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1 /* |
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2 * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. |
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8 * |
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9 * This code is distributed in the hope that it will be useful, but WITHOUT |
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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12 * version 2 for more details (a copy is included in the LICENSE file that |
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13 * accompanied this code). |
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14 * |
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15 * You should have received a copy of the GNU General Public License version |
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16 * 2 along with this work; if not, write to the Free Software Foundation, |
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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18 * |
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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20 * CA 95054 USA or visit www.sun.com if you need additional information or |
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21 * have any questions. |
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22 * |
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23 */ |
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24 |
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25 // Classes in support of keeping track of promotions into a non-Contiguous |
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26 // space, in this case a CompactibleFreeListSpace. |
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27 |
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28 #define CFLS_LAB_REFILL_STATS 0 |
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29 |
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30 // Forward declarations |
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31 class CompactibleFreeListSpace; |
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32 class BlkClosure; |
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33 class BlkClosureCareful; |
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34 class UpwardsObjectClosure; |
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35 class ObjectClosureCareful; |
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36 class Klass; |
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37 |
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38 class PromotedObject VALUE_OBJ_CLASS_SPEC { |
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39 private: |
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40 enum { |
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41 promoted_mask = right_n_bits(2), // i.e. 0x3 |
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42 displaced_mark = nth_bit(2), // i.e. 0x4 |
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43 next_mask = ~(right_n_bits(3)) // i.e. ~(0x7) |
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44 }; |
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45 intptr_t _next; |
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46 public: |
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47 inline PromotedObject* next() const { |
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48 return (PromotedObject*)(_next & next_mask); |
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49 } |
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50 inline void setNext(PromotedObject* x) { |
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51 assert(((intptr_t)x & ~next_mask) == 0, |
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52 "Conflict in bit usage, " |
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53 " or insufficient alignment of objects"); |
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54 _next |= (intptr_t)x; |
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55 } |
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56 inline void setPromotedMark() { |
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57 _next |= promoted_mask; |
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58 } |
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59 inline bool hasPromotedMark() const { |
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60 return (_next & promoted_mask) == promoted_mask; |
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61 } |
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62 inline void setDisplacedMark() { |
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63 _next |= displaced_mark; |
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64 } |
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65 inline bool hasDisplacedMark() const { |
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66 return (_next & displaced_mark) != 0; |
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67 } |
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68 inline void clearNext() { _next = 0; } |
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69 debug_only(void *next_addr() { return (void *) &_next; }) |
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70 }; |
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71 |
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72 class SpoolBlock: public FreeChunk { |
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73 friend class PromotionInfo; |
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74 protected: |
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75 SpoolBlock* nextSpoolBlock; |
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76 size_t bufferSize; // number of usable words in this block |
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77 markOop* displacedHdr; // the displaced headers start here |
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78 |
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79 // Note about bufferSize: it denotes the number of entries available plus 1; |
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80 // legal indices range from 1 through BufferSize - 1. See the verification |
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81 // code verify() that counts the number of displaced headers spooled. |
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82 size_t computeBufferSize() { |
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83 return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop); |
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84 } |
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85 |
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86 public: |
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87 void init() { |
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88 bufferSize = computeBufferSize(); |
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89 displacedHdr = (markOop*)&displacedHdr; |
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90 nextSpoolBlock = NULL; |
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91 } |
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92 }; |
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93 |
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94 class PromotionInfo VALUE_OBJ_CLASS_SPEC { |
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95 bool _tracking; // set if tracking |
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96 CompactibleFreeListSpace* _space; // the space to which this belongs |
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97 PromotedObject* _promoHead; // head of list of promoted objects |
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98 PromotedObject* _promoTail; // tail of list of promoted objects |
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99 SpoolBlock* _spoolHead; // first spooling block |
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100 SpoolBlock* _spoolTail; // last non-full spooling block or null |
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101 SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail |
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102 SpoolBlock* _spareSpool; // free spool buffer |
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103 size_t _firstIndex; // first active index in |
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104 // first spooling block (_spoolHead) |
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105 size_t _nextIndex; // last active index + 1 in last |
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106 // spooling block (_spoolTail) |
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107 private: |
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108 // ensure that spooling space exists; return true if there is spooling space |
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109 bool ensure_spooling_space_work(); |
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110 |
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111 public: |
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112 PromotionInfo() : |
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113 _tracking(0), _space(NULL), |
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114 _promoHead(NULL), _promoTail(NULL), |
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115 _spoolHead(NULL), _spoolTail(NULL), |
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116 _spareSpool(NULL), _firstIndex(1), |
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117 _nextIndex(1) {} |
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118 |
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119 bool noPromotions() const { |
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120 assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency"); |
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121 return _promoHead == NULL; |
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122 } |
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123 void startTrackingPromotions(); |
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124 void stopTrackingPromotions(); |
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125 bool tracking() const { return _tracking; } |
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126 void track(PromotedObject* trackOop); // keep track of a promoted oop |
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127 // The following variant must be used when trackOop is not fully |
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128 // initialized and has a NULL klass: |
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129 void track(PromotedObject* trackOop, klassOop klassOfOop); // keep track of a promoted oop |
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130 void setSpace(CompactibleFreeListSpace* sp) { _space = sp; } |
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131 CompactibleFreeListSpace* space() const { return _space; } |
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132 markOop nextDisplacedHeader(); // get next header & forward spool pointer |
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133 void saveDisplacedHeader(markOop hdr); |
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134 // save header and forward spool |
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135 |
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136 inline size_t refillSize() const; |
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137 |
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138 SpoolBlock* getSpoolBlock(); // return a free spooling block |
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139 inline bool has_spooling_space() { |
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140 return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex; |
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141 } |
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142 // ensure that spooling space exists |
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143 bool ensure_spooling_space() { |
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144 return has_spooling_space() || ensure_spooling_space_work(); |
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145 } |
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146 #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \ |
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147 void promoted_oops_iterate##nv_suffix(OopClosureType* cl); |
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148 ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL) |
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149 #undef PROMOTED_OOPS_ITERATE_DECL |
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150 void promoted_oops_iterate(OopsInGenClosure* cl) { |
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151 promoted_oops_iterate_v(cl); |
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152 } |
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153 void verify() const; |
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154 void reset() { |
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155 _promoHead = NULL; |
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156 _promoTail = NULL; |
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157 _spoolHead = NULL; |
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158 _spoolTail = NULL; |
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159 _spareSpool = NULL; |
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160 _firstIndex = 0; |
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161 _nextIndex = 0; |
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162 |
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163 } |
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164 }; |
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165 |
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166 class LinearAllocBlock VALUE_OBJ_CLASS_SPEC { |
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167 public: |
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168 LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0), |
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169 _allocation_size_limit(0) {} |
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170 void set(HeapWord* ptr, size_t word_size, size_t refill_size, |
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171 size_t allocation_size_limit) { |
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172 _ptr = ptr; |
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173 _word_size = word_size; |
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174 _refillSize = refill_size; |
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175 _allocation_size_limit = allocation_size_limit; |
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176 } |
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177 HeapWord* _ptr; |
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178 size_t _word_size; |
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179 size_t _refillSize; |
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180 size_t _allocation_size_limit; // largest size that will be allocated |
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181 }; |
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182 |
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183 // Concrete subclass of CompactibleSpace that implements |
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184 // a free list space, such as used in the concurrent mark sweep |
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185 // generation. |
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186 |
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187 class CompactibleFreeListSpace: public CompactibleSpace { |
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188 friend class VMStructs; |
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189 friend class ConcurrentMarkSweepGeneration; |
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190 friend class ASConcurrentMarkSweepGeneration; |
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191 friend class CMSCollector; |
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192 friend class CMSPermGenGen; |
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193 // Local alloc buffer for promotion into this space. |
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194 friend class CFLS_LAB; |
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195 |
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196 // "Size" of chunks of work (executed during parallel remark phases |
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197 // of CMS collection); this probably belongs in CMSCollector, although |
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198 // it's cached here because it's used in |
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199 // initialize_sequential_subtasks_for_rescan() which modifies |
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200 // par_seq_tasks which also lives in Space. XXX |
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201 const size_t _rescan_task_size; |
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202 const size_t _marking_task_size; |
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203 |
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204 // Yet another sequential tasks done structure. This supports |
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205 // CMS GC, where we have threads dynamically |
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206 // claiming sub-tasks from a larger parallel task. |
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207 SequentialSubTasksDone _conc_par_seq_tasks; |
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208 |
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209 BlockOffsetArrayNonContigSpace _bt; |
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210 |
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211 CMSCollector* _collector; |
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212 ConcurrentMarkSweepGeneration* _gen; |
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213 |
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214 // Data structures for free blocks (used during allocation/sweeping) |
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215 |
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216 // Allocation is done linearly from two different blocks depending on |
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217 // whether the request is small or large, in an effort to reduce |
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218 // fragmentation. We assume that any locking for allocation is done |
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219 // by the containing generation. Thus, none of the methods in this |
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220 // space are re-entrant. |
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221 enum SomeConstants { |
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222 SmallForLinearAlloc = 16, // size < this then use _sLAB |
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223 SmallForDictionary = 257, // size < this then use _indexedFreeList |
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224 IndexSetSize = SmallForDictionary, // keep this odd-sized |
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225 IndexSetStart = MinObjAlignment, |
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226 IndexSetStride = MinObjAlignment |
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227 }; |
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228 |
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229 private: |
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230 enum FitStrategyOptions { |
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231 FreeBlockStrategyNone = 0, |
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232 FreeBlockBestFitFirst |
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233 }; |
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234 |
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235 PromotionInfo _promoInfo; |
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236 |
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237 // helps to impose a global total order on freelistLock ranks; |
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238 // assumes that CFLSpace's are allocated in global total order |
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239 static int _lockRank; |
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240 |
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241 // a lock protecting the free lists and free blocks; |
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242 // mutable because of ubiquity of locking even for otherwise const methods |
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243 mutable Mutex _freelistLock; |
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244 // locking verifier convenience function |
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245 void assert_locked() const PRODUCT_RETURN; |
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246 |
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247 // Linear allocation blocks |
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248 LinearAllocBlock _smallLinearAllocBlock; |
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249 |
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250 FreeBlockDictionary::DictionaryChoice _dictionaryChoice; |
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251 FreeBlockDictionary* _dictionary; // ptr to dictionary for large size blocks |
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252 |
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253 FreeList _indexedFreeList[IndexSetSize]; |
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254 // indexed array for small size blocks |
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255 // allocation stategy |
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256 bool _fitStrategy; // Use best fit strategy. |
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257 bool _adaptive_freelists; // Use adaptive freelists |
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258 |
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259 // This is an address close to the largest free chunk in the heap. |
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260 // It is currently assumed to be at the end of the heap. Free |
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261 // chunks with addresses greater than nearLargestChunk are coalesced |
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262 // in an effort to maintain a large chunk at the end of the heap. |
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263 HeapWord* _nearLargestChunk; |
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264 |
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265 // Used to keep track of limit of sweep for the space |
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266 HeapWord* _sweep_limit; |
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267 |
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268 // Support for compacting cms |
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269 HeapWord* cross_threshold(HeapWord* start, HeapWord* end); |
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270 HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top); |
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271 |
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272 // Initialization helpers. |
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273 void initializeIndexedFreeListArray(); |
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274 |
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275 // Extra stuff to manage promotion parallelism. |
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276 |
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277 // a lock protecting the dictionary during par promotion allocation. |
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278 mutable Mutex _parDictionaryAllocLock; |
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279 Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; } |
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280 |
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281 // Locks protecting the exact lists during par promotion allocation. |
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282 Mutex* _indexedFreeListParLocks[IndexSetSize]; |
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283 |
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284 #if CFLS_LAB_REFILL_STATS |
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285 // Some statistics. |
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286 jint _par_get_chunk_from_small; |
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287 jint _par_get_chunk_from_large; |
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288 #endif |
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289 |
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290 |
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291 // Attempt to obtain up to "n" blocks of the size "word_sz" (which is |
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292 // required to be smaller than "IndexSetSize".) If successful, |
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293 // adds them to "fl", which is required to be an empty free list. |
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294 // If the count of "fl" is negative, it's absolute value indicates a |
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295 // number of free chunks that had been previously "borrowed" from global |
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296 // list of size "word_sz", and must now be decremented. |
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297 void par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl); |
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298 |
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299 // Allocation helper functions |
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300 // Allocate using a strategy that takes from the indexed free lists |
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301 // first. This allocation strategy assumes a companion sweeping |
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302 // strategy that attempts to keep the needed number of chunks in each |
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303 // indexed free lists. |
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304 HeapWord* allocate_adaptive_freelists(size_t size); |
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305 // Allocate from the linear allocation buffers first. This allocation |
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306 // strategy assumes maximal coalescing can maintain chunks large enough |
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307 // to be used as linear allocation buffers. |
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308 HeapWord* allocate_non_adaptive_freelists(size_t size); |
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309 |
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310 // Gets a chunk from the linear allocation block (LinAB). If there |
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311 // is not enough space in the LinAB, refills it. |
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312 HeapWord* getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size); |
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313 HeapWord* getChunkFromSmallLinearAllocBlock(size_t size); |
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314 // Get a chunk from the space remaining in the linear allocation block. Do |
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315 // not attempt to refill if the space is not available, return NULL. Do the |
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316 // repairs on the linear allocation block as appropriate. |
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317 HeapWord* getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size); |
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318 inline HeapWord* getChunkFromSmallLinearAllocBlockRemainder(size_t size); |
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319 |
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320 // Helper function for getChunkFromIndexedFreeList. |
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321 // Replenish the indexed free list for this "size". Do not take from an |
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322 // underpopulated size. |
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323 FreeChunk* getChunkFromIndexedFreeListHelper(size_t size); |
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324 |
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325 // Get a chunk from the indexed free list. If the indexed free list |
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326 // does not have a free chunk, try to replenish the indexed free list |
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327 // then get the free chunk from the replenished indexed free list. |
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328 inline FreeChunk* getChunkFromIndexedFreeList(size_t size); |
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329 |
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330 // The returned chunk may be larger than requested (or null). |
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331 FreeChunk* getChunkFromDictionary(size_t size); |
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332 // The returned chunk is the exact size requested (or null). |
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333 FreeChunk* getChunkFromDictionaryExact(size_t size); |
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334 |
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335 // Find a chunk in the indexed free list that is the best |
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336 // fit for size "numWords". |
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337 FreeChunk* bestFitSmall(size_t numWords); |
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338 // For free list "fl" of chunks of size > numWords, |
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339 // remove a chunk, split off a chunk of size numWords |
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340 // and return it. The split off remainder is returned to |
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341 // the free lists. The old name for getFromListGreater |
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342 // was lookInListGreater. |
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343 FreeChunk* getFromListGreater(FreeList* fl, size_t numWords); |
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344 // Get a chunk in the indexed free list or dictionary, |
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345 // by considering a larger chunk and splitting it. |
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346 FreeChunk* getChunkFromGreater(size_t numWords); |
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347 // Verify that the given chunk is in the indexed free lists. |
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348 bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const; |
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349 // Remove the specified chunk from the indexed free lists. |
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350 void removeChunkFromIndexedFreeList(FreeChunk* fc); |
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351 // Remove the specified chunk from the dictionary. |
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352 void removeChunkFromDictionary(FreeChunk* fc); |
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353 // Split a free chunk into a smaller free chunk of size "new_size". |
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354 // Return the smaller free chunk and return the remainder to the |
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355 // free lists. |
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356 FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size); |
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357 // Add a chunk to the free lists. |
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358 void addChunkToFreeLists(HeapWord* chunk, size_t size); |
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359 // Add a chunk to the free lists, preferring to suffix it |
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360 // to the last free chunk at end of space if possible, and |
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361 // updating the block census stats as well as block offset table. |
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362 // Take any locks as appropriate if we are multithreaded. |
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363 void addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size); |
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364 // Add a free chunk to the indexed free lists. |
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365 void returnChunkToFreeList(FreeChunk* chunk); |
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366 // Add a free chunk to the dictionary. |
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367 void returnChunkToDictionary(FreeChunk* chunk); |
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368 |
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369 // Functions for maintaining the linear allocation buffers (LinAB). |
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370 // Repairing a linear allocation block refers to operations |
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371 // performed on the remainder of a LinAB after an allocation |
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372 // has been made from it. |
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373 void repairLinearAllocationBlocks(); |
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374 void repairLinearAllocBlock(LinearAllocBlock* blk); |
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375 void refillLinearAllocBlock(LinearAllocBlock* blk); |
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376 void refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk); |
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377 void refillLinearAllocBlocksIfNeeded(); |
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378 |
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379 void verify_objects_initialized() const; |
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380 |
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381 // Statistics reporting helper functions |
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382 void reportFreeListStatistics() const; |
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383 void reportIndexedFreeListStatistics() const; |
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384 size_t maxChunkSizeInIndexedFreeLists() const; |
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385 size_t numFreeBlocksInIndexedFreeLists() const; |
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386 // Accessor |
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387 HeapWord* unallocated_block() const { |
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388 HeapWord* ub = _bt.unallocated_block(); |
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389 assert(ub >= bottom() && |
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390 ub <= end(), "space invariant"); |
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391 return ub; |
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392 } |
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393 void freed(HeapWord* start, size_t size) { |
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394 _bt.freed(start, size); |
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395 } |
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396 |
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397 protected: |
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398 // reset the indexed free list to its initial empty condition. |
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399 void resetIndexedFreeListArray(); |
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400 // reset to an initial state with a single free block described |
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401 // by the MemRegion parameter. |
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402 void reset(MemRegion mr); |
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403 // Return the total number of words in the indexed free lists. |
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404 size_t totalSizeInIndexedFreeLists() const; |
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405 |
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406 public: |
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407 // Constructor... |
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408 CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr, |
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409 bool use_adaptive_freelists, |
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410 FreeBlockDictionary::DictionaryChoice); |
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411 // accessors |
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412 bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; } |
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413 FreeBlockDictionary* dictionary() const { return _dictionary; } |
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414 HeapWord* nearLargestChunk() const { return _nearLargestChunk; } |
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415 void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; } |
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416 |
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417 // Return the free chunk at the end of the space. If no such |
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418 // chunk exists, return NULL. |
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419 FreeChunk* find_chunk_at_end(); |
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420 |
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421 bool adaptive_freelists() { return _adaptive_freelists; } |
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422 |
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423 void set_collector(CMSCollector* collector) { _collector = collector; } |
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424 |
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425 // Support for parallelization of rescan and marking |
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426 const size_t rescan_task_size() const { return _rescan_task_size; } |
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427 const size_t marking_task_size() const { return _marking_task_size; } |
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428 SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; } |
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429 void initialize_sequential_subtasks_for_rescan(int n_threads); |
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430 void initialize_sequential_subtasks_for_marking(int n_threads, |
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431 HeapWord* low = NULL); |
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432 |
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433 #if CFLS_LAB_REFILL_STATS |
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434 void print_par_alloc_stats(); |
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435 #endif |
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436 |
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437 // Space enquiries |
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438 size_t used() const; |
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439 size_t free() const; |
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440 size_t max_alloc_in_words() const; |
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441 // XXX: should have a less conservative used_region() than that of |
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442 // Space; we could consider keeping track of highest allocated |
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443 // address and correcting that at each sweep, as the sweeper |
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444 // goes through the entire allocated part of the generation. We |
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445 // could also use that information to keep the sweeper from |
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446 // sweeping more than is necessary. The allocator and sweeper will |
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447 // of course need to synchronize on this, since the sweeper will |
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448 // try to bump down the address and the allocator will try to bump it up. |
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449 // For now, however, we'll just use the default used_region() |
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450 // which overestimates the region by returning the entire |
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451 // committed region (this is safe, but inefficient). |
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452 |
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453 // Returns a subregion of the space containing all the objects in |
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454 // the space. |
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455 MemRegion used_region() const { |
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456 return MemRegion(bottom(), |
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457 BlockOffsetArrayUseUnallocatedBlock ? |
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458 unallocated_block() : end()); |
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459 } |
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460 |
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461 // This is needed because the default implementation uses block_start() |
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462 // which can;t be used at certain times (for example phase 3 of mark-sweep). |
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463 // A better fix is to change the assertions in phase 3 of mark-sweep to |
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464 // use is_in_reserved(), but that is deferred since the is_in() assertions |
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465 // are buried through several layers of callers and are used elsewhere |
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466 // as well. |
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467 bool is_in(const void* p) const { |
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468 return used_region().contains(p); |
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469 } |
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470 |
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471 virtual bool is_free_block(const HeapWord* p) const; |
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472 |
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473 // Resizing support |
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474 void set_end(HeapWord* value); // override |
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475 |
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476 // mutual exclusion support |
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477 Mutex* freelistLock() const { return &_freelistLock; } |
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478 |
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479 // Iteration support |
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480 void oop_iterate(MemRegion mr, OopClosure* cl); |
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481 void oop_iterate(OopClosure* cl); |
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482 |
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483 void object_iterate(ObjectClosure* blk); |
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484 void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl); |
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485 |
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486 // Requires that "mr" be entirely within the space. |
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487 // Apply "cl->do_object" to all objects that intersect with "mr". |
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488 // If the iteration encounters an unparseable portion of the region, |
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489 // terminate the iteration and return the address of the start of the |
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490 // subregion that isn't done. Return of "NULL" indicates that the |
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491 // interation completed. |
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492 virtual HeapWord* |
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493 object_iterate_careful_m(MemRegion mr, |
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494 ObjectClosureCareful* cl); |
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495 virtual HeapWord* |
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496 object_iterate_careful(ObjectClosureCareful* cl); |
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497 |
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498 // Override: provides a DCTO_CL specific to this kind of space. |
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499 DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl, |
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500 CardTableModRefBS::PrecisionStyle precision, |
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501 HeapWord* boundary); |
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502 |
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503 void blk_iterate(BlkClosure* cl); |
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504 void blk_iterate_careful(BlkClosureCareful* cl); |
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505 HeapWord* block_start(const void* p) const; |
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506 HeapWord* block_start_careful(const void* p) const; |
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507 size_t block_size(const HeapWord* p) const; |
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508 size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const; |
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509 bool block_is_obj(const HeapWord* p) const; |
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510 bool obj_is_alive(const HeapWord* p) const; |
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511 size_t block_size_nopar(const HeapWord* p) const; |
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512 bool block_is_obj_nopar(const HeapWord* p) const; |
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513 |
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514 // iteration support for promotion |
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515 void save_marks(); |
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516 bool no_allocs_since_save_marks(); |
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517 void object_iterate_since_last_GC(ObjectClosure* cl); |
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518 |
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519 // iteration support for sweeping |
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520 void save_sweep_limit() { |
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521 _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ? |
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522 unallocated_block() : end(); |
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523 } |
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524 NOT_PRODUCT( |
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525 void clear_sweep_limit() { _sweep_limit = NULL; } |
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526 ) |
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527 HeapWord* sweep_limit() { return _sweep_limit; } |
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528 |
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529 // Apply "blk->do_oop" to the addresses of all reference fields in objects |
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530 // promoted into this generation since the most recent save_marks() call. |
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531 // Fields in objects allocated by applications of the closure |
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532 // *are* included in the iteration. Thus, when the iteration completes |
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533 // there should be no further such objects remaining. |
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534 #define CFLS_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ |
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535 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk); |
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536 ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DECL) |
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537 #undef CFLS_OOP_SINCE_SAVE_MARKS_DECL |
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538 |
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539 // Allocation support |
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540 HeapWord* allocate(size_t size); |
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541 HeapWord* par_allocate(size_t size); |
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542 |
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543 oop promote(oop obj, size_t obj_size, oop* ref); |
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544 void gc_prologue(); |
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545 void gc_epilogue(); |
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546 |
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547 // This call is used by a containing CMS generation / collector |
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548 // to inform the CFLS space that a sweep has been completed |
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549 // and that the space can do any related house-keeping functions. |
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550 void sweep_completed(); |
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551 |
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552 // For an object in this space, the mark-word's two |
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553 // LSB's having the value [11] indicates that it has been |
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554 // promoted since the most recent call to save_marks() on |
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555 // this generation and has not subsequently been iterated |
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556 // over (using oop_since_save_marks_iterate() above). |
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557 bool obj_allocated_since_save_marks(const oop obj) const { |
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558 assert(is_in_reserved(obj), "Wrong space?"); |
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559 return ((PromotedObject*)obj)->hasPromotedMark(); |
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560 } |
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561 |
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562 // A worst-case estimate of the space required (in HeapWords) to expand the |
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563 // heap when promoting an obj of size obj_size. |
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564 size_t expansionSpaceRequired(size_t obj_size) const; |
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565 |
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566 FreeChunk* allocateScratch(size_t size); |
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567 |
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568 // returns true if either the small or large linear allocation buffer is empty. |
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569 bool linearAllocationWouldFail(); |
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570 |
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571 // Adjust the chunk for the minimum size. This version is called in |
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572 // most cases in CompactibleFreeListSpace methods. |
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573 inline static size_t adjustObjectSize(size_t size) { |
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574 return (size_t) align_object_size(MAX2(size, (size_t)MinChunkSize)); |
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575 } |
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576 // This is a virtual version of adjustObjectSize() that is called |
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577 // only occasionally when the compaction space changes and the type |
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578 // of the new compaction space is is only known to be CompactibleSpace. |
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579 size_t adjust_object_size_v(size_t size) const { |
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580 return adjustObjectSize(size); |
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581 } |
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582 // Minimum size of a free block. |
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583 virtual size_t minimum_free_block_size() const { return MinChunkSize; } |
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584 void removeFreeChunkFromFreeLists(FreeChunk* chunk); |
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585 void addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size, |
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586 bool coalesced); |
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587 |
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588 // Support for compaction |
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589 void prepare_for_compaction(CompactPoint* cp); |
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590 void adjust_pointers(); |
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591 void compact(); |
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592 // reset the space to reflect the fact that a compaction of the |
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593 // space has been done. |
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594 virtual void reset_after_compaction(); |
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595 |
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596 // Debugging support |
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597 void print() const; |
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598 void prepare_for_verify(); |
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599 void verify(bool allow_dirty) const; |
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600 void verifyFreeLists() const PRODUCT_RETURN; |
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601 void verifyIndexedFreeLists() const; |
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602 void verifyIndexedFreeList(size_t size) const; |
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603 // verify that the given chunk is in the free lists. |
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604 bool verifyChunkInFreeLists(FreeChunk* fc) const; |
|
605 // Do some basic checks on the the free lists. |
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606 void checkFreeListConsistency() const PRODUCT_RETURN; |
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607 |
|
608 NOT_PRODUCT ( |
|
609 void initializeIndexedFreeListArrayReturnedBytes(); |
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610 size_t sumIndexedFreeListArrayReturnedBytes(); |
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611 // Return the total number of chunks in the indexed free lists. |
|
612 size_t totalCountInIndexedFreeLists() const; |
|
613 // Return the total numberof chunks in the space. |
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614 size_t totalCount(); |
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615 ) |
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616 |
|
617 // The census consists of counts of the quantities such as |
|
618 // the current count of the free chunks, number of chunks |
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619 // created as a result of the split of a larger chunk or |
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620 // coalescing of smaller chucks, etc. The counts in the |
|
621 // census is used to make decisions on splitting and |
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622 // coalescing of chunks during the sweep of garbage. |
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623 |
|
624 // Print the statistics for the free lists. |
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625 void printFLCensus(int sweepCt) const; |
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626 |
|
627 // Statistics functions |
|
628 // Initialize census for lists before the sweep. |
|
629 void beginSweepFLCensus(float sweep_current, |
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630 float sweep_estimate); |
|
631 // Set the surplus for each of the free lists. |
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632 void setFLSurplus(); |
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633 // Set the hint for each of the free lists. |
|
634 void setFLHints(); |
|
635 // Clear the census for each of the free lists. |
|
636 void clearFLCensus(); |
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637 // Perform functions for the census after the end of the sweep. |
|
638 void endSweepFLCensus(int sweepCt); |
|
639 // Return true if the count of free chunks is greater |
|
640 // than the desired number of free chunks. |
|
641 bool coalOverPopulated(size_t size); |
|
642 |
|
643 |
|
644 // Record (for each size): |
|
645 // |
|
646 // split-births = #chunks added due to splits in (prev-sweep-end, |
|
647 // this-sweep-start) |
|
648 // split-deaths = #chunks removed for splits in (prev-sweep-end, |
|
649 // this-sweep-start) |
|
650 // num-curr = #chunks at start of this sweep |
|
651 // num-prev = #chunks at end of previous sweep |
|
652 // |
|
653 // The above are quantities that are measured. Now define: |
|
654 // |
|
655 // num-desired := num-prev + split-births - split-deaths - num-curr |
|
656 // |
|
657 // Roughly, num-prev + split-births is the supply, |
|
658 // split-deaths is demand due to other sizes |
|
659 // and num-curr is what we have left. |
|
660 // |
|
661 // Thus, num-desired is roughly speaking the "legitimate demand" |
|
662 // for blocks of this size and what we are striving to reach at the |
|
663 // end of the current sweep. |
|
664 // |
|
665 // For a given list, let num-len be its current population. |
|
666 // Define, for a free list of a given size: |
|
667 // |
|
668 // coal-overpopulated := num-len >= num-desired * coal-surplus |
|
669 // (coal-surplus is set to 1.05, i.e. we allow a little slop when |
|
670 // coalescing -- we do not coalesce unless we think that the current |
|
671 // supply has exceeded the estimated demand by more than 5%). |
|
672 // |
|
673 // For the set of sizes in the binary tree, which is neither dense nor |
|
674 // closed, it may be the case that for a particular size we have never |
|
675 // had, or do not now have, or did not have at the previous sweep, |
|
676 // chunks of that size. We need to extend the definition of |
|
677 // coal-overpopulated to such sizes as well: |
|
678 // |
|
679 // For a chunk in/not in the binary tree, extend coal-overpopulated |
|
680 // defined above to include all sizes as follows: |
|
681 // |
|
682 // . a size that is non-existent is coal-overpopulated |
|
683 // . a size that has a num-desired <= 0 as defined above is |
|
684 // coal-overpopulated. |
|
685 // |
|
686 // Also define, for a chunk heap-offset C and mountain heap-offset M: |
|
687 // |
|
688 // close-to-mountain := C >= 0.99 * M |
|
689 // |
|
690 // Now, the coalescing strategy is: |
|
691 // |
|
692 // Coalesce left-hand chunk with right-hand chunk if and |
|
693 // only if: |
|
694 // |
|
695 // EITHER |
|
696 // . left-hand chunk is of a size that is coal-overpopulated |
|
697 // OR |
|
698 // . right-hand chunk is close-to-mountain |
|
699 void smallCoalBirth(size_t size); |
|
700 void smallCoalDeath(size_t size); |
|
701 void coalBirth(size_t size); |
|
702 void coalDeath(size_t size); |
|
703 void smallSplitBirth(size_t size); |
|
704 void smallSplitDeath(size_t size); |
|
705 void splitBirth(size_t size); |
|
706 void splitDeath(size_t size); |
|
707 void split(size_t from, size_t to1); |
|
708 |
|
709 double flsFrag() const; |
|
710 }; |
|
711 |
|
712 // A parallel-GC-thread-local allocation buffer for allocation into a |
|
713 // CompactibleFreeListSpace. |
|
714 class CFLS_LAB : public CHeapObj { |
|
715 // The space that this buffer allocates into. |
|
716 CompactibleFreeListSpace* _cfls; |
|
717 |
|
718 // Our local free lists. |
|
719 FreeList _indexedFreeList[CompactibleFreeListSpace::IndexSetSize]; |
|
720 |
|
721 // Initialized from a command-line arg. |
|
722 size_t _blocks_to_claim; |
|
723 |
|
724 #if CFLS_LAB_REFILL_STATS |
|
725 // Some statistics. |
|
726 int _refills; |
|
727 int _blocksTaken; |
|
728 static int _tot_refills; |
|
729 static int _tot_blocksTaken; |
|
730 static int _next_threshold; |
|
731 #endif |
|
732 |
|
733 public: |
|
734 CFLS_LAB(CompactibleFreeListSpace* cfls); |
|
735 |
|
736 // Allocate and return a block of the given size, or else return NULL. |
|
737 HeapWord* alloc(size_t word_sz); |
|
738 |
|
739 // Return any unused portions of the buffer to the global pool. |
|
740 void retire(); |
|
741 }; |
|
742 |
|
743 size_t PromotionInfo::refillSize() const { |
|
744 const size_t CMSSpoolBlockSize = 256; |
|
745 const size_t sz = heap_word_size(sizeof(SpoolBlock) + sizeof(markOop) |
|
746 * CMSSpoolBlockSize); |
|
747 return CompactibleFreeListSpace::adjustObjectSize(sz); |
|
748 } |