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

Thu, 31 May 2012 21:10:33 +0200

author
brutisso
date
Thu, 31 May 2012 21:10:33 +0200
changeset 3812
bbc900c2482a
parent 3767
9d679effd28c
child 3923
922993931b3d
permissions
-rw-r--r--

7172279: G1: Clean up TraceGen0Time and TraceGen1Time data gathering
Summary: Simplify code, remove unused code, remove ExitAfterGCNum
Reviewed-by: huntch, johnc

     1 /*
     2  * Copyright (c) 2001, 2012, 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/g1ErgoVerbose.hpp"
    32 #include "gc_implementation/g1/g1Log.hpp"
    33 #include "gc_implementation/g1/heapRegionRemSet.hpp"
    34 #include "gc_implementation/shared/gcPolicyCounters.hpp"
    35 #include "runtime/arguments.hpp"
    36 #include "runtime/java.hpp"
    37 #include "runtime/mutexLocker.hpp"
    38 #include "utilities/debug.hpp"
    40 // Different defaults for different number of GC threads
    41 // They were chosen by running GCOld and SPECjbb on debris with different
    42 //   numbers of GC threads and choosing them based on the results
    44 // all the same
    45 static double rs_length_diff_defaults[] = {
    46   0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
    47 };
    49 static double cost_per_card_ms_defaults[] = {
    50   0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
    51 };
    53 // all the same
    54 static double young_cards_per_entry_ratio_defaults[] = {
    55   1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
    56 };
    58 static double cost_per_entry_ms_defaults[] = {
    59   0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
    60 };
    62 static double cost_per_byte_ms_defaults[] = {
    63   0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
    64 };
    66 // these should be pretty consistent
    67 static double constant_other_time_ms_defaults[] = {
    68   5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
    69 };
    72 static double young_other_cost_per_region_ms_defaults[] = {
    73   0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
    74 };
    76 static double non_young_other_cost_per_region_ms_defaults[] = {
    77   1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
    78 };
    80 // Help class for avoiding interleaved logging
    81 class LineBuffer: public StackObj {
    83 private:
    84   static const int BUFFER_LEN = 1024;
    85   static const int INDENT_CHARS = 3;
    86   char _buffer[BUFFER_LEN];
    87   int _indent_level;
    88   int _cur;
    90   void vappend(const char* format, va_list ap) {
    91     int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
    92     if (res != -1) {
    93       _cur += res;
    94     } else {
    95       DEBUG_ONLY(warning("buffer too small in LineBuffer");)
    96       _buffer[BUFFER_LEN -1] = 0;
    97       _cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
    98     }
    99   }
   101 public:
   102   explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
   103     for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
   104       _buffer[_cur] = ' ';
   105     }
   106   }
   108 #ifndef PRODUCT
   109   ~LineBuffer() {
   110     assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
   111   }
   112 #endif
   114   void append(const char* format, ...) {
   115     va_list ap;
   116     va_start(ap, format);
   117     vappend(format, ap);
   118     va_end(ap);
   119   }
   121   void append_and_print_cr(const char* format, ...) {
   122     va_list ap;
   123     va_start(ap, format);
   124     vappend(format, ap);
   125     va_end(ap);
   126     gclog_or_tty->print_cr("%s", _buffer);
   127     _cur = _indent_level * INDENT_CHARS;
   128   }
   129 };
   131 G1CollectorPolicy::G1CollectorPolicy() :
   132   _parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
   133                         ? ParallelGCThreads : 1),
   135   _recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   136   _stop_world_start(0.0),
   138   _cur_clear_ct_time_ms(0.0),
   139   _root_region_scan_wait_time_ms(0.0),
   141   _cur_ref_proc_time_ms(0.0),
   142   _cur_ref_enq_time_ms(0.0),
   144 #ifndef PRODUCT
   145   _min_clear_cc_time_ms(-1.0),
   146   _max_clear_cc_time_ms(-1.0),
   147   _cur_clear_cc_time_ms(0.0),
   148   _cum_clear_cc_time_ms(0.0),
   149   _num_cc_clears(0L),
   150 #endif
   152   _concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   153   _concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
   155   _alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   156   _prev_collection_pause_end_ms(0.0),
   157   _pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   158   _rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
   159   _cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   160   _young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
   161   _mixed_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
   162   _cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   163   _mixed_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   164   _cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   165   _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
   166   _constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   167   _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
   168   _non_young_other_cost_per_region_ms_seq(
   169                                          new TruncatedSeq(TruncatedSeqLength)),
   171   _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
   172   _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
   174   _pause_time_target_ms((double) MaxGCPauseMillis),
   176   _gcs_are_young(true),
   178   _during_marking(false),
   179   _in_marking_window(false),
   180   _in_marking_window_im(false),
   182   _recent_prev_end_times_for_all_gcs_sec(
   183                                 new TruncatedSeq(NumPrevPausesForHeuristics)),
   185   _recent_avg_pause_time_ratio(0.0),
   187   _initiate_conc_mark_if_possible(false),
   188   _during_initial_mark_pause(false),
   189   _last_young_gc(false),
   190   _last_gc_was_young(false),
   192   _eden_bytes_before_gc(0),
   193   _survivor_bytes_before_gc(0),
   194   _capacity_before_gc(0),
   196   _eden_cset_region_length(0),
   197   _survivor_cset_region_length(0),
   198   _old_cset_region_length(0),
   200   _collection_set(NULL),
   201   _collection_set_bytes_used_before(0),
   203   // Incremental CSet attributes
   204   _inc_cset_build_state(Inactive),
   205   _inc_cset_head(NULL),
   206   _inc_cset_tail(NULL),
   207   _inc_cset_bytes_used_before(0),
   208   _inc_cset_max_finger(NULL),
   209   _inc_cset_recorded_rs_lengths(0),
   210   _inc_cset_recorded_rs_lengths_diffs(0),
   211   _inc_cset_predicted_elapsed_time_ms(0.0),
   212   _inc_cset_predicted_elapsed_time_ms_diffs(0.0),
   214 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
   215 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
   216 #endif // _MSC_VER
   218   _short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
   219                                                  G1YoungSurvRateNumRegionsSummary)),
   220   _survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
   221                                               G1YoungSurvRateNumRegionsSummary)),
   222   // add here any more surv rate groups
   223   _recorded_survivor_regions(0),
   224   _recorded_survivor_head(NULL),
   225   _recorded_survivor_tail(NULL),
   226   _survivors_age_table(true),
   228   _gc_overhead_perc(0.0) {
   230   // Set up the region size and associated fields. Given that the
   231   // policy is created before the heap, we have to set this up here,
   232   // so it's done as soon as possible.
   233   HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
   234   HeapRegionRemSet::setup_remset_size();
   236   G1ErgoVerbose::initialize();
   237   if (PrintAdaptiveSizePolicy) {
   238     // Currently, we only use a single switch for all the heuristics.
   239     G1ErgoVerbose::set_enabled(true);
   240     // Given that we don't currently have a verboseness level
   241     // parameter, we'll hardcode this to high. This can be easily
   242     // changed in the future.
   243     G1ErgoVerbose::set_level(ErgoHigh);
   244   } else {
   245     G1ErgoVerbose::set_enabled(false);
   246   }
   248   // Verify PLAB sizes
   249   const size_t region_size = HeapRegion::GrainWords;
   250   if (YoungPLABSize > region_size || OldPLABSize > region_size) {
   251     char buffer[128];
   252     jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most "SIZE_FORMAT,
   253                  OldPLABSize > region_size ? "Old" : "Young", region_size);
   254     vm_exit_during_initialization(buffer);
   255   }
   257   _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
   258   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
   260   _par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
   261   _par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
   262   _par_last_satb_filtering_times_ms = new double[_parallel_gc_threads];
   264   _par_last_update_rs_times_ms = new double[_parallel_gc_threads];
   265   _par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
   267   _par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
   269   _par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
   271   _par_last_termination_times_ms = new double[_parallel_gc_threads];
   272   _par_last_termination_attempts = new double[_parallel_gc_threads];
   273   _par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
   274   _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
   275   _par_last_gc_worker_other_times_ms = new double[_parallel_gc_threads];
   277   int index;
   278   if (ParallelGCThreads == 0)
   279     index = 0;
   280   else if (ParallelGCThreads > 8)
   281     index = 7;
   282   else
   283     index = ParallelGCThreads - 1;
   285   _pending_card_diff_seq->add(0.0);
   286   _rs_length_diff_seq->add(rs_length_diff_defaults[index]);
   287   _cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
   288   _young_cards_per_entry_ratio_seq->add(
   289                                   young_cards_per_entry_ratio_defaults[index]);
   290   _cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
   291   _cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
   292   _constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
   293   _young_other_cost_per_region_ms_seq->add(
   294                                young_other_cost_per_region_ms_defaults[index]);
   295   _non_young_other_cost_per_region_ms_seq->add(
   296                            non_young_other_cost_per_region_ms_defaults[index]);
   298   // Below, we might need to calculate the pause time target based on
   299   // the pause interval. When we do so we are going to give G1 maximum
   300   // flexibility and allow it to do pauses when it needs to. So, we'll
   301   // arrange that the pause interval to be pause time target + 1 to
   302   // ensure that a) the pause time target is maximized with respect to
   303   // the pause interval and b) we maintain the invariant that pause
   304   // time target < pause interval. If the user does not want this
   305   // maximum flexibility, they will have to set the pause interval
   306   // explicitly.
   308   // First make sure that, if either parameter is set, its value is
   309   // reasonable.
   310   if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
   311     if (MaxGCPauseMillis < 1) {
   312       vm_exit_during_initialization("MaxGCPauseMillis should be "
   313                                     "greater than 0");
   314     }
   315   }
   316   if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
   317     if (GCPauseIntervalMillis < 1) {
   318       vm_exit_during_initialization("GCPauseIntervalMillis should be "
   319                                     "greater than 0");
   320     }
   321   }
   323   // Then, if the pause time target parameter was not set, set it to
   324   // the default value.
   325   if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
   326     if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
   327       // The default pause time target in G1 is 200ms
   328       FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
   329     } else {
   330       // We do not allow the pause interval to be set without the
   331       // pause time target
   332       vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
   333                                     "without setting MaxGCPauseMillis");
   334     }
   335   }
   337   // Then, if the interval parameter was not set, set it according to
   338   // the pause time target (this will also deal with the case when the
   339   // pause time target is the default value).
   340   if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
   341     FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
   342   }
   344   // Finally, make sure that the two parameters are consistent.
   345   if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
   346     char buffer[256];
   347     jio_snprintf(buffer, 256,
   348                  "MaxGCPauseMillis (%u) should be less than "
   349                  "GCPauseIntervalMillis (%u)",
   350                  MaxGCPauseMillis, GCPauseIntervalMillis);
   351     vm_exit_during_initialization(buffer);
   352   }
   354   double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
   355   double time_slice  = (double) GCPauseIntervalMillis / 1000.0;
   356   _mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
   357   _sigma = (double) G1ConfidencePercent / 100.0;
   359   // start conservatively (around 50ms is about right)
   360   _concurrent_mark_remark_times_ms->add(0.05);
   361   _concurrent_mark_cleanup_times_ms->add(0.20);
   362   _tenuring_threshold = MaxTenuringThreshold;
   363   // _max_survivor_regions will be calculated by
   364   // update_young_list_target_length() during initialization.
   365   _max_survivor_regions = 0;
   367   assert(GCTimeRatio > 0,
   368          "we should have set it to a default value set_g1_gc_flags() "
   369          "if a user set it to 0");
   370   _gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
   372   uintx reserve_perc = G1ReservePercent;
   373   // Put an artificial ceiling on this so that it's not set to a silly value.
   374   if (reserve_perc > 50) {
   375     reserve_perc = 50;
   376     warning("G1ReservePercent is set to a value that is too large, "
   377             "it's been updated to %u", reserve_perc);
   378   }
   379   _reserve_factor = (double) reserve_perc / 100.0;
   380   // This will be set when the heap is expanded
   381   // for the first time during initialization.
   382   _reserve_regions = 0;
   384   initialize_all();
   385   _collectionSetChooser = new CollectionSetChooser();
   386   _young_gen_sizer = new G1YoungGenSizer(); // Must be after call to initialize_flags
   387 }
   389 void G1CollectorPolicy::initialize_flags() {
   390   set_min_alignment(HeapRegion::GrainBytes);
   391   set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
   392   if (SurvivorRatio < 1) {
   393     vm_exit_during_initialization("Invalid survivor ratio specified");
   394   }
   395   CollectorPolicy::initialize_flags();
   396 }
   398 G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(true) {
   399   assert(G1DefaultMinNewGenPercent <= G1DefaultMaxNewGenPercent, "Min larger than max");
   400   assert(G1DefaultMinNewGenPercent > 0 && G1DefaultMinNewGenPercent < 100, "Min out of bounds");
   401   assert(G1DefaultMaxNewGenPercent > 0 && G1DefaultMaxNewGenPercent < 100, "Max out of bounds");
   403   if (FLAG_IS_CMDLINE(NewRatio)) {
   404     if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
   405       warning("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
   406     } else {
   407       _sizer_kind = SizerNewRatio;
   408       _adaptive_size = false;
   409       return;
   410     }
   411   }
   413   if (FLAG_IS_CMDLINE(NewSize)) {
   414     _min_desired_young_length = MAX2((uint) (NewSize / HeapRegion::GrainBytes),
   415                                      1U);
   416     if (FLAG_IS_CMDLINE(MaxNewSize)) {
   417       _max_desired_young_length =
   418                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
   419                                   1U);
   420       _sizer_kind = SizerMaxAndNewSize;
   421       _adaptive_size = _min_desired_young_length == _max_desired_young_length;
   422     } else {
   423       _sizer_kind = SizerNewSizeOnly;
   424     }
   425   } else if (FLAG_IS_CMDLINE(MaxNewSize)) {
   426     _max_desired_young_length =
   427                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
   428                                   1U);
   429     _sizer_kind = SizerMaxNewSizeOnly;
   430   }
   431 }
   433 uint G1YoungGenSizer::calculate_default_min_length(uint new_number_of_heap_regions) {
   434   uint default_value = (new_number_of_heap_regions * G1DefaultMinNewGenPercent) / 100;
   435   return MAX2(1U, default_value);
   436 }
   438 uint G1YoungGenSizer::calculate_default_max_length(uint new_number_of_heap_regions) {
   439   uint default_value = (new_number_of_heap_regions * G1DefaultMaxNewGenPercent) / 100;
   440   return MAX2(1U, default_value);
   441 }
   443 void G1YoungGenSizer::heap_size_changed(uint new_number_of_heap_regions) {
   444   assert(new_number_of_heap_regions > 0, "Heap must be initialized");
   446   switch (_sizer_kind) {
   447     case SizerDefaults:
   448       _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
   449       _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
   450       break;
   451     case SizerNewSizeOnly:
   452       _max_desired_young_length = calculate_default_max_length(new_number_of_heap_regions);
   453       _max_desired_young_length = MAX2(_min_desired_young_length, _max_desired_young_length);
   454       break;
   455     case SizerMaxNewSizeOnly:
   456       _min_desired_young_length = calculate_default_min_length(new_number_of_heap_regions);
   457       _min_desired_young_length = MIN2(_min_desired_young_length, _max_desired_young_length);
   458       break;
   459     case SizerMaxAndNewSize:
   460       // Do nothing. Values set on the command line, don't update them at runtime.
   461       break;
   462     case SizerNewRatio:
   463       _min_desired_young_length = new_number_of_heap_regions / (NewRatio + 1);
   464       _max_desired_young_length = _min_desired_young_length;
   465       break;
   466     default:
   467       ShouldNotReachHere();
   468   }
   470   assert(_min_desired_young_length <= _max_desired_young_length, "Invalid min/max young gen size values");
   471 }
   473 void G1CollectorPolicy::init() {
   474   // Set aside an initial future to_space.
   475   _g1 = G1CollectedHeap::heap();
   477   assert(Heap_lock->owned_by_self(), "Locking discipline.");
   479   initialize_gc_policy_counters();
   481   if (adaptive_young_list_length()) {
   482     _young_list_fixed_length = 0;
   483   } else {
   484     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
   485   }
   486   _free_regions_at_end_of_collection = _g1->free_regions();
   487   update_young_list_target_length();
   488   _prev_eden_capacity = _young_list_target_length * HeapRegion::GrainBytes;
   490   // We may immediately start allocating regions and placing them on the
   491   // collection set list. Initialize the per-collection set info
   492   start_incremental_cset_building();
   493 }
   495 // Create the jstat counters for the policy.
   496 void G1CollectorPolicy::initialize_gc_policy_counters() {
   497   _gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 3);
   498 }
   500 bool G1CollectorPolicy::predict_will_fit(uint young_length,
   501                                          double base_time_ms,
   502                                          uint base_free_regions,
   503                                          double target_pause_time_ms) {
   504   if (young_length >= base_free_regions) {
   505     // end condition 1: not enough space for the young regions
   506     return false;
   507   }
   509   double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
   510   size_t bytes_to_copy =
   511                (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
   512   double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
   513   double young_other_time_ms = predict_young_other_time_ms(young_length);
   514   double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
   515   if (pause_time_ms > target_pause_time_ms) {
   516     // end condition 2: prediction is over the target pause time
   517     return false;
   518   }
   520   size_t free_bytes =
   521                    (base_free_regions - young_length) * HeapRegion::GrainBytes;
   522   if ((2.0 * sigma()) * (double) bytes_to_copy > (double) free_bytes) {
   523     // end condition 3: out-of-space (conservatively!)
   524     return false;
   525   }
   527   // success!
   528   return true;
   529 }
   531 void G1CollectorPolicy::record_new_heap_size(uint new_number_of_regions) {
   532   // re-calculate the necessary reserve
   533   double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
   534   // We use ceiling so that if reserve_regions_d is > 0.0 (but
   535   // smaller than 1.0) we'll get 1.
   536   _reserve_regions = (uint) ceil(reserve_regions_d);
   538   _young_gen_sizer->heap_size_changed(new_number_of_regions);
   539 }
   541 uint G1CollectorPolicy::calculate_young_list_desired_min_length(
   542                                                        uint base_min_length) {
   543   uint desired_min_length = 0;
   544   if (adaptive_young_list_length()) {
   545     if (_alloc_rate_ms_seq->num() > 3) {
   546       double now_sec = os::elapsedTime();
   547       double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
   548       double alloc_rate_ms = predict_alloc_rate_ms();
   549       desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
   550     } else {
   551       // otherwise we don't have enough info to make the prediction
   552     }
   553   }
   554   desired_min_length += base_min_length;
   555   // make sure we don't go below any user-defined minimum bound
   556   return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length);
   557 }
   559 uint G1CollectorPolicy::calculate_young_list_desired_max_length() {
   560   // Here, we might want to also take into account any additional
   561   // constraints (i.e., user-defined minimum bound). Currently, we
   562   // effectively don't set this bound.
   563   return _young_gen_sizer->max_desired_young_length();
   564 }
   566 void G1CollectorPolicy::update_young_list_target_length(size_t rs_lengths) {
   567   if (rs_lengths == (size_t) -1) {
   568     // if it's set to the default value (-1), we should predict it;
   569     // otherwise, use the given value.
   570     rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
   571   }
   573   // Calculate the absolute and desired min bounds.
   575   // This is how many young regions we already have (currently: the survivors).
   576   uint base_min_length = recorded_survivor_regions();
   577   // This is the absolute minimum young length, which ensures that we
   578   // can allocate one eden region in the worst-case.
   579   uint absolute_min_length = base_min_length + 1;
   580   uint desired_min_length =
   581                      calculate_young_list_desired_min_length(base_min_length);
   582   if (desired_min_length < absolute_min_length) {
   583     desired_min_length = absolute_min_length;
   584   }
   586   // Calculate the absolute and desired max bounds.
   588   // We will try our best not to "eat" into the reserve.
   589   uint absolute_max_length = 0;
   590   if (_free_regions_at_end_of_collection > _reserve_regions) {
   591     absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
   592   }
   593   uint desired_max_length = calculate_young_list_desired_max_length();
   594   if (desired_max_length > absolute_max_length) {
   595     desired_max_length = absolute_max_length;
   596   }
   598   uint young_list_target_length = 0;
   599   if (adaptive_young_list_length()) {
   600     if (gcs_are_young()) {
   601       young_list_target_length =
   602                         calculate_young_list_target_length(rs_lengths,
   603                                                            base_min_length,
   604                                                            desired_min_length,
   605                                                            desired_max_length);
   606       _rs_lengths_prediction = rs_lengths;
   607     } else {
   608       // Don't calculate anything and let the code below bound it to
   609       // the desired_min_length, i.e., do the next GC as soon as
   610       // possible to maximize how many old regions we can add to it.
   611     }
   612   } else {
   613     // The user asked for a fixed young gen so we'll fix the young gen
   614     // whether the next GC is young or mixed.
   615     young_list_target_length = _young_list_fixed_length;
   616   }
   618   // Make sure we don't go over the desired max length, nor under the
   619   // desired min length. In case they clash, desired_min_length wins
   620   // which is why that test is second.
   621   if (young_list_target_length > desired_max_length) {
   622     young_list_target_length = desired_max_length;
   623   }
   624   if (young_list_target_length < desired_min_length) {
   625     young_list_target_length = desired_min_length;
   626   }
   628   assert(young_list_target_length > recorded_survivor_regions(),
   629          "we should be able to allocate at least one eden region");
   630   assert(young_list_target_length >= absolute_min_length, "post-condition");
   631   _young_list_target_length = young_list_target_length;
   633   update_max_gc_locker_expansion();
   634 }
   636 uint
   637 G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths,
   638                                                      uint base_min_length,
   639                                                      uint desired_min_length,
   640                                                      uint desired_max_length) {
   641   assert(adaptive_young_list_length(), "pre-condition");
   642   assert(gcs_are_young(), "only call this for young GCs");
   644   // In case some edge-condition makes the desired max length too small...
   645   if (desired_max_length <= desired_min_length) {
   646     return desired_min_length;
   647   }
   649   // We'll adjust min_young_length and max_young_length not to include
   650   // the already allocated young regions (i.e., so they reflect the
   651   // min and max eden regions we'll allocate). The base_min_length
   652   // will be reflected in the predictions by the
   653   // survivor_regions_evac_time prediction.
   654   assert(desired_min_length > base_min_length, "invariant");
   655   uint min_young_length = desired_min_length - base_min_length;
   656   assert(desired_max_length > base_min_length, "invariant");
   657   uint max_young_length = desired_max_length - base_min_length;
   659   double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
   660   double survivor_regions_evac_time = predict_survivor_regions_evac_time();
   661   size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
   662   size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
   663   size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
   664   double base_time_ms =
   665     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
   666     survivor_regions_evac_time;
   667   uint available_free_regions = _free_regions_at_end_of_collection;
   668   uint base_free_regions = 0;
   669   if (available_free_regions > _reserve_regions) {
   670     base_free_regions = available_free_regions - _reserve_regions;
   671   }
   673   // Here, we will make sure that the shortest young length that
   674   // makes sense fits within the target pause time.
   676   if (predict_will_fit(min_young_length, base_time_ms,
   677                        base_free_regions, target_pause_time_ms)) {
   678     // The shortest young length will fit into the target pause time;
   679     // we'll now check whether the absolute maximum number of young
   680     // regions will fit in the target pause time. If not, we'll do
   681     // a binary search between min_young_length and max_young_length.
   682     if (predict_will_fit(max_young_length, base_time_ms,
   683                          base_free_regions, target_pause_time_ms)) {
   684       // The maximum young length will fit into the target pause time.
   685       // We are done so set min young length to the maximum length (as
   686       // the result is assumed to be returned in min_young_length).
   687       min_young_length = max_young_length;
   688     } else {
   689       // The maximum possible number of young regions will not fit within
   690       // the target pause time so we'll search for the optimal
   691       // length. The loop invariants are:
   692       //
   693       // min_young_length < max_young_length
   694       // min_young_length is known to fit into the target pause time
   695       // max_young_length is known not to fit into the target pause time
   696       //
   697       // Going into the loop we know the above hold as we've just
   698       // checked them. Every time around the loop we check whether
   699       // the middle value between min_young_length and
   700       // max_young_length fits into the target pause time. If it
   701       // does, it becomes the new min. If it doesn't, it becomes
   702       // the new max. This way we maintain the loop invariants.
   704       assert(min_young_length < max_young_length, "invariant");
   705       uint diff = (max_young_length - min_young_length) / 2;
   706       while (diff > 0) {
   707         uint young_length = min_young_length + diff;
   708         if (predict_will_fit(young_length, base_time_ms,
   709                              base_free_regions, target_pause_time_ms)) {
   710           min_young_length = young_length;
   711         } else {
   712           max_young_length = young_length;
   713         }
   714         assert(min_young_length <  max_young_length, "invariant");
   715         diff = (max_young_length - min_young_length) / 2;
   716       }
   717       // The results is min_young_length which, according to the
   718       // loop invariants, should fit within the target pause time.
   720       // These are the post-conditions of the binary search above:
   721       assert(min_young_length < max_young_length,
   722              "otherwise we should have discovered that max_young_length "
   723              "fits into the pause target and not done the binary search");
   724       assert(predict_will_fit(min_young_length, base_time_ms,
   725                               base_free_regions, target_pause_time_ms),
   726              "min_young_length, the result of the binary search, should "
   727              "fit into the pause target");
   728       assert(!predict_will_fit(min_young_length + 1, base_time_ms,
   729                                base_free_regions, target_pause_time_ms),
   730              "min_young_length, the result of the binary search, should be "
   731              "optimal, so no larger length should fit into the pause target");
   732     }
   733   } else {
   734     // Even the minimum length doesn't fit into the pause time
   735     // target, return it as the result nevertheless.
   736   }
   737   return base_min_length + min_young_length;
   738 }
   740 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
   741   double survivor_regions_evac_time = 0.0;
   742   for (HeapRegion * r = _recorded_survivor_head;
   743        r != NULL && r != _recorded_survivor_tail->get_next_young_region();
   744        r = r->get_next_young_region()) {
   745     survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
   746   }
   747   return survivor_regions_evac_time;
   748 }
   750 void G1CollectorPolicy::revise_young_list_target_length_if_necessary() {
   751   guarantee( adaptive_young_list_length(), "should not call this otherwise" );
   753   size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
   754   if (rs_lengths > _rs_lengths_prediction) {
   755     // add 10% to avoid having to recalculate often
   756     size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
   757     update_young_list_target_length(rs_lengths_prediction);
   758   }
   759 }
   763 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
   764                                                bool is_tlab,
   765                                                bool* gc_overhead_limit_was_exceeded) {
   766   guarantee(false, "Not using this policy feature yet.");
   767   return NULL;
   768 }
   770 // This method controls how a collector handles one or more
   771 // of its generations being fully allocated.
   772 HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
   773                                                        bool is_tlab) {
   774   guarantee(false, "Not using this policy feature yet.");
   775   return NULL;
   776 }
   779 #ifndef PRODUCT
   780 bool G1CollectorPolicy::verify_young_ages() {
   781   HeapRegion* head = _g1->young_list()->first_region();
   782   return
   783     verify_young_ages(head, _short_lived_surv_rate_group);
   784   // also call verify_young_ages on any additional surv rate groups
   785 }
   787 bool
   788 G1CollectorPolicy::verify_young_ages(HeapRegion* head,
   789                                      SurvRateGroup *surv_rate_group) {
   790   guarantee( surv_rate_group != NULL, "pre-condition" );
   792   const char* name = surv_rate_group->name();
   793   bool ret = true;
   794   int prev_age = -1;
   796   for (HeapRegion* curr = head;
   797        curr != NULL;
   798        curr = curr->get_next_young_region()) {
   799     SurvRateGroup* group = curr->surv_rate_group();
   800     if (group == NULL && !curr->is_survivor()) {
   801       gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
   802       ret = false;
   803     }
   805     if (surv_rate_group == group) {
   806       int age = curr->age_in_surv_rate_group();
   808       if (age < 0) {
   809         gclog_or_tty->print_cr("## %s: encountered negative age", name);
   810         ret = false;
   811       }
   813       if (age <= prev_age) {
   814         gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
   815                                "(%d, %d)", name, age, prev_age);
   816         ret = false;
   817       }
   818       prev_age = age;
   819     }
   820   }
   822   return ret;
   823 }
   824 #endif // PRODUCT
   826 void G1CollectorPolicy::record_full_collection_start() {
   827   _cur_collection_start_sec = os::elapsedTime();
   828   // Release the future to-space so that it is available for compaction into.
   829   _g1->set_full_collection();
   830 }
   832 void G1CollectorPolicy::record_full_collection_end() {
   833   // Consider this like a collection pause for the purposes of allocation
   834   // since last pause.
   835   double end_sec = os::elapsedTime();
   836   double full_gc_time_sec = end_sec - _cur_collection_start_sec;
   837   double full_gc_time_ms = full_gc_time_sec * 1000.0;
   839   _trace_gen1_time_data.record_full_collection(full_gc_time_ms);
   841   update_recent_gc_times(end_sec, full_gc_time_ms);
   843   _g1->clear_full_collection();
   845   // "Nuke" the heuristics that control the young/mixed GC
   846   // transitions and make sure we start with young GCs after the Full GC.
   847   set_gcs_are_young(true);
   848   _last_young_gc = false;
   849   clear_initiate_conc_mark_if_possible();
   850   clear_during_initial_mark_pause();
   851   _in_marking_window = false;
   852   _in_marking_window_im = false;
   854   _short_lived_surv_rate_group->start_adding_regions();
   855   // also call this on any additional surv rate groups
   857   record_survivor_regions(0, NULL, NULL);
   859   _free_regions_at_end_of_collection = _g1->free_regions();
   860   // Reset survivors SurvRateGroup.
   861   _survivor_surv_rate_group->reset();
   862   update_young_list_target_length();
   863   _collectionSetChooser->clear();
   864 }
   866 void G1CollectorPolicy::record_stop_world_start() {
   867   _stop_world_start = os::elapsedTime();
   868 }
   870 void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
   871                                                       size_t start_used) {
   872   if (G1Log::finer()) {
   873     gclog_or_tty->stamp(PrintGCTimeStamps);
   874     gclog_or_tty->print("[%s", (const char*)GCCauseString("GC pause", _g1->gc_cause())
   875       .append(gcs_are_young() ? " (young)" : " (mixed)"));
   876   }
   878   // We only need to do this here as the policy will only be applied
   879   // to the GC we're about to start. so, no point is calculating this
   880   // every time we calculate / recalculate the target young length.
   881   update_survivors_policy();
   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   _trace_gen0_time_data.record_start_collection(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_collection_set_before_gc = 0;
   898   _bytes_copied_during_gc = 0;
   900   YoungList* young_list = _g1->young_list();
   901   _eden_bytes_before_gc = young_list->eden_used_bytes();
   902   _survivor_bytes_before_gc = young_list->survivor_used_bytes();
   903   _capacity_before_gc = _g1->capacity();
   905 #ifdef DEBUG
   906   // initialise these to something well known so that we can spot
   907   // if they are not set properly
   909   for (int i = 0; i < _parallel_gc_threads; ++i) {
   910     _par_last_gc_worker_start_times_ms[i] = -1234.0;
   911     _par_last_ext_root_scan_times_ms[i] = -1234.0;
   912     _par_last_satb_filtering_times_ms[i] = -1234.0;
   913     _par_last_update_rs_times_ms[i] = -1234.0;
   914     _par_last_update_rs_processed_buffers[i] = -1234.0;
   915     _par_last_scan_rs_times_ms[i] = -1234.0;
   916     _par_last_obj_copy_times_ms[i] = -1234.0;
   917     _par_last_termination_times_ms[i] = -1234.0;
   918     _par_last_termination_attempts[i] = -1234.0;
   919     _par_last_gc_worker_end_times_ms[i] = -1234.0;
   920     _par_last_gc_worker_times_ms[i] = -1234.0;
   921     _par_last_gc_worker_other_times_ms[i] = -1234.0;
   922   }
   923 #endif
   925   // This is initialized to zero here and is set during the evacuation
   926   // pause if we actually waited for the root region scanning to finish.
   927   _root_region_scan_wait_time_ms = 0.0;
   929   _last_gc_was_young = false;
   931   // do that for any other surv rate groups
   932   _short_lived_surv_rate_group->stop_adding_regions();
   933   _survivors_age_table.clear();
   935   assert( verify_young_ages(), "region age verification" );
   936 }
   938 void G1CollectorPolicy::record_concurrent_mark_init_end(double
   939                                                    mark_init_elapsed_time_ms) {
   940   _during_marking = true;
   941   assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
   942   clear_during_initial_mark_pause();
   943   _cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
   944 }
   946 void G1CollectorPolicy::record_concurrent_mark_remark_start() {
   947   _mark_remark_start_sec = os::elapsedTime();
   948   _during_marking = false;
   949 }
   951 void G1CollectorPolicy::record_concurrent_mark_remark_end() {
   952   double end_time_sec = os::elapsedTime();
   953   double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
   954   _concurrent_mark_remark_times_ms->add(elapsed_time_ms);
   955   _cur_mark_stop_world_time_ms += elapsed_time_ms;
   956   _prev_collection_pause_end_ms += elapsed_time_ms;
   958   _mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
   959 }
   961 void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
   962   _mark_cleanup_start_sec = os::elapsedTime();
   963 }
   965 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
   966   _last_young_gc = true;
   967   _in_marking_window = false;
   968 }
   970 void G1CollectorPolicy::record_concurrent_pause() {
   971   if (_stop_world_start > 0.0) {
   972     double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
   973     _trace_gen0_time_data.record_yield_time(yield_ms);
   974   }
   975 }
   977 void G1CollectorPolicy::record_concurrent_pause_end() {
   978 }
   980 template<class T>
   981 T sum_of(T* sum_arr, int start, int n, int N) {
   982   T sum = (T)0;
   983   for (int i = 0; i < n; i++) {
   984     int j = (start + i) % N;
   985     sum += sum_arr[j];
   986   }
   987   return sum;
   988 }
   990 void G1CollectorPolicy::print_par_stats(int level,
   991                                         const char* str,
   992                                         double* data,
   993                                         bool showDecimals) {
   994   double min = data[0], max = data[0];
   995   double total = 0.0;
   996   LineBuffer buf(level);
   997   buf.append("[%s (ms):", str);
   998   for (uint i = 0; i < no_of_gc_threads(); ++i) {
   999     double val = data[i];
  1000     if (val < min)
  1001       min = val;
  1002     if (val > max)
  1003       max = val;
  1004     total += val;
  1005     if (G1Log::finest()) {
  1006       if (showDecimals) {
  1007         buf.append("  %.1lf", val);
  1008       } else {
  1009         buf.append("  %d", (int)val);
  1014   if (G1Log::finest()) {
  1015     buf.append_and_print_cr("");
  1017   double avg = total / (double) no_of_gc_threads();
  1018   if (showDecimals) {
  1019     buf.append_and_print_cr(" Min: %.1lf, Avg: %.1lf, Max: %.1lf, Diff: %.1lf, Sum: %.1lf]",
  1020       min, avg, max, max - min, total);
  1021   } else {
  1022     buf.append_and_print_cr(" Min: %d, Avg: %d, Max: %d, Diff: %d, Sum: %d]",
  1023       (int)min, (int)avg, (int)max, (int)max - (int)min, (int)total);
  1027 void G1CollectorPolicy::print_stats(int level,
  1028                                     const char* str,
  1029                                     double value) {
  1030   LineBuffer(level).append_and_print_cr("[%s: %.1lf ms]", str, value);
  1033 void G1CollectorPolicy::print_stats(int level,
  1034                                     const char* str,
  1035                                     double value,
  1036                                     int workers) {
  1037   LineBuffer(level).append_and_print_cr("[%s: %.1lf ms, GC Workers: %d]", str, value, workers);
  1040 void G1CollectorPolicy::print_stats(int level,
  1041                                     const char* str,
  1042                                     int value) {
  1043   LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
  1046 double G1CollectorPolicy::avg_value(double* data) {
  1047   if (G1CollectedHeap::use_parallel_gc_threads()) {
  1048     double ret = 0.0;
  1049     for (uint i = 0; i < no_of_gc_threads(); ++i) {
  1050       ret += data[i];
  1052     return ret / (double) no_of_gc_threads();
  1053   } else {
  1054     return data[0];
  1058 double G1CollectorPolicy::max_value(double* data) {
  1059   if (G1CollectedHeap::use_parallel_gc_threads()) {
  1060     double ret = data[0];
  1061     for (uint i = 1; i < no_of_gc_threads(); ++i) {
  1062       if (data[i] > ret) {
  1063         ret = data[i];
  1066     return ret;
  1067   } else {
  1068     return data[0];
  1072 double G1CollectorPolicy::sum_of_values(double* data) {
  1073   if (G1CollectedHeap::use_parallel_gc_threads()) {
  1074     double sum = 0.0;
  1075     for (uint i = 0; i < no_of_gc_threads(); i++) {
  1076       sum += data[i];
  1078     return sum;
  1079   } else {
  1080     return data[0];
  1084 double G1CollectorPolicy::max_sum(double* data1, double* data2) {
  1085   double ret = data1[0] + data2[0];
  1087   if (G1CollectedHeap::use_parallel_gc_threads()) {
  1088     for (uint i = 1; i < no_of_gc_threads(); ++i) {
  1089       double data = data1[i] + data2[i];
  1090       if (data > ret) {
  1091         ret = data;
  1095   return ret;
  1098 bool G1CollectorPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
  1099   if (_g1->concurrent_mark()->cmThread()->during_cycle()) {
  1100     return false;
  1103   size_t marking_initiating_used_threshold =
  1104     (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
  1105   size_t cur_used_bytes = _g1->non_young_capacity_bytes();
  1106   size_t alloc_byte_size = alloc_word_size * HeapWordSize;
  1108   if ((cur_used_bytes + alloc_byte_size) > marking_initiating_used_threshold) {
  1109     if (gcs_are_young()) {
  1110       ergo_verbose5(ErgoConcCycles,
  1111         "request concurrent cycle initiation",
  1112         ergo_format_reason("occupancy higher than threshold")
  1113         ergo_format_byte("occupancy")
  1114         ergo_format_byte("allocation request")
  1115         ergo_format_byte_perc("threshold")
  1116         ergo_format_str("source"),
  1117         cur_used_bytes,
  1118         alloc_byte_size,
  1119         marking_initiating_used_threshold,
  1120         (double) InitiatingHeapOccupancyPercent,
  1121         source);
  1122       return true;
  1123     } else {
  1124       ergo_verbose5(ErgoConcCycles,
  1125         "do not request concurrent cycle initiation",
  1126         ergo_format_reason("still doing mixed collections")
  1127         ergo_format_byte("occupancy")
  1128         ergo_format_byte("allocation request")
  1129         ergo_format_byte_perc("threshold")
  1130         ergo_format_str("source"),
  1131         cur_used_bytes,
  1132         alloc_byte_size,
  1133         marking_initiating_used_threshold,
  1134         (double) InitiatingHeapOccupancyPercent,
  1135         source);
  1139   return false;
  1142 // Anything below that is considered to be zero
  1143 #define MIN_TIMER_GRANULARITY 0.0000001
  1145 void G1CollectorPolicy::record_collection_pause_end(int no_of_gc_threads) {
  1146   double end_time_sec = os::elapsedTime();
  1147   double elapsed_ms = _last_pause_time_ms;
  1148   bool parallel = G1CollectedHeap::use_parallel_gc_threads();
  1149   assert(_cur_collection_pause_used_regions_at_start >= cset_region_length(),
  1150          "otherwise, the subtraction below does not make sense");
  1151   size_t rs_size =
  1152             _cur_collection_pause_used_regions_at_start - cset_region_length();
  1153   size_t cur_used_bytes = _g1->used();
  1154   assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
  1155   bool last_pause_included_initial_mark = false;
  1156   bool update_stats = !_g1->evacuation_failed();
  1157   set_no_of_gc_threads(no_of_gc_threads);
  1159 #ifndef PRODUCT
  1160   if (G1YoungSurvRateVerbose) {
  1161     gclog_or_tty->print_cr("");
  1162     _short_lived_surv_rate_group->print();
  1163     // do that for any other surv rate groups too
  1165 #endif // PRODUCT
  1167   last_pause_included_initial_mark = during_initial_mark_pause();
  1168   if (last_pause_included_initial_mark) {
  1169     record_concurrent_mark_init_end(0.0);
  1170   } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
  1171     // Note: this might have already been set, if during the last
  1172     // pause we decided to start a cycle but at the beginning of
  1173     // this pause we decided to postpone it. That's OK.
  1174     set_initiate_conc_mark_if_possible();
  1177   _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
  1178                           end_time_sec, false);
  1180   size_t freed_bytes =
  1181     _cur_collection_pause_used_at_start_bytes - cur_used_bytes;
  1182   size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
  1184   double survival_fraction =
  1185     (double)surviving_bytes/
  1186     (double)_collection_set_bytes_used_before;
  1188   // These values are used to update the summary information that is
  1189   // displayed when TraceGen0Time is enabled, and are output as part
  1190   // of the "finer" output, in the non-parallel case.
  1192   double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
  1193   double satb_filtering_time = avg_value(_par_last_satb_filtering_times_ms);
  1194   double update_rs_time = avg_value(_par_last_update_rs_times_ms);
  1195   double update_rs_processed_buffers =
  1196     sum_of_values(_par_last_update_rs_processed_buffers);
  1197   double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
  1198   double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
  1199   double termination_time = avg_value(_par_last_termination_times_ms);
  1201   double known_time = ext_root_scan_time +
  1202                       satb_filtering_time +
  1203                       update_rs_time +
  1204                       scan_rs_time +
  1205                       obj_copy_time;
  1207   double other_time_ms = elapsed_ms;
  1209   // Subtract the root region scanning wait time. It's initialized to
  1210   // zero at the start of the pause.
  1211   other_time_ms -= _root_region_scan_wait_time_ms;
  1213   if (parallel) {
  1214     other_time_ms -= _cur_collection_par_time_ms;
  1215   } else {
  1216     other_time_ms -= known_time;
  1219   // Now subtract the time taken to fix up roots in generated code
  1220   other_time_ms -= _cur_collection_code_root_fixup_time_ms;
  1222   // Subtract the time taken to clean the card table from the
  1223   // current value of "other time"
  1224   other_time_ms -= _cur_clear_ct_time_ms;
  1226   // TraceGen0Time and TraceGen1Time summary info updating.
  1228   if (update_stats) {
  1229     double parallel_known_time = known_time + termination_time;
  1230     double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
  1232     _trace_gen0_time_data.record_end_collection(
  1233       elapsed_ms, other_time_ms, _root_region_scan_wait_time_ms, _cur_collection_par_time_ms,
  1234       ext_root_scan_time, satb_filtering_time, update_rs_time, scan_rs_time, obj_copy_time,
  1235       termination_time, parallel_other_time, _cur_clear_ct_time_ms);
  1237     // this is where we update the allocation rate of the application
  1238     double app_time_ms =
  1239       (_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
  1240     if (app_time_ms < MIN_TIMER_GRANULARITY) {
  1241       // This usually happens due to the timer not having the required
  1242       // granularity. Some Linuxes are the usual culprits.
  1243       // We'll just set it to something (arbitrarily) small.
  1244       app_time_ms = 1.0;
  1246     // We maintain the invariant that all objects allocated by mutator
  1247     // threads will be allocated out of eden regions. So, we can use
  1248     // the eden region number allocated since the previous GC to
  1249     // calculate the application's allocate rate. The only exception
  1250     // to that is humongous objects that are allocated separately. But
  1251     // given that humongous object allocations do not really affect
  1252     // either the pause's duration nor when the next pause will take
  1253     // place we can safely ignore them here.
  1254     uint regions_allocated = eden_cset_region_length();
  1255     double alloc_rate_ms = (double) regions_allocated / app_time_ms;
  1256     _alloc_rate_ms_seq->add(alloc_rate_ms);
  1258     double interval_ms =
  1259       (end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
  1260     update_recent_gc_times(end_time_sec, elapsed_ms);
  1261     _recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
  1262     if (recent_avg_pause_time_ratio() < 0.0 ||
  1263         (recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
  1264 #ifndef PRODUCT
  1265       // Dump info to allow post-facto debugging
  1266       gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
  1267       gclog_or_tty->print_cr("-------------------------------------------");
  1268       gclog_or_tty->print_cr("Recent GC Times (ms):");
  1269       _recent_gc_times_ms->dump();
  1270       gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
  1271       _recent_prev_end_times_for_all_gcs_sec->dump();
  1272       gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
  1273                              _recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
  1274       // In debug mode, terminate the JVM if the user wants to debug at this point.
  1275       assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
  1276 #endif  // !PRODUCT
  1277       // Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
  1278       // CR 6902692 by redoing the manner in which the ratio is incrementally computed.
  1279       if (_recent_avg_pause_time_ratio < 0.0) {
  1280         _recent_avg_pause_time_ratio = 0.0;
  1281       } else {
  1282         assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
  1283         _recent_avg_pause_time_ratio = 1.0;
  1288   if (G1Log::finer()) {
  1289     bool print_marking_info =
  1290       _g1->mark_in_progress() && !last_pause_included_initial_mark;
  1292     gclog_or_tty->print_cr("%s, %1.8lf secs]",
  1293                            (last_pause_included_initial_mark) ? " (initial-mark)" : "",
  1294                            elapsed_ms / 1000.0);
  1296     if (_root_region_scan_wait_time_ms > 0.0) {
  1297       print_stats(1, "Root Region Scan Waiting", _root_region_scan_wait_time_ms);
  1299     if (parallel) {
  1300       print_stats(1, "Parallel Time", _cur_collection_par_time_ms, no_of_gc_threads);
  1301       print_par_stats(2, "GC Worker Start", _par_last_gc_worker_start_times_ms);
  1302       print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
  1303       if (print_marking_info) {
  1304         print_par_stats(2, "SATB Filtering", _par_last_satb_filtering_times_ms);
  1306       print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
  1307       if (G1Log::finest()) {
  1308         print_par_stats(3, "Processed Buffers", _par_last_update_rs_processed_buffers,
  1309           false /* showDecimals */);
  1311       print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
  1312       print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
  1313       print_par_stats(2, "Termination", _par_last_termination_times_ms);
  1314       if (G1Log::finest()) {
  1315         print_par_stats(3, "Termination Attempts", _par_last_termination_attempts,
  1316           false /* showDecimals */);
  1319       for (int i = 0; i < _parallel_gc_threads; i++) {
  1320         _par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] -
  1321                                           _par_last_gc_worker_start_times_ms[i];
  1323         double worker_known_time = _par_last_ext_root_scan_times_ms[i] +
  1324                                    _par_last_satb_filtering_times_ms[i] +
  1325                                    _par_last_update_rs_times_ms[i] +
  1326                                    _par_last_scan_rs_times_ms[i] +
  1327                                    _par_last_obj_copy_times_ms[i] +
  1328                                    _par_last_termination_times_ms[i];
  1330         _par_last_gc_worker_other_times_ms[i] = _par_last_gc_worker_times_ms[i] -
  1331                                                 worker_known_time;
  1334       print_par_stats(2, "GC Worker Other", _par_last_gc_worker_other_times_ms);
  1335       print_par_stats(2, "GC Worker Total", _par_last_gc_worker_times_ms);
  1336       print_par_stats(2, "GC Worker End", _par_last_gc_worker_end_times_ms);
  1337     } else {
  1338       print_stats(1, "Ext Root Scanning", ext_root_scan_time);
  1339       if (print_marking_info) {
  1340         print_stats(1, "SATB Filtering", satb_filtering_time);
  1342       print_stats(1, "Update RS", update_rs_time);
  1343       if (G1Log::finest()) {
  1344         print_stats(2, "Processed Buffers", (int)update_rs_processed_buffers);
  1346       print_stats(1, "Scan RS", scan_rs_time);
  1347       print_stats(1, "Object Copying", obj_copy_time);
  1349     print_stats(1, "Code Root Fixup", _cur_collection_code_root_fixup_time_ms);
  1350     print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
  1351 #ifndef PRODUCT
  1352     print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
  1353     print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
  1354     print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
  1355     print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
  1356     if (_num_cc_clears > 0) {
  1357       print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
  1359 #endif
  1360     print_stats(1, "Other", other_time_ms);
  1361     print_stats(2, "Choose CSet",
  1362                    (_recorded_young_cset_choice_time_ms +
  1363                     _recorded_non_young_cset_choice_time_ms));
  1364     print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);
  1365     print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);
  1366     print_stats(2, "Free CSet",
  1367                    (_recorded_young_free_cset_time_ms +
  1368                     _recorded_non_young_free_cset_time_ms));
  1371   bool new_in_marking_window = _in_marking_window;
  1372   bool new_in_marking_window_im = false;
  1373   if (during_initial_mark_pause()) {
  1374     new_in_marking_window = true;
  1375     new_in_marking_window_im = true;
  1378   if (_last_young_gc) {
  1379     // This is supposed to to be the "last young GC" before we start
  1380     // doing mixed GCs. Here we decide whether to start mixed GCs or not.
  1382     if (!last_pause_included_initial_mark) {
  1383       if (next_gc_should_be_mixed("start mixed GCs",
  1384                                   "do not start mixed GCs")) {
  1385         set_gcs_are_young(false);
  1387     } else {
  1388       ergo_verbose0(ErgoMixedGCs,
  1389                     "do not start mixed GCs",
  1390                     ergo_format_reason("concurrent cycle is about to start"));
  1392     _last_young_gc = false;
  1395   if (!_last_gc_was_young) {
  1396     // This is a mixed GC. Here we decide whether to continue doing
  1397     // mixed GCs or not.
  1399     if (!next_gc_should_be_mixed("continue mixed GCs",
  1400                                  "do not continue mixed GCs")) {
  1401       set_gcs_are_young(true);
  1405   _short_lived_surv_rate_group->start_adding_regions();
  1406   // do that for any other surv rate groupsx
  1408   if (update_stats) {
  1409     double pause_time_ms = elapsed_ms;
  1411     size_t diff = 0;
  1412     if (_max_pending_cards >= _pending_cards) {
  1413       diff = _max_pending_cards - _pending_cards;
  1415     _pending_card_diff_seq->add((double) diff);
  1417     double cost_per_card_ms = 0.0;
  1418     if (_pending_cards > 0) {
  1419       cost_per_card_ms = update_rs_time / (double) _pending_cards;
  1420       _cost_per_card_ms_seq->add(cost_per_card_ms);
  1423     size_t cards_scanned = _g1->cards_scanned();
  1425     double cost_per_entry_ms = 0.0;
  1426     if (cards_scanned > 10) {
  1427       cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
  1428       if (_last_gc_was_young) {
  1429         _cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1430       } else {
  1431         _mixed_cost_per_entry_ms_seq->add(cost_per_entry_ms);
  1435     if (_max_rs_lengths > 0) {
  1436       double cards_per_entry_ratio =
  1437         (double) cards_scanned / (double) _max_rs_lengths;
  1438       if (_last_gc_was_young) {
  1439         _young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1440       } else {
  1441         _mixed_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
  1445     // This is defensive. For a while _max_rs_lengths could get
  1446     // smaller than _recorded_rs_lengths which was causing
  1447     // rs_length_diff to get very large and mess up the RSet length
  1448     // predictions. The reason was unsafe concurrent updates to the
  1449     // _inc_cset_recorded_rs_lengths field which the code below guards
  1450     // against (see CR 7118202). This bug has now been fixed (see CR
  1451     // 7119027). However, I'm still worried that
  1452     // _inc_cset_recorded_rs_lengths might still end up somewhat
  1453     // inaccurate. The concurrent refinement thread calculates an
  1454     // RSet's length concurrently with other CR threads updating it
  1455     // which might cause it to calculate the length incorrectly (if,
  1456     // say, it's in mid-coarsening). So I'll leave in the defensive
  1457     // conditional below just in case.
  1458     size_t rs_length_diff = 0;
  1459     if (_max_rs_lengths > _recorded_rs_lengths) {
  1460       rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
  1462     _rs_length_diff_seq->add((double) rs_length_diff);
  1464     size_t copied_bytes = surviving_bytes;
  1465     double cost_per_byte_ms = 0.0;
  1466     if (copied_bytes > 0) {
  1467       cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
  1468       if (_in_marking_window) {
  1469         _cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
  1470       } else {
  1471         _cost_per_byte_ms_seq->add(cost_per_byte_ms);
  1475     double all_other_time_ms = pause_time_ms -
  1476       (update_rs_time + scan_rs_time + obj_copy_time + termination_time);
  1478     double young_other_time_ms = 0.0;
  1479     if (young_cset_region_length() > 0) {
  1480       young_other_time_ms =
  1481         _recorded_young_cset_choice_time_ms +
  1482         _recorded_young_free_cset_time_ms;
  1483       _young_other_cost_per_region_ms_seq->add(young_other_time_ms /
  1484                                           (double) young_cset_region_length());
  1486     double non_young_other_time_ms = 0.0;
  1487     if (old_cset_region_length() > 0) {
  1488       non_young_other_time_ms =
  1489         _recorded_non_young_cset_choice_time_ms +
  1490         _recorded_non_young_free_cset_time_ms;
  1492       _non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
  1493                                             (double) old_cset_region_length());
  1496     double constant_other_time_ms = all_other_time_ms -
  1497       (young_other_time_ms + non_young_other_time_ms);
  1498     _constant_other_time_ms_seq->add(constant_other_time_ms);
  1500     double survival_ratio = 0.0;
  1501     if (_bytes_in_collection_set_before_gc > 0) {
  1502       survival_ratio = (double) _bytes_copied_during_gc /
  1503                                    (double) _bytes_in_collection_set_before_gc;
  1506     _pending_cards_seq->add((double) _pending_cards);
  1507     _rs_lengths_seq->add((double) _max_rs_lengths);
  1510   _in_marking_window = new_in_marking_window;
  1511   _in_marking_window_im = new_in_marking_window_im;
  1512   _free_regions_at_end_of_collection = _g1->free_regions();
  1513   update_young_list_target_length();
  1515   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
  1516   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
  1517   adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
  1519   _collectionSetChooser->verify();
  1522 #define EXT_SIZE_FORMAT "%.1f%s"
  1523 #define EXT_SIZE_PARAMS(bytes)                                  \
  1524   byte_size_in_proper_unit((double)(bytes)),                    \
  1525   proper_unit_for_byte_size((bytes))
  1527 void G1CollectorPolicy::print_heap_transition() {
  1528   if (G1Log::finer()) {
  1529     YoungList* young_list = _g1->young_list();
  1530     size_t eden_bytes = young_list->eden_used_bytes();
  1531     size_t survivor_bytes = young_list->survivor_used_bytes();
  1532     size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
  1533     size_t used = _g1->used();
  1534     size_t capacity = _g1->capacity();
  1535     size_t eden_capacity =
  1536       (_young_list_target_length * HeapRegion::GrainBytes) - survivor_bytes;
  1538     gclog_or_tty->print_cr(
  1539       "   [Eden: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT") "
  1540       "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
  1541       "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
  1542       EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
  1543       EXT_SIZE_PARAMS(_eden_bytes_before_gc),
  1544       EXT_SIZE_PARAMS(_prev_eden_capacity),
  1545       EXT_SIZE_PARAMS(eden_bytes),
  1546       EXT_SIZE_PARAMS(eden_capacity),
  1547       EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
  1548       EXT_SIZE_PARAMS(survivor_bytes),
  1549       EXT_SIZE_PARAMS(used_before_gc),
  1550       EXT_SIZE_PARAMS(_capacity_before_gc),
  1551       EXT_SIZE_PARAMS(used),
  1552       EXT_SIZE_PARAMS(capacity));
  1554     _prev_eden_capacity = eden_capacity;
  1555   } else if (G1Log::fine()) {
  1556     _g1->print_size_transition(gclog_or_tty,
  1557                                _cur_collection_pause_used_at_start_bytes,
  1558                                _g1->used(), _g1->capacity());
  1562 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
  1563                                                      double update_rs_processed_buffers,
  1564                                                      double goal_ms) {
  1565   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  1566   ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
  1568   if (G1UseAdaptiveConcRefinement) {
  1569     const int k_gy = 3, k_gr = 6;
  1570     const double inc_k = 1.1, dec_k = 0.9;
  1572     int g = cg1r->green_zone();
  1573     if (update_rs_time > goal_ms) {
  1574       g = (int)(g * dec_k);  // Can become 0, that's OK. That would mean a mutator-only processing.
  1575     } else {
  1576       if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
  1577         g = (int)MAX2(g * inc_k, g + 1.0);
  1580     // Change the refinement threads params
  1581     cg1r->set_green_zone(g);
  1582     cg1r->set_yellow_zone(g * k_gy);
  1583     cg1r->set_red_zone(g * k_gr);
  1584     cg1r->reinitialize_threads();
  1586     int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
  1587     int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
  1588                                     cg1r->yellow_zone());
  1589     // Change the barrier params
  1590     dcqs.set_process_completed_threshold(processing_threshold);
  1591     dcqs.set_max_completed_queue(cg1r->red_zone());
  1594   int curr_queue_size = dcqs.completed_buffers_num();
  1595   if (curr_queue_size >= cg1r->yellow_zone()) {
  1596     dcqs.set_completed_queue_padding(curr_queue_size);
  1597   } else {
  1598     dcqs.set_completed_queue_padding(0);
  1600   dcqs.notify_if_necessary();
  1603 double
  1604 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
  1605   size_t rs_length = predict_rs_length_diff();
  1606   size_t card_num;
  1607   if (gcs_are_young()) {
  1608     card_num = predict_young_card_num(rs_length);
  1609   } else {
  1610     card_num = predict_non_young_card_num(rs_length);
  1612   return predict_base_elapsed_time_ms(pending_cards, card_num);
  1615 double
  1616 G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
  1617                                                 size_t scanned_cards) {
  1618   return
  1619     predict_rs_update_time_ms(pending_cards) +
  1620     predict_rs_scan_time_ms(scanned_cards) +
  1621     predict_constant_other_time_ms();
  1624 double
  1625 G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
  1626                                                   bool young) {
  1627   size_t rs_length = hr->rem_set()->occupied();
  1628   size_t card_num;
  1629   if (gcs_are_young()) {
  1630     card_num = predict_young_card_num(rs_length);
  1631   } else {
  1632     card_num = predict_non_young_card_num(rs_length);
  1634   size_t bytes_to_copy = predict_bytes_to_copy(hr);
  1636   double region_elapsed_time_ms =
  1637     predict_rs_scan_time_ms(card_num) +
  1638     predict_object_copy_time_ms(bytes_to_copy);
  1640   if (young)
  1641     region_elapsed_time_ms += predict_young_other_time_ms(1);
  1642   else
  1643     region_elapsed_time_ms += predict_non_young_other_time_ms(1);
  1645   return region_elapsed_time_ms;
  1648 size_t G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
  1649   size_t bytes_to_copy;
  1650   if (hr->is_marked())
  1651     bytes_to_copy = hr->max_live_bytes();
  1652   else {
  1653     assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
  1654     int age = hr->age_in_surv_rate_group();
  1655     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
  1656     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
  1658   return bytes_to_copy;
  1661 void
  1662 G1CollectorPolicy::init_cset_region_lengths(uint eden_cset_region_length,
  1663                                             uint survivor_cset_region_length) {
  1664   _eden_cset_region_length     = eden_cset_region_length;
  1665   _survivor_cset_region_length = survivor_cset_region_length;
  1666   _old_cset_region_length      = 0;
  1669 void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
  1670   _recorded_rs_lengths = rs_lengths;
  1673 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
  1674                                                double elapsed_ms) {
  1675   _recent_gc_times_ms->add(elapsed_ms);
  1676   _recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
  1677   _prev_collection_pause_end_ms = end_time_sec * 1000.0;
  1680 size_t G1CollectorPolicy::expansion_amount() {
  1681   double recent_gc_overhead = recent_avg_pause_time_ratio() * 100.0;
  1682   double threshold = _gc_overhead_perc;
  1683   if (recent_gc_overhead > threshold) {
  1684     // We will double the existing space, or take
  1685     // G1ExpandByPercentOfAvailable % of the available expansion
  1686     // space, whichever is smaller, bounded below by a minimum
  1687     // expansion (unless that's all that's left.)
  1688     const size_t min_expand_bytes = 1*M;
  1689     size_t reserved_bytes = _g1->max_capacity();
  1690     size_t committed_bytes = _g1->capacity();
  1691     size_t uncommitted_bytes = reserved_bytes - committed_bytes;
  1692     size_t expand_bytes;
  1693     size_t expand_bytes_via_pct =
  1694       uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
  1695     expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
  1696     expand_bytes = MAX2(expand_bytes, min_expand_bytes);
  1697     expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
  1699     ergo_verbose5(ErgoHeapSizing,
  1700                   "attempt heap expansion",
  1701                   ergo_format_reason("recent GC overhead higher than "
  1702                                      "threshold after GC")
  1703                   ergo_format_perc("recent GC overhead")
  1704                   ergo_format_perc("threshold")
  1705                   ergo_format_byte("uncommitted")
  1706                   ergo_format_byte_perc("calculated expansion amount"),
  1707                   recent_gc_overhead, threshold,
  1708                   uncommitted_bytes,
  1709                   expand_bytes_via_pct, (double) G1ExpandByPercentOfAvailable);
  1711     return expand_bytes;
  1712   } else {
  1713     return 0;
  1717 class CountCSClosure: public HeapRegionClosure {
  1718   G1CollectorPolicy* _g1_policy;
  1719 public:
  1720   CountCSClosure(G1CollectorPolicy* g1_policy) :
  1721     _g1_policy(g1_policy) {}
  1722   bool doHeapRegion(HeapRegion* r) {
  1723     _g1_policy->_bytes_in_collection_set_before_gc += r->used();
  1724     return false;
  1726 };
  1728 void G1CollectorPolicy::count_CS_bytes_used() {
  1729   CountCSClosure cs_closure(this);
  1730   _g1->collection_set_iterate(&cs_closure);
  1733 void G1CollectorPolicy::print_tracing_info() const {
  1734   _trace_gen0_time_data.print();
  1735   _trace_gen1_time_data.print();
  1738 void G1CollectorPolicy::print_yg_surv_rate_info() const {
  1739 #ifndef PRODUCT
  1740   _short_lived_surv_rate_group->print_surv_rate_summary();
  1741   // add this call for any other surv rate groups
  1742 #endif // PRODUCT
  1745 #ifndef PRODUCT
  1746 // for debugging, bit of a hack...
  1747 static char*
  1748 region_num_to_mbs(int length) {
  1749   static char buffer[64];
  1750   double bytes = (double) (length * HeapRegion::GrainBytes);
  1751   double mbs = bytes / (double) (1024 * 1024);
  1752   sprintf(buffer, "%7.2lfMB", mbs);
  1753   return buffer;
  1755 #endif // PRODUCT
  1757 uint G1CollectorPolicy::max_regions(int purpose) {
  1758   switch (purpose) {
  1759     case GCAllocForSurvived:
  1760       return _max_survivor_regions;
  1761     case GCAllocForTenured:
  1762       return REGIONS_UNLIMITED;
  1763     default:
  1764       ShouldNotReachHere();
  1765       return REGIONS_UNLIMITED;
  1766   };
  1769 void G1CollectorPolicy::update_max_gc_locker_expansion() {
  1770   uint expansion_region_num = 0;
  1771   if (GCLockerEdenExpansionPercent > 0) {
  1772     double perc = (double) GCLockerEdenExpansionPercent / 100.0;
  1773     double expansion_region_num_d = perc * (double) _young_list_target_length;
  1774     // We use ceiling so that if expansion_region_num_d is > 0.0 (but
  1775     // less than 1.0) we'll get 1.
  1776     expansion_region_num = (uint) ceil(expansion_region_num_d);
  1777   } else {
  1778     assert(expansion_region_num == 0, "sanity");
  1780   _young_list_max_length = _young_list_target_length + expansion_region_num;
  1781   assert(_young_list_target_length <= _young_list_max_length, "post-condition");
  1784 // Calculates survivor space parameters.
  1785 void G1CollectorPolicy::update_survivors_policy() {
  1786   double max_survivor_regions_d =
  1787                  (double) _young_list_target_length / (double) SurvivorRatio;
  1788   // We use ceiling so that if max_survivor_regions_d is > 0.0 (but
  1789   // smaller than 1.0) we'll get 1.
  1790   _max_survivor_regions = (uint) ceil(max_survivor_regions_d);
  1792   _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
  1793         HeapRegion::GrainWords * _max_survivor_regions);
  1796 bool G1CollectorPolicy::force_initial_mark_if_outside_cycle(
  1797                                                      GCCause::Cause gc_cause) {
  1798   bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
  1799   if (!during_cycle) {
  1800     ergo_verbose1(ErgoConcCycles,
  1801                   "request concurrent cycle initiation",
  1802                   ergo_format_reason("requested by GC cause")
  1803                   ergo_format_str("GC cause"),
  1804                   GCCause::to_string(gc_cause));
  1805     set_initiate_conc_mark_if_possible();
  1806     return true;
  1807   } else {
  1808     ergo_verbose1(ErgoConcCycles,
  1809                   "do not request concurrent cycle initiation",
  1810                   ergo_format_reason("concurrent cycle already in progress")
  1811                   ergo_format_str("GC cause"),
  1812                   GCCause::to_string(gc_cause));
  1813     return false;
  1817 void
  1818 G1CollectorPolicy::decide_on_conc_mark_initiation() {
  1819   // We are about to decide on whether this pause will be an
  1820   // initial-mark pause.
  1822   // First, during_initial_mark_pause() should not be already set. We
  1823   // will set it here if we have to. However, it should be cleared by
  1824   // the end of the pause (it's only set for the duration of an
  1825   // initial-mark pause).
  1826   assert(!during_initial_mark_pause(), "pre-condition");
  1828   if (initiate_conc_mark_if_possible()) {
  1829     // We had noticed on a previous pause that the heap occupancy has
  1830     // gone over the initiating threshold and we should start a
  1831     // concurrent marking cycle. So we might initiate one.
  1833     bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
  1834     if (!during_cycle) {
  1835       // The concurrent marking thread is not "during a cycle", i.e.,
  1836       // it has completed the last one. So we can go ahead and
  1837       // initiate a new cycle.
  1839       set_during_initial_mark_pause();
  1840       // We do not allow mixed GCs during marking.
  1841       if (!gcs_are_young()) {
  1842         set_gcs_are_young(true);
  1843         ergo_verbose0(ErgoMixedGCs,
  1844                       "end mixed GCs",
  1845                       ergo_format_reason("concurrent cycle is about to start"));
  1848       // And we can now clear initiate_conc_mark_if_possible() as
  1849       // we've already acted on it.
  1850       clear_initiate_conc_mark_if_possible();
  1852       ergo_verbose0(ErgoConcCycles,
  1853                   "initiate concurrent cycle",
  1854                   ergo_format_reason("concurrent cycle initiation requested"));
  1855     } else {
  1856       // The concurrent marking thread is still finishing up the
  1857       // previous cycle. If we start one right now the two cycles
  1858       // overlap. In particular, the concurrent marking thread might
  1859       // be in the process of clearing the next marking bitmap (which
  1860       // we will use for the next cycle if we start one). Starting a
  1861       // cycle now will be bad given that parts of the marking
  1862       // information might get cleared by the marking thread. And we
  1863       // cannot wait for the marking thread to finish the cycle as it
  1864       // periodically yields while clearing the next marking bitmap
  1865       // and, if it's in a yield point, it's waiting for us to
  1866       // finish. So, at this point we will not start a cycle and we'll
  1867       // let the concurrent marking thread complete the last one.
  1868       ergo_verbose0(ErgoConcCycles,
  1869                     "do not initiate concurrent cycle",
  1870                     ergo_format_reason("concurrent cycle already in progress"));
  1875 class KnownGarbageClosure: public HeapRegionClosure {
  1876   G1CollectedHeap* _g1h;
  1877   CollectionSetChooser* _hrSorted;
  1879 public:
  1880   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
  1881     _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
  1883   bool doHeapRegion(HeapRegion* r) {
  1884     // We only include humongous regions in collection
  1885     // sets when concurrent mark shows that their contained object is
  1886     // unreachable.
  1888     // Do we have any marking information for this region?
  1889     if (r->is_marked()) {
  1890       // We will skip any region that's currently used as an old GC
  1891       // alloc region (we should not consider those for collection
  1892       // before we fill them up).
  1893       if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
  1894         _hrSorted->add_region(r);
  1897     return false;
  1899 };
  1901 class ParKnownGarbageHRClosure: public HeapRegionClosure {
  1902   G1CollectedHeap* _g1h;
  1903   CollectionSetChooser* _hrSorted;
  1904   uint _marked_regions_added;
  1905   size_t _reclaimable_bytes_added;
  1906   uint _chunk_size;
  1907   uint _cur_chunk_idx;
  1908   uint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
  1910   void get_new_chunk() {
  1911     _cur_chunk_idx = _hrSorted->claim_array_chunk(_chunk_size);
  1912     _cur_chunk_end = _cur_chunk_idx + _chunk_size;
  1914   void add_region(HeapRegion* r) {
  1915     if (_cur_chunk_idx == _cur_chunk_end) {
  1916       get_new_chunk();
  1918     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
  1919     _hrSorted->set_region(_cur_chunk_idx, r);
  1920     _marked_regions_added++;
  1921     _reclaimable_bytes_added += r->reclaimable_bytes();
  1922     _cur_chunk_idx++;
  1925 public:
  1926   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
  1927                            uint chunk_size) :
  1928       _g1h(G1CollectedHeap::heap()),
  1929       _hrSorted(hrSorted), _chunk_size(chunk_size),
  1930       _marked_regions_added(0), _reclaimable_bytes_added(0),
  1931       _cur_chunk_idx(0), _cur_chunk_end(0) { }
  1933   bool doHeapRegion(HeapRegion* r) {
  1934     // Do we have any marking information for this region?
  1935     if (r->is_marked()) {
  1936       // We will skip any region that's currently used as an old GC
  1937       // alloc region (we should not consider those for collection
  1938       // before we fill them up).
  1939       if (_hrSorted->should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
  1940         add_region(r);
  1943     return false;
  1945   uint marked_regions_added() { return _marked_regions_added; }
  1946   size_t reclaimable_bytes_added() { return _reclaimable_bytes_added; }
  1947 };
  1949 class ParKnownGarbageTask: public AbstractGangTask {
  1950   CollectionSetChooser* _hrSorted;
  1951   uint _chunk_size;
  1952   G1CollectedHeap* _g1;
  1953 public:
  1954   ParKnownGarbageTask(CollectionSetChooser* hrSorted, uint chunk_size) :
  1955     AbstractGangTask("ParKnownGarbageTask"),
  1956     _hrSorted(hrSorted), _chunk_size(chunk_size),
  1957     _g1(G1CollectedHeap::heap()) { }
  1959   void work(uint worker_id) {
  1960     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size);
  1962     // Back to zero for the claim value.
  1963     _g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, worker_id,
  1964                                          _g1->workers()->active_workers(),
  1965                                          HeapRegion::InitialClaimValue);
  1966     uint regions_added = parKnownGarbageCl.marked_regions_added();
  1967     size_t reclaimable_bytes_added =
  1968                                    parKnownGarbageCl.reclaimable_bytes_added();
  1969     _hrSorted->update_totals(regions_added, reclaimable_bytes_added);
  1971 };
  1973 void
  1974 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
  1975   _collectionSetChooser->clear();
  1977   uint region_num = _g1->n_regions();
  1978   if (G1CollectedHeap::use_parallel_gc_threads()) {
  1979     const uint OverpartitionFactor = 4;
  1980     uint WorkUnit;
  1981     // The use of MinChunkSize = 8 in the original code
  1982     // causes some assertion failures when the total number of
  1983     // region is less than 8.  The code here tries to fix that.
  1984     // Should the original code also be fixed?
  1985     if (no_of_gc_threads > 0) {
  1986       const uint MinWorkUnit = MAX2(region_num / no_of_gc_threads, 1U);
  1987       WorkUnit = MAX2(region_num / (no_of_gc_threads * OverpartitionFactor),
  1988                       MinWorkUnit);
  1989     } else {
  1990       assert(no_of_gc_threads > 0,
  1991         "The active gc workers should be greater than 0");
  1992       // In a product build do something reasonable to avoid a crash.
  1993       const uint MinWorkUnit = MAX2(region_num / (uint) ParallelGCThreads, 1U);
  1994       WorkUnit =
  1995         MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
  1996              MinWorkUnit);
  1998     _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
  1999                                                            WorkUnit);
  2000     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
  2001                                             (int) WorkUnit);
  2002     _g1->workers()->run_task(&parKnownGarbageTask);
  2004     assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
  2005            "sanity check");
  2006   } else {
  2007     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
  2008     _g1->heap_region_iterate(&knownGarbagecl);
  2011   _collectionSetChooser->sort_regions();
  2013   double end_sec = os::elapsedTime();
  2014   double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
  2015   _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
  2016   _cur_mark_stop_world_time_ms += elapsed_time_ms;
  2017   _prev_collection_pause_end_ms += elapsed_time_ms;
  2018   _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
  2021 // Add the heap region at the head of the non-incremental collection set
  2022 void G1CollectorPolicy::add_old_region_to_cset(HeapRegion* hr) {
  2023   assert(_inc_cset_build_state == Active, "Precondition");
  2024   assert(!hr->is_young(), "non-incremental add of young region");
  2026   assert(!hr->in_collection_set(), "should not already be in the CSet");
  2027   hr->set_in_collection_set(true);
  2028   hr->set_next_in_collection_set(_collection_set);
  2029   _collection_set = hr;
  2030   _collection_set_bytes_used_before += hr->used();
  2031   _g1->register_region_with_in_cset_fast_test(hr);
  2032   size_t rs_length = hr->rem_set()->occupied();
  2033   _recorded_rs_lengths += rs_length;
  2034   _old_cset_region_length += 1;
  2037 // Initialize the per-collection-set information
  2038 void G1CollectorPolicy::start_incremental_cset_building() {
  2039   assert(_inc_cset_build_state == Inactive, "Precondition");
  2041   _inc_cset_head = NULL;
  2042   _inc_cset_tail = NULL;
  2043   _inc_cset_bytes_used_before = 0;
  2045   _inc_cset_max_finger = 0;
  2046   _inc_cset_recorded_rs_lengths = 0;
  2047   _inc_cset_recorded_rs_lengths_diffs = 0;
  2048   _inc_cset_predicted_elapsed_time_ms = 0.0;
  2049   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
  2050   _inc_cset_build_state = Active;
  2053 void G1CollectorPolicy::finalize_incremental_cset_building() {
  2054   assert(_inc_cset_build_state == Active, "Precondition");
  2055   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
  2057   // The two "main" fields, _inc_cset_recorded_rs_lengths and
  2058   // _inc_cset_predicted_elapsed_time_ms, are updated by the thread
  2059   // that adds a new region to the CSet. Further updates by the
  2060   // concurrent refinement thread that samples the young RSet lengths
  2061   // are accumulated in the *_diffs fields. Here we add the diffs to
  2062   // the "main" fields.
  2064   if (_inc_cset_recorded_rs_lengths_diffs >= 0) {
  2065     _inc_cset_recorded_rs_lengths += _inc_cset_recorded_rs_lengths_diffs;
  2066   } else {
  2067     // This is defensive. The diff should in theory be always positive
  2068     // as RSets can only grow between GCs. However, given that we
  2069     // sample their size concurrently with other threads updating them
  2070     // it's possible that we might get the wrong size back, which
  2071     // could make the calculations somewhat inaccurate.
  2072     size_t diffs = (size_t) (-_inc_cset_recorded_rs_lengths_diffs);
  2073     if (_inc_cset_recorded_rs_lengths >= diffs) {
  2074       _inc_cset_recorded_rs_lengths -= diffs;
  2075     } else {
  2076       _inc_cset_recorded_rs_lengths = 0;
  2079   _inc_cset_predicted_elapsed_time_ms +=
  2080                                      _inc_cset_predicted_elapsed_time_ms_diffs;
  2082   _inc_cset_recorded_rs_lengths_diffs = 0;
  2083   _inc_cset_predicted_elapsed_time_ms_diffs = 0.0;
  2086 void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
  2087   // This routine is used when:
  2088   // * adding survivor regions to the incremental cset at the end of an
  2089   //   evacuation pause,
  2090   // * adding the current allocation region to the incremental cset
  2091   //   when it is retired, and
  2092   // * updating existing policy information for a region in the
  2093   //   incremental cset via young list RSet sampling.
  2094   // Therefore this routine may be called at a safepoint by the
  2095   // VM thread, or in-between safepoints by mutator threads (when
  2096   // retiring the current allocation region) or a concurrent
  2097   // refine thread (RSet sampling).
  2099   double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
  2100   size_t used_bytes = hr->used();
  2101   _inc_cset_recorded_rs_lengths += rs_length;
  2102   _inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
  2103   _inc_cset_bytes_used_before += used_bytes;
  2105   // Cache the values we have added to the aggregated informtion
  2106   // in the heap region in case we have to remove this region from
  2107   // the incremental collection set, or it is updated by the
  2108   // rset sampling code
  2109   hr->set_recorded_rs_length(rs_length);
  2110   hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
  2113 void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr,
  2114                                                      size_t new_rs_length) {
  2115   // Update the CSet information that is dependent on the new RS length
  2116   assert(hr->is_young(), "Precondition");
  2117   assert(!SafepointSynchronize::is_at_safepoint(),
  2118                                                "should not be at a safepoint");
  2120   // We could have updated _inc_cset_recorded_rs_lengths and
  2121   // _inc_cset_predicted_elapsed_time_ms directly but we'd need to do
  2122   // that atomically, as this code is executed by a concurrent
  2123   // refinement thread, potentially concurrently with a mutator thread
  2124   // allocating a new region and also updating the same fields. To
  2125   // avoid the atomic operations we accumulate these updates on two
  2126   // separate fields (*_diffs) and we'll just add them to the "main"
  2127   // fields at the start of a GC.
  2129   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
  2130   ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
  2131   _inc_cset_recorded_rs_lengths_diffs += rs_lengths_diff;
  2133   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
  2134   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
  2135   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
  2136   _inc_cset_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
  2138   hr->set_recorded_rs_length(new_rs_length);
  2139   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
  2142 void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
  2143   assert(hr->is_young(), "invariant");
  2144   assert(hr->young_index_in_cset() > -1, "should have already been set");
  2145   assert(_inc_cset_build_state == Active, "Precondition");
  2147   // We need to clear and set the cached recorded/cached collection set
  2148   // information in the heap region here (before the region gets added
  2149   // to the collection set). An individual heap region's cached values
  2150   // are calculated, aggregated with the policy collection set info,
  2151   // and cached in the heap region here (initially) and (subsequently)
  2152   // by the Young List sampling code.
  2154   size_t rs_length = hr->rem_set()->occupied();
  2155   add_to_incremental_cset_info(hr, rs_length);
  2157   HeapWord* hr_end = hr->end();
  2158   _inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
  2160   assert(!hr->in_collection_set(), "invariant");
  2161   hr->set_in_collection_set(true);
  2162   assert( hr->next_in_collection_set() == NULL, "invariant");
  2164   _g1->register_region_with_in_cset_fast_test(hr);
  2167 // Add the region at the RHS of the incremental cset
  2168 void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
  2169   // We should only ever be appending survivors at the end of a pause
  2170   assert( hr->is_survivor(), "Logic");
  2172   // Do the 'common' stuff
  2173   add_region_to_incremental_cset_common(hr);
  2175   // Now add the region at the right hand side
  2176   if (_inc_cset_tail == NULL) {
  2177     assert(_inc_cset_head == NULL, "invariant");
  2178     _inc_cset_head = hr;
  2179   } else {
  2180     _inc_cset_tail->set_next_in_collection_set(hr);
  2182   _inc_cset_tail = hr;
  2185 // Add the region to the LHS of the incremental cset
  2186 void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
  2187   // Survivors should be added to the RHS at the end of a pause
  2188   assert(!hr->is_survivor(), "Logic");
  2190   // Do the 'common' stuff
  2191   add_region_to_incremental_cset_common(hr);
  2193   // Add the region at the left hand side
  2194   hr->set_next_in_collection_set(_inc_cset_head);
  2195   if (_inc_cset_head == NULL) {
  2196     assert(_inc_cset_tail == NULL, "Invariant");
  2197     _inc_cset_tail = hr;
  2199   _inc_cset_head = hr;
  2202 #ifndef PRODUCT
  2203 void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
  2204   assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
  2206   st->print_cr("\nCollection_set:");
  2207   HeapRegion* csr = list_head;
  2208   while (csr != NULL) {
  2209     HeapRegion* next = csr->next_in_collection_set();
  2210     assert(csr->in_collection_set(), "bad CS");
  2211     st->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
  2212                  HR_FORMAT_PARAMS(csr),
  2213                  csr->prev_top_at_mark_start(), csr->next_top_at_mark_start(),
  2214                  csr->age_in_surv_rate_group_cond());
  2215     csr = next;
  2218 #endif // !PRODUCT
  2220 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
  2221                                                 const char* false_action_str) {
  2222   CollectionSetChooser* cset_chooser = _collectionSetChooser;
  2223   if (cset_chooser->is_empty()) {
  2224     ergo_verbose0(ErgoMixedGCs,
  2225                   false_action_str,
  2226                   ergo_format_reason("candidate old regions not available"));
  2227     return false;
  2229   size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
  2230   size_t capacity_bytes = _g1->capacity();
  2231   double perc = (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
  2232   double threshold = (double) G1HeapWastePercent;
  2233   if (perc < threshold) {
  2234     ergo_verbose4(ErgoMixedGCs,
  2235               false_action_str,
  2236               ergo_format_reason("reclaimable percentage lower than threshold")
  2237               ergo_format_region("candidate old regions")
  2238               ergo_format_byte_perc("reclaimable")
  2239               ergo_format_perc("threshold"),
  2240               cset_chooser->remaining_regions(),
  2241               reclaimable_bytes, perc, threshold);
  2242     return false;
  2245   ergo_verbose4(ErgoMixedGCs,
  2246                 true_action_str,
  2247                 ergo_format_reason("candidate old regions available")
  2248                 ergo_format_region("candidate old regions")
  2249                 ergo_format_byte_perc("reclaimable")
  2250                 ergo_format_perc("threshold"),
  2251                 cset_chooser->remaining_regions(),
  2252                 reclaimable_bytes, perc, threshold);
  2253   return true;
  2256 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms) {
  2257   // Set this here - in case we're not doing young collections.
  2258   double non_young_start_time_sec = os::elapsedTime();
  2260   YoungList* young_list = _g1->young_list();
  2261   finalize_incremental_cset_building();
  2263   guarantee(target_pause_time_ms > 0.0,
  2264             err_msg("target_pause_time_ms = %1.6lf should be positive",
  2265                     target_pause_time_ms));
  2266   guarantee(_collection_set == NULL, "Precondition");
  2268   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
  2269   double predicted_pause_time_ms = base_time_ms;
  2270   double time_remaining_ms = target_pause_time_ms - base_time_ms;
  2272   ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
  2273                 "start choosing CSet",
  2274                 ergo_format_ms("predicted base time")
  2275                 ergo_format_ms("remaining time")
  2276                 ergo_format_ms("target pause time"),
  2277                 base_time_ms, time_remaining_ms, target_pause_time_ms);
  2279   HeapRegion* hr;
  2280   double young_start_time_sec = os::elapsedTime();
  2282   _collection_set_bytes_used_before = 0;
  2283   _last_gc_was_young = gcs_are_young() ? true : false;
  2285   if (_last_gc_was_young) {
  2286     _trace_gen0_time_data.increment_young_collection_count();
  2287   } else {
  2288     _trace_gen0_time_data.increment_mixed_collection_count();
  2291   // The young list is laid with the survivor regions from the previous
  2292   // pause are appended to the RHS of the young list, i.e.
  2293   //   [Newly Young Regions ++ Survivors from last pause].
  2295   uint survivor_region_length = young_list->survivor_length();
  2296   uint eden_region_length = young_list->length() - survivor_region_length;
  2297   init_cset_region_lengths(eden_region_length, survivor_region_length);
  2298   hr = young_list->first_survivor_region();
  2299   while (hr != NULL) {
  2300     assert(hr->is_survivor(), "badly formed young list");
  2301     hr->set_young();
  2302     hr = hr->get_next_young_region();
  2305   // Clear the fields that point to the survivor list - they are all young now.
  2306   young_list->clear_survivors();
  2308   _collection_set = _inc_cset_head;
  2309   _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
  2310   time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
  2311   predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
  2313   ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
  2314                 "add young regions to CSet",
  2315                 ergo_format_region("eden")
  2316                 ergo_format_region("survivors")
  2317                 ergo_format_ms("predicted young region time"),
  2318                 eden_region_length, survivor_region_length,
  2319                 _inc_cset_predicted_elapsed_time_ms);
  2321   // The number of recorded young regions is the incremental
  2322   // collection set's current size
  2323   set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
  2325   double young_end_time_sec = os::elapsedTime();
  2326   _recorded_young_cset_choice_time_ms =
  2327     (young_end_time_sec - young_start_time_sec) * 1000.0;
  2329   // We are doing young collections so reset this.
  2330   non_young_start_time_sec = young_end_time_sec;
  2332   if (!gcs_are_young()) {
  2333     CollectionSetChooser* cset_chooser = _collectionSetChooser;
  2334     cset_chooser->verify();
  2335     const uint min_old_cset_length = cset_chooser->calc_min_old_cset_length();
  2336     const uint max_old_cset_length = cset_chooser->calc_max_old_cset_length();
  2338     uint expensive_region_num = 0;
  2339     bool check_time_remaining = adaptive_young_list_length();
  2340     HeapRegion* hr = cset_chooser->peek();
  2341     while (hr != NULL) {
  2342       if (old_cset_region_length() >= max_old_cset_length) {
  2343         // Added maximum number of old regions to the CSet.
  2344         ergo_verbose2(ErgoCSetConstruction,
  2345                       "finish adding old regions to CSet",
  2346                       ergo_format_reason("old CSet region num reached max")
  2347                       ergo_format_region("old")
  2348                       ergo_format_region("max"),
  2349                       old_cset_region_length(), max_old_cset_length);
  2350         break;
  2353       double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
  2354       if (check_time_remaining) {
  2355         if (predicted_time_ms > time_remaining_ms) {
  2356           // Too expensive for the current CSet.
  2358           if (old_cset_region_length() >= min_old_cset_length) {
  2359             // We have added the minimum number of old regions to the CSet,
  2360             // we are done with this CSet.
  2361             ergo_verbose4(ErgoCSetConstruction,
  2362                           "finish adding old regions to CSet",
  2363                           ergo_format_reason("predicted time is too high")
  2364                           ergo_format_ms("predicted time")
  2365                           ergo_format_ms("remaining time")
  2366                           ergo_format_region("old")
  2367                           ergo_format_region("min"),
  2368                           predicted_time_ms, time_remaining_ms,
  2369                           old_cset_region_length(), min_old_cset_length);
  2370             break;
  2373           // We'll add it anyway given that we haven't reached the
  2374           // minimum number of old regions.
  2375           expensive_region_num += 1;
  2377       } else {
  2378         if (old_cset_region_length() >= min_old_cset_length) {
  2379           // In the non-auto-tuning case, we'll finish adding regions
  2380           // to the CSet if we reach the minimum.
  2381           ergo_verbose2(ErgoCSetConstruction,
  2382                         "finish adding old regions to CSet",
  2383                         ergo_format_reason("old CSet region num reached min")
  2384                         ergo_format_region("old")
  2385                         ergo_format_region("min"),
  2386                         old_cset_region_length(), min_old_cset_length);
  2387           break;
  2391       // We will add this region to the CSet.
  2392       time_remaining_ms -= predicted_time_ms;
  2393       predicted_pause_time_ms += predicted_time_ms;
  2394       cset_chooser->remove_and_move_to_next(hr);
  2395       _g1->old_set_remove(hr);
  2396       add_old_region_to_cset(hr);
  2398       hr = cset_chooser->peek();
  2400     if (hr == NULL) {
  2401       ergo_verbose0(ErgoCSetConstruction,
  2402                     "finish adding old regions to CSet",
  2403                     ergo_format_reason("candidate old regions not available"));
  2406     if (expensive_region_num > 0) {
  2407       // We print the information once here at the end, predicated on
  2408       // whether we added any apparently expensive regions or not, to
  2409       // avoid generating output per region.
  2410       ergo_verbose4(ErgoCSetConstruction,
  2411                     "added expensive regions to CSet",
  2412                     ergo_format_reason("old CSet region num not reached min")
  2413                     ergo_format_region("old")
  2414                     ergo_format_region("expensive")
  2415                     ergo_format_region("min")
  2416                     ergo_format_ms("remaining time"),
  2417                     old_cset_region_length(),
  2418                     expensive_region_num,
  2419                     min_old_cset_length,
  2420                     time_remaining_ms);
  2423     cset_chooser->verify();
  2426   stop_incremental_cset_building();
  2428   count_CS_bytes_used();
  2430   ergo_verbose5(ErgoCSetConstruction,
  2431                 "finish choosing CSet",
  2432                 ergo_format_region("eden")
  2433                 ergo_format_region("survivors")
  2434                 ergo_format_region("old")
  2435                 ergo_format_ms("predicted pause time")
  2436                 ergo_format_ms("target pause time"),
  2437                 eden_region_length, survivor_region_length,
  2438                 old_cset_region_length(),
  2439                 predicted_pause_time_ms, target_pause_time_ms);
  2441   double non_young_end_time_sec = os::elapsedTime();
  2442   _recorded_non_young_cset_choice_time_ms =
  2443     (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
  2446 void TraceGen0TimeData::record_start_collection(double time_to_stop_the_world_ms) {
  2447   if(TraceGen0Time) {
  2448     _all_stop_world_times_ms.add(time_to_stop_the_world_ms);
  2452 void TraceGen0TimeData::record_yield_time(double yield_time_ms) {
  2453   if(TraceGen0Time) {
  2454     _all_yield_times_ms.add(yield_time_ms);
  2458 void TraceGen0TimeData::record_end_collection(
  2459      double total_ms,
  2460      double other_ms,
  2461      double root_region_scan_wait_ms,
  2462      double parallel_ms,
  2463      double ext_root_scan_ms,
  2464      double satb_filtering_ms,
  2465      double update_rs_ms,
  2466      double scan_rs_ms,
  2467      double obj_copy_ms,
  2468      double termination_ms,
  2469      double parallel_other_ms,
  2470      double clear_ct_ms)
  2472   if(TraceGen0Time) {
  2473     _total.add(total_ms);
  2474     _other.add(other_ms);
  2475     _root_region_scan_wait.add(root_region_scan_wait_ms);
  2476     _parallel.add(parallel_ms);
  2477     _ext_root_scan.add(ext_root_scan_ms);
  2478     _satb_filtering.add(satb_filtering_ms);
  2479     _update_rs.add(update_rs_ms);
  2480     _scan_rs.add(scan_rs_ms);
  2481     _obj_copy.add(obj_copy_ms);
  2482     _termination.add(termination_ms);
  2483     _parallel_other.add(parallel_other_ms);
  2484     _clear_ct.add(clear_ct_ms);
  2488 void TraceGen0TimeData::increment_young_collection_count() {
  2489   if(TraceGen0Time) {
  2490     ++_young_pause_num;
  2494 void TraceGen0TimeData::increment_mixed_collection_count() {
  2495   if(TraceGen0Time) {
  2496     ++_mixed_pause_num;
  2500 void TraceGen0TimeData::print_summary(int level,
  2501                                       const char* str,
  2502                                       const NumberSeq* seq) const {
  2503   double sum = seq->sum();
  2504   LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
  2505                 str, sum / 1000.0, seq->avg());
  2508 void TraceGen0TimeData::print_summary_sd(int level,
  2509                                          const char* str,
  2510                                          const NumberSeq* seq) const {
  2511   print_summary(level, str, seq);
  2512   LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
  2513                 seq->num(), seq->sd(), seq->maximum());
  2516 void TraceGen0TimeData::print() const {
  2517   if (!TraceGen0Time) {
  2518     return;
  2521   gclog_or_tty->print_cr("ALL PAUSES");
  2522   print_summary_sd(0, "Total", &_total);
  2523   gclog_or_tty->print_cr("");
  2524   gclog_or_tty->print_cr("");
  2525   gclog_or_tty->print_cr("   Young GC Pauses: %8d", _young_pause_num);
  2526   gclog_or_tty->print_cr("   Mixed GC Pauses: %8d", _mixed_pause_num);
  2527   gclog_or_tty->print_cr("");
  2529   gclog_or_tty->print_cr("EVACUATION PAUSES");
  2531   if (_young_pause_num == 0 && _mixed_pause_num == 0) {
  2532     gclog_or_tty->print_cr("none");
  2533   } else {
  2534     print_summary_sd(0, "Evacuation Pauses", &_total);
  2535     print_summary(1, "Root Region Scan Wait", &_root_region_scan_wait);
  2536     print_summary(1, "Parallel Time", &_parallel);
  2537     print_summary(2, "Ext Root Scanning", &_ext_root_scan);
  2538     print_summary(2, "SATB Filtering", &_satb_filtering);
  2539     print_summary(2, "Update RS", &_update_rs);
  2540     print_summary(2, "Scan RS", &_scan_rs);
  2541     print_summary(2, "Object Copy", &_obj_copy);
  2542     print_summary(2, "Termination", &_termination);
  2543     print_summary(2, "Parallel Other", &_parallel_other);
  2544     print_summary(1, "Clear CT", &_clear_ct);
  2545     print_summary(1, "Other", &_other);
  2547   gclog_or_tty->print_cr("");
  2549   gclog_or_tty->print_cr("MISC");
  2550   print_summary_sd(0, "Stop World", &_all_stop_world_times_ms);
  2551   print_summary_sd(0, "Yields", &_all_yield_times_ms);
  2554 void TraceGen1TimeData::record_full_collection(double full_gc_time_ms) {
  2555   if (TraceGen1Time) {
  2556     _all_full_gc_times.add(full_gc_time_ms);
  2560 void TraceGen1TimeData::print() const {
  2561   if (!TraceGen1Time) {
  2562     return;
  2565   if (_all_full_gc_times.num() > 0) {
  2566     gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
  2567       _all_full_gc_times.num(),
  2568       _all_full_gc_times.sum() / 1000.0);
  2569     gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times.avg());
  2570     gclog_or_tty->print_cr("                     [std. dev = %8.2f ms, max = %8.2f ms]",
  2571       _all_full_gc_times.sd(),
  2572       _all_full_gc_times.maximum());

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