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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 for the concurrent mark sweep collector.
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27 //
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28 // Cost for garbage collector include cost for
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29 // minor collection
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30 // concurrent collection
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31 // stop-the-world component
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32 // concurrent component
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33 // major compacting collection
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34 // uses decaying cost
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35
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36 // Forward decls
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37 class elapsedTimer;
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38
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39 class CMSAdaptiveSizePolicy : public AdaptiveSizePolicy {
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40 friend class CMSGCAdaptivePolicyCounters;
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41 friend class CMSCollector;
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42 private:
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43
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44 // Total number of processors available
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45 int _processor_count;
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46 // Number of processors used by the concurrent phases of GC
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47 // This number is assumed to be the same for all concurrent
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48 // phases.
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49 int _concurrent_processor_count;
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50
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51 // Time that the mutators run exclusive of a particular
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52 // phase. For example, the time the mutators run excluding
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53 // the time during which the cms collector runs concurrently
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54 // with the mutators.
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55 // Between end of most recent cms reset and start of initial mark
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56 // This may be redundant
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57 double _latest_cms_reset_end_to_initial_mark_start_secs;
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58 // Between end of the most recent initial mark and start of remark
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59 double _latest_cms_initial_mark_end_to_remark_start_secs;
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60 // Between end of most recent collection and start of
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61 // a concurrent collection
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62 double _latest_cms_collection_end_to_collection_start_secs;
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63 // Times of the concurrent phases of the most recent
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64 // concurrent collection
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65 double _latest_cms_concurrent_marking_time_secs;
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66 double _latest_cms_concurrent_precleaning_time_secs;
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67 double _latest_cms_concurrent_sweeping_time_secs;
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68 // Between end of most recent STW MSC and start of next STW MSC
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69 double _latest_cms_msc_end_to_msc_start_time_secs;
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70 // Between end of most recent MS and start of next MS
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71 // This does not include any time spent during a concurrent
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72 // collection.
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73 double _latest_cms_ms_end_to_ms_start;
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74 // Between start and end of the initial mark of the most recent
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75 // concurrent collection.
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76 double _latest_cms_initial_mark_start_to_end_time_secs;
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77 // Between start and end of the remark phase of the most recent
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78 // concurrent collection
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79 double _latest_cms_remark_start_to_end_time_secs;
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80 // Between start and end of the most recent MS STW marking phase
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81 double _latest_cms_ms_marking_start_to_end_time_secs;
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82
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83 // Pause time timers
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84 static elapsedTimer _STW_timer;
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85 // Concurrent collection timer. Used for total of all concurrent phases
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86 // during 1 collection cycle.
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87 static elapsedTimer _concurrent_timer;
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88
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89 // When the size of the generation is changed, the size
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90 // of the change will rounded up or down (depending on the
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91 // type of change) by this value.
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92 size_t _generation_alignment;
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93
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94 // If this variable is true, the size of the young generation
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95 // may be changed in order to reduce the pause(s) of the
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96 // collection of the tenured generation in order to meet the
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97 // pause time goal. It is common to change the size of the
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98 // tenured generation in order to meet the pause time goal
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99 // for the tenured generation. With the CMS collector for
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100 // the tenured generation, the size of the young generation
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101 // can have an significant affect on the pause times for collecting the
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102 // tenured generation.
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103 // This is a duplicate of a variable in PSAdaptiveSizePolicy. It
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104 // is duplicated because it is not clear that it is general enough
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105 // to go into AdaptiveSizePolicy.
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106 int _change_young_gen_for_maj_pauses;
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107
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108 // Variable that is set to true after a collection.
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109 bool _first_after_collection;
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110
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111 // Fraction of collections that are of each type
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112 double concurrent_fraction() const;
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113 double STW_msc_fraction() const;
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114 double STW_ms_fraction() const;
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115
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116 // This call cannot be put into the epilogue as long as some
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117 // of the counters can be set during concurrent phases.
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118 virtual void clear_generation_free_space_flags();
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119
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120 void set_first_after_collection() { _first_after_collection = true; }
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121
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122 protected:
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123 // Average of the sum of the concurrent times for
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124 // one collection in seconds.
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125 AdaptiveWeightedAverage* _avg_concurrent_time;
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126 // Average time between concurrent collections in seconds.
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127 AdaptiveWeightedAverage* _avg_concurrent_interval;
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128 // Average cost of the concurrent part of a collection
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129 // in seconds.
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130 AdaptiveWeightedAverage* _avg_concurrent_gc_cost;
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131
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132 // Average of the initial pause of a concurrent collection in seconds.
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133 AdaptivePaddedAverage* _avg_initial_pause;
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134 // Average of the remark pause of a concurrent collection in seconds.
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135 AdaptivePaddedAverage* _avg_remark_pause;
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136
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137 // Average of the stop-the-world (STW) (initial mark + remark)
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138 // times in seconds for concurrent collections.
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139 AdaptiveWeightedAverage* _avg_cms_STW_time;
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140 // Average of the STW collection cost for concurrent collections.
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141 AdaptiveWeightedAverage* _avg_cms_STW_gc_cost;
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142
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143 // Average of the bytes free at the start of the sweep.
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144 AdaptiveWeightedAverage* _avg_cms_free_at_sweep;
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145 // Average of the bytes free at the end of the collection.
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146 AdaptiveWeightedAverage* _avg_cms_free;
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147 // Average of the bytes promoted between cms collections.
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148 AdaptiveWeightedAverage* _avg_cms_promo;
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149
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150 // stop-the-world (STW) mark-sweep-compact
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151 // Average of the pause time in seconds for STW mark-sweep-compact
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152 // collections.
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153 AdaptiveWeightedAverage* _avg_msc_pause;
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154 // Average of the interval in seconds between STW mark-sweep-compact
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155 // collections.
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156 AdaptiveWeightedAverage* _avg_msc_interval;
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157 // Average of the collection costs for STW mark-sweep-compact
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158 // collections.
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159 AdaptiveWeightedAverage* _avg_msc_gc_cost;
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160
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161 // Averages for mark-sweep collections.
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162 // The collection may have started as a background collection
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163 // that completes in a stop-the-world (STW) collection.
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164 // Average of the pause time in seconds for mark-sweep
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165 // collections.
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166 AdaptiveWeightedAverage* _avg_ms_pause;
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167 // Average of the interval in seconds between mark-sweep
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168 // collections.
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169 AdaptiveWeightedAverage* _avg_ms_interval;
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170 // Average of the collection costs for mark-sweep
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171 // collections.
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172 AdaptiveWeightedAverage* _avg_ms_gc_cost;
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173
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174 // These variables contain a linear fit of
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175 // a generation size as the independent variable
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176 // and a pause time as the dependent variable.
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177 // For example _remark_pause_old_estimator
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178 // is a fit of the old generation size as the
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179 // independent variable and the remark pause
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180 // as the dependent variable.
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181 // remark pause time vs. cms gen size
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182 LinearLeastSquareFit* _remark_pause_old_estimator;
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183 // initial pause time vs. cms gen size
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184 LinearLeastSquareFit* _initial_pause_old_estimator;
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185 // remark pause time vs. young gen size
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186 LinearLeastSquareFit* _remark_pause_young_estimator;
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187 // initial pause time vs. young gen size
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188 LinearLeastSquareFit* _initial_pause_young_estimator;
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189
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190 // Accessors
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191 int processor_count() const { return _processor_count; }
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192 int concurrent_processor_count() const { return _concurrent_processor_count; }
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193
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194 AdaptiveWeightedAverage* avg_concurrent_time() const {
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195 return _avg_concurrent_time;
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196 }
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197
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198 AdaptiveWeightedAverage* avg_concurrent_interval() const {
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199 return _avg_concurrent_interval;
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200 }
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201
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202 AdaptiveWeightedAverage* avg_concurrent_gc_cost() const {
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203 return _avg_concurrent_gc_cost;
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204 }
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205
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206 AdaptiveWeightedAverage* avg_cms_STW_time() const {
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207 return _avg_cms_STW_time;
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208 }
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209
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210 AdaptiveWeightedAverage* avg_cms_STW_gc_cost() const {
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211 return _avg_cms_STW_gc_cost;
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212 }
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213
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214 AdaptivePaddedAverage* avg_initial_pause() const {
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215 return _avg_initial_pause;
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216 }
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217
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218 AdaptivePaddedAverage* avg_remark_pause() const {
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219 return _avg_remark_pause;
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220 }
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221
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222 AdaptiveWeightedAverage* avg_cms_free() const {
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223 return _avg_cms_free;
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224 }
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225
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226 AdaptiveWeightedAverage* avg_cms_free_at_sweep() const {
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227 return _avg_cms_free_at_sweep;
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228 }
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229
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230 AdaptiveWeightedAverage* avg_msc_pause() const {
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231 return _avg_msc_pause;
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232 }
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233
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234 AdaptiveWeightedAverage* avg_msc_interval() const {
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235 return _avg_msc_interval;
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236 }
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237
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238 AdaptiveWeightedAverage* avg_msc_gc_cost() const {
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239 return _avg_msc_gc_cost;
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240 }
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241
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242 AdaptiveWeightedAverage* avg_ms_pause() const {
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243 return _avg_ms_pause;
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244 }
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245
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246 AdaptiveWeightedAverage* avg_ms_interval() const {
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247 return _avg_ms_interval;
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248 }
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249
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250 AdaptiveWeightedAverage* avg_ms_gc_cost() const {
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251 return _avg_ms_gc_cost;
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252 }
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253
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254 LinearLeastSquareFit* remark_pause_old_estimator() {
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255 return _remark_pause_old_estimator;
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256 }
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257 LinearLeastSquareFit* initial_pause_old_estimator() {
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258 return _initial_pause_old_estimator;
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259 }
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260 LinearLeastSquareFit* remark_pause_young_estimator() {
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261 return _remark_pause_young_estimator;
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262 }
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263 LinearLeastSquareFit* initial_pause_young_estimator() {
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264 return _initial_pause_young_estimator;
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265 }
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266
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267 // These *slope() methods return the slope
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268 // m for the linear fit of an independent
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269 // variable vs. a dependent variable. For
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270 // example
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271 // remark_pause = m * old_generation_size + c
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272 // These may be used to determine if an
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273 // adjustment should be made to achieve a goal.
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274 // For example, if remark_pause_old_slope() is
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275 // positive, a reduction of the old generation
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276 // size has on average resulted in the reduction
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277 // of the remark pause.
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278 float remark_pause_old_slope() {
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279 return _remark_pause_old_estimator->slope();
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280 }
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281
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282 float initial_pause_old_slope() {
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283 return _initial_pause_old_estimator->slope();
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284 }
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285
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286 float remark_pause_young_slope() {
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287 return _remark_pause_young_estimator->slope();
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288 }
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289
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290 float initial_pause_young_slope() {
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291 return _initial_pause_young_estimator->slope();
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292 }
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293
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294 // Update estimators
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295 void update_minor_pause_old_estimator(double minor_pause_in_ms);
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296
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297 // Fraction of processors used by the concurrent phases.
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298 double concurrent_processor_fraction();
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299
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300 // Returns the total times for the concurrent part of the
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301 // latest collection in seconds.
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302 double concurrent_collection_time();
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303
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304 // Return the total times for the concurrent part of the
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305 // latest collection in seconds where the times of the various
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306 // concurrent phases are scaled by the processor fraction used
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307 // during the phase.
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308 double scaled_concurrent_collection_time();
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309
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310 // Dimensionless concurrent GC cost for all the concurrent phases.
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311 double concurrent_collection_cost(double interval_in_seconds);
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312
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313 // Dimensionless GC cost
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314 double collection_cost(double pause_in_seconds, double interval_in_seconds);
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315
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316 virtual GCPolicyKind kind() const { return _gc_cms_adaptive_size_policy; }
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317
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318 virtual double time_since_major_gc() const;
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319
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320 // This returns the maximum average for the concurrent, ms, and
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321 // msc collections. This is meant to be used for the calculation
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322 // of the decayed major gc cost and is not in general the
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323 // average of all the different types of major collections.
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324 virtual double major_gc_interval_average_for_decay() const;
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325
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326 public:
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327 CMSAdaptiveSizePolicy(size_t init_eden_size,
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328 size_t init_promo_size,
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329 size_t init_survivor_size,
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330 double max_gc_minor_pause_sec,
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331 double max_gc_pause_sec,
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332 uint gc_cost_ratio);
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333
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334 // The timers for the stop-the-world phases measure a total
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335 // stop-the-world time. The timer is started and stopped
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336 // for each phase but is only reset after the final checkpoint.
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337 void checkpoint_roots_initial_begin();
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338 void checkpoint_roots_initial_end(GCCause::Cause gc_cause);
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339 void checkpoint_roots_final_begin();
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340 void checkpoint_roots_final_end(GCCause::Cause gc_cause);
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341
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342 // Methods for gathering information about the
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343 // concurrent marking phase of the collection.
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344 // Records the mutator times and
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345 // resets the concurrent timer.
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346 void concurrent_marking_begin();
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347 // Resets concurrent phase timer in the begin methods and
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348 // saves the time for a phase in the end methods.
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349 void concurrent_marking_end();
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350 void concurrent_sweeping_begin();
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351 void concurrent_sweeping_end();
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352 // Similar to the above (e.g., concurrent_marking_end()) and
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353 // is used for both the precleaning an abortable precleaing
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354 // phases.
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355 void concurrent_precleaning_begin();
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356 void concurrent_precleaning_end();
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357 // Stops the concurrent phases time. Gathers
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358 // information and resets the timer.
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359 void concurrent_phases_end(GCCause::Cause gc_cause,
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360 size_t cur_eden,
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361 size_t cur_promo);
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362
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363 // Methods for gather information about STW Mark-Sweep-Compact
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364 void msc_collection_begin();
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365 void msc_collection_end(GCCause::Cause gc_cause);
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366
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367 // Methods for gather information about Mark-Sweep done
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368 // in the foreground.
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369 void ms_collection_begin();
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370 void ms_collection_end(GCCause::Cause gc_cause);
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371
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372 // Cost for a mark-sweep tenured gen collection done in the foreground
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373 double ms_gc_cost() const {
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374 return MAX2(0.0F, _avg_ms_gc_cost->average());
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375 }
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376
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377 // Cost of collecting the tenured generation. Includes
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378 // concurrent collection and STW collection costs
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379 double cms_gc_cost() const;
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380
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381 // Cost of STW mark-sweep-compact tenured gen collection.
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382 double msc_gc_cost() const {
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383 return MAX2(0.0F, _avg_msc_gc_cost->average());
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384 }
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385
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386 //
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387 double compacting_gc_cost() const {
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388 double result = MIN2(1.0, minor_gc_cost() + msc_gc_cost());
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389 assert(result >= 0.0, "Both minor and major costs are non-negative");
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390 return result;
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391 }
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392
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393 // Restarts the concurrent phases timer.
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394 void concurrent_phases_resume();
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395
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396 // Time begining and end of the marking phase for
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397 // a synchronous MS collection. A MS collection
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398 // that finishes in the foreground can have started
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399 // in the background. These methods capture the
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400 // completion of the marking (after the initial
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401 // marking) that is done in the foreground.
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402 void ms_collection_marking_begin();
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403 void ms_collection_marking_end(GCCause::Cause gc_cause);
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404
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405 static elapsedTimer* concurrent_timer_ptr() {
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406 return &_concurrent_timer;
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407 }
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408
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409 AdaptiveWeightedAverage* avg_cms_promo() const {
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410 return _avg_cms_promo;
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411 }
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412
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413 int change_young_gen_for_maj_pauses() {
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414 return _change_young_gen_for_maj_pauses;
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415 }
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416 void set_change_young_gen_for_maj_pauses(int v) {
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417 _change_young_gen_for_maj_pauses = v;
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418 }
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419
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420 void clear_internal_time_intervals();
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421
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422
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423 // Either calculated_promo_size_in_bytes() or promo_size()
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424 // should be deleted.
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425 size_t promo_size() { return _promo_size; }
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426 void set_promo_size(size_t v) { _promo_size = v; }
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427
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428 // Cost of GC for all types of collections.
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429 virtual double gc_cost() const;
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430
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431 size_t generation_alignment() { return _generation_alignment; }
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432
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433 virtual void compute_young_generation_free_space(size_t cur_eden,
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434 size_t max_eden_size);
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435 // Calculates new survivor space size; returns a new tenuring threshold
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436 // value. Stores new survivor size in _survivor_size.
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437 virtual int compute_survivor_space_size_and_threshold(
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438 bool is_survivor_overflow,
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439 int tenuring_threshold,
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440 size_t survivor_limit);
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441
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442 virtual void compute_tenured_generation_free_space(size_t cur_tenured_free,
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443 size_t max_tenured_available,
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444 size_t cur_eden);
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445
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446 size_t eden_decrement_aligned_down(size_t cur_eden);
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447 size_t eden_increment_aligned_up(size_t cur_eden);
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448
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449 size_t adjust_eden_for_pause_time(size_t cur_eden);
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450 size_t adjust_eden_for_throughput(size_t cur_eden);
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451 size_t adjust_eden_for_footprint(size_t cur_eden);
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452
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453 size_t promo_decrement_aligned_down(size_t cur_promo);
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454 size_t promo_increment_aligned_up(size_t cur_promo);
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455
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456 size_t adjust_promo_for_pause_time(size_t cur_promo);
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457 size_t adjust_promo_for_throughput(size_t cur_promo);
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458 size_t adjust_promo_for_footprint(size_t cur_promo, size_t cur_eden);
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459
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460 // Scale down the input size by the ratio of the cost to collect the
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461 // generation to the total GC cost.
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462 size_t scale_by_gen_gc_cost(size_t base_change, double gen_gc_cost);
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463
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464 // Return the value and clear it.
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465 bool get_and_clear_first_after_collection();
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466
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467 // Printing support
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468 virtual bool print_adaptive_size_policy_on(outputStream* st) const;
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469 };
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