2348
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1 /*
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2 * Copyright (c) 2010, 2011 Oracle and/or its affiliates. All rights reserved.
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3 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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4 */
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5
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6 #include "precompiled.hpp"
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7 #include "runtime/advancedThresholdPolicy.hpp"
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8 #include "runtime/simpleThresholdPolicy.inline.hpp"
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9
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10 #ifdef TIERED
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11 // Print an event.
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12 void AdvancedThresholdPolicy::print_specific(EventType type, methodHandle mh, methodHandle imh,
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13 int bci, CompLevel level) {
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14 tty->print(" rate: ");
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15 if (mh->prev_time() == 0) tty->print("n/a");
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16 else tty->print("%f", mh->rate());
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17
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18 tty->print(" k: %.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),
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19 threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));
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20
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21 }
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22
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23 void AdvancedThresholdPolicy::initialize() {
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24 // Turn on ergonomic compiler count selection
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25 if (FLAG_IS_DEFAULT(CICompilerCountPerCPU) && FLAG_IS_DEFAULT(CICompilerCount)) {
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26 FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);
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27 }
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28 int count = CICompilerCount;
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29 if (CICompilerCountPerCPU) {
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30 // Simple log n seems to grow too slowly for tiered, try something faster: log n * log log n
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31 int log_cpu = log2_intptr(os::active_processor_count());
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32 int loglog_cpu = log2_intptr(MAX2(log_cpu, 1));
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33 count = MAX2(log_cpu * loglog_cpu, 1) * 3 / 2;
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34 }
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35
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36 set_c1_count(MAX2(count / 3, 1));
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37 set_c2_count(MAX2(count - count / 3, 1));
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38
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39 // Some inlining tuning
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40 #ifdef X86
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41 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
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42 FLAG_SET_DEFAULT(InlineSmallCode, 2000);
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43 }
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44 #endif
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45
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46 #ifdef SPARC
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47 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
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48 FLAG_SET_DEFAULT(InlineSmallCode, 2500);
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49 }
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50 #endif
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51
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52
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53 set_start_time(os::javaTimeMillis());
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54 }
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55
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56 // update_rate() is called from select_task() while holding a compile queue lock.
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57 void AdvancedThresholdPolicy::update_rate(jlong t, methodOop m) {
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58 if (is_old(m)) {
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59 // We don't remove old methods from the queue,
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60 // so we can just zero the rate.
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61 m->set_rate(0);
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62 return;
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63 }
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64
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65 // We don't update the rate if we've just came out of a safepoint.
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66 // delta_s is the time since last safepoint in milliseconds.
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67 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
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68 jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
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69 // How many events were there since the last time?
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70 int event_count = m->invocation_count() + m->backedge_count();
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71 int delta_e = event_count - m->prev_event_count();
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72
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73 // We should be running for at least 1ms.
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74 if (delta_s >= TieredRateUpdateMinTime) {
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75 // And we must've taken the previous point at least 1ms before.
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76 if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {
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77 m->set_prev_time(t);
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78 m->set_prev_event_count(event_count);
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79 m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond
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80 } else
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81 if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {
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82 // If nothing happened for 25ms, zero the rate. Don't modify prev values.
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83 m->set_rate(0);
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84 }
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85 }
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86 }
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87
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88 // Check if this method has been stale from a given number of milliseconds.
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89 // See select_task().
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90 bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, methodOop m) {
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91 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
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92 jlong delta_t = t - m->prev_time();
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93 if (delta_t > timeout && delta_s > timeout) {
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94 int event_count = m->invocation_count() + m->backedge_count();
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95 int delta_e = event_count - m->prev_event_count();
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96 // Return true if there were no events.
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97 return delta_e == 0;
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98 }
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99 return false;
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100 }
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101
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102 // We don't remove old methods from the compile queue even if they have
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103 // very low activity. See select_task().
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104 bool AdvancedThresholdPolicy::is_old(methodOop method) {
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105 return method->invocation_count() > 50000 || method->backedge_count() > 500000;
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106 }
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107
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108 double AdvancedThresholdPolicy::weight(methodOop method) {
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109 return (method->rate() + 1) * ((method->invocation_count() + 1) * (method->backedge_count() + 1));
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110 }
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111
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112 // Apply heuristics and return true if x should be compiled before y
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113 bool AdvancedThresholdPolicy::compare_methods(methodOop x, methodOop y) {
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114 if (x->highest_comp_level() > y->highest_comp_level()) {
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115 // recompilation after deopt
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116 return true;
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117 } else
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118 if (x->highest_comp_level() == y->highest_comp_level()) {
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119 if (weight(x) > weight(y)) {
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120 return true;
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121 }
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122 }
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123 return false;
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124 }
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125
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126 // Is method profiled enough?
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127 bool AdvancedThresholdPolicy::is_method_profiled(methodOop method) {
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128 methodDataOop mdo = method->method_data();
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129 if (mdo != NULL) {
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130 int i = mdo->invocation_count_delta();
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131 int b = mdo->backedge_count_delta();
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132 return call_predicate_helper<CompLevel_full_profile>(i, b, 1);
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133 }
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134 return false;
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135 }
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136
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137 // Called with the queue locked and with at least one element
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138 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
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139 CompileTask *max_task = NULL;
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140 methodOop max_method;
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141 jlong t = os::javaTimeMillis();
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142 // Iterate through the queue and find a method with a maximum rate.
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143 for (CompileTask* task = compile_queue->first(); task != NULL;) {
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144 CompileTask* next_task = task->next();
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145 methodOop method = (methodOop)JNIHandles::resolve(task->method_handle());
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146 methodDataOop mdo = method->method_data();
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147 update_rate(t, method);
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148 if (max_task == NULL) {
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149 max_task = task;
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150 max_method = method;
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151 } else {
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152 // If a method has been stale for some time, remove it from the queue.
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153 if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {
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154 if (PrintTieredEvents) {
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155 print_event(KILL, method, method, task->osr_bci(), (CompLevel)task->comp_level());
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156 }
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157 CompileTaskWrapper ctw(task); // Frees the task
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158 compile_queue->remove(task);
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159 method->clear_queued_for_compilation();
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160 task = next_task;
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161 continue;
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162 }
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163
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164 // Select a method with a higher rate
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165 if (compare_methods(method, max_method)) {
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166 max_task = task;
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167 max_method = method;
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168 }
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169 }
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170 task = next_task;
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171 }
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172
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173 if (max_task->comp_level() == CompLevel_full_profile && is_method_profiled(max_method)) {
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174 max_task->set_comp_level(CompLevel_limited_profile);
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175 if (PrintTieredEvents) {
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176 print_event(UPDATE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
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177 }
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178 }
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179
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180 return max_task;
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181 }
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182
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183 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
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184 double queue_size = CompileBroker::queue_size(level);
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185 int comp_count = compiler_count(level);
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186 double k = queue_size / (feedback_k * comp_count) + 1;
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187 return k;
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188 }
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189
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190 // Call and loop predicates determine whether a transition to a higher
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191 // compilation level should be performed (pointers to predicate functions
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192 // are passed to common()).
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193 // Tier?LoadFeedback is basically a coefficient that determines of
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194 // how many methods per compiler thread can be in the queue before
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195 // the threshold values double.
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196 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) {
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197 switch(cur_level) {
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198 case CompLevel_none:
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199 case CompLevel_limited_profile: {
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200 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
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201 return loop_predicate_helper<CompLevel_none>(i, b, k);
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202 }
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203 case CompLevel_full_profile: {
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204 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
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205 return loop_predicate_helper<CompLevel_full_profile>(i, b, k);
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206 }
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207 default:
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208 return true;
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209 }
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210 }
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211
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212 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) {
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213 switch(cur_level) {
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214 case CompLevel_none:
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215 case CompLevel_limited_profile: {
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216 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
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217 return call_predicate_helper<CompLevel_none>(i, b, k);
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218 }
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219 case CompLevel_full_profile: {
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220 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
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221 return call_predicate_helper<CompLevel_full_profile>(i, b, k);
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222 }
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223 default:
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224 return true;
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225 }
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226 }
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227
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228 // If a method is old enough and is still in the interpreter we would want to
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229 // start profiling without waiting for the compiled method to arrive.
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230 // We also take the load on compilers into the account.
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231 bool AdvancedThresholdPolicy::should_create_mdo(methodOop method, CompLevel cur_level) {
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232 if (cur_level == CompLevel_none &&
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233 CompileBroker::queue_size(CompLevel_full_optimization) <=
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234 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
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235 int i = method->invocation_count();
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236 int b = method->backedge_count();
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237 double k = Tier0ProfilingStartPercentage / 100.0;
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238 return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k);
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239 }
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240 return false;
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241 }
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242
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243 // Create MDO if necessary.
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244 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, TRAPS) {
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245 if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;
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246 if (mh->method_data() == NULL) {
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247 methodOopDesc::build_interpreter_method_data(mh, THREAD);
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248 if (HAS_PENDING_EXCEPTION) {
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249 CLEAR_PENDING_EXCEPTION;
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250 }
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251 }
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252 }
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253
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254
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255 /*
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256 * Method states:
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257 * 0 - interpreter (CompLevel_none)
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258 * 1 - pure C1 (CompLevel_simple)
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259 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
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260 * 3 - C1 with full profiling (CompLevel_full_profile)
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261 * 4 - C2 (CompLevel_full_optimization)
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262 *
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263 * Common state transition patterns:
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264 * a. 0 -> 3 -> 4.
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265 * The most common path. But note that even in this straightforward case
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266 * profiling can start at level 0 and finish at level 3.
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267 *
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268 * b. 0 -> 2 -> 3 -> 4.
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269 * This case occures when the load on C2 is deemed too high. So, instead of transitioning
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270 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
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271 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
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272 *
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273 * c. 0 -> (3->2) -> 4.
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274 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
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275 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
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276 * of the method to 2, because it'll allow it to run much faster without full profiling while c2
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277 * is compiling.
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278 *
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279 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
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280 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
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281 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
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282 *
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283 * e. 0 -> 4.
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284 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
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285 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
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286 * the compiled version already exists).
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287 *
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288 * Note that since state 0 can be reached from any other state via deoptimization different loops
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289 * are possible.
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290 *
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291 */
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292
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293 // Common transition function. Given a predicate determines if a method should transition to another level.
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294 CompLevel AdvancedThresholdPolicy::common(Predicate p, methodOop method, CompLevel cur_level) {
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295 if (is_trivial(method)) return CompLevel_simple;
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296
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297 CompLevel next_level = cur_level;
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298 int i = method->invocation_count();
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299 int b = method->backedge_count();
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300
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301 switch(cur_level) {
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302 case CompLevel_none:
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303 // If we were at full profile level, would we switch to full opt?
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304 if (common(p, method, CompLevel_full_profile) == CompLevel_full_optimization) {
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305 next_level = CompLevel_full_optimization;
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306 } else if ((this->*p)(i, b, cur_level)) {
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307 // C1-generated fully profiled code is about 30% slower than the limited profile
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308 // code that has only invocation and backedge counters. The observation is that
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309 // if C2 queue is large enough we can spend too much time in the fully profiled code
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310 // while waiting for C2 to pick the method from the queue. To alleviate this problem
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311 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
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312 // we choose to compile a limited profiled version and then recompile with full profiling
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313 // when the load on C2 goes down.
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314 if (CompileBroker::queue_size(CompLevel_full_optimization) >
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315 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
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316 next_level = CompLevel_limited_profile;
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317 } else {
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318 next_level = CompLevel_full_profile;
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319 }
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320 }
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321 break;
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322 case CompLevel_limited_profile:
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323 if (is_method_profiled(method)) {
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324 // Special case: we got here because this method was fully profiled in the interpreter.
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325 next_level = CompLevel_full_optimization;
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326 } else {
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327 methodDataOop mdo = method->method_data();
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328 if (mdo != NULL) {
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329 if (mdo->would_profile()) {
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330 if (CompileBroker::queue_size(CompLevel_full_optimization) <=
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331 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
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332 (this->*p)(i, b, cur_level)) {
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333 next_level = CompLevel_full_profile;
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334 }
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335 } else {
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336 next_level = CompLevel_full_optimization;
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337 }
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338 }
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339 }
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340 break;
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341 case CompLevel_full_profile:
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342 {
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343 methodDataOop mdo = method->method_data();
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344 if (mdo != NULL) {
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345 if (mdo->would_profile()) {
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346 int mdo_i = mdo->invocation_count_delta();
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347 int mdo_b = mdo->backedge_count_delta();
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348 if ((this->*p)(mdo_i, mdo_b, cur_level)) {
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349 next_level = CompLevel_full_optimization;
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350 }
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351 } else {
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352 next_level = CompLevel_full_optimization;
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353 }
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354 }
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355 }
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356 break;
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357 }
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358 return next_level;
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359 }
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360
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361 // Determine if a method should be compiled with a normal entry point at a different level.
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362 CompLevel AdvancedThresholdPolicy::call_event(methodOop method, CompLevel cur_level) {
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363 CompLevel osr_level = (CompLevel) method->highest_osr_comp_level();
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364 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);
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365
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366 // If OSR method level is greater than the regular method level, the levels should be
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367 // equalized by raising the regular method level in order to avoid OSRs during each
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368 // invocation of the method.
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369 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
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370 methodDataOop mdo = method->method_data();
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371 guarantee(mdo != NULL, "MDO should not be NULL");
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372 if (mdo->invocation_count() >= 1) {
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373 next_level = CompLevel_full_optimization;
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374 }
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375 } else {
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376 next_level = MAX2(osr_level, next_level);
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377 }
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378
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379 return next_level;
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380 }
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381
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382 // Determine if we should do an OSR compilation of a given method.
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383 CompLevel AdvancedThresholdPolicy::loop_event(methodOop method, CompLevel cur_level) {
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384 if (cur_level == CompLevel_none) {
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385 // If there is a live OSR method that means that we deopted to the interpreter
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386 // for the transition.
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387 CompLevel osr_level = (CompLevel)method->highest_osr_comp_level();
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388 if (osr_level > CompLevel_none) {
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389 return osr_level;
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390 }
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391 }
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392 return common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level);
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393 }
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394
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395 // Update the rate and submit compile
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396 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, TRAPS) {
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397 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
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398 update_rate(os::javaTimeMillis(), mh());
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399 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", THREAD);
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400 }
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401
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402
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403 // Handle the invocation event.
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404 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
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405 CompLevel level, TRAPS) {
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406 if (should_create_mdo(mh(), level)) {
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407 create_mdo(mh, THREAD);
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408 }
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409 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) {
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410 CompLevel next_level = call_event(mh(), level);
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411 if (next_level != level) {
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412 compile(mh, InvocationEntryBci, next_level, THREAD);
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413 }
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414 }
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415 }
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416
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417 // Handle the back branch event. Notice that we can compile the method
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418 // with a regular entry from here.
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419 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
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420 int bci, CompLevel level, TRAPS) {
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421 if (should_create_mdo(mh(), level)) {
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422 create_mdo(mh, THREAD);
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423 }
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424
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425 // If the method is already compiling, quickly bail out.
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426 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, bci)) {
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427 // Use loop event as an opportinity to also check there's been
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428 // enough calls.
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429 CompLevel cur_level = comp_level(mh());
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430 CompLevel next_level = call_event(mh(), cur_level);
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431 CompLevel next_osr_level = loop_event(mh(), level);
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432 if (next_osr_level == CompLevel_limited_profile) {
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433 next_osr_level = CompLevel_full_profile; // OSRs are supposed to be for very hot methods.
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434 }
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435 next_level = MAX2(next_level,
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436 next_osr_level < CompLevel_full_optimization ? next_osr_level : cur_level);
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437 bool is_compiling = false;
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438 if (next_level != cur_level) {
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439 compile(mh, InvocationEntryBci, next_level, THREAD);
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440 is_compiling = true;
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441 }
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442
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443 // Do the OSR version
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444 if (!is_compiling && next_osr_level != level) {
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445 compile(mh, bci, next_osr_level, THREAD);
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446 }
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447 }
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448 }
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449
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450 #endif // TIERED
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