2348
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1 /*
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3358
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2 * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 *
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23 */
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2348
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24
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25 #include "precompiled.hpp"
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26 #include "runtime/advancedThresholdPolicy.hpp"
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27 #include "runtime/simpleThresholdPolicy.inline.hpp"
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28
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29 #ifdef TIERED
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30 // Print an event.
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31 void AdvancedThresholdPolicy::print_specific(EventType type, methodHandle mh, methodHandle imh,
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32 int bci, CompLevel level) {
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33 tty->print(" rate: ");
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34 if (mh->prev_time() == 0) tty->print("n/a");
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35 else tty->print("%f", mh->rate());
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36
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37 tty->print(" k: %.2lf,%.2lf", threshold_scale(CompLevel_full_profile, Tier3LoadFeedback),
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38 threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback));
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39
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40 }
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41
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42 void AdvancedThresholdPolicy::initialize() {
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43 // Turn on ergonomic compiler count selection
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44 if (FLAG_IS_DEFAULT(CICompilerCountPerCPU) && FLAG_IS_DEFAULT(CICompilerCount)) {
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45 FLAG_SET_DEFAULT(CICompilerCountPerCPU, true);
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46 }
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47 int count = CICompilerCount;
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48 if (CICompilerCountPerCPU) {
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49 // Simple log n seems to grow too slowly for tiered, try something faster: log n * log log n
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50 int log_cpu = log2_intptr(os::active_processor_count());
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51 int loglog_cpu = log2_intptr(MAX2(log_cpu, 1));
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52 count = MAX2(log_cpu * loglog_cpu, 1) * 3 / 2;
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53 }
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54
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55 set_c1_count(MAX2(count / 3, 1));
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56 set_c2_count(MAX2(count - count / 3, 1));
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57
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58 // Some inlining tuning
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59 #ifdef X86
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60 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
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61 FLAG_SET_DEFAULT(InlineSmallCode, 2000);
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62 }
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63 #endif
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64
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65 #ifdef SPARC
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66 if (FLAG_IS_DEFAULT(InlineSmallCode)) {
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67 FLAG_SET_DEFAULT(InlineSmallCode, 2500);
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68 }
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69 #endif
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70
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71
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72 set_start_time(os::javaTimeMillis());
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73 }
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74
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75 // update_rate() is called from select_task() while holding a compile queue lock.
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76 void AdvancedThresholdPolicy::update_rate(jlong t, methodOop m) {
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77 if (is_old(m)) {
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78 // We don't remove old methods from the queue,
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79 // so we can just zero the rate.
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80 m->set_rate(0);
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81 return;
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82 }
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83
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84 // We don't update the rate if we've just came out of a safepoint.
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85 // delta_s is the time since last safepoint in milliseconds.
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86 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
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87 jlong delta_t = t - (m->prev_time() != 0 ? m->prev_time() : start_time()); // milliseconds since the last measurement
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88 // How many events were there since the last time?
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89 int event_count = m->invocation_count() + m->backedge_count();
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90 int delta_e = event_count - m->prev_event_count();
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91
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92 // We should be running for at least 1ms.
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93 if (delta_s >= TieredRateUpdateMinTime) {
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94 // And we must've taken the previous point at least 1ms before.
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95 if (delta_t >= TieredRateUpdateMinTime && delta_e > 0) {
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96 m->set_prev_time(t);
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97 m->set_prev_event_count(event_count);
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98 m->set_rate((float)delta_e / (float)delta_t); // Rate is events per millisecond
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99 } else
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100 if (delta_t > TieredRateUpdateMaxTime && delta_e == 0) {
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101 // If nothing happened for 25ms, zero the rate. Don't modify prev values.
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102 m->set_rate(0);
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103 }
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104 }
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105 }
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106
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107 // Check if this method has been stale from a given number of milliseconds.
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108 // See select_task().
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109 bool AdvancedThresholdPolicy::is_stale(jlong t, jlong timeout, methodOop m) {
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110 jlong delta_s = t - SafepointSynchronize::end_of_last_safepoint();
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111 jlong delta_t = t - m->prev_time();
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112 if (delta_t > timeout && delta_s > timeout) {
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113 int event_count = m->invocation_count() + m->backedge_count();
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114 int delta_e = event_count - m->prev_event_count();
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115 // Return true if there were no events.
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116 return delta_e == 0;
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117 }
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118 return false;
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119 }
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120
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121 // We don't remove old methods from the compile queue even if they have
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122 // very low activity. See select_task().
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123 bool AdvancedThresholdPolicy::is_old(methodOop method) {
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124 return method->invocation_count() > 50000 || method->backedge_count() > 500000;
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125 }
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126
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127 double AdvancedThresholdPolicy::weight(methodOop method) {
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128 return (method->rate() + 1) * ((method->invocation_count() + 1) * (method->backedge_count() + 1));
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129 }
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130
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131 // Apply heuristics and return true if x should be compiled before y
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132 bool AdvancedThresholdPolicy::compare_methods(methodOop x, methodOop y) {
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133 if (x->highest_comp_level() > y->highest_comp_level()) {
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134 // recompilation after deopt
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135 return true;
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136 } else
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137 if (x->highest_comp_level() == y->highest_comp_level()) {
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138 if (weight(x) > weight(y)) {
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139 return true;
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140 }
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141 }
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142 return false;
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143 }
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144
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145 // Is method profiled enough?
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146 bool AdvancedThresholdPolicy::is_method_profiled(methodOop method) {
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147 methodDataOop mdo = method->method_data();
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148 if (mdo != NULL) {
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149 int i = mdo->invocation_count_delta();
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150 int b = mdo->backedge_count_delta();
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151 return call_predicate_helper<CompLevel_full_profile>(i, b, 1);
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152 }
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153 return false;
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154 }
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155
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156 // Called with the queue locked and with at least one element
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157 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
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158 CompileTask *max_task = NULL;
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159 methodOop max_method;
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160 jlong t = os::javaTimeMillis();
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161 // Iterate through the queue and find a method with a maximum rate.
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162 for (CompileTask* task = compile_queue->first(); task != NULL;) {
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163 CompileTask* next_task = task->next();
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164 methodOop method = (methodOop)JNIHandles::resolve(task->method_handle());
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165 methodDataOop mdo = method->method_data();
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166 update_rate(t, method);
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167 if (max_task == NULL) {
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168 max_task = task;
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169 max_method = method;
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170 } else {
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171 // If a method has been stale for some time, remove it from the queue.
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172 if (is_stale(t, TieredCompileTaskTimeout, method) && !is_old(method)) {
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173 if (PrintTieredEvents) {
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174 print_event(KILL, method, method, task->osr_bci(), (CompLevel)task->comp_level());
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175 }
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176 CompileTaskWrapper ctw(task); // Frees the task
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177 compile_queue->remove(task);
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178 method->clear_queued_for_compilation();
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179 task = next_task;
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180 continue;
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181 }
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182
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183 // Select a method with a higher rate
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184 if (compare_methods(method, max_method)) {
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185 max_task = task;
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186 max_method = method;
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187 }
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188 }
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189 task = next_task;
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190 }
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191
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192 if (max_task->comp_level() == CompLevel_full_profile && is_method_profiled(max_method)) {
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193 max_task->set_comp_level(CompLevel_limited_profile);
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194 if (PrintTieredEvents) {
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195 print_event(UPDATE, max_method, max_method, max_task->osr_bci(), (CompLevel)max_task->comp_level());
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196 }
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197 }
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198
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199 return max_task;
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200 }
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201
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202 double AdvancedThresholdPolicy::threshold_scale(CompLevel level, int feedback_k) {
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203 double queue_size = CompileBroker::queue_size(level);
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204 int comp_count = compiler_count(level);
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205 double k = queue_size / (feedback_k * comp_count) + 1;
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206 return k;
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207 }
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208
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209 // Call and loop predicates determine whether a transition to a higher
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210 // compilation level should be performed (pointers to predicate functions
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211 // are passed to common()).
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212 // Tier?LoadFeedback is basically a coefficient that determines of
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213 // how many methods per compiler thread can be in the queue before
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214 // the threshold values double.
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215 bool AdvancedThresholdPolicy::loop_predicate(int i, int b, CompLevel cur_level) {
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216 switch(cur_level) {
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217 case CompLevel_none:
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218 case CompLevel_limited_profile: {
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219 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
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220 return loop_predicate_helper<CompLevel_none>(i, b, k);
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221 }
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222 case CompLevel_full_profile: {
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223 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
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224 return loop_predicate_helper<CompLevel_full_profile>(i, b, k);
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225 }
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226 default:
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227 return true;
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228 }
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229 }
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230
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231 bool AdvancedThresholdPolicy::call_predicate(int i, int b, CompLevel cur_level) {
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232 switch(cur_level) {
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233 case CompLevel_none:
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234 case CompLevel_limited_profile: {
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235 double k = threshold_scale(CompLevel_full_profile, Tier3LoadFeedback);
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236 return call_predicate_helper<CompLevel_none>(i, b, k);
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237 }
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238 case CompLevel_full_profile: {
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239 double k = threshold_scale(CompLevel_full_optimization, Tier4LoadFeedback);
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240 return call_predicate_helper<CompLevel_full_profile>(i, b, k);
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241 }
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242 default:
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243 return true;
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244 }
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245 }
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246
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247 // If a method is old enough and is still in the interpreter we would want to
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248 // start profiling without waiting for the compiled method to arrive.
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249 // We also take the load on compilers into the account.
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250 bool AdvancedThresholdPolicy::should_create_mdo(methodOop method, CompLevel cur_level) {
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251 if (cur_level == CompLevel_none &&
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252 CompileBroker::queue_size(CompLevel_full_optimization) <=
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253 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
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254 int i = method->invocation_count();
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255 int b = method->backedge_count();
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256 double k = Tier0ProfilingStartPercentage / 100.0;
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257 return call_predicate_helper<CompLevel_none>(i, b, k) || loop_predicate_helper<CompLevel_none>(i, b, k);
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258 }
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259 return false;
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260 }
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261
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262 // Create MDO if necessary.
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263 void AdvancedThresholdPolicy::create_mdo(methodHandle mh, TRAPS) {
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264 if (mh->is_native() || mh->is_abstract() || mh->is_accessor()) return;
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265 if (mh->method_data() == NULL) {
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266 methodOopDesc::build_interpreter_method_data(mh, THREAD);
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267 if (HAS_PENDING_EXCEPTION) {
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268 CLEAR_PENDING_EXCEPTION;
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269 }
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270 }
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271 }
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272
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273
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274 /*
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275 * Method states:
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276 * 0 - interpreter (CompLevel_none)
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277 * 1 - pure C1 (CompLevel_simple)
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278 * 2 - C1 with invocation and backedge counting (CompLevel_limited_profile)
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279 * 3 - C1 with full profiling (CompLevel_full_profile)
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280 * 4 - C2 (CompLevel_full_optimization)
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281 *
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282 * Common state transition patterns:
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283 * a. 0 -> 3 -> 4.
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284 * The most common path. But note that even in this straightforward case
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285 * profiling can start at level 0 and finish at level 3.
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286 *
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287 * b. 0 -> 2 -> 3 -> 4.
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288 * This case occures when the load on C2 is deemed too high. So, instead of transitioning
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289 * into state 3 directly and over-profiling while a method is in the C2 queue we transition to
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290 * level 2 and wait until the load on C2 decreases. This path is disabled for OSRs.
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291 *
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292 * c. 0 -> (3->2) -> 4.
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293 * In this case we enqueue a method for compilation at level 3, but the C1 queue is long enough
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294 * to enable the profiling to fully occur at level 0. In this case we change the compilation level
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295 * of the method to 2, because it'll allow it to run much faster without full profiling while c2
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296 * is compiling.
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297 *
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298 * d. 0 -> 3 -> 1 or 0 -> 2 -> 1.
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299 * After a method was once compiled with C1 it can be identified as trivial and be compiled to
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300 * level 1. These transition can also occur if a method can't be compiled with C2 but can with C1.
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301 *
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302 * e. 0 -> 4.
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303 * This can happen if a method fails C1 compilation (it will still be profiled in the interpreter)
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304 * or because of a deopt that didn't require reprofiling (compilation won't happen in this case because
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305 * the compiled version already exists).
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306 *
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307 * Note that since state 0 can be reached from any other state via deoptimization different loops
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308 * are possible.
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309 *
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310 */
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311
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312 // Common transition function. Given a predicate determines if a method should transition to another level.
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313 CompLevel AdvancedThresholdPolicy::common(Predicate p, methodOop method, CompLevel cur_level) {
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314 if (is_trivial(method)) return CompLevel_simple;
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315
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316 CompLevel next_level = cur_level;
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317 int i = method->invocation_count();
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318 int b = method->backedge_count();
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319
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320 switch(cur_level) {
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321 case CompLevel_none:
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322 // If we were at full profile level, would we switch to full opt?
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323 if (common(p, method, CompLevel_full_profile) == CompLevel_full_optimization) {
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324 next_level = CompLevel_full_optimization;
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325 } else if ((this->*p)(i, b, cur_level)) {
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326 // C1-generated fully profiled code is about 30% slower than the limited profile
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327 // code that has only invocation and backedge counters. The observation is that
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328 // if C2 queue is large enough we can spend too much time in the fully profiled code
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329 // while waiting for C2 to pick the method from the queue. To alleviate this problem
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330 // we introduce a feedback on the C2 queue size. If the C2 queue is sufficiently long
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331 // we choose to compile a limited profiled version and then recompile with full profiling
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332 // when the load on C2 goes down.
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333 if (CompileBroker::queue_size(CompLevel_full_optimization) >
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334 Tier3DelayOn * compiler_count(CompLevel_full_optimization)) {
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335 next_level = CompLevel_limited_profile;
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336 } else {
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337 next_level = CompLevel_full_profile;
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338 }
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339 }
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340 break;
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341 case CompLevel_limited_profile:
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342 if (is_method_profiled(method)) {
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343 // Special case: we got here because this method was fully profiled in the interpreter.
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344 next_level = CompLevel_full_optimization;
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345 } else {
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346 methodDataOop mdo = method->method_data();
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347 if (mdo != NULL) {
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348 if (mdo->would_profile()) {
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349 if (CompileBroker::queue_size(CompLevel_full_optimization) <=
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350 Tier3DelayOff * compiler_count(CompLevel_full_optimization) &&
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351 (this->*p)(i, b, cur_level)) {
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352 next_level = CompLevel_full_profile;
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353 }
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354 } else {
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355 next_level = CompLevel_full_optimization;
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356 }
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357 }
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358 }
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359 break;
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360 case CompLevel_full_profile:
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361 {
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362 methodDataOop mdo = method->method_data();
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363 if (mdo != NULL) {
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364 if (mdo->would_profile()) {
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365 int mdo_i = mdo->invocation_count_delta();
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366 int mdo_b = mdo->backedge_count_delta();
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367 if ((this->*p)(mdo_i, mdo_b, cur_level)) {
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368 next_level = CompLevel_full_optimization;
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369 }
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370 } else {
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371 next_level = CompLevel_full_optimization;
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372 }
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373 }
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374 }
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375 break;
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376 }
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377 return next_level;
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378 }
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379
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380 // Determine if a method should be compiled with a normal entry point at a different level.
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381 CompLevel AdvancedThresholdPolicy::call_event(methodOop method, CompLevel cur_level) {
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382 CompLevel osr_level = (CompLevel) method->highest_osr_comp_level();
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383 CompLevel next_level = common(&AdvancedThresholdPolicy::call_predicate, method, cur_level);
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384
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385 // If OSR method level is greater than the regular method level, the levels should be
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386 // equalized by raising the regular method level in order to avoid OSRs during each
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387 // invocation of the method.
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388 if (osr_level == CompLevel_full_optimization && cur_level == CompLevel_full_profile) {
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389 methodDataOop mdo = method->method_data();
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390 guarantee(mdo != NULL, "MDO should not be NULL");
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391 if (mdo->invocation_count() >= 1) {
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392 next_level = CompLevel_full_optimization;
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393 }
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394 } else {
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395 next_level = MAX2(osr_level, next_level);
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396 }
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397
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398 return next_level;
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399 }
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400
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401 // Determine if we should do an OSR compilation of a given method.
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402 CompLevel AdvancedThresholdPolicy::loop_event(methodOop method, CompLevel cur_level) {
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403 if (cur_level == CompLevel_none) {
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404 // If there is a live OSR method that means that we deopted to the interpreter
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405 // for the transition.
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406 CompLevel osr_level = (CompLevel)method->highest_osr_comp_level();
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407 if (osr_level > CompLevel_none) {
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408 return osr_level;
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409 }
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410 }
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411 return common(&AdvancedThresholdPolicy::loop_predicate, method, cur_level);
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412 }
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413
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414 // Update the rate and submit compile
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415 void AdvancedThresholdPolicy::submit_compile(methodHandle mh, int bci, CompLevel level, TRAPS) {
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416 int hot_count = (bci == InvocationEntryBci) ? mh->invocation_count() : mh->backedge_count();
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417 update_rate(os::javaTimeMillis(), mh());
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418 CompileBroker::compile_method(mh, bci, level, mh, hot_count, "tiered", THREAD);
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419 }
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420
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421
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422 // Handle the invocation event.
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423 void AdvancedThresholdPolicy::method_invocation_event(methodHandle mh, methodHandle imh,
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424 CompLevel level, TRAPS) {
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425 if (should_create_mdo(mh(), level)) {
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426 create_mdo(mh, THREAD);
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427 }
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428 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, InvocationEntryBci)) {
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429 CompLevel next_level = call_event(mh(), level);
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430 if (next_level != level) {
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431 compile(mh, InvocationEntryBci, next_level, THREAD);
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432 }
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433 }
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434 }
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435
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436 // Handle the back branch event. Notice that we can compile the method
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437 // with a regular entry from here.
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438 void AdvancedThresholdPolicy::method_back_branch_event(methodHandle mh, methodHandle imh,
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439 int bci, CompLevel level, TRAPS) {
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440 if (should_create_mdo(mh(), level)) {
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441 create_mdo(mh, THREAD);
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442 }
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443
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444 // If the method is already compiling, quickly bail out.
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445 if (is_compilation_enabled() && !CompileBroker::compilation_is_in_queue(mh, bci)) {
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446 // Use loop event as an opportinity to also check there's been
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447 // enough calls.
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448 CompLevel cur_level = comp_level(mh());
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449 CompLevel next_level = call_event(mh(), cur_level);
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450 CompLevel next_osr_level = loop_event(mh(), level);
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451 if (next_osr_level == CompLevel_limited_profile) {
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452 next_osr_level = CompLevel_full_profile; // OSRs are supposed to be for very hot methods.
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453 }
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454 next_level = MAX2(next_level,
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455 next_osr_level < CompLevel_full_optimization ? next_osr_level : cur_level);
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456 bool is_compiling = false;
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457 if (next_level != cur_level) {
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458 compile(mh, InvocationEntryBci, next_level, THREAD);
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459 is_compiling = true;
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460 }
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461
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462 // Do the OSR version
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463 if (!is_compiling && next_osr_level != level) {
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464 compile(mh, bci, next_osr_level, THREAD);
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465 }
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466 }
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467 }
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468
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469 #endif // TIERED
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