1 /* |
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2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. |
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8 * |
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9 * This code is distributed in the hope that it will be useful, but WITHOUT |
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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12 * version 2 for more details (a copy is included in the LICENSE file that |
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13 * accompanied this code). |
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14 * |
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15 * You should have received a copy of the GNU General Public License version |
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16 * 2 along with this work; if not, write to the Free Software Foundation, |
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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18 * |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #include "precompiled.hpp" |
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26 #include "gc/g1/concurrentMarkThread.inline.hpp" |
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27 #include "gc/g1/g1Analytics.hpp" |
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28 #include "gc/g1/g1CollectedHeap.inline.hpp" |
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29 #include "gc/g1/g1CollectionSet.hpp" |
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30 #include "gc/g1/g1ConcurrentMark.hpp" |
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31 #include "gc/g1/g1ConcurrentRefine.hpp" |
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32 #include "gc/g1/g1DefaultPolicy.hpp" |
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33 #include "gc/g1/g1HotCardCache.hpp" |
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34 #include "gc/g1/g1IHOPControl.hpp" |
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35 #include "gc/g1/g1GCPhaseTimes.hpp" |
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36 #include "gc/g1/g1Policy.hpp" |
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37 #include "gc/g1/g1SurvivorRegions.hpp" |
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38 #include "gc/g1/g1YoungGenSizer.hpp" |
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39 #include "gc/g1/heapRegion.inline.hpp" |
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40 #include "gc/g1/heapRegionRemSet.hpp" |
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41 #include "gc/shared/gcPolicyCounters.hpp" |
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42 #include "logging/logStream.hpp" |
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43 #include "runtime/arguments.hpp" |
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44 #include "runtime/java.hpp" |
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45 #include "runtime/mutexLocker.hpp" |
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46 #include "utilities/debug.hpp" |
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47 #include "utilities/growableArray.hpp" |
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48 #include "utilities/pair.hpp" |
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49 |
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50 G1DefaultPolicy::G1DefaultPolicy(STWGCTimer* gc_timer) : |
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51 _predictor(G1ConfidencePercent / 100.0), |
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52 _analytics(new G1Analytics(&_predictor)), |
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53 _mmu_tracker(new G1MMUTrackerQueue(GCPauseIntervalMillis / 1000.0, MaxGCPauseMillis / 1000.0)), |
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54 _ihop_control(create_ihop_control(&_predictor)), |
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55 _policy_counters(new GCPolicyCounters("GarbageFirst", 1, 2)), |
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56 _young_list_fixed_length(0), |
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57 _short_lived_surv_rate_group(new SurvRateGroup()), |
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58 _survivor_surv_rate_group(new SurvRateGroup()), |
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59 _reserve_factor((double) G1ReservePercent / 100.0), |
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60 _reserve_regions(0), |
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61 _rs_lengths_prediction(0), |
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62 _bytes_allocated_in_old_since_last_gc(0), |
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63 _initial_mark_to_mixed(), |
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64 _collection_set(NULL), |
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65 _g1(NULL), |
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66 _phase_times(new G1GCPhaseTimes(gc_timer, ParallelGCThreads)), |
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67 _tenuring_threshold(MaxTenuringThreshold), |
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68 _max_survivor_regions(0), |
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69 _survivors_age_table(true), |
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70 _collection_pause_end_millis(os::javaTimeNanos() / NANOSECS_PER_MILLISEC) { } |
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71 |
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72 G1DefaultPolicy::~G1DefaultPolicy() { |
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73 delete _ihop_control; |
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74 } |
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75 |
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76 G1CollectorState* G1DefaultPolicy::collector_state() const { return _g1->collector_state(); } |
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77 |
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78 void G1DefaultPolicy::init(G1CollectedHeap* g1h, G1CollectionSet* collection_set) { |
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79 _g1 = g1h; |
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80 _collection_set = collection_set; |
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81 |
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82 assert(Heap_lock->owned_by_self(), "Locking discipline."); |
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83 |
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84 if (!adaptive_young_list_length()) { |
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85 _young_list_fixed_length = _young_gen_sizer.min_desired_young_length(); |
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86 } |
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87 _young_gen_sizer.adjust_max_new_size(_g1->max_regions()); |
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88 |
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89 _free_regions_at_end_of_collection = _g1->num_free_regions(); |
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90 |
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91 update_young_list_max_and_target_length(); |
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92 // We may immediately start allocating regions and placing them on the |
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93 // collection set list. Initialize the per-collection set info |
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94 _collection_set->start_incremental_building(); |
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95 } |
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96 |
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97 void G1DefaultPolicy::note_gc_start() { |
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98 phase_times()->note_gc_start(); |
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99 } |
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100 |
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101 class G1YoungLengthPredictor VALUE_OBJ_CLASS_SPEC { |
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102 const bool _during_cm; |
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103 const double _base_time_ms; |
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104 const double _base_free_regions; |
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105 const double _target_pause_time_ms; |
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106 const G1DefaultPolicy* const _policy; |
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107 |
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108 public: |
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109 G1YoungLengthPredictor(bool during_cm, |
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110 double base_time_ms, |
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111 double base_free_regions, |
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112 double target_pause_time_ms, |
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113 const G1DefaultPolicy* policy) : |
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114 _during_cm(during_cm), |
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115 _base_time_ms(base_time_ms), |
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116 _base_free_regions(base_free_regions), |
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117 _target_pause_time_ms(target_pause_time_ms), |
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118 _policy(policy) {} |
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119 |
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120 bool will_fit(uint young_length) const { |
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121 if (young_length >= _base_free_regions) { |
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122 // end condition 1: not enough space for the young regions |
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123 return false; |
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124 } |
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125 |
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126 const double accum_surv_rate = _policy->accum_yg_surv_rate_pred((int) young_length - 1); |
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127 const size_t bytes_to_copy = |
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128 (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes); |
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129 const double copy_time_ms = |
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130 _policy->analytics()->predict_object_copy_time_ms(bytes_to_copy, _during_cm); |
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131 const double young_other_time_ms = _policy->analytics()->predict_young_other_time_ms(young_length); |
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132 const double pause_time_ms = _base_time_ms + copy_time_ms + young_other_time_ms; |
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133 if (pause_time_ms > _target_pause_time_ms) { |
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134 // end condition 2: prediction is over the target pause time |
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135 return false; |
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136 } |
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137 |
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138 const size_t free_bytes = (_base_free_regions - young_length) * HeapRegion::GrainBytes; |
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139 |
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140 // When copying, we will likely need more bytes free than is live in the region. |
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141 // Add some safety margin to factor in the confidence of our guess, and the |
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142 // natural expected waste. |
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143 // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty |
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144 // of the calculation: the lower the confidence, the more headroom. |
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145 // (100 + TargetPLABWastePct) represents the increase in expected bytes during |
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146 // copying due to anticipated waste in the PLABs. |
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147 const double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0; |
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148 const size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy); |
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149 |
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150 if (expected_bytes_to_copy > free_bytes) { |
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151 // end condition 3: out-of-space |
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152 return false; |
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153 } |
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154 |
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155 // success! |
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156 return true; |
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157 } |
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158 }; |
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159 |
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160 void G1DefaultPolicy::record_new_heap_size(uint new_number_of_regions) { |
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161 // re-calculate the necessary reserve |
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162 double reserve_regions_d = (double) new_number_of_regions * _reserve_factor; |
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163 // We use ceiling so that if reserve_regions_d is > 0.0 (but |
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164 // smaller than 1.0) we'll get 1. |
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165 _reserve_regions = (uint) ceil(reserve_regions_d); |
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166 |
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167 _young_gen_sizer.heap_size_changed(new_number_of_regions); |
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168 |
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169 _ihop_control->update_target_occupancy(new_number_of_regions * HeapRegion::GrainBytes); |
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170 } |
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171 |
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172 uint G1DefaultPolicy::calculate_young_list_desired_min_length(uint base_min_length) const { |
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173 uint desired_min_length = 0; |
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174 if (adaptive_young_list_length()) { |
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175 if (_analytics->num_alloc_rate_ms() > 3) { |
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176 double now_sec = os::elapsedTime(); |
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177 double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0; |
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178 double alloc_rate_ms = _analytics->predict_alloc_rate_ms(); |
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179 desired_min_length = (uint) ceil(alloc_rate_ms * when_ms); |
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180 } else { |
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181 // otherwise we don't have enough info to make the prediction |
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182 } |
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183 } |
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184 desired_min_length += base_min_length; |
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185 // make sure we don't go below any user-defined minimum bound |
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186 return MAX2(_young_gen_sizer.min_desired_young_length(), desired_min_length); |
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187 } |
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188 |
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189 uint G1DefaultPolicy::calculate_young_list_desired_max_length() const { |
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190 // Here, we might want to also take into account any additional |
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191 // constraints (i.e., user-defined minimum bound). Currently, we |
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192 // effectively don't set this bound. |
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193 return _young_gen_sizer.max_desired_young_length(); |
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194 } |
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195 |
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196 uint G1DefaultPolicy::update_young_list_max_and_target_length() { |
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197 return update_young_list_max_and_target_length(_analytics->predict_rs_lengths()); |
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198 } |
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199 |
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200 uint G1DefaultPolicy::update_young_list_max_and_target_length(size_t rs_lengths) { |
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201 uint unbounded_target_length = update_young_list_target_length(rs_lengths); |
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202 update_max_gc_locker_expansion(); |
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203 return unbounded_target_length; |
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204 } |
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205 |
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206 uint G1DefaultPolicy::update_young_list_target_length(size_t rs_lengths) { |
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207 YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths); |
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208 _young_list_target_length = young_lengths.first; |
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209 return young_lengths.second; |
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210 } |
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211 |
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212 G1DefaultPolicy::YoungTargetLengths G1DefaultPolicy::young_list_target_lengths(size_t rs_lengths) const { |
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213 YoungTargetLengths result; |
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214 |
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215 // Calculate the absolute and desired min bounds first. |
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216 |
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217 // This is how many young regions we already have (currently: the survivors). |
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218 const uint base_min_length = _g1->survivor_regions_count(); |
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219 uint desired_min_length = calculate_young_list_desired_min_length(base_min_length); |
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220 // This is the absolute minimum young length. Ensure that we |
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221 // will at least have one eden region available for allocation. |
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222 uint absolute_min_length = base_min_length + MAX2(_g1->eden_regions_count(), (uint)1); |
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223 // If we shrank the young list target it should not shrink below the current size. |
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224 desired_min_length = MAX2(desired_min_length, absolute_min_length); |
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225 // Calculate the absolute and desired max bounds. |
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226 |
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227 uint desired_max_length = calculate_young_list_desired_max_length(); |
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228 |
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229 uint young_list_target_length = 0; |
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230 if (adaptive_young_list_length()) { |
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231 if (collector_state()->gcs_are_young()) { |
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232 young_list_target_length = |
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233 calculate_young_list_target_length(rs_lengths, |
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234 base_min_length, |
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235 desired_min_length, |
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236 desired_max_length); |
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237 } else { |
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238 // Don't calculate anything and let the code below bound it to |
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239 // the desired_min_length, i.e., do the next GC as soon as |
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240 // possible to maximize how many old regions we can add to it. |
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241 } |
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242 } else { |
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243 // The user asked for a fixed young gen so we'll fix the young gen |
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244 // whether the next GC is young or mixed. |
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245 young_list_target_length = _young_list_fixed_length; |
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246 } |
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247 |
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248 result.second = young_list_target_length; |
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249 |
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250 // We will try our best not to "eat" into the reserve. |
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251 uint absolute_max_length = 0; |
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252 if (_free_regions_at_end_of_collection > _reserve_regions) { |
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253 absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions; |
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254 } |
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255 if (desired_max_length > absolute_max_length) { |
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256 desired_max_length = absolute_max_length; |
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257 } |
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258 |
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259 // Make sure we don't go over the desired max length, nor under the |
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260 // desired min length. In case they clash, desired_min_length wins |
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261 // which is why that test is second. |
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262 if (young_list_target_length > desired_max_length) { |
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263 young_list_target_length = desired_max_length; |
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264 } |
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265 if (young_list_target_length < desired_min_length) { |
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266 young_list_target_length = desired_min_length; |
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267 } |
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268 |
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269 assert(young_list_target_length > base_min_length, |
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270 "we should be able to allocate at least one eden region"); |
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271 assert(young_list_target_length >= absolute_min_length, "post-condition"); |
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272 |
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273 result.first = young_list_target_length; |
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274 return result; |
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275 } |
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276 |
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277 uint |
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278 G1DefaultPolicy::calculate_young_list_target_length(size_t rs_lengths, |
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279 uint base_min_length, |
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280 uint desired_min_length, |
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281 uint desired_max_length) const { |
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282 assert(adaptive_young_list_length(), "pre-condition"); |
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283 assert(collector_state()->gcs_are_young(), "only call this for young GCs"); |
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284 |
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285 // In case some edge-condition makes the desired max length too small... |
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286 if (desired_max_length <= desired_min_length) { |
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287 return desired_min_length; |
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288 } |
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289 |
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290 // We'll adjust min_young_length and max_young_length not to include |
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291 // the already allocated young regions (i.e., so they reflect the |
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292 // min and max eden regions we'll allocate). The base_min_length |
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293 // will be reflected in the predictions by the |
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294 // survivor_regions_evac_time prediction. |
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295 assert(desired_min_length > base_min_length, "invariant"); |
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296 uint min_young_length = desired_min_length - base_min_length; |
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297 assert(desired_max_length > base_min_length, "invariant"); |
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298 uint max_young_length = desired_max_length - base_min_length; |
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299 |
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300 const double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0; |
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301 const double survivor_regions_evac_time = predict_survivor_regions_evac_time(); |
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302 const size_t pending_cards = _analytics->predict_pending_cards(); |
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303 const size_t adj_rs_lengths = rs_lengths + _analytics->predict_rs_length_diff(); |
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304 const size_t scanned_cards = _analytics->predict_card_num(adj_rs_lengths, /* gcs_are_young */ true); |
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305 const double base_time_ms = |
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306 predict_base_elapsed_time_ms(pending_cards, scanned_cards) + |
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307 survivor_regions_evac_time; |
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308 const uint available_free_regions = _free_regions_at_end_of_collection; |
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309 const uint base_free_regions = |
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310 available_free_regions > _reserve_regions ? available_free_regions - _reserve_regions : 0; |
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311 |
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312 // Here, we will make sure that the shortest young length that |
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313 // makes sense fits within the target pause time. |
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314 |
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315 G1YoungLengthPredictor p(collector_state()->during_concurrent_mark(), |
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316 base_time_ms, |
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317 base_free_regions, |
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318 target_pause_time_ms, |
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319 this); |
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320 if (p.will_fit(min_young_length)) { |
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321 // The shortest young length will fit into the target pause time; |
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322 // we'll now check whether the absolute maximum number of young |
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323 // regions will fit in the target pause time. If not, we'll do |
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324 // a binary search between min_young_length and max_young_length. |
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325 if (p.will_fit(max_young_length)) { |
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326 // The maximum young length will fit into the target pause time. |
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327 // We are done so set min young length to the maximum length (as |
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328 // the result is assumed to be returned in min_young_length). |
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329 min_young_length = max_young_length; |
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330 } else { |
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331 // The maximum possible number of young regions will not fit within |
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332 // the target pause time so we'll search for the optimal |
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333 // length. The loop invariants are: |
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334 // |
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335 // min_young_length < max_young_length |
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336 // min_young_length is known to fit into the target pause time |
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337 // max_young_length is known not to fit into the target pause time |
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338 // |
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339 // Going into the loop we know the above hold as we've just |
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340 // checked them. Every time around the loop we check whether |
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341 // the middle value between min_young_length and |
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342 // max_young_length fits into the target pause time. If it |
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343 // does, it becomes the new min. If it doesn't, it becomes |
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344 // the new max. This way we maintain the loop invariants. |
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345 |
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346 assert(min_young_length < max_young_length, "invariant"); |
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347 uint diff = (max_young_length - min_young_length) / 2; |
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348 while (diff > 0) { |
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349 uint young_length = min_young_length + diff; |
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350 if (p.will_fit(young_length)) { |
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351 min_young_length = young_length; |
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352 } else { |
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353 max_young_length = young_length; |
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354 } |
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355 assert(min_young_length < max_young_length, "invariant"); |
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356 diff = (max_young_length - min_young_length) / 2; |
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357 } |
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358 // The results is min_young_length which, according to the |
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359 // loop invariants, should fit within the target pause time. |
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360 |
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361 // These are the post-conditions of the binary search above: |
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362 assert(min_young_length < max_young_length, |
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363 "otherwise we should have discovered that max_young_length " |
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364 "fits into the pause target and not done the binary search"); |
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365 assert(p.will_fit(min_young_length), |
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366 "min_young_length, the result of the binary search, should " |
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367 "fit into the pause target"); |
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368 assert(!p.will_fit(min_young_length + 1), |
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369 "min_young_length, the result of the binary search, should be " |
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370 "optimal, so no larger length should fit into the pause target"); |
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371 } |
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372 } else { |
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373 // Even the minimum length doesn't fit into the pause time |
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374 // target, return it as the result nevertheless. |
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375 } |
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376 return base_min_length + min_young_length; |
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377 } |
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378 |
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379 double G1DefaultPolicy::predict_survivor_regions_evac_time() const { |
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380 double survivor_regions_evac_time = 0.0; |
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381 const GrowableArray<HeapRegion*>* survivor_regions = _g1->survivor()->regions(); |
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382 |
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383 for (GrowableArrayIterator<HeapRegion*> it = survivor_regions->begin(); |
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384 it != survivor_regions->end(); |
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385 ++it) { |
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386 survivor_regions_evac_time += predict_region_elapsed_time_ms(*it, collector_state()->gcs_are_young()); |
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387 } |
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388 return survivor_regions_evac_time; |
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389 } |
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390 |
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391 void G1DefaultPolicy::revise_young_list_target_length_if_necessary(size_t rs_lengths) { |
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392 guarantee( adaptive_young_list_length(), "should not call this otherwise" ); |
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393 |
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394 if (rs_lengths > _rs_lengths_prediction) { |
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395 // add 10% to avoid having to recalculate often |
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396 size_t rs_lengths_prediction = rs_lengths * 1100 / 1000; |
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397 update_rs_lengths_prediction(rs_lengths_prediction); |
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398 |
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399 update_young_list_max_and_target_length(rs_lengths_prediction); |
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400 } |
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401 } |
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402 |
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403 void G1DefaultPolicy::update_rs_lengths_prediction() { |
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404 update_rs_lengths_prediction(_analytics->predict_rs_lengths()); |
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405 } |
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406 |
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407 void G1DefaultPolicy::update_rs_lengths_prediction(size_t prediction) { |
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408 if (collector_state()->gcs_are_young() && adaptive_young_list_length()) { |
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409 _rs_lengths_prediction = prediction; |
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410 } |
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411 } |
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412 |
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413 void G1DefaultPolicy::record_full_collection_start() { |
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414 _full_collection_start_sec = os::elapsedTime(); |
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415 // Release the future to-space so that it is available for compaction into. |
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416 collector_state()->set_full_collection(true); |
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417 } |
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418 |
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419 void G1DefaultPolicy::record_full_collection_end() { |
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420 // Consider this like a collection pause for the purposes of allocation |
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421 // since last pause. |
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422 double end_sec = os::elapsedTime(); |
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423 double full_gc_time_sec = end_sec - _full_collection_start_sec; |
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424 double full_gc_time_ms = full_gc_time_sec * 1000.0; |
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425 |
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426 _analytics->update_recent_gc_times(end_sec, full_gc_time_ms); |
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427 |
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428 collector_state()->set_full_collection(false); |
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429 |
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430 // "Nuke" the heuristics that control the young/mixed GC |
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431 // transitions and make sure we start with young GCs after the Full GC. |
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432 collector_state()->set_gcs_are_young(true); |
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433 collector_state()->set_last_young_gc(false); |
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434 collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0)); |
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435 collector_state()->set_during_initial_mark_pause(false); |
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436 collector_state()->set_in_marking_window(false); |
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437 collector_state()->set_in_marking_window_im(false); |
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438 |
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439 _short_lived_surv_rate_group->start_adding_regions(); |
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440 // also call this on any additional surv rate groups |
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441 |
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442 _free_regions_at_end_of_collection = _g1->num_free_regions(); |
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443 // Reset survivors SurvRateGroup. |
|
444 _survivor_surv_rate_group->reset(); |
|
445 update_young_list_max_and_target_length(); |
|
446 update_rs_lengths_prediction(); |
|
447 cset_chooser()->clear(); |
|
448 |
|
449 _bytes_allocated_in_old_since_last_gc = 0; |
|
450 |
|
451 record_pause(FullGC, _full_collection_start_sec, end_sec); |
|
452 } |
|
453 |
|
454 void G1DefaultPolicy::record_collection_pause_start(double start_time_sec) { |
|
455 // We only need to do this here as the policy will only be applied |
|
456 // to the GC we're about to start. so, no point is calculating this |
|
457 // every time we calculate / recalculate the target young length. |
|
458 update_survivors_policy(); |
|
459 |
|
460 assert(_g1->used() == _g1->recalculate_used(), |
|
461 "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT, |
|
462 _g1->used(), _g1->recalculate_used()); |
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463 |
|
464 phase_times()->record_cur_collection_start_sec(start_time_sec); |
|
465 _pending_cards = _g1->pending_card_num(); |
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466 |
|
467 _collection_set->reset_bytes_used_before(); |
|
468 _bytes_copied_during_gc = 0; |
|
469 |
|
470 collector_state()->set_last_gc_was_young(false); |
|
471 |
|
472 // do that for any other surv rate groups |
|
473 _short_lived_surv_rate_group->stop_adding_regions(); |
|
474 _survivors_age_table.clear(); |
|
475 |
|
476 assert(_g1->collection_set()->verify_young_ages(), "region age verification failed"); |
|
477 } |
|
478 |
|
479 void G1DefaultPolicy::record_concurrent_mark_init_end(double mark_init_elapsed_time_ms) { |
|
480 collector_state()->set_during_marking(true); |
|
481 assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now"); |
|
482 collector_state()->set_during_initial_mark_pause(false); |
|
483 } |
|
484 |
|
485 void G1DefaultPolicy::record_concurrent_mark_remark_start() { |
|
486 _mark_remark_start_sec = os::elapsedTime(); |
|
487 collector_state()->set_during_marking(false); |
|
488 } |
|
489 |
|
490 void G1DefaultPolicy::record_concurrent_mark_remark_end() { |
|
491 double end_time_sec = os::elapsedTime(); |
|
492 double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0; |
|
493 _analytics->report_concurrent_mark_remark_times_ms(elapsed_time_ms); |
|
494 _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms); |
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495 |
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496 record_pause(Remark, _mark_remark_start_sec, end_time_sec); |
|
497 } |
|
498 |
|
499 void G1DefaultPolicy::record_concurrent_mark_cleanup_start() { |
|
500 _mark_cleanup_start_sec = os::elapsedTime(); |
|
501 } |
|
502 |
|
503 void G1DefaultPolicy::record_concurrent_mark_cleanup_completed() { |
|
504 bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc", |
|
505 "skip last young-only gc"); |
|
506 collector_state()->set_last_young_gc(should_continue_with_reclaim); |
|
507 // We skip the marking phase. |
|
508 if (!should_continue_with_reclaim) { |
|
509 abort_time_to_mixed_tracking(); |
|
510 } |
|
511 collector_state()->set_in_marking_window(false); |
|
512 } |
|
513 |
|
514 double G1DefaultPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const { |
|
515 return phase_times()->average_time_ms(phase); |
|
516 } |
|
517 |
|
518 double G1DefaultPolicy::young_other_time_ms() const { |
|
519 return phase_times()->young_cset_choice_time_ms() + |
|
520 phase_times()->average_time_ms(G1GCPhaseTimes::YoungFreeCSet); |
|
521 } |
|
522 |
|
523 double G1DefaultPolicy::non_young_other_time_ms() const { |
|
524 return phase_times()->non_young_cset_choice_time_ms() + |
|
525 phase_times()->average_time_ms(G1GCPhaseTimes::NonYoungFreeCSet); |
|
526 } |
|
527 |
|
528 double G1DefaultPolicy::other_time_ms(double pause_time_ms) const { |
|
529 return pause_time_ms - phase_times()->cur_collection_par_time_ms(); |
|
530 } |
|
531 |
|
532 double G1DefaultPolicy::constant_other_time_ms(double pause_time_ms) const { |
|
533 return other_time_ms(pause_time_ms) - phase_times()->total_free_cset_time_ms(); |
|
534 } |
|
535 |
|
536 CollectionSetChooser* G1DefaultPolicy::cset_chooser() const { |
|
537 return _collection_set->cset_chooser(); |
|
538 } |
|
539 |
|
540 bool G1DefaultPolicy::about_to_start_mixed_phase() const { |
|
541 return _g1->concurrent_mark()->cm_thread()->during_cycle() || collector_state()->last_young_gc(); |
|
542 } |
|
543 |
|
544 bool G1DefaultPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) { |
|
545 if (about_to_start_mixed_phase()) { |
|
546 return false; |
|
547 } |
|
548 |
|
549 size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold(); |
|
550 |
|
551 size_t cur_used_bytes = _g1->non_young_capacity_bytes(); |
|
552 size_t alloc_byte_size = alloc_word_size * HeapWordSize; |
|
553 size_t marking_request_bytes = cur_used_bytes + alloc_byte_size; |
|
554 |
|
555 bool result = false; |
|
556 if (marking_request_bytes > marking_initiating_used_threshold) { |
|
557 result = collector_state()->gcs_are_young() && !collector_state()->last_young_gc(); |
|
558 log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) source: %s", |
|
559 result ? "Request concurrent cycle initiation (occupancy higher than threshold)" : "Do not request concurrent cycle initiation (still doing mixed collections)", |
|
560 cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, (double) marking_initiating_used_threshold / _g1->capacity() * 100, source); |
|
561 } |
|
562 |
|
563 return result; |
|
564 } |
|
565 |
|
566 // Anything below that is considered to be zero |
|
567 #define MIN_TIMER_GRANULARITY 0.0000001 |
|
568 |
|
569 void G1DefaultPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc) { |
|
570 double end_time_sec = os::elapsedTime(); |
|
571 |
|
572 size_t cur_used_bytes = _g1->used(); |
|
573 assert(cur_used_bytes == _g1->recalculate_used(), "It should!"); |
|
574 bool last_pause_included_initial_mark = false; |
|
575 bool update_stats = !_g1->evacuation_failed(); |
|
576 |
|
577 record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec); |
|
578 |
|
579 _collection_pause_end_millis = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; |
|
580 |
|
581 last_pause_included_initial_mark = collector_state()->during_initial_mark_pause(); |
|
582 if (last_pause_included_initial_mark) { |
|
583 record_concurrent_mark_init_end(0.0); |
|
584 } else { |
|
585 maybe_start_marking(); |
|
586 } |
|
587 |
|
588 double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _analytics->prev_collection_pause_end_ms()); |
|
589 if (app_time_ms < MIN_TIMER_GRANULARITY) { |
|
590 // This usually happens due to the timer not having the required |
|
591 // granularity. Some Linuxes are the usual culprits. |
|
592 // We'll just set it to something (arbitrarily) small. |
|
593 app_time_ms = 1.0; |
|
594 } |
|
595 |
|
596 if (update_stats) { |
|
597 // We maintain the invariant that all objects allocated by mutator |
|
598 // threads will be allocated out of eden regions. So, we can use |
|
599 // the eden region number allocated since the previous GC to |
|
600 // calculate the application's allocate rate. The only exception |
|
601 // to that is humongous objects that are allocated separately. But |
|
602 // given that humongous object allocations do not really affect |
|
603 // either the pause's duration nor when the next pause will take |
|
604 // place we can safely ignore them here. |
|
605 uint regions_allocated = _collection_set->eden_region_length(); |
|
606 double alloc_rate_ms = (double) regions_allocated / app_time_ms; |
|
607 _analytics->report_alloc_rate_ms(alloc_rate_ms); |
|
608 |
|
609 double interval_ms = |
|
610 (end_time_sec - _analytics->last_known_gc_end_time_sec()) * 1000.0; |
|
611 _analytics->update_recent_gc_times(end_time_sec, pause_time_ms); |
|
612 _analytics->compute_pause_time_ratio(interval_ms, pause_time_ms); |
|
613 } |
|
614 |
|
615 bool new_in_marking_window = collector_state()->in_marking_window(); |
|
616 bool new_in_marking_window_im = false; |
|
617 if (last_pause_included_initial_mark) { |
|
618 new_in_marking_window = true; |
|
619 new_in_marking_window_im = true; |
|
620 } |
|
621 |
|
622 if (collector_state()->last_young_gc()) { |
|
623 // This is supposed to to be the "last young GC" before we start |
|
624 // doing mixed GCs. Here we decide whether to start mixed GCs or not. |
|
625 assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC"); |
|
626 |
|
627 if (next_gc_should_be_mixed("start mixed GCs", |
|
628 "do not start mixed GCs")) { |
|
629 collector_state()->set_gcs_are_young(false); |
|
630 } else { |
|
631 // We aborted the mixed GC phase early. |
|
632 abort_time_to_mixed_tracking(); |
|
633 } |
|
634 |
|
635 collector_state()->set_last_young_gc(false); |
|
636 } |
|
637 |
|
638 if (!collector_state()->last_gc_was_young()) { |
|
639 // This is a mixed GC. Here we decide whether to continue doing |
|
640 // mixed GCs or not. |
|
641 if (!next_gc_should_be_mixed("continue mixed GCs", |
|
642 "do not continue mixed GCs")) { |
|
643 collector_state()->set_gcs_are_young(true); |
|
644 |
|
645 maybe_start_marking(); |
|
646 } |
|
647 } |
|
648 |
|
649 _short_lived_surv_rate_group->start_adding_regions(); |
|
650 // Do that for any other surv rate groups |
|
651 |
|
652 double scan_hcc_time_ms = G1HotCardCache::default_use_cache() ? average_time_ms(G1GCPhaseTimes::ScanHCC) : 0.0; |
|
653 |
|
654 if (update_stats) { |
|
655 double cost_per_card_ms = 0.0; |
|
656 if (_pending_cards > 0) { |
|
657 cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms) / (double) _pending_cards; |
|
658 _analytics->report_cost_per_card_ms(cost_per_card_ms); |
|
659 } |
|
660 _analytics->report_cost_scan_hcc(scan_hcc_time_ms); |
|
661 |
|
662 double cost_per_entry_ms = 0.0; |
|
663 if (cards_scanned > 10) { |
|
664 cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned; |
|
665 _analytics->report_cost_per_entry_ms(cost_per_entry_ms, collector_state()->last_gc_was_young()); |
|
666 } |
|
667 |
|
668 if (_max_rs_lengths > 0) { |
|
669 double cards_per_entry_ratio = |
|
670 (double) cards_scanned / (double) _max_rs_lengths; |
|
671 _analytics->report_cards_per_entry_ratio(cards_per_entry_ratio, collector_state()->last_gc_was_young()); |
|
672 } |
|
673 |
|
674 // This is defensive. For a while _max_rs_lengths could get |
|
675 // smaller than _recorded_rs_lengths which was causing |
|
676 // rs_length_diff to get very large and mess up the RSet length |
|
677 // predictions. The reason was unsafe concurrent updates to the |
|
678 // _inc_cset_recorded_rs_lengths field which the code below guards |
|
679 // against (see CR 7118202). This bug has now been fixed (see CR |
|
680 // 7119027). However, I'm still worried that |
|
681 // _inc_cset_recorded_rs_lengths might still end up somewhat |
|
682 // inaccurate. The concurrent refinement thread calculates an |
|
683 // RSet's length concurrently with other CR threads updating it |
|
684 // which might cause it to calculate the length incorrectly (if, |
|
685 // say, it's in mid-coarsening). So I'll leave in the defensive |
|
686 // conditional below just in case. |
|
687 size_t rs_length_diff = 0; |
|
688 size_t recorded_rs_lengths = _collection_set->recorded_rs_lengths(); |
|
689 if (_max_rs_lengths > recorded_rs_lengths) { |
|
690 rs_length_diff = _max_rs_lengths - recorded_rs_lengths; |
|
691 } |
|
692 _analytics->report_rs_length_diff((double) rs_length_diff); |
|
693 |
|
694 size_t freed_bytes = heap_used_bytes_before_gc - cur_used_bytes; |
|
695 size_t copied_bytes = _collection_set->bytes_used_before() - freed_bytes; |
|
696 double cost_per_byte_ms = 0.0; |
|
697 |
|
698 if (copied_bytes > 0) { |
|
699 cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes; |
|
700 _analytics->report_cost_per_byte_ms(cost_per_byte_ms, collector_state()->in_marking_window()); |
|
701 } |
|
702 |
|
703 if (_collection_set->young_region_length() > 0) { |
|
704 _analytics->report_young_other_cost_per_region_ms(young_other_time_ms() / |
|
705 _collection_set->young_region_length()); |
|
706 } |
|
707 |
|
708 if (_collection_set->old_region_length() > 0) { |
|
709 _analytics->report_non_young_other_cost_per_region_ms(non_young_other_time_ms() / |
|
710 _collection_set->old_region_length()); |
|
711 } |
|
712 |
|
713 _analytics->report_constant_other_time_ms(constant_other_time_ms(pause_time_ms)); |
|
714 |
|
715 _analytics->report_pending_cards((double) _pending_cards); |
|
716 _analytics->report_rs_lengths((double) _max_rs_lengths); |
|
717 } |
|
718 |
|
719 collector_state()->set_in_marking_window(new_in_marking_window); |
|
720 collector_state()->set_in_marking_window_im(new_in_marking_window_im); |
|
721 _free_regions_at_end_of_collection = _g1->num_free_regions(); |
|
722 // IHOP control wants to know the expected young gen length if it were not |
|
723 // restrained by the heap reserve. Using the actual length would make the |
|
724 // prediction too small and the limit the young gen every time we get to the |
|
725 // predicted target occupancy. |
|
726 size_t last_unrestrained_young_length = update_young_list_max_and_target_length(); |
|
727 update_rs_lengths_prediction(); |
|
728 |
|
729 update_ihop_prediction(app_time_ms / 1000.0, |
|
730 _bytes_allocated_in_old_since_last_gc, |
|
731 last_unrestrained_young_length * HeapRegion::GrainBytes); |
|
732 _bytes_allocated_in_old_since_last_gc = 0; |
|
733 |
|
734 _ihop_control->send_trace_event(_g1->gc_tracer_stw()); |
|
735 |
|
736 // Note that _mmu_tracker->max_gc_time() returns the time in seconds. |
|
737 double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0; |
|
738 |
|
739 if (update_rs_time_goal_ms < scan_hcc_time_ms) { |
|
740 log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)." |
|
741 "Update RS time goal: %1.2fms Scan HCC time: %1.2fms", |
|
742 update_rs_time_goal_ms, scan_hcc_time_ms); |
|
743 |
|
744 update_rs_time_goal_ms = 0; |
|
745 } else { |
|
746 update_rs_time_goal_ms -= scan_hcc_time_ms; |
|
747 } |
|
748 _g1->concurrent_refine()->adjust(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms, |
|
749 phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS), |
|
750 update_rs_time_goal_ms); |
|
751 |
|
752 cset_chooser()->verify(); |
|
753 } |
|
754 |
|
755 G1IHOPControl* G1DefaultPolicy::create_ihop_control(const G1Predictions* predictor){ |
|
756 if (G1UseAdaptiveIHOP) { |
|
757 return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent, |
|
758 predictor, |
|
759 G1ReservePercent, |
|
760 G1HeapWastePercent); |
|
761 } else { |
|
762 return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent); |
|
763 } |
|
764 } |
|
765 |
|
766 void G1DefaultPolicy::update_ihop_prediction(double mutator_time_s, |
|
767 size_t mutator_alloc_bytes, |
|
768 size_t young_gen_size) { |
|
769 // Always try to update IHOP prediction. Even evacuation failures give information |
|
770 // about e.g. whether to start IHOP earlier next time. |
|
771 |
|
772 // Avoid using really small application times that might create samples with |
|
773 // very high or very low values. They may be caused by e.g. back-to-back gcs. |
|
774 double const min_valid_time = 1e-6; |
|
775 |
|
776 bool report = false; |
|
777 |
|
778 double marking_to_mixed_time = -1.0; |
|
779 if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) { |
|
780 marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time(); |
|
781 assert(marking_to_mixed_time > 0.0, |
|
782 "Initial mark to mixed time must be larger than zero but is %.3f", |
|
783 marking_to_mixed_time); |
|
784 if (marking_to_mixed_time > min_valid_time) { |
|
785 _ihop_control->update_marking_length(marking_to_mixed_time); |
|
786 report = true; |
|
787 } |
|
788 } |
|
789 |
|
790 // As an approximation for the young gc promotion rates during marking we use |
|
791 // all of them. In many applications there are only a few if any young gcs during |
|
792 // marking, which makes any prediction useless. This increases the accuracy of the |
|
793 // prediction. |
|
794 if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) { |
|
795 _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size); |
|
796 report = true; |
|
797 } |
|
798 |
|
799 if (report) { |
|
800 report_ihop_statistics(); |
|
801 } |
|
802 } |
|
803 |
|
804 void G1DefaultPolicy::report_ihop_statistics() { |
|
805 _ihop_control->print(); |
|
806 } |
|
807 |
|
808 void G1DefaultPolicy::print_phases() { |
|
809 phase_times()->print(); |
|
810 } |
|
811 |
|
812 double G1DefaultPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const { |
|
813 TruncatedSeq* seq = surv_rate_group->get_seq(age); |
|
814 guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age); |
|
815 double pred = _predictor.get_new_prediction(seq); |
|
816 if (pred > 1.0) { |
|
817 pred = 1.0; |
|
818 } |
|
819 return pred; |
|
820 } |
|
821 |
|
822 double G1DefaultPolicy::accum_yg_surv_rate_pred(int age) const { |
|
823 return _short_lived_surv_rate_group->accum_surv_rate_pred(age); |
|
824 } |
|
825 |
|
826 double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards, |
|
827 size_t scanned_cards) const { |
|
828 return |
|
829 _analytics->predict_rs_update_time_ms(pending_cards) + |
|
830 _analytics->predict_rs_scan_time_ms(scanned_cards, collector_state()->gcs_are_young()) + |
|
831 _analytics->predict_constant_other_time_ms(); |
|
832 } |
|
833 |
|
834 double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const { |
|
835 size_t rs_length = _analytics->predict_rs_lengths() + _analytics->predict_rs_length_diff(); |
|
836 size_t card_num = _analytics->predict_card_num(rs_length, collector_state()->gcs_are_young()); |
|
837 return predict_base_elapsed_time_ms(pending_cards, card_num); |
|
838 } |
|
839 |
|
840 size_t G1DefaultPolicy::predict_bytes_to_copy(HeapRegion* hr) const { |
|
841 size_t bytes_to_copy; |
|
842 if (hr->is_marked()) |
|
843 bytes_to_copy = hr->max_live_bytes(); |
|
844 else { |
|
845 assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant"); |
|
846 int age = hr->age_in_surv_rate_group(); |
|
847 double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group()); |
|
848 bytes_to_copy = (size_t) (hr->used() * yg_surv_rate); |
|
849 } |
|
850 return bytes_to_copy; |
|
851 } |
|
852 |
|
853 double G1DefaultPolicy::predict_region_elapsed_time_ms(HeapRegion* hr, |
|
854 bool for_young_gc) const { |
|
855 size_t rs_length = hr->rem_set()->occupied(); |
|
856 // Predicting the number of cards is based on which type of GC |
|
857 // we're predicting for. |
|
858 size_t card_num = _analytics->predict_card_num(rs_length, for_young_gc); |
|
859 size_t bytes_to_copy = predict_bytes_to_copy(hr); |
|
860 |
|
861 double region_elapsed_time_ms = |
|
862 _analytics->predict_rs_scan_time_ms(card_num, collector_state()->gcs_are_young()) + |
|
863 _analytics->predict_object_copy_time_ms(bytes_to_copy, collector_state()->during_concurrent_mark()); |
|
864 |
|
865 // The prediction of the "other" time for this region is based |
|
866 // upon the region type and NOT the GC type. |
|
867 if (hr->is_young()) { |
|
868 region_elapsed_time_ms += _analytics->predict_young_other_time_ms(1); |
|
869 } else { |
|
870 region_elapsed_time_ms += _analytics->predict_non_young_other_time_ms(1); |
|
871 } |
|
872 return region_elapsed_time_ms; |
|
873 } |
|
874 |
|
875 bool G1DefaultPolicy::should_allocate_mutator_region() const { |
|
876 uint young_list_length = _g1->young_regions_count(); |
|
877 uint young_list_target_length = _young_list_target_length; |
|
878 return young_list_length < young_list_target_length; |
|
879 } |
|
880 |
|
881 bool G1DefaultPolicy::can_expand_young_list() const { |
|
882 uint young_list_length = _g1->young_regions_count(); |
|
883 uint young_list_max_length = _young_list_max_length; |
|
884 return young_list_length < young_list_max_length; |
|
885 } |
|
886 |
|
887 bool G1DefaultPolicy::adaptive_young_list_length() const { |
|
888 return _young_gen_sizer.adaptive_young_list_length(); |
|
889 } |
|
890 |
|
891 size_t G1DefaultPolicy::desired_survivor_size() const { |
|
892 size_t const survivor_capacity = HeapRegion::GrainWords * _max_survivor_regions; |
|
893 return (size_t)((((double)survivor_capacity) * TargetSurvivorRatio) / 100); |
|
894 } |
|
895 |
|
896 void G1DefaultPolicy::print_age_table() { |
|
897 _survivors_age_table.print_age_table(_tenuring_threshold); |
|
898 } |
|
899 |
|
900 void G1DefaultPolicy::update_max_gc_locker_expansion() { |
|
901 uint expansion_region_num = 0; |
|
902 if (GCLockerEdenExpansionPercent > 0) { |
|
903 double perc = (double) GCLockerEdenExpansionPercent / 100.0; |
|
904 double expansion_region_num_d = perc * (double) _young_list_target_length; |
|
905 // We use ceiling so that if expansion_region_num_d is > 0.0 (but |
|
906 // less than 1.0) we'll get 1. |
|
907 expansion_region_num = (uint) ceil(expansion_region_num_d); |
|
908 } else { |
|
909 assert(expansion_region_num == 0, "sanity"); |
|
910 } |
|
911 _young_list_max_length = _young_list_target_length + expansion_region_num; |
|
912 assert(_young_list_target_length <= _young_list_max_length, "post-condition"); |
|
913 } |
|
914 |
|
915 // Calculates survivor space parameters. |
|
916 void G1DefaultPolicy::update_survivors_policy() { |
|
917 double max_survivor_regions_d = |
|
918 (double) _young_list_target_length / (double) SurvivorRatio; |
|
919 // We use ceiling so that if max_survivor_regions_d is > 0.0 (but |
|
920 // smaller than 1.0) we'll get 1. |
|
921 _max_survivor_regions = (uint) ceil(max_survivor_regions_d); |
|
922 |
|
923 _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(desired_survivor_size()); |
|
924 if (UsePerfData) { |
|
925 _policy_counters->tenuring_threshold()->set_value(_tenuring_threshold); |
|
926 _policy_counters->desired_survivor_size()->set_value(desired_survivor_size() * oopSize); |
|
927 } |
|
928 } |
|
929 |
|
930 bool G1DefaultPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) { |
|
931 // We actually check whether we are marking here and not if we are in a |
|
932 // reclamation phase. This means that we will schedule a concurrent mark |
|
933 // even while we are still in the process of reclaiming memory. |
|
934 bool during_cycle = _g1->concurrent_mark()->cm_thread()->during_cycle(); |
|
935 if (!during_cycle) { |
|
936 log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause)); |
|
937 collector_state()->set_initiate_conc_mark_if_possible(true); |
|
938 return true; |
|
939 } else { |
|
940 log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause)); |
|
941 return false; |
|
942 } |
|
943 } |
|
944 |
|
945 void G1DefaultPolicy::initiate_conc_mark() { |
|
946 collector_state()->set_during_initial_mark_pause(true); |
|
947 collector_state()->set_initiate_conc_mark_if_possible(false); |
|
948 } |
|
949 |
|
950 void G1DefaultPolicy::decide_on_conc_mark_initiation() { |
|
951 // We are about to decide on whether this pause will be an |
|
952 // initial-mark pause. |
|
953 |
|
954 // First, collector_state()->during_initial_mark_pause() should not be already set. We |
|
955 // will set it here if we have to. However, it should be cleared by |
|
956 // the end of the pause (it's only set for the duration of an |
|
957 // initial-mark pause). |
|
958 assert(!collector_state()->during_initial_mark_pause(), "pre-condition"); |
|
959 |
|
960 if (collector_state()->initiate_conc_mark_if_possible()) { |
|
961 // We had noticed on a previous pause that the heap occupancy has |
|
962 // gone over the initiating threshold and we should start a |
|
963 // concurrent marking cycle. So we might initiate one. |
|
964 |
|
965 if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) { |
|
966 // Initiate a new initial mark if there is no marking or reclamation going on. |
|
967 initiate_conc_mark(); |
|
968 log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)"); |
|
969 } else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) { |
|
970 // Initiate a user requested initial mark. An initial mark must be young only |
|
971 // GC, so the collector state must be updated to reflect this. |
|
972 collector_state()->set_gcs_are_young(true); |
|
973 collector_state()->set_last_young_gc(false); |
|
974 |
|
975 abort_time_to_mixed_tracking(); |
|
976 initiate_conc_mark(); |
|
977 log_debug(gc, ergo)("Initiate concurrent cycle (user requested concurrent cycle)"); |
|
978 } else { |
|
979 // The concurrent marking thread is still finishing up the |
|
980 // previous cycle. If we start one right now the two cycles |
|
981 // overlap. In particular, the concurrent marking thread might |
|
982 // be in the process of clearing the next marking bitmap (which |
|
983 // we will use for the next cycle if we start one). Starting a |
|
984 // cycle now will be bad given that parts of the marking |
|
985 // information might get cleared by the marking thread. And we |
|
986 // cannot wait for the marking thread to finish the cycle as it |
|
987 // periodically yields while clearing the next marking bitmap |
|
988 // and, if it's in a yield point, it's waiting for us to |
|
989 // finish. So, at this point we will not start a cycle and we'll |
|
990 // let the concurrent marking thread complete the last one. |
|
991 log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)"); |
|
992 } |
|
993 } |
|
994 } |
|
995 |
|
996 void G1DefaultPolicy::record_concurrent_mark_cleanup_end() { |
|
997 cset_chooser()->rebuild(_g1->workers(), _g1->num_regions()); |
|
998 |
|
999 double end_sec = os::elapsedTime(); |
|
1000 double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0; |
|
1001 _analytics->report_concurrent_mark_cleanup_times_ms(elapsed_time_ms); |
|
1002 _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms); |
|
1003 |
|
1004 record_pause(Cleanup, _mark_cleanup_start_sec, end_sec); |
|
1005 } |
|
1006 |
|
1007 double G1DefaultPolicy::reclaimable_bytes_percent(size_t reclaimable_bytes) const { |
|
1008 return percent_of(reclaimable_bytes, _g1->capacity()); |
|
1009 } |
|
1010 |
|
1011 void G1DefaultPolicy::maybe_start_marking() { |
|
1012 if (need_to_start_conc_mark("end of GC")) { |
|
1013 // Note: this might have already been set, if during the last |
|
1014 // pause we decided to start a cycle but at the beginning of |
|
1015 // this pause we decided to postpone it. That's OK. |
|
1016 collector_state()->set_initiate_conc_mark_if_possible(true); |
|
1017 } |
|
1018 } |
|
1019 |
|
1020 G1DefaultPolicy::PauseKind G1DefaultPolicy::young_gc_pause_kind() const { |
|
1021 assert(!collector_state()->full_collection(), "must be"); |
|
1022 if (collector_state()->during_initial_mark_pause()) { |
|
1023 assert(collector_state()->last_gc_was_young(), "must be"); |
|
1024 assert(!collector_state()->last_young_gc(), "must be"); |
|
1025 return InitialMarkGC; |
|
1026 } else if (collector_state()->last_young_gc()) { |
|
1027 assert(!collector_state()->during_initial_mark_pause(), "must be"); |
|
1028 assert(collector_state()->last_gc_was_young(), "must be"); |
|
1029 return LastYoungGC; |
|
1030 } else if (!collector_state()->last_gc_was_young()) { |
|
1031 assert(!collector_state()->during_initial_mark_pause(), "must be"); |
|
1032 assert(!collector_state()->last_young_gc(), "must be"); |
|
1033 return MixedGC; |
|
1034 } else { |
|
1035 assert(collector_state()->last_gc_was_young(), "must be"); |
|
1036 assert(!collector_state()->during_initial_mark_pause(), "must be"); |
|
1037 assert(!collector_state()->last_young_gc(), "must be"); |
|
1038 return YoungOnlyGC; |
|
1039 } |
|
1040 } |
|
1041 |
|
1042 void G1DefaultPolicy::record_pause(PauseKind kind, double start, double end) { |
|
1043 // Manage the MMU tracker. For some reason it ignores Full GCs. |
|
1044 if (kind != FullGC) { |
|
1045 _mmu_tracker->add_pause(start, end); |
|
1046 } |
|
1047 // Manage the mutator time tracking from initial mark to first mixed gc. |
|
1048 switch (kind) { |
|
1049 case FullGC: |
|
1050 abort_time_to_mixed_tracking(); |
|
1051 break; |
|
1052 case Cleanup: |
|
1053 case Remark: |
|
1054 case YoungOnlyGC: |
|
1055 case LastYoungGC: |
|
1056 _initial_mark_to_mixed.add_pause(end - start); |
|
1057 break; |
|
1058 case InitialMarkGC: |
|
1059 _initial_mark_to_mixed.record_initial_mark_end(end); |
|
1060 break; |
|
1061 case MixedGC: |
|
1062 _initial_mark_to_mixed.record_mixed_gc_start(start); |
|
1063 break; |
|
1064 default: |
|
1065 ShouldNotReachHere(); |
|
1066 } |
|
1067 } |
|
1068 |
|
1069 void G1DefaultPolicy::abort_time_to_mixed_tracking() { |
|
1070 _initial_mark_to_mixed.reset(); |
|
1071 } |
|
1072 |
|
1073 bool G1DefaultPolicy::next_gc_should_be_mixed(const char* true_action_str, |
|
1074 const char* false_action_str) const { |
|
1075 if (cset_chooser()->is_empty()) { |
|
1076 log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str); |
|
1077 return false; |
|
1078 } |
|
1079 |
|
1080 // Is the amount of uncollected reclaimable space above G1HeapWastePercent? |
|
1081 size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes(); |
|
1082 double reclaimable_percent = reclaimable_bytes_percent(reclaimable_bytes); |
|
1083 double threshold = (double) G1HeapWastePercent; |
|
1084 if (reclaimable_percent <= threshold) { |
|
1085 log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT, |
|
1086 false_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_percent, G1HeapWastePercent); |
|
1087 return false; |
|
1088 } |
|
1089 log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT, |
|
1090 true_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_percent, G1HeapWastePercent); |
|
1091 return true; |
|
1092 } |
|
1093 |
|
1094 uint G1DefaultPolicy::calc_min_old_cset_length() const { |
|
1095 // The min old CSet region bound is based on the maximum desired |
|
1096 // number of mixed GCs after a cycle. I.e., even if some old regions |
|
1097 // look expensive, we should add them to the CSet anyway to make |
|
1098 // sure we go through the available old regions in no more than the |
|
1099 // maximum desired number of mixed GCs. |
|
1100 // |
|
1101 // The calculation is based on the number of marked regions we added |
|
1102 // to the CSet chooser in the first place, not how many remain, so |
|
1103 // that the result is the same during all mixed GCs that follow a cycle. |
|
1104 |
|
1105 const size_t region_num = (size_t) cset_chooser()->length(); |
|
1106 const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1); |
|
1107 size_t result = region_num / gc_num; |
|
1108 // emulate ceiling |
|
1109 if (result * gc_num < region_num) { |
|
1110 result += 1; |
|
1111 } |
|
1112 return (uint) result; |
|
1113 } |
|
1114 |
|
1115 uint G1DefaultPolicy::calc_max_old_cset_length() const { |
|
1116 // The max old CSet region bound is based on the threshold expressed |
|
1117 // as a percentage of the heap size. I.e., it should bound the |
|
1118 // number of old regions added to the CSet irrespective of how many |
|
1119 // of them are available. |
|
1120 |
|
1121 const G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
|
1122 const size_t region_num = g1h->num_regions(); |
|
1123 const size_t perc = (size_t) G1OldCSetRegionThresholdPercent; |
|
1124 size_t result = region_num * perc / 100; |
|
1125 // emulate ceiling |
|
1126 if (100 * result < region_num * perc) { |
|
1127 result += 1; |
|
1128 } |
|
1129 return (uint) result; |
|
1130 } |
|
1131 |
|
1132 void G1DefaultPolicy::finalize_collection_set(double target_pause_time_ms, G1SurvivorRegions* survivor) { |
|
1133 double time_remaining_ms = _collection_set->finalize_young_part(target_pause_time_ms, survivor); |
|
1134 _collection_set->finalize_old_part(time_remaining_ms); |
|
1135 } |
|
1136 |
|
1137 void G1DefaultPolicy::transfer_survivors_to_cset(const G1SurvivorRegions* survivors) { |
|
1138 |
|
1139 // Add survivor regions to SurvRateGroup. |
|
1140 note_start_adding_survivor_regions(); |
|
1141 finished_recalculating_age_indexes(true /* is_survivors */); |
|
1142 |
|
1143 HeapRegion* last = NULL; |
|
1144 for (GrowableArrayIterator<HeapRegion*> it = survivors->regions()->begin(); |
|
1145 it != survivors->regions()->end(); |
|
1146 ++it) { |
|
1147 HeapRegion* curr = *it; |
|
1148 set_region_survivor(curr); |
|
1149 |
|
1150 // The region is a non-empty survivor so let's add it to |
|
1151 // the incremental collection set for the next evacuation |
|
1152 // pause. |
|
1153 _collection_set->add_survivor_regions(curr); |
|
1154 |
|
1155 last = curr; |
|
1156 } |
|
1157 note_stop_adding_survivor_regions(); |
|
1158 |
|
1159 // Don't clear the survivor list handles until the start of |
|
1160 // the next evacuation pause - we need it in order to re-tag |
|
1161 // the survivor regions from this evacuation pause as 'young' |
|
1162 // at the start of the next. |
|
1163 |
|
1164 finished_recalculating_age_indexes(false /* is_survivors */); |
|
1165 } |
|