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1 /*
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2 * Copyright 2004-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // This class keeps statistical information and computes the
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26 // size of the heap.
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27
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28 // Forward decls
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29 class elapsedTimer;
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30
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31 class AdaptiveSizePolicy : public CHeapObj {
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32 friend class GCAdaptivePolicyCounters;
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33 friend class PSGCAdaptivePolicyCounters;
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34 friend class CMSGCAdaptivePolicyCounters;
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35 protected:
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36
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37 enum GCPolicyKind {
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38 _gc_adaptive_size_policy,
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39 _gc_ps_adaptive_size_policy,
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40 _gc_cms_adaptive_size_policy
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41 };
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42 virtual GCPolicyKind kind() const { return _gc_adaptive_size_policy; }
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43
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44 enum SizePolicyTrueValues {
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45 decrease_old_gen_for_throughput_true = -7,
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46 decrease_young_gen_for_througput_true = -6,
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47
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48 increase_old_gen_for_min_pauses_true = -5,
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49 decrease_old_gen_for_min_pauses_true = -4,
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50 decrease_young_gen_for_maj_pauses_true = -3,
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51 increase_young_gen_for_min_pauses_true = -2,
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52 increase_old_gen_for_maj_pauses_true = -1,
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53
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54 decrease_young_gen_for_min_pauses_true = 1,
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55 decrease_old_gen_for_maj_pauses_true = 2,
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56 increase_young_gen_for_maj_pauses_true = 3,
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57
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58 increase_old_gen_for_throughput_true = 4,
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59 increase_young_gen_for_througput_true = 5,
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60
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61 decrease_young_gen_for_footprint_true = 6,
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62 decrease_old_gen_for_footprint_true = 7,
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63 decide_at_full_gc_true = 8
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64 };
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65
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66 // Goal for the fraction of the total time during which application
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67 // threads run.
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68 const double _throughput_goal;
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69
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70 // Last calculated sizes, in bytes, and aligned
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71 size_t _eden_size; // calculated eden free space in bytes
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72 size_t _promo_size; // calculated cms gen free space in bytes
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73
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74 size_t _survivor_size; // calculated survivor size in bytes
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75
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76 // This is a hint for the heap: we've detected that gc times
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77 // are taking longer than GCTimeLimit allows.
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78 bool _gc_time_limit_exceeded;
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79 // Use for diagnostics only. If UseGCTimeLimit is false,
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80 // this variable is still set.
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81 bool _print_gc_time_limit_would_be_exceeded;
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82 // Count of consecutive GC that have exceeded the
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83 // GC time limit criterion.
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84 uint _gc_time_limit_count;
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85
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86 // Minor collection timers used to determine both
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87 // pause and interval times for collections.
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88 static elapsedTimer _minor_timer;
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89
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90 // Major collection timers, used to determine both
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91 // pause and interval times for collections
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92 static elapsedTimer _major_timer;
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93
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94 // Time statistics
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95 AdaptivePaddedAverage* _avg_minor_pause;
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96 AdaptiveWeightedAverage* _avg_minor_interval;
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97 AdaptiveWeightedAverage* _avg_minor_gc_cost;
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98
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99 AdaptiveWeightedAverage* _avg_major_interval;
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100 AdaptiveWeightedAverage* _avg_major_gc_cost;
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101
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102 // Footprint statistics
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103 AdaptiveWeightedAverage* _avg_young_live;
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104 AdaptiveWeightedAverage* _avg_eden_live;
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105 AdaptiveWeightedAverage* _avg_old_live;
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106
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107 // Statistics for survivor space calculation for young generation
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108 AdaptivePaddedAverage* _avg_survived;
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109
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110 // Objects that have been directly allocated in the old generation.
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111 AdaptivePaddedNoZeroDevAverage* _avg_pretenured;
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112
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113 // Variable for estimating the major and minor pause times.
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114 // These variables represent linear least-squares fits of
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115 // the data.
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116 // minor pause time vs. old gen size
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117 LinearLeastSquareFit* _minor_pause_old_estimator;
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118 // minor pause time vs. young gen size
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119 LinearLeastSquareFit* _minor_pause_young_estimator;
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120
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121 // Variables for estimating the major and minor collection costs
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122 // minor collection time vs. young gen size
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123 LinearLeastSquareFit* _minor_collection_estimator;
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124 // major collection time vs. cms gen size
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125 LinearLeastSquareFit* _major_collection_estimator;
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126
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127 // These record the most recent collection times. They
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128 // are available as an alternative to using the averages
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129 // for making ergonomic decisions.
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130 double _latest_minor_mutator_interval_seconds;
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131
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132 // Allowed difference between major and minor gc times, used
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133 // for computing tenuring_threshold.
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134 const double _threshold_tolerance_percent;
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135
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136 const double _gc_pause_goal_sec; // goal for maximum gc pause
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137
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138 // Flag indicating that the adaptive policy is ready to use
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139 bool _young_gen_policy_is_ready;
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140
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141 // decrease/increase the young generation for minor pause time
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142 int _change_young_gen_for_min_pauses;
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143
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144 // decrease/increase the old generation for major pause time
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145 int _change_old_gen_for_maj_pauses;
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146
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147 // change old geneneration for throughput
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148 int _change_old_gen_for_throughput;
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149
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150 // change young generation for throughput
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151 int _change_young_gen_for_throughput;
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152
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153 // Flag indicating that the policy would
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154 // increase the tenuring threshold because of the total major gc cost
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155 // is greater than the total minor gc cost
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156 bool _increment_tenuring_threshold_for_gc_cost;
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157 // decrease the tenuring threshold because of the the total minor gc
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158 // cost is greater than the total major gc cost
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159 bool _decrement_tenuring_threshold_for_gc_cost;
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160 // decrease due to survivor size limit
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161 bool _decrement_tenuring_threshold_for_survivor_limit;
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162
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163 // decrease generation sizes for footprint
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164 int _decrease_for_footprint;
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165
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166 // Set if the ergonomic decisions were made at a full GC.
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167 int _decide_at_full_gc;
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168
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169 // Changing the generation sizing depends on the data that is
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170 // gathered about the effects of changes on the pause times and
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171 // throughput. These variable count the number of data points
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172 // gathered. The policy may use these counters as a threshhold
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173 // for reliable data.
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174 julong _young_gen_change_for_minor_throughput;
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175 julong _old_gen_change_for_major_throughput;
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176
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177 // Accessors
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178
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179 double gc_pause_goal_sec() const { return _gc_pause_goal_sec; }
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180 // The value returned is unitless: it's the proportion of time
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181 // spent in a particular collection type.
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182 // An interval time will be 0.0 if a collection type hasn't occurred yet.
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183 // The 1.4.2 implementation put a floor on the values of major_gc_cost
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184 // and minor_gc_cost. This was useful because of the way major_gc_cost
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185 // and minor_gc_cost was used in calculating the sizes of the generations.
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186 // Do not use a floor in this implementation because any finite value
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187 // will put a limit on the throughput that can be achieved and any
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188 // throughput goal above that limit will drive the generations sizes
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189 // to extremes.
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190 double major_gc_cost() const {
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191 return MAX2(0.0F, _avg_major_gc_cost->average());
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192 }
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193
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194 // The value returned is unitless: it's the proportion of time
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195 // spent in a particular collection type.
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196 // An interval time will be 0.0 if a collection type hasn't occurred yet.
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197 // The 1.4.2 implementation put a floor on the values of major_gc_cost
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198 // and minor_gc_cost. This was useful because of the way major_gc_cost
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199 // and minor_gc_cost was used in calculating the sizes of the generations.
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200 // Do not use a floor in this implementation because any finite value
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201 // will put a limit on the throughput that can be achieved and any
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202 // throughput goal above that limit will drive the generations sizes
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203 // to extremes.
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204
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205 double minor_gc_cost() const {
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206 return MAX2(0.0F, _avg_minor_gc_cost->average());
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207 }
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208
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209 // Because we're dealing with averages, gc_cost() can be
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210 // larger than 1.0 if just the sum of the minor cost the
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211 // the major cost is used. Worse than that is the
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212 // fact that the minor cost and the major cost each
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213 // tend toward 1.0 in the extreme of high gc costs.
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214 // Limit the value of gc_cost to 1.0 so that the mutator
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215 // cost stays non-negative.
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216 virtual double gc_cost() const {
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217 double result = MIN2(1.0, minor_gc_cost() + major_gc_cost());
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218 assert(result >= 0.0, "Both minor and major costs are non-negative");
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219 return result;
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220 }
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221
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222 // Elapsed time since the last major collection.
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223 virtual double time_since_major_gc() const;
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224
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225 // Average interval between major collections to be used
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226 // in calculating the decaying major gc cost. An overestimate
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227 // of this time would be a conservative estimate because
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228 // this time is used to decide if the major GC cost
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229 // should be decayed (i.e., if the time since the last
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230 // major gc is long compared to the time returned here,
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231 // then the major GC cost will be decayed). See the
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232 // implementations for the specifics.
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233 virtual double major_gc_interval_average_for_decay() const {
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234 return _avg_major_interval->average();
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235 }
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236
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237 // Return the cost of the GC where the major gc cost
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238 // has been decayed based on the time since the last
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239 // major collection.
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240 double decaying_gc_cost() const;
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241
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242 // Decay the major gc cost. Use this only for decisions on
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243 // whether to adjust, not to determine by how much to adjust.
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244 // This approximation is crude and may not be good enough for the
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245 // latter.
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246 double decaying_major_gc_cost() const;
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247
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248 // Return the mutator cost using the decayed
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249 // GC cost.
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250 double adjusted_mutator_cost() const {
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251 double result = 1.0 - decaying_gc_cost();
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252 assert(result >= 0.0, "adjusted mutator cost calculation is incorrect");
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253 return result;
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254 }
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255
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256 virtual double mutator_cost() const {
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257 double result = 1.0 - gc_cost();
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258 assert(result >= 0.0, "mutator cost calculation is incorrect");
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259 return result;
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260 }
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261
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262
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263 bool young_gen_policy_is_ready() { return _young_gen_policy_is_ready; }
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264
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265 void update_minor_pause_young_estimator(double minor_pause_in_ms);
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266 virtual void update_minor_pause_old_estimator(double minor_pause_in_ms) {
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267 // This is not meaningful for all policies but needs to be present
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268 // to use minor_collection_end() in its current form.
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269 }
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270
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271 virtual size_t eden_increment(size_t cur_eden);
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272 virtual size_t eden_increment(size_t cur_eden, uint percent_change);
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273 virtual size_t eden_decrement(size_t cur_eden);
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274 virtual size_t promo_increment(size_t cur_eden);
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275 virtual size_t promo_increment(size_t cur_eden, uint percent_change);
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276 virtual size_t promo_decrement(size_t cur_eden);
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277
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278 virtual void clear_generation_free_space_flags();
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279
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280 int change_old_gen_for_throughput() const {
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281 return _change_old_gen_for_throughput;
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282 }
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283 void set_change_old_gen_for_throughput(int v) {
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284 _change_old_gen_for_throughput = v;
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285 }
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286 int change_young_gen_for_throughput() const {
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287 return _change_young_gen_for_throughput;
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288 }
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289 void set_change_young_gen_for_throughput(int v) {
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290 _change_young_gen_for_throughput = v;
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291 }
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292
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293 int change_old_gen_for_maj_pauses() const {
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294 return _change_old_gen_for_maj_pauses;
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295 }
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296 void set_change_old_gen_for_maj_pauses(int v) {
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297 _change_old_gen_for_maj_pauses = v;
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298 }
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299
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300 bool decrement_tenuring_threshold_for_gc_cost() const {
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301 return _decrement_tenuring_threshold_for_gc_cost;
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302 }
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303 void set_decrement_tenuring_threshold_for_gc_cost(bool v) {
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304 _decrement_tenuring_threshold_for_gc_cost = v;
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305 }
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306 bool increment_tenuring_threshold_for_gc_cost() const {
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307 return _increment_tenuring_threshold_for_gc_cost;
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308 }
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309 void set_increment_tenuring_threshold_for_gc_cost(bool v) {
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310 _increment_tenuring_threshold_for_gc_cost = v;
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311 }
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312 bool decrement_tenuring_threshold_for_survivor_limit() const {
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313 return _decrement_tenuring_threshold_for_survivor_limit;
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314 }
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315 void set_decrement_tenuring_threshold_for_survivor_limit(bool v) {
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316 _decrement_tenuring_threshold_for_survivor_limit = v;
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317 }
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318 // Return true if the policy suggested a change.
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319 bool tenuring_threshold_change() const;
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320
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321 public:
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322 AdaptiveSizePolicy(size_t init_eden_size,
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323 size_t init_promo_size,
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324 size_t init_survivor_size,
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325 double gc_pause_goal_sec,
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326 uint gc_cost_ratio);
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327
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328 bool is_gc_cms_adaptive_size_policy() {
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329 return kind() == _gc_cms_adaptive_size_policy;
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330 }
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331 bool is_gc_ps_adaptive_size_policy() {
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332 return kind() == _gc_ps_adaptive_size_policy;
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333 }
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334
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335 AdaptivePaddedAverage* avg_minor_pause() const { return _avg_minor_pause; }
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336 AdaptiveWeightedAverage* avg_minor_interval() const {
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337 return _avg_minor_interval;
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338 }
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339 AdaptiveWeightedAverage* avg_minor_gc_cost() const {
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340 return _avg_minor_gc_cost;
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341 }
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342
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343 AdaptiveWeightedAverage* avg_major_gc_cost() const {
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344 return _avg_major_gc_cost;
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345 }
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346
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347 AdaptiveWeightedAverage* avg_young_live() const { return _avg_young_live; }
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348 AdaptiveWeightedAverage* avg_eden_live() const { return _avg_eden_live; }
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349 AdaptiveWeightedAverage* avg_old_live() const { return _avg_old_live; }
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350
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351 AdaptivePaddedAverage* avg_survived() const { return _avg_survived; }
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352 AdaptivePaddedNoZeroDevAverage* avg_pretenured() { return _avg_pretenured; }
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353
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354 // Methods indicating events of interest to the adaptive size policy,
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355 // called by GC algorithms. It is the responsibility of users of this
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356 // policy to call these methods at the correct times!
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357 virtual void minor_collection_begin();
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358 virtual void minor_collection_end(GCCause::Cause gc_cause);
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359 virtual LinearLeastSquareFit* minor_pause_old_estimator() const {
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360 return _minor_pause_old_estimator;
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361 }
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362
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363 LinearLeastSquareFit* minor_pause_young_estimator() {
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364 return _minor_pause_young_estimator;
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365 }
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366 LinearLeastSquareFit* minor_collection_estimator() {
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367 return _minor_collection_estimator;
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368 }
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369
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370 LinearLeastSquareFit* major_collection_estimator() {
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371 return _major_collection_estimator;
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372 }
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373
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374 float minor_pause_young_slope() {
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375 return _minor_pause_young_estimator->slope();
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376 }
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377
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378 float minor_collection_slope() { return _minor_collection_estimator->slope();}
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379 float major_collection_slope() { return _major_collection_estimator->slope();}
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380
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381 float minor_pause_old_slope() {
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382 return _minor_pause_old_estimator->slope();
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383 }
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384
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385 void set_eden_size(size_t new_size) {
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386 _eden_size = new_size;
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387 }
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388 void set_survivor_size(size_t new_size) {
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389 _survivor_size = new_size;
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390 }
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391
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392 size_t calculated_eden_size_in_bytes() const {
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393 return _eden_size;
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394 }
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395
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396 size_t calculated_promo_size_in_bytes() const {
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397 return _promo_size;
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398 }
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399
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400 size_t calculated_survivor_size_in_bytes() const {
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401 return _survivor_size;
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402 }
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403
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404 // This is a hint for the heap: we've detected that gc times
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405 // are taking longer than GCTimeLimit allows.
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406 // Most heaps will choose to throw an OutOfMemoryError when
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407 // this occurs but it is up to the heap to request this information
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408 // of the policy
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409 bool gc_time_limit_exceeded() {
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410 return _gc_time_limit_exceeded;
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411 }
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412 void set_gc_time_limit_exceeded(bool v) {
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413 _gc_time_limit_exceeded = v;
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414 }
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415 bool print_gc_time_limit_would_be_exceeded() {
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416 return _print_gc_time_limit_would_be_exceeded;
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417 }
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418 void set_print_gc_time_limit_would_be_exceeded(bool v) {
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419 _print_gc_time_limit_would_be_exceeded = v;
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420 }
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421
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422 uint gc_time_limit_count() { return _gc_time_limit_count; }
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423 void reset_gc_time_limit_count() { _gc_time_limit_count = 0; }
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424 void inc_gc_time_limit_count() { _gc_time_limit_count++; }
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425 // accessors for flags recording the decisions to resize the
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426 // generations to meet the pause goal.
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427
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428 int change_young_gen_for_min_pauses() const {
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429 return _change_young_gen_for_min_pauses;
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430 }
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431 void set_change_young_gen_for_min_pauses(int v) {
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432 _change_young_gen_for_min_pauses = v;
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433 }
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434 void set_decrease_for_footprint(int v) { _decrease_for_footprint = v; }
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435 int decrease_for_footprint() const { return _decrease_for_footprint; }
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436 int decide_at_full_gc() { return _decide_at_full_gc; }
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437 void set_decide_at_full_gc(int v) { _decide_at_full_gc = v; }
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438
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439 // Printing support
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440 virtual bool print_adaptive_size_policy_on(outputStream* st) const;
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441 bool print_adaptive_size_policy_on(outputStream* st, int
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442 tenuring_threshold) const;
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443 };
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444
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445 // Class that can be used to print information about the
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446 // adaptive size policy at intervals specified by
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447 // AdaptiveSizePolicyOutputInterval. Only print information
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448 // if an adaptive size policy is in use.
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449 class AdaptiveSizePolicyOutput : StackObj {
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450 AdaptiveSizePolicy* _size_policy;
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451 bool _do_print;
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452 bool print_test(uint count) {
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453 // A count of zero is a special value that indicates that the
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454 // interval test should be ignored. An interval is of zero is
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455 // a special value that indicates that the interval test should
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456 // always fail (never do the print based on the interval test).
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457 return PrintGCDetails &&
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458 UseAdaptiveSizePolicy &&
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459 (UseParallelGC || UseConcMarkSweepGC) &&
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460 (AdaptiveSizePolicyOutputInterval > 0) &&
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461 ((count == 0) ||
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462 ((count % AdaptiveSizePolicyOutputInterval) == 0));
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463 }
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464 public:
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465 // The special value of a zero count can be used to ignore
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466 // the count test.
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467 AdaptiveSizePolicyOutput(uint count) {
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468 if (UseAdaptiveSizePolicy && (AdaptiveSizePolicyOutputInterval > 0)) {
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469 CollectedHeap* heap = Universe::heap();
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470 _size_policy = heap->size_policy();
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471 _do_print = print_test(count);
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472 } else {
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473 _size_policy = NULL;
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474 _do_print = false;
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475 }
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476 }
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477 AdaptiveSizePolicyOutput(AdaptiveSizePolicy* size_policy,
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478 uint count) :
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479 _size_policy(size_policy) {
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480 if (UseAdaptiveSizePolicy && (AdaptiveSizePolicyOutputInterval > 0)) {
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481 _do_print = print_test(count);
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482 } else {
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483 _do_print = false;
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484 }
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485 }
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486 ~AdaptiveSizePolicyOutput() {
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487 if (_do_print) {
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488 assert(UseAdaptiveSizePolicy, "Should not be in use");
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489 _size_policy->print_adaptive_size_policy_on(gclog_or_tty);
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490 }
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491 }
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492 };
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