1 /* |
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2 * Copyright (c) 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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24 |
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25 #include "precompiled.hpp" |
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26 #include "gc_implementation/g1/heapRegionRemSet.hpp" |
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27 #include "gc_implementation/g1/heapRegionSets.hpp" |
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28 |
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29 // Note on the check_mt_safety() methods below: |
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30 // |
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31 // Verification of the "master" heap region sets / lists that are |
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32 // maintained by G1CollectedHeap is always done during a STW pause and |
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33 // by the VM thread at the start / end of the pause. The standard |
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34 // verification methods all assert check_mt_safety(). This is |
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35 // important as it ensures that verification is done without |
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36 // concurrent updates taking place at the same time. It follows, that, |
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37 // for the "master" heap region sets / lists, the check_mt_safety() |
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38 // method should include the VM thread / STW case. |
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39 |
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40 //////////////////// FreeRegionList //////////////////// |
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41 |
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42 const char* FreeRegionList::verify_region_extra(HeapRegion* hr) { |
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43 if (hr->is_young()) { |
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44 return "the region should not be young"; |
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45 } |
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46 // The superclass will check that the region is empty and |
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47 // not humongous. |
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48 return HeapRegionLinkedList::verify_region_extra(hr); |
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49 } |
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50 |
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51 //////////////////// MasterFreeRegionList //////////////////// |
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52 |
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53 const char* MasterFreeRegionList::verify_region_extra(HeapRegion* hr) { |
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54 // We should reset the RSet for parallel iteration before we add it |
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55 // to the master free list so that it is ready when the region is |
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56 // re-allocated. |
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57 if (!hr->rem_set()->verify_ready_for_par_iteration()) { |
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58 return "the region's RSet should be ready for parallel iteration"; |
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59 } |
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60 return FreeRegionList::verify_region_extra(hr); |
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61 } |
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62 |
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63 bool MasterFreeRegionList::check_mt_safety() { |
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64 // Master Free List MT safety protocol: |
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65 // (a) If we're at a safepoint, operations on the master free list |
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66 // should be invoked by either the VM thread (which will serialize |
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67 // them) or by the GC workers while holding the |
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68 // FreeList_lock. |
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69 // (b) If we're not at a safepoint, operations on the master free |
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70 // list should be invoked while holding the Heap_lock. |
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71 |
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72 if (SafepointSynchronize::is_at_safepoint()) { |
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73 guarantee(Thread::current()->is_VM_thread() || |
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74 FreeList_lock->owned_by_self(), |
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75 hrs_ext_msg(this, "master free list MT safety protocol " |
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76 "at a safepoint")); |
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77 } else { |
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78 guarantee(Heap_lock->owned_by_self(), |
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79 hrs_ext_msg(this, "master free list MT safety protocol " |
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80 "outside a safepoint")); |
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81 } |
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82 |
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83 return FreeRegionList::check_mt_safety(); |
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84 } |
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85 |
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86 //////////////////// SecondaryFreeRegionList //////////////////// |
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87 |
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88 bool SecondaryFreeRegionList::check_mt_safety() { |
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89 // Secondary Free List MT safety protocol: |
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90 // Operations on the secondary free list should always be invoked |
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91 // while holding the SecondaryFreeList_lock. |
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92 |
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93 guarantee(SecondaryFreeList_lock->owned_by_self(), |
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94 hrs_ext_msg(this, "secondary free list MT safety protocol")); |
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95 |
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96 return FreeRegionList::check_mt_safety(); |
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97 } |
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98 |
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99 //////////////////// OldRegionSet //////////////////// |
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100 |
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101 const char* OldRegionSet::verify_region_extra(HeapRegion* hr) { |
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102 if (hr->is_young()) { |
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103 return "the region should not be young"; |
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104 } |
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105 // The superclass will check that the region is not empty and not |
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106 // humongous. |
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107 return HeapRegionSet::verify_region_extra(hr); |
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108 } |
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109 |
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110 //////////////////// MasterOldRegionSet //////////////////// |
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111 |
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112 bool MasterOldRegionSet::check_mt_safety() { |
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113 // Master Old Set MT safety protocol: |
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114 // (a) If we're at a safepoint, operations on the master old set |
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115 // should be invoked: |
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116 // - by the VM thread (which will serialize them), or |
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117 // - by the GC workers while holding the FreeList_lock, if we're |
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118 // at a safepoint for an evacuation pause (this lock is taken |
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119 // anyway when an GC alloc region is retired so that a new one |
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120 // is allocated from the free list), or |
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121 // - by the GC workers while holding the OldSets_lock, if we're at a |
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122 // safepoint for a cleanup pause. |
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123 // (b) If we're not at a safepoint, operations on the master old set |
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124 // should be invoked while holding the Heap_lock. |
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125 |
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126 if (SafepointSynchronize::is_at_safepoint()) { |
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127 guarantee(Thread::current()->is_VM_thread() || |
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128 _phase == HRSPhaseEvacuation && FreeList_lock->owned_by_self() || |
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129 _phase == HRSPhaseCleanup && OldSets_lock->owned_by_self(), |
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130 hrs_ext_msg(this, "master old set MT safety protocol " |
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131 "at a safepoint")); |
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132 } else { |
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133 guarantee(Heap_lock->owned_by_self(), |
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134 hrs_ext_msg(this, "master old set MT safety protocol " |
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135 "outside a safepoint")); |
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136 } |
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137 |
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138 return OldRegionSet::check_mt_safety(); |
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139 } |
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140 |
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141 //////////////////// HumongousRegionSet //////////////////// |
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142 |
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143 const char* HumongousRegionSet::verify_region_extra(HeapRegion* hr) { |
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144 if (hr->is_young()) { |
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145 return "the region should not be young"; |
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146 } |
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147 // The superclass will check that the region is not empty and |
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148 // humongous. |
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149 return HeapRegionSet::verify_region_extra(hr); |
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150 } |
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151 |
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152 //////////////////// MasterHumongousRegionSet //////////////////// |
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153 |
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154 bool MasterHumongousRegionSet::check_mt_safety() { |
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155 // Master Humongous Set MT safety protocol: |
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156 // (a) If we're at a safepoint, operations on the master humongous |
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157 // set should be invoked by either the VM thread (which will |
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158 // serialize them) or by the GC workers while holding the |
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159 // OldSets_lock. |
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160 // (b) If we're not at a safepoint, operations on the master |
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161 // humongous set should be invoked while holding the Heap_lock. |
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162 |
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163 if (SafepointSynchronize::is_at_safepoint()) { |
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164 guarantee(Thread::current()->is_VM_thread() || |
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165 OldSets_lock->owned_by_self(), |
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166 hrs_ext_msg(this, "master humongous set MT safety protocol " |
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167 "at a safepoint")); |
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168 } else { |
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169 guarantee(Heap_lock->owned_by_self(), |
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170 hrs_ext_msg(this, "master humongous set MT safety protocol " |
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171 "outside a safepoint")); |
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172 } |
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173 |
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174 return HumongousRegionSet::check_mt_safety(); |
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175 } |
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