0
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1 /*
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2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 # include "incls/_precompiled.incl"
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26 # include "incls/_tenuredGeneration.cpp.incl"
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27
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28 TenuredGeneration::TenuredGeneration(ReservedSpace rs,
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29 size_t initial_byte_size, int level,
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30 GenRemSet* remset) :
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31 OneContigSpaceCardGeneration(rs, initial_byte_size,
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32 MinHeapDeltaBytes, level, remset, NULL)
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33 {
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34 HeapWord* bottom = (HeapWord*) _virtual_space.low();
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35 HeapWord* end = (HeapWord*) _virtual_space.high();
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36 _the_space = new TenuredSpace(_bts, MemRegion(bottom, end));
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37 _the_space->reset_saved_mark();
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38 _shrink_factor = 0;
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39 _capacity_at_prologue = 0;
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40
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41 _gc_stats = new GCStats();
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42
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43 // initialize performance counters
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44
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45 const char* gen_name = "old";
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46
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47 // Generation Counters -- generation 1, 1 subspace
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48 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space);
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49
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50 _gc_counters = new CollectorCounters("MSC", 1);
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51
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52 _space_counters = new CSpaceCounters(gen_name, 0,
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53 _virtual_space.reserved_size(),
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54 _the_space, _gen_counters);
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55 #ifndef SERIALGC
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56 if (UseParNewGC && ParallelGCThreads > 0) {
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57 typedef ParGCAllocBufferWithBOT* ParGCAllocBufferWithBOTPtr;
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58 _alloc_buffers = NEW_C_HEAP_ARRAY(ParGCAllocBufferWithBOTPtr,
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59 ParallelGCThreads);
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60 if (_alloc_buffers == NULL)
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61 vm_exit_during_initialization("Could not allocate alloc_buffers");
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62 for (uint i = 0; i < ParallelGCThreads; i++) {
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63 _alloc_buffers[i] =
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64 new ParGCAllocBufferWithBOT(OldPLABSize, _bts);
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65 if (_alloc_buffers[i] == NULL)
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66 vm_exit_during_initialization("Could not allocate alloc_buffers");
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67 }
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68 } else {
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69 _alloc_buffers = NULL;
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70 }
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71 #endif // SERIALGC
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72 }
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73
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74
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75 const char* TenuredGeneration::name() const {
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76 return "tenured generation";
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77 }
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78
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79 void TenuredGeneration::compute_new_size() {
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80 assert(_shrink_factor <= 100, "invalid shrink factor");
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81 size_t current_shrink_factor = _shrink_factor;
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82 _shrink_factor = 0;
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83
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84 // We don't have floating point command-line arguments
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85 // Note: argument processing ensures that MinHeapFreeRatio < 100.
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86 const double minimum_free_percentage = MinHeapFreeRatio / 100.0;
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87 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
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88
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89 // Compute some numbers about the state of the heap.
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90 const size_t used_after_gc = used();
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91 const size_t capacity_after_gc = capacity();
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92
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93 const double min_tmp = used_after_gc / maximum_used_percentage;
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94 size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx));
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95 // Don't shrink less than the initial generation size
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96 minimum_desired_capacity = MAX2(minimum_desired_capacity,
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97 spec()->init_size());
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98 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
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99
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100 if (PrintGC && Verbose) {
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101 const size_t free_after_gc = free();
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102 const double free_percentage = ((double)free_after_gc) / capacity_after_gc;
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103 gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: ");
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104 gclog_or_tty->print_cr(" "
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105 " minimum_free_percentage: %6.2f"
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106 " maximum_used_percentage: %6.2f",
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107 minimum_free_percentage,
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108 maximum_used_percentage);
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109 gclog_or_tty->print_cr(" "
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110 " free_after_gc : %6.1fK"
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111 " used_after_gc : %6.1fK"
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112 " capacity_after_gc : %6.1fK",
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113 free_after_gc / (double) K,
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114 used_after_gc / (double) K,
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115 capacity_after_gc / (double) K);
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116 gclog_or_tty->print_cr(" "
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117 " free_percentage: %6.2f",
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118 free_percentage);
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119 }
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120
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121 if (capacity_after_gc < minimum_desired_capacity) {
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122 // If we have less free space than we want then expand
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123 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
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124 // Don't expand unless it's significant
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125 if (expand_bytes >= _min_heap_delta_bytes) {
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126 expand(expand_bytes, 0); // safe if expansion fails
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127 }
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128 if (PrintGC && Verbose) {
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129 gclog_or_tty->print_cr(" expanding:"
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130 " minimum_desired_capacity: %6.1fK"
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131 " expand_bytes: %6.1fK"
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132 " _min_heap_delta_bytes: %6.1fK",
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133 minimum_desired_capacity / (double) K,
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134 expand_bytes / (double) K,
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135 _min_heap_delta_bytes / (double) K);
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136 }
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137 return;
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138 }
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139
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140 // No expansion, now see if we want to shrink
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141 size_t shrink_bytes = 0;
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142 // We would never want to shrink more than this
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143 size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity;
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144
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145 if (MaxHeapFreeRatio < 100) {
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146 const double maximum_free_percentage = MaxHeapFreeRatio / 100.0;
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147 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
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148 const double max_tmp = used_after_gc / minimum_used_percentage;
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149 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx));
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150 maximum_desired_capacity = MAX2(maximum_desired_capacity,
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151 spec()->init_size());
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152 if (PrintGC && Verbose) {
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153 gclog_or_tty->print_cr(" "
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154 " maximum_free_percentage: %6.2f"
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155 " minimum_used_percentage: %6.2f",
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156 maximum_free_percentage,
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157 minimum_used_percentage);
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158 gclog_or_tty->print_cr(" "
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159 " _capacity_at_prologue: %6.1fK"
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160 " minimum_desired_capacity: %6.1fK"
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161 " maximum_desired_capacity: %6.1fK",
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162 _capacity_at_prologue / (double) K,
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163 minimum_desired_capacity / (double) K,
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164 maximum_desired_capacity / (double) K);
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165 }
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166 assert(minimum_desired_capacity <= maximum_desired_capacity,
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167 "sanity check");
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168
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169 if (capacity_after_gc > maximum_desired_capacity) {
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170 // Capacity too large, compute shrinking size
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171 shrink_bytes = capacity_after_gc - maximum_desired_capacity;
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172 // We don't want shrink all the way back to initSize if people call
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173 // System.gc(), because some programs do that between "phases" and then
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174 // we'd just have to grow the heap up again for the next phase. So we
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175 // damp the shrinking: 0% on the first call, 10% on the second call, 40%
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176 // on the third call, and 100% by the fourth call. But if we recompute
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177 // size without shrinking, it goes back to 0%.
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178 shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
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179 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
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180 if (current_shrink_factor == 0) {
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181 _shrink_factor = 10;
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182 } else {
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183 _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100);
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184 }
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185 if (PrintGC && Verbose) {
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186 gclog_or_tty->print_cr(" "
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187 " shrinking:"
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188 " initSize: %.1fK"
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189 " maximum_desired_capacity: %.1fK",
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190 spec()->init_size() / (double) K,
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191 maximum_desired_capacity / (double) K);
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192 gclog_or_tty->print_cr(" "
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193 " shrink_bytes: %.1fK"
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194 " current_shrink_factor: %d"
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195 " new shrink factor: %d"
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196 " _min_heap_delta_bytes: %.1fK",
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197 shrink_bytes / (double) K,
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198 current_shrink_factor,
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199 _shrink_factor,
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200 _min_heap_delta_bytes / (double) K);
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201 }
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202 }
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203 }
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204
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205 if (capacity_after_gc > _capacity_at_prologue) {
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206 // We might have expanded for promotions, in which case we might want to
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207 // take back that expansion if there's room after GC. That keeps us from
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208 // stretching the heap with promotions when there's plenty of room.
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209 size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue;
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210 expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes);
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211 // We have two shrinking computations, take the largest
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212 shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion);
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213 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
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214 if (PrintGC && Verbose) {
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215 gclog_or_tty->print_cr(" "
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216 " aggressive shrinking:"
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217 " _capacity_at_prologue: %.1fK"
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218 " capacity_after_gc: %.1fK"
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219 " expansion_for_promotion: %.1fK"
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220 " shrink_bytes: %.1fK",
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221 capacity_after_gc / (double) K,
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222 _capacity_at_prologue / (double) K,
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223 expansion_for_promotion / (double) K,
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224 shrink_bytes / (double) K);
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225 }
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226 }
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227 // Don't shrink unless it's significant
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228 if (shrink_bytes >= _min_heap_delta_bytes) {
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229 shrink(shrink_bytes);
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230 }
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231 assert(used() == used_after_gc && used_after_gc <= capacity(),
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232 "sanity check");
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233 }
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234
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235 void TenuredGeneration::gc_prologue(bool full) {
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236 _capacity_at_prologue = capacity();
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237 _used_at_prologue = used();
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238 if (VerifyBeforeGC) {
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239 verify_alloc_buffers_clean();
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240 }
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241 }
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242
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243 void TenuredGeneration::gc_epilogue(bool full) {
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244 if (VerifyAfterGC) {
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245 verify_alloc_buffers_clean();
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246 }
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247 OneContigSpaceCardGeneration::gc_epilogue(full);
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248 }
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249
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250
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251 bool TenuredGeneration::should_collect(bool full,
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252 size_t size,
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253 bool is_tlab) {
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254 // This should be one big conditional or (||), but I want to be able to tell
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255 // why it returns what it returns (without re-evaluating the conditionals
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256 // in case they aren't idempotent), so I'm doing it this way.
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257 // DeMorgan says it's okay.
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258 bool result = false;
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259 if (!result && full) {
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260 result = true;
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261 if (PrintGC && Verbose) {
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262 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
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263 " full");
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264 }
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265 }
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266 if (!result && should_allocate(size, is_tlab)) {
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267 result = true;
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268 if (PrintGC && Verbose) {
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269 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
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270 " should_allocate(" SIZE_FORMAT ")",
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271 size);
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272 }
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273 }
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274 // If we don't have very much free space.
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275 // XXX: 10000 should be a percentage of the capacity!!!
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276 if (!result && free() < 10000) {
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277 result = true;
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278 if (PrintGC && Verbose) {
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279 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
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280 " free(): " SIZE_FORMAT,
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281 free());
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282 }
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283 }
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284 // If we had to expand to accomodate promotions from younger generations
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285 if (!result && _capacity_at_prologue < capacity()) {
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286 result = true;
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287 if (PrintGC && Verbose) {
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288 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
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289 "_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,
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290 _capacity_at_prologue, capacity());
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291 }
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292 }
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293 return result;
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294 }
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295
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296 void TenuredGeneration::collect(bool full,
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297 bool clear_all_soft_refs,
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298 size_t size,
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299 bool is_tlab) {
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300 retire_alloc_buffers_before_full_gc();
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301 OneContigSpaceCardGeneration::collect(full, clear_all_soft_refs,
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302 size, is_tlab);
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303 }
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304
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305 void TenuredGeneration::update_gc_stats(int current_level,
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306 bool full) {
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307 // If the next lower level(s) has been collected, gather any statistics
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308 // that are of interest at this point.
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309 if (!full && (current_level + 1) == level()) {
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310 // Calculate size of data promoted from the younger generations
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311 // before doing the collection.
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312 size_t used_before_gc = used();
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313
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314 // If the younger gen collections were skipped, then the
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315 // number of promoted bytes will be 0 and adding it to the
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316 // average will incorrectly lessen the average. It is, however,
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317 // also possible that no promotion was needed.
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318 if (used_before_gc >= _used_at_prologue) {
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319 size_t promoted_in_bytes = used_before_gc - _used_at_prologue;
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320 gc_stats()->avg_promoted()->sample(promoted_in_bytes);
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321 }
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322 }
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323 }
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324
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325 void TenuredGeneration::update_counters() {
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326 if (UsePerfData) {
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327 _space_counters->update_all();
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328 _gen_counters->update_all();
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329 }
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330 }
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331
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332
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333 #ifndef SERIALGC
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334 oop TenuredGeneration::par_promote(int thread_num,
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335 oop old, markOop m, size_t word_sz) {
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336
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337 ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
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338 HeapWord* obj_ptr = buf->allocate(word_sz);
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339 bool is_lab = true;
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340 if (obj_ptr == NULL) {
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341 #ifndef PRODUCT
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342 if (Universe::heap()->promotion_should_fail()) {
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343 return NULL;
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344 }
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345 #endif // #ifndef PRODUCT
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346
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347 // Slow path:
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348 if (word_sz * 100 < ParallelGCBufferWastePct * buf->word_sz()) {
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349 // Is small enough; abandon this buffer and start a new one.
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350 size_t buf_size = buf->word_sz();
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351 HeapWord* buf_space =
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352 TenuredGeneration::par_allocate(buf_size, false);
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353 if (buf_space == NULL) {
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354 buf_space = expand_and_allocate(buf_size, false, true /* parallel*/);
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355 }
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356 if (buf_space != NULL) {
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357 buf->retire(false, false);
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358 buf->set_buf(buf_space);
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359 obj_ptr = buf->allocate(word_sz);
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360 assert(obj_ptr != NULL, "Buffer was definitely big enough...");
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361 }
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362 };
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363 // Otherwise, buffer allocation failed; try allocating object
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364 // individually.
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365 if (obj_ptr == NULL) {
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366 obj_ptr = TenuredGeneration::par_allocate(word_sz, false);
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367 if (obj_ptr == NULL) {
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368 obj_ptr = expand_and_allocate(word_sz, false, true /* parallel */);
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369 }
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370 }
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371 if (obj_ptr == NULL) return NULL;
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372 }
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373 assert(obj_ptr != NULL, "program logic");
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374 Copy::aligned_disjoint_words((HeapWord*)old, obj_ptr, word_sz);
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375 oop obj = oop(obj_ptr);
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376 // Restore the mark word copied above.
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377 obj->set_mark(m);
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378 return obj;
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379 }
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380
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381 void TenuredGeneration::par_promote_alloc_undo(int thread_num,
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382 HeapWord* obj,
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383 size_t word_sz) {
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384 ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
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385 if (buf->contains(obj)) {
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386 guarantee(buf->contains(obj + word_sz - 1),
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387 "should contain whole object");
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388 buf->undo_allocation(obj, word_sz);
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389 } else {
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390 SharedHeap::fill_region_with_object(MemRegion(obj, word_sz));
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391 }
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392 }
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393
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394 void TenuredGeneration::par_promote_alloc_done(int thread_num) {
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395 ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
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396 buf->retire(true, ParallelGCRetainPLAB);
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397 }
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398
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399 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {
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400 if (UseParNewGC) {
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401 for (uint i = 0; i < ParallelGCThreads; i++) {
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402 _alloc_buffers[i]->retire(true /*end_of_gc*/, false /*retain*/);
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403 }
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404 }
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405 }
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406
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407 // Verify that any retained parallel allocation buffers do not
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408 // intersect with dirty cards.
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409 void TenuredGeneration::verify_alloc_buffers_clean() {
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410 if (UseParNewGC) {
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411 for (uint i = 0; i < ParallelGCThreads; i++) {
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412 _rs->verify_empty(_alloc_buffers[i]->range());
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413 }
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414 }
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415 }
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416 #else // SERIALGC
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417 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {}
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418 void TenuredGeneration::verify_alloc_buffers_clean() {}
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419 #endif // SERIALGC
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420
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421 bool TenuredGeneration::promotion_attempt_is_safe(
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422 size_t max_promotion_in_bytes,
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423 bool younger_handles_promotion_failure) const {
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424
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425 bool result = max_contiguous_available() >= max_promotion_in_bytes;
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426
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427 if (younger_handles_promotion_failure && !result) {
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428 result = max_contiguous_available() >=
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429 (size_t) gc_stats()->avg_promoted()->padded_average();
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430 if (PrintGC && Verbose && result) {
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431 gclog_or_tty->print_cr("TenuredGeneration::promotion_attempt_is_safe"
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432 " contiguous_available: " SIZE_FORMAT
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433 " avg_promoted: " SIZE_FORMAT,
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434 max_contiguous_available(),
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435 gc_stats()->avg_promoted()->padded_average());
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436 }
|
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437 } else {
|
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438 if (PrintGC && Verbose) {
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439 gclog_or_tty->print_cr("TenuredGeneration::promotion_attempt_is_safe"
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440 " contiguous_available: " SIZE_FORMAT
|
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441 " promotion_in_bytes: " SIZE_FORMAT,
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|
442 max_contiguous_available(), max_promotion_in_bytes);
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443 }
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444 }
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445 return result;
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446 }
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