() as
  2415       // we've already acted on it.
  2416       clear_initiate_conc_mark_if_possible();
  2417     } else {
  2418       // The concurrent marking thread is still finishing up the
  2419       // previous cycle. If we start one right now the two cycles
  2420       // overlap. In particular, the concurrent marking thread might
  2421       // be in the process of clearing the next marking bitmap (which
  2422       // we will use for the next cycle if we start one). Starting a
  2423       // cycle now will be bad given that parts of the marking
  2424       // information might get cleared by the marking thread. And we
  2425       // cannot wait for the marking thread to finish the cycle as it
  2426       // periodically yields while clearing the next marking bitmap
  2427       // and, if it's in a yield point, it's waiting for us to
  2428       // finish. So, at this point we will not start a cycle and we'll
  2429       // let the concurrent marking thread complete the last one.
  2434 void
  2435 G1CollectorPolicy_BestRegionsFirst::
  2436 record_collection_pause_start(double start_time_sec, size_t start_used) {
  2437   G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
  2440 class KnownGarbageClosure: public HeapRegionClosure {
  2441   CollectionSetChooser* _hrSorted;
  2443 public:
  2444   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
  2445     _hrSorted(hrSorted)
  2446   {}
  2448   bool doHeapRegion(HeapRegion* r) {
  2449     // We only include humongous regions in collection
  2450     // sets when concurrent mark shows that their contained object is
  2451     // unreachable.
  2453     // Do we have any marking information for this region?
  2454     if (r->is_marked()) {
  2455       // We don't include humongous regions in collection
  2456       // sets because we collect them immediately at the end of a marking
  2457       // cycle.  We also don't include young regions because we *must*
  2458       // include them in the next collection pause.
  2459       if (!r->isHumongous() && !r->is_young()) {
  2460         _hrSorted->addMarkedHeapRegion(r);
  2463     return false;
  2465 };
  2467 class ParKnownGarbageHRClosure: public HeapRegionClosure {
  2468   CollectionSetChooser* _hrSorted;
  2469   jint _marked_regions_added;
  2470   jint _chunk_size;
  2471   jint _cur_chunk_idx;
  2472   jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
  2473   int _worker;
  2474   int _invokes;
  2476   void get_new_chunk() {
  2477     _cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
  2478     _cur_chunk_end = _cur_chunk_idx + _chunk_size;
  2480   void add_region(HeapRegion* r) {
  2481     if (_cur_chunk_idx == _cur_chunk_end) {
  2482       get_new_chunk();
  2484     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
  2485     _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
  2486     _marked_regions_added++;
  2487     _cur_chunk_idx++;
  2490 public:
  2491   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
  2492                            jint chunk_size,
  2493                            int worker) :
  2494     _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
  2495     _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
  2496     _invokes(0)
  2497   {}
  2499   bool doHeapRegion(HeapRegion* r) {
  2500     // We only include humongous regions in collection
  2501     // sets when concurrent mark shows that their contained object is
  2502     // unreachable.
  2503     _invokes++;
  2505     // Do we have any marking information for this region?
  2506     if (r->is_marked()) {
  2507       // We don't include humongous regions in collection
  2508       // sets because we collect them immediately at the end of a marking
  2509       // cycle.
  2510       // We also do not include young regions in collection sets
  2511       if (!r->isHumongous() && !r->is_young()) {
  2512         add_region(r);
  2515     return false;
  2517   jint marked_regions_added() { return _marked_regions_added; }
  2518   int invokes() { return _invokes; }
  2519 };
  2521 class ParKnownGarbageTask: public AbstractGangTask {
  2522   CollectionSetChooser* _hrSorted;
  2523   jint _chunk_size;
  2524   G1CollectedHeap* _g1;
  2525 public:
  2526   ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
  2527     AbstractGangTask("ParKnownGarbageTask"),
  2528     _hrSorted(hrSorted), _chunk_size(chunk_size),
  2529     _g1(G1CollectedHeap::heap())
  2530   {}
  2532   void work(int i) {
  2533     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
  2534     // Back to zero for the claim value.
  2535     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
  2536                                          HeapRegion::InitialClaimValue);
  2537     jint regions_added = parKnownGarbageCl.marked_regions_added();
  2538     _hrSorted->incNumMarkedHeapRegions(regions_added);
  2539     if (G1PrintParCleanupStats) {
  2540       gclog_or_tty->print_cr("     Thread %d called %d times, added %d regions to list.",
  2541                  i, parKnownGarbageCl.invokes(), regions_added);
  2544 };
  2546 void
  2547 G1CollectorPolicy_BestRegionsFirst::
  2548 record_concurrent_mark_cleanup_end(size_t freed_bytes,
  2549                                    size_t max_live_bytes) {
  2550   double start;
  2551   if (G1PrintParCleanupStats) start = os::elapsedTime();
  2552   record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
  2554   _collectionSetChooser->clearMarkedHeapRegions();
  2555   double clear_marked_end;
  2556   if (G1PrintParCleanupStats) {
  2557     clear_marked_end = os::elapsedTime();
  2558     gclog_or_tty->print_cr("  clear marked regions + work1: %8.3f ms.",
  2559                   (clear_marked_end - start)*1000.0);
  2561   if (G1CollectedHeap::use_parallel_gc_threads()) {
  2562     const size_t OverpartitionFactor = 4;
  2563     const size_t MinWorkUnit = 8;
  2564     const size_t WorkUnit =
  2565       MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
  2566            MinWorkUnit);
  2567     _collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
  2568                                                              WorkUnit);
  2569     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
  2570                                             (int) WorkUnit);
  2571     _g1->workers()->run_task(&parKnownGarbageTask);
  2573     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
  2574            "sanity check");
  2575   } else {
  2576     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
  2577     _g1->heap_region_iterate(&knownGarbagecl);
  2579   double known_garbage_end;
  2580   if (G1PrintParCleanupStats) {
  2581     known_garbage_end = os::elapsedTime();
  2582     gclog_or_tty->print_cr("  compute known garbage: %8.3f ms.",
  2583                   (known_garbage_end - clear_marked_end)*1000.0);
  2585   _collectionSetChooser->sortMarkedHeapRegions();
  2586   double sort_end;
  2587   if (G1PrintParCleanupStats) {
  2588     sort_end = os::elapsedTime();
  2589     gclog_or_tty->print_cr("  sorting: %8.3f ms.",
  2590                   (sort_end - known_garbage_end)*1000.0);
  2593   record_concurrent_mark_cleanup_end_work2();
  2594   double work2_end;
  2595   if (G1PrintParCleanupStats) {
  2596     work2_end = os::elapsedTime();
  2597     gclog_or_tty->print_cr("  work2: %8.3f ms.",
  2598                   (work2_end - sort_end)*1000.0);
  2602 // Add the heap region at the head of the non-incremental collection set
  2603 void G1CollectorPolicy::
  2604 add_to_collection_set(HeapRegion* hr) {
  2605   assert(_inc_cset_build_state == Active, "Precondition");
  2606   assert(!hr->is_young(), "non-incremental add of young region");
  2608   if (_g1->mark_in_progress())
  2609     _g1->concurrent_mark()->registerCSetRegion(hr);
  2611   assert(!hr->in_collection_set(), "should not already be in the CSet");
  2612   hr->set_in_collection_set(true);
  2613   hr->set_next_in_collection_set(_collection_set);
  2614   _collection_set = hr;
  2615   _collection_set_size++;
  2616   _collection_set_bytes_used_before += hr->used();
  2617   _g1->register_region_with_in_cset_fast_test(hr);
  2620 // Initialize the per-collection-set information
  2621 void G1CollectorPolicy::start_incremental_cset_building() {
  2622   assert(_inc_cset_build_state == Inactive, "Precondition");
  2624   _inc_cset_head = NULL;
  2625   _inc_cset_tail = NULL;
  2626   _inc_cset_size = 0;
  2627   _inc_cset_bytes_used_before = 0;
  2629   if (in_young_gc_mode()) {
  2630     _inc_cset_young_index = 0;
  2633   _inc_cset_max_finger = 0;
  2634   _inc_cset_recorded_young_bytes = 0;
  2635   _inc_cset_recorded_rs_lengths = 0;
  2636   _inc_cset_predicted_elapsed_time_ms = 0;
  2637   _inc_cset_predicted_bytes_to_copy = 0;
  2638   _inc_cset_build_state = Active;
  2641 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
  2642   // This routine is used when:
  2643   // * adding survivor regions to the incremental cset at the end of an
  2644   //   evacuation pause,
  2645   // * adding the current allocation region to the incremental cset
  2646   //   when it is retired, and
  2647   // * updating existing policy information for a region in the
  2648   //   incremental cset via young list RSet sampling.
  2649   // Therefore this routine may be called at a safepoint by the
  2650   // VM thread, or in-between safepoints by mutator threads (when
  2651   // retiring the current allocation region) or a concurrent
  2652   // refine thread (RSet sampling).
  2654   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
  2655   size_t used_bytes = hr->used();
  2657   _inc_cset_recorded_rs_lengths += rs_length;
  2658   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
  2660   _inc_cset_bytes_used_before += used_bytes;
  2662   // Cache the values we have added to the aggregated informtion
  2663   // in the heap region in case we have to remove this region from
  2664   // the incremental collection set, or it is updated by the
  2665   // rset sampling code
  2666   hr->set_recorded_rs_length(rs_length);
  2667   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
  2669 #if PREDICTIONS_VERBOSE
  2670   size_t bytes_to_copy = predict_bytes_to_copy(hr);
  2671   _inc_cset_predicted_bytes_to_copy += bytes_to_copy;
  2673   // Record the number of bytes used in this region
  2674   _inc_cset_recorded_young_bytes += used_bytes;
  2676   // Cache the values we have added to the aggregated informtion
  2677   // in the heap region in case we have to remove this region from
  2678   // the incremental collection set, or it is updated by the
  2679   // rset sampling code
  2680   hr->set_predicted_bytes_to_copy(bytes_to_copy);
  2681 #endif // PREDICTIONS_VERBOSE
  2684 void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
  2685   // This routine is currently only called as part of the updating of
  2686   // existing policy information for regions in the incremental cset that
  2687   // is performed by the concurrent refine thread(s) as part of young list
  2688   // RSet sampling. Therefore we should not be at a safepoint.
  2690   assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
  2691   assert(hr->is_young(), "it should be");
  2693   size_t used_bytes = hr->used();
  2694   size_t old_rs_length = hr->recorded_rs_length();
  2695   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
  2697   // Subtract the old recorded/predicted policy information for
  2698   // the given heap region from the collection set info.
  2699   _inc_cset_recorded_rs_lengths -= old_rs_length;
  2700   _inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
  2702   _inc_cset_bytes_used_before -= used_bytes;
  2704   // Clear the values cached in the heap region
  2705   hr->set_recorded_rs_length(0);
  2706   hr->set_predicted_elapsed_time_ms(0);
  2708 #if PREDICTIONS_VERBOSE
  2709   size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
  2710   _inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
  2712   // Subtract the number of bytes used in this region
  2713   _inc_cset_recorded_young_bytes -= used_bytes;
  2715   // Clear the values cached in the heap region
  2716   hr->set_predicted_bytes_to_copy(0);
  2717 #endif // PREDICTIONS_VERBOSE
  2720 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
  2721   // Update the collection set information that is dependent on the new RS length
  2722   assert(hr->is_young(), "Precondition");
  2724   remove_from_incremental_cset_info(hr);
  2725   add_to_incremental_cset_info(hr, new_rs_length);
  2728 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
  2729   assert( hr->is_young(), "invariant");
  2730   assert( hr->young_index_in_cset() == -1, "invariant" );
  2731   assert(_inc_cset_build_state == Active, "Precondition");
  2733   // We need to clear and set the cached recorded/cached collection set
  2734   // information in the heap region here (before the region gets added
  2735   // to the collection set). An individual heap region's cached values
  2736   // are calculated, aggregated with the policy collection set info,
  2737   // and cached in the heap region here (initially) and (subsequently)
  2738   // by the Young List sampling code.
  2740   size_t rs_length = hr->rem_set()->occupied();
  2741   add_to_incremental_cset_info(hr, rs_length);
  2743   HeapWord* hr_end = hr->end();
  2744   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
  2746   assert(!hr->in_collection_set(), "invariant");
  2747   hr->set_in_collection_set(true);
  2748   assert( hr->next_in_collection_set() == NULL, "invariant");
  2750   _inc_cset_size++;
  2751   _g1->register_region_with_in_cset_fast_test(hr);
  2753   hr->set_young_index_in_cset((int) _inc_cset_young_index);
  2754   ++_inc_cset_young_index;
  2757 // Add the region at the RHS of the incremental cset
  2758 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
  2759   // We should only ever be appending survivors at the end of a pause
  2760   assert( hr->is_survivor(), "Logic");
  2762   // Do the 'common' stuff
  2763   add_region_to_incremental_cset_common(hr);
  2765   // Now add the region at the right hand side
  2766   if (_inc_cset_tail == NULL) {
  2767     assert(_inc_cset_head == NULL, "invariant");
  2768     _inc_cset_head = hr;
  2769   } else {
  2770     _inc_cset_tail->set_next_in_collection_set(hr);
  2772   _inc_cset_tail = hr;
  2775 // Add the region to the LHS of the incremental cset
  2776 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
  2777   // Survivors should be added to the RHS at the end of a pause
  2778   assert(!hr->is_survivor(), "Logic");
  2780   // Do the 'common' stuff
  2781   add_region_to_incremental_cset_common(hr);
  2783   // Add the region at the left hand side
  2784   hr->set_next_in_collection_set(_inc_cset_head);
  2785   if (_inc_cset_head == NULL) {
  2786     assert(_inc_cset_tail == NULL, "Invariant");
  2787     _inc_cset_tail = hr;
  2789   _inc_cset_head = hr;
  2792 #ifndef PRODUCT
  2793 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
  2794   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
  2796   st->print_cr("\nCollection_set:");
  2797   HeapRegion* csr = list_head;
  2798   while (csr != NULL) {
  2799     HeapRegion* next = csr->next_in_collection_set();
  2800     assert(csr->in_collection_set(), "bad CS");
  2801     st->print_cr("  [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
  2802                  "age: %4d, y: %d, surv: %d",
  2803                         csr->bottom(), csr->end(),
  2804                         csr->top(),
  2805                         csr->prev_top_at_mark_start(),
  2806                         csr->next_top_at_mark_start(),
  2807                         csr->top_at_conc_mark_count(),
  2808                         csr->age_in_surv_rate_group_cond(),
  2809                         csr->is_young(),
  2810                         csr->is_survivor());
  2811     csr = next;
  2814 #endif // !PRODUCT
  2816 void
  2817 G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
  2818                                                   double target_pause_time_ms) {
  2819   // Set this here - in case we're not doing young collections.
  2820   double non_young_start_time_sec = os::elapsedTime();
  2822   start_recording_regions();
  2824   guarantee(target_pause_time_ms > 0.0,
  2825             err_msg("target_pause_time_ms = %1.6lf should be positive",
  2826                     target_pause_time_ms));
  2827   guarantee(_collection_set == NULL, "Precondition");
  2829   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
  2830   double predicted_pause_time_ms = base_time_ms;
  2832   double time_remaining_ms = target_pause_time_ms - base_time_ms;
  2834   // the 10% and 50% values are arbitrary...
  2835   if (time_remaining_ms < 0.10 * target_pause_time_ms) {
  2836     time_remaining_ms = 0.50 * target_pause_time_ms;
  2837     _within_target = false;
  2838   } else {
  2839     _within_target = true;
  2842   // We figure out the number of bytes available for future to-space.
  2843   // For new regions without marking information, we must assume the
  2844   // worst-case of complete survival.  If we have marking information for a
  2845   // region, we can bound the amount of live data.  We can add a number of
  2846   // such regions, as long as the sum of the live data bounds does not
  2847   // exceed the available evacuation space.
  2848   size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
  2850   size_t expansion_bytes =
  2851     _g1->expansion_regions() * HeapRegion::GrainBytes;
  2853   _collection_set_bytes_used_before = 0;
  2854   _collection_set_size = 0;
  2856   // Adjust for expansion and slop.
  2857   max_live_bytes = max_live_bytes + expansion_bytes;
  2859   HeapRegion* hr;
  2860   if (in_young_gc_mode()) {
  2861     double young_start_time_sec = os::elapsedTime();
  2863     if (G1PolicyVerbose > 0) {
  2864       gclog_or_tty->print_cr("Adding %d young regions to the CSet",
  2865                     _g1->young_list()->length());
  2868     _young_cset_length  = 0;
  2869     _last_young_gc_full = full_young_gcs() ? true : false;
  2871     if (_last_young_gc_full)
  2872       ++_full_young_pause_num;
  2873     else
  2874       ++_partial_young_pause_num;
  2876     // The young list is laid with the survivor regions from the previous
  2877     // pause are appended to the RHS of the young list, i.e.
  2878     //   [Newly Young Regions ++ Survivors from last pause].
  2880     hr = _g1->young_list()->first_survivor_region();
  2881     while (hr != NULL) {
  2882       assert(hr->is_survivor(), "badly formed young list");
  2883       hr->set_young();
  2884       hr = hr->get_next_young_region();
  2887     // Clear the fields that point to the survivor list - they are
  2888     // all young now.
  2889     _g1->young_list()->clear_survivors();
  2891     if (_g1->mark_in_progress())
  2892       _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
  2894     _young_cset_length = _inc_cset_young_index;
  2895     _collection_set = _inc_cset_head;
  2896     _collection_set_size = _inc_cset_size;
  2897     _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
  2899     // For young regions in the collection set, we assume the worst
  2900     // case of complete survival
  2901     max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
  2903     time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
  2904     predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
  2906     // The number of recorded young regions is the incremental
  2907     // collection set's current size
  2908     set_recorded_young_regions(_inc_cset_size);
  2909     set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
  2910     set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
  2911 #if PREDICTIONS_VERBOSE
  2912     set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
  2913 #endif // PREDICTIONS_VERBOSE
  2915     if (G1PolicyVerbose > 0) {
  2916       gclog_or_tty->print_cr("  Added " PTR_FORMAT " Young Regions to CS.",
  2917                              _inc_cset_size);
  2918       gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  2919                             max_live_bytes/K);
  2922     assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
  2924     double young_end_time_sec = os::elapsedTime();
  2925     _recorded_young_cset_choice_time_ms =
  2926       (young_end_time_sec - young_start_time_sec) * 1000.0;
  2928     // We are doing young collections so reset this.
  2929     non_young_start_time_sec = young_end_time_sec;
  2931     // Note we can use either _collection_set_size or
  2932     // _young_cset_length here
  2933     if (_collection_set_size > 0 && _last_young_gc_full) {
  2934       // don't bother adding more regions...
  2935       goto choose_collection_set_end;
  2939   if (!in_young_gc_mode() || !full_young_gcs()) {
  2940     bool should_continue = true;
  2941     NumberSeq seq;
  2942     double avg_prediction = 100000000000000000.0; // something very large
  2944     do {
  2945       hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
  2946                                                       avg_prediction);
  2947       if (hr != NULL) {
  2948         double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
  2949         time_remaining_ms -= predicted_time_ms;
  2950         predicted_pause_time_ms += predicted_time_ms;
  2951         add_to_collection_set(hr);
  2952         record_non_young_cset_region(hr);
  2953         max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
  2954         if (G1PolicyVerbose > 0) {
  2955           gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
  2956                         max_live_bytes/K);
  2958         seq.add(predicted_time_ms);
  2959         avg_prediction = seq.avg() + seq.sd();
  2961       should_continue =
  2962         ( hr != NULL) &&
  2963         ( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
  2964           : _collection_set_size < _young_list_fixed_length );
  2965     } while (should_continue);
  2967     if (!adaptive_young_list_length() &&
  2968         _collection_set_size < _young_list_fixed_length)
  2969       _should_revert_to_full_young_gcs  = true;
  2972 choose_collection_set_end:
  2973   stop_incremental_cset_building();
  2975   count_CS_bytes_used();
  2977   end_recording_regions();
  2979   double non_young_end_time_sec = os::elapsedTime();
  2980   _recorded_non_young_cset_choice_time_ms =
  2981     (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
  2984 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
  2985   G1CollectorPolicy::record_full_collection_end();
  2986   _collectionSetChooser->updateAfterFullCollection();
  2989 void G1CollectorPolicy_BestRegionsFirst::
  2990 expand_if_possible(size_t numRegions) {
  2991   size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
  2992   _g1->expand(expansion_bytes);
  2995 void G1CollectorPolicy_BestRegionsFirst::
  2996 record_collection_pause_end() {
  2997   G1CollectorPolicy::record_collection_pause_end();
  2998   assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");

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