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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 #include "incls/_precompiled.incl"
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25 #include "incls/_adaptiveSizePolicy.cpp.incl"
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26
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27 elapsedTimer AdaptiveSizePolicy::_minor_timer;
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28 elapsedTimer AdaptiveSizePolicy::_major_timer;
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29
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30 // The throughput goal is implemented as
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31 // _throughput_goal = 1 - ( 1 / (1 + gc_cost_ratio))
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32 // gc_cost_ratio is the ratio
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33 // application cost / gc cost
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34 // For example a gc_cost_ratio of 4 translates into a
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35 // throughput goal of .80
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36
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37 AdaptiveSizePolicy::AdaptiveSizePolicy(size_t init_eden_size,
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38 size_t init_promo_size,
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39 size_t init_survivor_size,
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40 double gc_pause_goal_sec,
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41 uint gc_cost_ratio) :
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42 _eden_size(init_eden_size),
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43 _promo_size(init_promo_size),
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44 _survivor_size(init_survivor_size),
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45 _gc_pause_goal_sec(gc_pause_goal_sec),
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46 _throughput_goal(1.0 - double(1.0 / (1.0 + (double) gc_cost_ratio))),
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47 _gc_time_limit_exceeded(false),
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48 _print_gc_time_limit_would_be_exceeded(false),
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49 _gc_time_limit_count(0),
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50 _latest_minor_mutator_interval_seconds(0),
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51 _threshold_tolerance_percent(1.0 + ThresholdTolerance/100.0),
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52 _young_gen_change_for_minor_throughput(0),
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53 _old_gen_change_for_major_throughput(0) {
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54 _avg_minor_pause =
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55 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
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56 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
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57 _avg_minor_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
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58 _avg_major_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
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59
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60 _avg_young_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
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61 _avg_old_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
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62 _avg_eden_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
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63
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64 _avg_survived = new AdaptivePaddedAverage(AdaptiveSizePolicyWeight,
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65 SurvivorPadding);
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66 _avg_pretenured = new AdaptivePaddedNoZeroDevAverage(
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67 AdaptiveSizePolicyWeight,
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68 SurvivorPadding);
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69
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70 _minor_pause_old_estimator =
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71 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
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72 _minor_pause_young_estimator =
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73 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
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74 _minor_collection_estimator =
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75 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
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76 _major_collection_estimator =
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77 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
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78
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79 // Start the timers
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80 _minor_timer.start();
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81
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82 _young_gen_policy_is_ready = false;
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83 }
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84
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85 bool AdaptiveSizePolicy::tenuring_threshold_change() const {
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86 return decrement_tenuring_threshold_for_gc_cost() ||
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87 increment_tenuring_threshold_for_gc_cost() ||
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88 decrement_tenuring_threshold_for_survivor_limit();
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89 }
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90
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91 void AdaptiveSizePolicy::minor_collection_begin() {
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92 // Update the interval time
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93 _minor_timer.stop();
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94 // Save most recent collection time
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95 _latest_minor_mutator_interval_seconds = _minor_timer.seconds();
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96 _minor_timer.reset();
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97 _minor_timer.start();
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98 }
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99
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100 void AdaptiveSizePolicy::update_minor_pause_young_estimator(
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101 double minor_pause_in_ms) {
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102 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
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103 _minor_pause_young_estimator->update(eden_size_in_mbytes,
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104 minor_pause_in_ms);
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105 }
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106
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107 void AdaptiveSizePolicy::minor_collection_end(GCCause::Cause gc_cause) {
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108 // Update the pause time.
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109 _minor_timer.stop();
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110
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111 if (gc_cause != GCCause::_java_lang_system_gc ||
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112 UseAdaptiveSizePolicyWithSystemGC) {
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113 double minor_pause_in_seconds = _minor_timer.seconds();
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114 double minor_pause_in_ms = minor_pause_in_seconds * MILLIUNITS;
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115
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116 // Sample for performance counter
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117 _avg_minor_pause->sample(minor_pause_in_seconds);
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118
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119 // Cost of collection (unit-less)
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120 double collection_cost = 0.0;
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121 if ((_latest_minor_mutator_interval_seconds > 0.0) &&
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122 (minor_pause_in_seconds > 0.0)) {
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123 double interval_in_seconds =
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124 _latest_minor_mutator_interval_seconds + minor_pause_in_seconds;
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125 collection_cost =
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126 minor_pause_in_seconds / interval_in_seconds;
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127 _avg_minor_gc_cost->sample(collection_cost);
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128 // Sample for performance counter
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129 _avg_minor_interval->sample(interval_in_seconds);
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130 }
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131
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132 // The policy does not have enough data until at least some
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133 // minor collections have been done.
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134 _young_gen_policy_is_ready =
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135 (_avg_minor_gc_cost->count() >= AdaptiveSizePolicyReadyThreshold);
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136
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137 // Calculate variables used to estimate pause time vs. gen sizes
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138 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
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139 update_minor_pause_young_estimator(minor_pause_in_ms);
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140 update_minor_pause_old_estimator(minor_pause_in_ms);
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141
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142 if (PrintAdaptiveSizePolicy && Verbose) {
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143 gclog_or_tty->print("AdaptiveSizePolicy::minor_collection_end: "
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144 "minor gc cost: %f average: %f", collection_cost,
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145 _avg_minor_gc_cost->average());
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146 gclog_or_tty->print_cr(" minor pause: %f minor period %f",
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147 minor_pause_in_ms,
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148 _latest_minor_mutator_interval_seconds * MILLIUNITS);
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149 }
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150
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151 // Calculate variable used to estimate collection cost vs. gen sizes
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152 assert(collection_cost >= 0.0, "Expected to be non-negative");
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153 _minor_collection_estimator->update(eden_size_in_mbytes, collection_cost);
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154 }
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155
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156 // Interval times use this timer to measure the mutator time.
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157 // Reset the timer after the GC pause.
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158 _minor_timer.reset();
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159 _minor_timer.start();
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160 }
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161
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162 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden,
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163 uint percent_change) {
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164 size_t eden_heap_delta;
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165 eden_heap_delta = cur_eden / 100 * percent_change;
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166 return eden_heap_delta;
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167 }
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168
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169 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden) {
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170 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
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171 }
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172
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173 size_t AdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
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174 size_t eden_heap_delta = eden_increment(cur_eden) /
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175 AdaptiveSizeDecrementScaleFactor;
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176 return eden_heap_delta;
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177 }
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178
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179 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo,
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180 uint percent_change) {
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181 size_t promo_heap_delta;
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182 promo_heap_delta = cur_promo / 100 * percent_change;
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183 return promo_heap_delta;
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184 }
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185
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186 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo) {
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187 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
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188 }
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189
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190 size_t AdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
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191 size_t promo_heap_delta = promo_increment(cur_promo);
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192 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
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193 return promo_heap_delta;
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194 }
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195
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196 double AdaptiveSizePolicy::time_since_major_gc() const {
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197 _major_timer.stop();
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198 double result = _major_timer.seconds();
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199 _major_timer.start();
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200 return result;
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201 }
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202
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203 // Linear decay of major gc cost
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204 double AdaptiveSizePolicy::decaying_major_gc_cost() const {
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205 double major_interval = major_gc_interval_average_for_decay();
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206 double major_gc_cost_average = major_gc_cost();
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207 double decayed_major_gc_cost = major_gc_cost_average;
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208 if(time_since_major_gc() > 0.0) {
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209 decayed_major_gc_cost = major_gc_cost() *
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210 (((double) AdaptiveSizeMajorGCDecayTimeScale) * major_interval)
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211 / time_since_major_gc();
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212 }
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213
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214 // The decayed cost should always be smaller than the
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215 // average cost but the vagaries of finite arithmetic could
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216 // produce a larger value in decayed_major_gc_cost so protect
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217 // against that.
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218 return MIN2(major_gc_cost_average, decayed_major_gc_cost);
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219 }
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220
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221 // Use a value of the major gc cost that has been decayed
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222 // by the factor
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223 //
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224 // average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale /
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225 // time-since-last-major-gc
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226 //
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227 // if the average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale
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228 // is less than time-since-last-major-gc.
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229 //
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230 // In cases where there are initial major gc's that
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231 // are of a relatively high cost but no later major
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232 // gc's, the total gc cost can remain high because
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233 // the major gc cost remains unchanged (since there are no major
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234 // gc's). In such a situation the value of the unchanging
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235 // major gc cost can keep the mutator throughput below
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236 // the goal when in fact the major gc cost is becoming diminishingly
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237 // small. Use the decaying gc cost only to decide whether to
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238 // adjust for throughput. Using it also to determine the adjustment
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239 // to be made for throughput also seems reasonable but there is
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240 // no test case to use to decide if it is the right thing to do
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241 // don't do it yet.
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242
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243 double AdaptiveSizePolicy::decaying_gc_cost() const {
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244 double decayed_major_gc_cost = major_gc_cost();
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245 double avg_major_interval = major_gc_interval_average_for_decay();
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246 if (UseAdaptiveSizeDecayMajorGCCost &&
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247 (AdaptiveSizeMajorGCDecayTimeScale > 0) &&
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248 (avg_major_interval > 0.00)) {
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249 double time_since_last_major_gc = time_since_major_gc();
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250
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251 // Decay the major gc cost?
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252 if (time_since_last_major_gc >
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253 ((double) AdaptiveSizeMajorGCDecayTimeScale) * avg_major_interval) {
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254
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255 // Decay using the time-since-last-major-gc
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256 decayed_major_gc_cost = decaying_major_gc_cost();
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257 if (PrintGCDetails && Verbose) {
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258 gclog_or_tty->print_cr("\ndecaying_gc_cost: major interval average:"
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259 " %f time since last major gc: %f",
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260 avg_major_interval, time_since_last_major_gc);
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261 gclog_or_tty->print_cr(" major gc cost: %f decayed major gc cost: %f",
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262 major_gc_cost(), decayed_major_gc_cost);
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263 }
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264 }
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265 }
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266 double result = MIN2(1.0, decayed_major_gc_cost + minor_gc_cost());
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267 return result;
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268 }
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269
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270
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271 void AdaptiveSizePolicy::clear_generation_free_space_flags() {
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272 set_change_young_gen_for_min_pauses(0);
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273 set_change_old_gen_for_maj_pauses(0);
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274
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275 set_change_old_gen_for_throughput(0);
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276 set_change_young_gen_for_throughput(0);
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277 set_decrease_for_footprint(0);
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278 set_decide_at_full_gc(0);
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279 }
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280
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281 // Printing
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282
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283 bool AdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st) const {
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284
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285 // Should only be used with adaptive size policy turned on.
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286 // Otherwise, there may be variables that are undefined.
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287 if (!UseAdaptiveSizePolicy) return false;
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288
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289 // Print goal for which action is needed.
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290 char* action = NULL;
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291 bool change_for_pause = false;
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292 if ((change_old_gen_for_maj_pauses() ==
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293 decrease_old_gen_for_maj_pauses_true) ||
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294 (change_young_gen_for_min_pauses() ==
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295 decrease_young_gen_for_min_pauses_true)) {
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296 action = (char*) " *** pause time goal ***";
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297 change_for_pause = true;
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298 } else if ((change_old_gen_for_throughput() ==
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299 increase_old_gen_for_throughput_true) ||
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300 (change_young_gen_for_throughput() ==
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301 increase_young_gen_for_througput_true)) {
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302 action = (char*) " *** throughput goal ***";
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303 } else if (decrease_for_footprint()) {
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304 action = (char*) " *** reduced footprint ***";
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305 } else {
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306 // No actions were taken. This can legitimately be the
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307 // situation if not enough data has been gathered to make
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308 // decisions.
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309 return false;
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310 }
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311
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312 // Pauses
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313 // Currently the size of the old gen is only adjusted to
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314 // change the major pause times.
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315 char* young_gen_action = NULL;
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316 char* tenured_gen_action = NULL;
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317
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318 char* shrink_msg = (char*) "(attempted to shrink)";
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319 char* grow_msg = (char*) "(attempted to grow)";
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320 char* no_change_msg = (char*) "(no change)";
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321 if (change_young_gen_for_min_pauses() ==
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322 decrease_young_gen_for_min_pauses_true) {
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323 young_gen_action = shrink_msg;
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324 } else if (change_for_pause) {
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325 young_gen_action = no_change_msg;
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326 }
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327
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328 if (change_old_gen_for_maj_pauses() == decrease_old_gen_for_maj_pauses_true) {
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329 tenured_gen_action = shrink_msg;
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330 } else if (change_for_pause) {
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331 tenured_gen_action = no_change_msg;
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332 }
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333
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334 // Throughput
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335 if (change_old_gen_for_throughput() == increase_old_gen_for_throughput_true) {
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336 assert(change_young_gen_for_throughput() ==
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337 increase_young_gen_for_througput_true,
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338 "Both generations should be growing");
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339 young_gen_action = grow_msg;
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340 tenured_gen_action = grow_msg;
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341 } else if (change_young_gen_for_throughput() ==
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342 increase_young_gen_for_througput_true) {
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343 // Only the young generation may grow at start up (before
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344 // enough full collections have been done to grow the old generation).
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345 young_gen_action = grow_msg;
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346 tenured_gen_action = no_change_msg;
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347 }
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348
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349 // Minimum footprint
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350 if (decrease_for_footprint() != 0) {
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351 young_gen_action = shrink_msg;
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352 tenured_gen_action = shrink_msg;
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353 }
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354
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355 st->print_cr(" UseAdaptiveSizePolicy actions to meet %s", action);
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356 st->print_cr(" GC overhead (%%)");
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357 st->print_cr(" Young generation: %7.2f\t %s",
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358 100.0 * avg_minor_gc_cost()->average(),
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359 young_gen_action);
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360 st->print_cr(" Tenured generation: %7.2f\t %s",
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361 100.0 * avg_major_gc_cost()->average(),
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362 tenured_gen_action);
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363 return true;
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364 }
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365
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366 bool AdaptiveSizePolicy::print_adaptive_size_policy_on(
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367 outputStream* st,
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368 int tenuring_threshold_arg) const {
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369 if (!AdaptiveSizePolicy::print_adaptive_size_policy_on(st)) {
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370 return false;
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371 }
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372
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373 // Tenuring threshold
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374 bool tenuring_threshold_changed = true;
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375 if (decrement_tenuring_threshold_for_survivor_limit()) {
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376 st->print(" Tenuring threshold: (attempted to decrease to avoid"
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377 " survivor space overflow) = ");
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378 } else if (decrement_tenuring_threshold_for_gc_cost()) {
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379 st->print(" Tenuring threshold: (attempted to decrease to balance"
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380 " GC costs) = ");
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381 } else if (increment_tenuring_threshold_for_gc_cost()) {
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382 st->print(" Tenuring threshold: (attempted to increase to balance"
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383 " GC costs) = ");
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384 } else {
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385 tenuring_threshold_changed = false;
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386 assert(!tenuring_threshold_change(), "(no change was attempted)");
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387 }
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388 if (tenuring_threshold_changed) {
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389 st->print_cr("%d", tenuring_threshold_arg);
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390 }
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391 return true;
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392 }
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