0
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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 # include "incls/_precompiled.incl"
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26 # include "incls/_cardTableRS.cpp.incl"
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27
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28 CardTableRS::CardTableRS(MemRegion whole_heap,
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29 int max_covered_regions) :
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30 GenRemSet(&_ct_bs),
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31 _ct_bs(whole_heap, max_covered_regions),
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32 _cur_youngergen_card_val(youngergenP1_card)
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33 {
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34 _last_cur_val_in_gen = new jbyte[GenCollectedHeap::max_gens + 1];
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35 if (_last_cur_val_in_gen == NULL) {
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36 vm_exit_during_initialization("Could not last_cur_val_in_gen array.");
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37 }
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38 for (int i = 0; i < GenCollectedHeap::max_gens + 1; i++) {
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39 _last_cur_val_in_gen[i] = clean_card_val();
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40 }
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41 _ct_bs.set_CTRS(this);
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42 }
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43
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44 void CardTableRS::resize_covered_region(MemRegion new_region) {
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45 _ct_bs.resize_covered_region(new_region);
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46 }
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47
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48 jbyte CardTableRS::find_unused_youngergenP_card_value() {
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49 GenCollectedHeap* gch = GenCollectedHeap::heap();
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50 for (jbyte v = youngergenP1_card;
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51 v < cur_youngergen_and_prev_nonclean_card;
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52 v++) {
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53 bool seen = false;
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54 for (int g = 0; g < gch->n_gens()+1; g++) {
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55 if (_last_cur_val_in_gen[g] == v) {
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56 seen = true;
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57 break;
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58 }
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59 }
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60 if (!seen) return v;
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61 }
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62 ShouldNotReachHere();
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63 return 0;
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64 }
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65
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66 void CardTableRS::prepare_for_younger_refs_iterate(bool parallel) {
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67 // Parallel or sequential, we must always set the prev to equal the
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68 // last one written.
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69 if (parallel) {
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70 // Find a parallel value to be used next.
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71 jbyte next_val = find_unused_youngergenP_card_value();
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72 set_cur_youngergen_card_val(next_val);
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73
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74 } else {
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75 // In an sequential traversal we will always write youngergen, so that
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76 // the inline barrier is correct.
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77 set_cur_youngergen_card_val(youngergen_card);
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78 }
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79 }
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80
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81 void CardTableRS::younger_refs_iterate(Generation* g,
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82 OopsInGenClosure* blk) {
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83 _last_cur_val_in_gen[g->level()+1] = cur_youngergen_card_val();
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84 g->younger_refs_iterate(blk);
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85 }
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86
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87 class ClearNoncleanCardWrapper: public MemRegionClosure {
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88 MemRegionClosure* _dirty_card_closure;
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89 CardTableRS* _ct;
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90 bool _is_par;
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91 private:
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92 // Clears the given card, return true if the corresponding card should be
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93 // processed.
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94 bool clear_card(jbyte* entry) {
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95 if (_is_par) {
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96 while (true) {
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97 // In the parallel case, we may have to do this several times.
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98 jbyte entry_val = *entry;
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99 assert(entry_val != CardTableRS::clean_card_val(),
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100 "We shouldn't be looking at clean cards, and this should "
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101 "be the only place they get cleaned.");
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102 if (CardTableRS::card_is_dirty_wrt_gen_iter(entry_val)
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103 || _ct->is_prev_youngergen_card_val(entry_val)) {
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104 jbyte res =
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105 Atomic::cmpxchg(CardTableRS::clean_card_val(), entry, entry_val);
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106 if (res == entry_val) {
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107 break;
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108 } else {
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109 assert(res == CardTableRS::cur_youngergen_and_prev_nonclean_card,
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110 "The CAS above should only fail if another thread did "
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111 "a GC write barrier.");
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112 }
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113 } else if (entry_val ==
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114 CardTableRS::cur_youngergen_and_prev_nonclean_card) {
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115 // Parallelism shouldn't matter in this case. Only the thread
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116 // assigned to scan the card should change this value.
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117 *entry = _ct->cur_youngergen_card_val();
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118 break;
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119 } else {
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120 assert(entry_val == _ct->cur_youngergen_card_val(),
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121 "Should be the only possibility.");
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122 // In this case, the card was clean before, and become
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123 // cur_youngergen only because of processing of a promoted object.
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124 // We don't have to look at the card.
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125 return false;
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126 }
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127 }
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128 return true;
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129 } else {
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130 jbyte entry_val = *entry;
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131 assert(entry_val != CardTableRS::clean_card_val(),
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132 "We shouldn't be looking at clean cards, and this should "
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133 "be the only place they get cleaned.");
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134 assert(entry_val != CardTableRS::cur_youngergen_and_prev_nonclean_card,
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135 "This should be possible in the sequential case.");
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136 *entry = CardTableRS::clean_card_val();
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137 return true;
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138 }
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139 }
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140
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141 public:
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142 ClearNoncleanCardWrapper(MemRegionClosure* dirty_card_closure,
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143 CardTableRS* ct) :
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144 _dirty_card_closure(dirty_card_closure), _ct(ct) {
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145 _is_par = (SharedHeap::heap()->n_par_threads() > 0);
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146 }
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147 void do_MemRegion(MemRegion mr) {
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148 // We start at the high end of "mr", walking backwards
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149 // while accumulating a contiguous dirty range of cards in
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150 // [start_of_non_clean, end_of_non_clean) which we then
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151 // process en masse.
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152 HeapWord* end_of_non_clean = mr.end();
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153 HeapWord* start_of_non_clean = end_of_non_clean;
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154 jbyte* entry = _ct->byte_for(mr.last());
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155 const jbyte* first_entry = _ct->byte_for(mr.start());
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156 while (entry >= first_entry) {
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157 HeapWord* cur = _ct->addr_for(entry);
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158 if (!clear_card(entry)) {
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159 // We hit a clean card; process any non-empty
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160 // dirty range accumulated so far.
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161 if (start_of_non_clean < end_of_non_clean) {
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162 MemRegion mr2(start_of_non_clean, end_of_non_clean);
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163 _dirty_card_closure->do_MemRegion(mr2);
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164 }
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165 // Reset the dirty window while continuing to
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166 // look for the next dirty window to process.
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167 end_of_non_clean = cur;
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168 start_of_non_clean = end_of_non_clean;
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169 }
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170 // Open the left end of the window one card to the left.
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171 start_of_non_clean = cur;
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172 // Note that "entry" leads "start_of_non_clean" in
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173 // its leftward excursion after this point
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174 // in the loop and, when we hit the left end of "mr",
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175 // will point off of the left end of the card-table
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176 // for "mr".
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177 entry--;
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178 }
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179 // If the first card of "mr" was dirty, we will have
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180 // been left with a dirty window, co-initial with "mr",
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181 // which we now process.
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182 if (start_of_non_clean < end_of_non_clean) {
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183 MemRegion mr2(start_of_non_clean, end_of_non_clean);
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184 _dirty_card_closure->do_MemRegion(mr2);
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185 }
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186 }
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187 };
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188 // clean (by dirty->clean before) ==> cur_younger_gen
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189 // dirty ==> cur_youngergen_and_prev_nonclean_card
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190 // precleaned ==> cur_youngergen_and_prev_nonclean_card
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191 // prev-younger-gen ==> cur_youngergen_and_prev_nonclean_card
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192 // cur-younger-gen ==> cur_younger_gen
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193 // cur_youngergen_and_prev_nonclean_card ==> no change.
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194 void CardTableRS::write_ref_field_gc_par(oop* field, oop new_val) {
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195 jbyte* entry = ct_bs()->byte_for(field);
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196 do {
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197 jbyte entry_val = *entry;
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198 // We put this first because it's probably the most common case.
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199 if (entry_val == clean_card_val()) {
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200 // No threat of contention with cleaning threads.
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201 *entry = cur_youngergen_card_val();
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202 return;
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203 } else if (card_is_dirty_wrt_gen_iter(entry_val)
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204 || is_prev_youngergen_card_val(entry_val)) {
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205 // Mark it as both cur and prev youngergen; card cleaning thread will
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206 // eventually remove the previous stuff.
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207 jbyte new_val = cur_youngergen_and_prev_nonclean_card;
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208 jbyte res = Atomic::cmpxchg(new_val, entry, entry_val);
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209 // Did the CAS succeed?
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210 if (res == entry_val) return;
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211 // Otherwise, retry, to see the new value.
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212 continue;
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213 } else {
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214 assert(entry_val == cur_youngergen_and_prev_nonclean_card
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215 || entry_val == cur_youngergen_card_val(),
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216 "should be only possibilities.");
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217 return;
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218 }
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219 } while (true);
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220 }
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221
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222 void CardTableRS::younger_refs_in_space_iterate(Space* sp,
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223 OopsInGenClosure* cl) {
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224 DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, _ct_bs.precision(),
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225 cl->gen_boundary());
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226 ClearNoncleanCardWrapper clear_cl(dcto_cl, this);
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227
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228 _ct_bs.non_clean_card_iterate(sp, sp->used_region_at_save_marks(),
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229 dcto_cl, &clear_cl, false);
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230 }
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231
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232 void CardTableRS::clear_into_younger(Generation* gen, bool clear_perm) {
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233 GenCollectedHeap* gch = GenCollectedHeap::heap();
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234 // Generations younger than gen have been evacuated. We can clear
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235 // card table entries for gen (we know that it has no pointers
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236 // to younger gens) and for those below. The card tables for
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237 // the youngest gen need never be cleared, and those for perm gen
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238 // will be cleared based on the parameter clear_perm.
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239 // There's a bit of subtlety in the clear() and invalidate()
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240 // methods that we exploit here and in invalidate_or_clear()
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241 // below to avoid missing cards at the fringes. If clear() or
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242 // invalidate() are changed in the future, this code should
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243 // be revisited. 20040107.ysr
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244 Generation* g = gen;
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245 for(Generation* prev_gen = gch->prev_gen(g);
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246 prev_gen != NULL;
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247 g = prev_gen, prev_gen = gch->prev_gen(g)) {
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248 MemRegion to_be_cleared_mr = g->prev_used_region();
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249 clear(to_be_cleared_mr);
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250 }
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251 // Clear perm gen cards if asked to do so.
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252 if (clear_perm) {
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253 MemRegion to_be_cleared_mr = gch->perm_gen()->prev_used_region();
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254 clear(to_be_cleared_mr);
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255 }
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256 }
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257
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258 void CardTableRS::invalidate_or_clear(Generation* gen, bool younger,
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259 bool perm) {
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260 GenCollectedHeap* gch = GenCollectedHeap::heap();
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261 // For each generation gen (and younger and/or perm)
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262 // invalidate the cards for the currently occupied part
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263 // of that generation and clear the cards for the
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264 // unoccupied part of the generation (if any, making use
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265 // of that generation's prev_used_region to determine that
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266 // region). No need to do anything for the youngest
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267 // generation. Also see note#20040107.ysr above.
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268 Generation* g = gen;
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269 for(Generation* prev_gen = gch->prev_gen(g); prev_gen != NULL;
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270 g = prev_gen, prev_gen = gch->prev_gen(g)) {
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271 MemRegion used_mr = g->used_region();
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272 MemRegion to_be_cleared_mr = g->prev_used_region().minus(used_mr);
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273 if (!to_be_cleared_mr.is_empty()) {
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274 clear(to_be_cleared_mr);
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275 }
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276 invalidate(used_mr);
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277 if (!younger) break;
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278 }
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279 // Clear perm gen cards if asked to do so.
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280 if (perm) {
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281 g = gch->perm_gen();
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282 MemRegion used_mr = g->used_region();
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283 MemRegion to_be_cleared_mr = g->prev_used_region().minus(used_mr);
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284 if (!to_be_cleared_mr.is_empty()) {
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285 clear(to_be_cleared_mr);
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286 }
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287 invalidate(used_mr);
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288 }
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289 }
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290
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291
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292 class VerifyCleanCardClosure: public OopClosure {
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293 HeapWord* boundary;
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294 HeapWord* begin; HeapWord* end;
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295 public:
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296 void do_oop(oop* p) {
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297 HeapWord* jp = (HeapWord*)p;
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298 if (jp >= begin && jp < end) {
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299 guarantee(*p == NULL || (HeapWord*)p < boundary
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300 || (HeapWord*)(*p) >= boundary,
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301 "pointer on clean card crosses boundary");
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302 }
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303 }
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304 VerifyCleanCardClosure(HeapWord* b, HeapWord* _begin, HeapWord* _end) :
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305 boundary(b), begin(_begin), end(_end) {}
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306 };
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307
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308 class VerifyCTSpaceClosure: public SpaceClosure {
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309 CardTableRS* _ct;
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310 HeapWord* _boundary;
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311 public:
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312 VerifyCTSpaceClosure(CardTableRS* ct, HeapWord* boundary) :
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313 _ct(ct), _boundary(boundary) {}
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314 void do_space(Space* s) { _ct->verify_space(s, _boundary); }
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315 };
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316
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317 class VerifyCTGenClosure: public GenCollectedHeap::GenClosure {
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318 CardTableRS* _ct;
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319 public:
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320 VerifyCTGenClosure(CardTableRS* ct) : _ct(ct) {}
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321 void do_generation(Generation* gen) {
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322 // Skip the youngest generation.
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323 if (gen->level() == 0) return;
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324 // Normally, we're interested in pointers to younger generations.
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325 VerifyCTSpaceClosure blk(_ct, gen->reserved().start());
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326 gen->space_iterate(&blk, true);
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327 }
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328 };
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329
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330 void CardTableRS::verify_space(Space* s, HeapWord* gen_boundary) {
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331 // We don't need to do young-gen spaces.
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332 if (s->end() <= gen_boundary) return;
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333 MemRegion used = s->used_region();
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334
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335 jbyte* cur_entry = byte_for(used.start());
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336 jbyte* limit = byte_after(used.last());
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337 while (cur_entry < limit) {
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338 if (*cur_entry == CardTableModRefBS::clean_card) {
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339 jbyte* first_dirty = cur_entry+1;
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340 while (first_dirty < limit &&
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341 *first_dirty == CardTableModRefBS::clean_card) {
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342 first_dirty++;
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343 }
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344 // If the first object is a regular object, and it has a
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345 // young-to-old field, that would mark the previous card.
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346 HeapWord* boundary = addr_for(cur_entry);
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347 HeapWord* end = (first_dirty >= limit) ? used.end() : addr_for(first_dirty);
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348 HeapWord* boundary_block = s->block_start(boundary);
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349 HeapWord* begin = boundary; // Until proven otherwise.
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350 HeapWord* start_block = boundary_block; // Until proven otherwise.
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351 if (boundary_block < boundary) {
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352 if (s->block_is_obj(boundary_block) && s->obj_is_alive(boundary_block)) {
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353 oop boundary_obj = oop(boundary_block);
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354 if (!boundary_obj->is_objArray() &&
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355 !boundary_obj->is_typeArray()) {
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356 guarantee(cur_entry > byte_for(used.start()),
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357 "else boundary would be boundary_block");
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358 if (*byte_for(boundary_block) != CardTableModRefBS::clean_card) {
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359 begin = boundary_block + s->block_size(boundary_block);
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360 start_block = begin;
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361 }
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362 }
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363 }
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364 }
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365 // Now traverse objects until end.
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366 HeapWord* cur = start_block;
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367 VerifyCleanCardClosure verify_blk(gen_boundary, begin, end);
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368 while (cur < end) {
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369 if (s->block_is_obj(cur) && s->obj_is_alive(cur)) {
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370 oop(cur)->oop_iterate(&verify_blk);
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371 }
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372 cur += s->block_size(cur);
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373 }
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374 cur_entry = first_dirty;
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375 } else {
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376 // We'd normally expect that cur_youngergen_and_prev_nonclean_card
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377 // is a transient value, that cannot be in the card table
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378 // except during GC, and thus assert that:
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379 // guarantee(*cur_entry != cur_youngergen_and_prev_nonclean_card,
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380 // "Illegal CT value");
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381 // That however, need not hold, as will become clear in the
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382 // following...
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383
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384 // We'd normally expect that if we are in the parallel case,
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385 // we can't have left a prev value (which would be different
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386 // from the current value) in the card table, and so we'd like to
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387 // assert that:
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388 // guarantee(cur_youngergen_card_val() == youngergen_card
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389 // || !is_prev_youngergen_card_val(*cur_entry),
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390 // "Illegal CT value");
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391 // That, however, may not hold occasionally, because of
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392 // CMS or MSC in the old gen. To wit, consider the
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393 // following two simple illustrative scenarios:
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394 // (a) CMS: Consider the case where a large object L
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395 // spanning several cards is allocated in the old
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396 // gen, and has a young gen reference stored in it, dirtying
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397 // some interior cards. A young collection scans the card,
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398 // finds a young ref and installs a youngergenP_n value.
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399 // L then goes dead. Now a CMS collection starts,
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400 // finds L dead and sweeps it up. Assume that L is
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401 // abutting _unallocated_blk, so _unallocated_blk is
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402 // adjusted down to (below) L. Assume further that
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403 // no young collection intervenes during this CMS cycle.
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404 // The next young gen cycle will not get to look at this
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405 // youngergenP_n card since it lies in the unoccupied
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406 // part of the space.
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407 // Some young collections later the blocks on this
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408 // card can be re-allocated either due to direct allocation
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409 // or due to absorbing promotions. At this time, the
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410 // before-gc verification will fail the above assert.
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411 // (b) MSC: In this case, an object L with a young reference
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412 // is on a card that (therefore) holds a youngergen_n value.
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413 // Suppose also that L lies towards the end of the used
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414 // the used space before GC. An MSC collection
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415 // occurs that compacts to such an extent that this
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416 // card is no longer in the occupied part of the space.
|
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417 // Since current code in MSC does not always clear cards
|
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418 // in the unused part of old gen, this stale youngergen_n
|
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419 // value is left behind and can later be covered by
|
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420 // an object when promotion or direct allocation
|
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421 // re-allocates that part of the heap.
|
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422 //
|
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423 // Fortunately, the presence of such stale card values is
|
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424 // "only" a minor annoyance in that subsequent young collections
|
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425 // might needlessly scan such cards, but would still never corrupt
|
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426 // the heap as a result. However, it's likely not to be a significant
|
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427 // performance inhibitor in practice. For instance,
|
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428 // some recent measurements with unoccupied cards eagerly cleared
|
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429 // out to maintain this invariant, showed next to no
|
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430 // change in young collection times; of course one can construct
|
|
431 // degenerate examples where the cost can be significant.)
|
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432 // Note, in particular, that if the "stale" card is modified
|
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433 // after re-allocation, it would be dirty, not "stale". Thus,
|
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434 // we can never have a younger ref in such a card and it is
|
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435 // safe not to scan that card in any collection. [As we see
|
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436 // below, we do some unnecessary scanning
|
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437 // in some cases in the current parallel scanning algorithm.]
|
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438 //
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439 // The main point below is that the parallel card scanning code
|
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440 // deals correctly with these stale card values. There are two main
|
|
441 // cases to consider where we have a stale "younger gen" value and a
|
|
442 // "derivative" case to consider, where we have a stale
|
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443 // "cur_younger_gen_and_prev_non_clean" value, as will become
|
|
444 // apparent in the case analysis below.
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|
445 // o Case 1. If the stale value corresponds to a younger_gen_n
|
|
446 // value other than the cur_younger_gen value then the code
|
|
447 // treats this as being tantamount to a prev_younger_gen
|
|
448 // card. This means that the card may be unnecessarily scanned.
|
|
449 // There are two sub-cases to consider:
|
|
450 // o Case 1a. Let us say that the card is in the occupied part
|
|
451 // of the generation at the time the collection begins. In
|
|
452 // that case the card will be either cleared when it is scanned
|
|
453 // for young pointers, or will be set to cur_younger_gen as a
|
|
454 // result of promotion. (We have elided the normal case where
|
|
455 // the scanning thread and the promoting thread interleave
|
|
456 // possibly resulting in a transient
|
|
457 // cur_younger_gen_and_prev_non_clean value before settling
|
|
458 // to cur_younger_gen. [End Case 1a.]
|
|
459 // o Case 1b. Consider now the case when the card is in the unoccupied
|
|
460 // part of the space which becomes occupied because of promotions
|
|
461 // into it during the current young GC. In this case the card
|
|
462 // will never be scanned for young references. The current
|
|
463 // code will set the card value to either
|
|
464 // cur_younger_gen_and_prev_non_clean or leave
|
|
465 // it with its stale value -- because the promotions didn't
|
|
466 // result in any younger refs on that card. Of these two
|
|
467 // cases, the latter will be covered in Case 1a during
|
|
468 // a subsequent scan. To deal with the former case, we need
|
|
469 // to further consider how we deal with a stale value of
|
|
470 // cur_younger_gen_and_prev_non_clean in our case analysis
|
|
471 // below. This we do in Case 3 below. [End Case 1b]
|
|
472 // [End Case 1]
|
|
473 // o Case 2. If the stale value corresponds to cur_younger_gen being
|
|
474 // a value not necessarily written by a current promotion, the
|
|
475 // card will not be scanned by the younger refs scanning code.
|
|
476 // (This is OK since as we argued above such cards cannot contain
|
|
477 // any younger refs.) The result is that this value will be
|
|
478 // treated as a prev_younger_gen value in a subsequent collection,
|
|
479 // which is addressed in Case 1 above. [End Case 2]
|
|
480 // o Case 3. We here consider the "derivative" case from Case 1b. above
|
|
481 // because of which we may find a stale
|
|
482 // cur_younger_gen_and_prev_non_clean card value in the table.
|
|
483 // Once again, as in Case 1, we consider two subcases, depending
|
|
484 // on whether the card lies in the occupied or unoccupied part
|
|
485 // of the space at the start of the young collection.
|
|
486 // o Case 3a. Let us say the card is in the occupied part of
|
|
487 // the old gen at the start of the young collection. In that
|
|
488 // case, the card will be scanned by the younger refs scanning
|
|
489 // code which will set it to cur_younger_gen. In a subsequent
|
|
490 // scan, the card will be considered again and get its final
|
|
491 // correct value. [End Case 3a]
|
|
492 // o Case 3b. Now consider the case where the card is in the
|
|
493 // unoccupied part of the old gen, and is occupied as a result
|
|
494 // of promotions during thus young gc. In that case,
|
|
495 // the card will not be scanned for younger refs. The presence
|
|
496 // of newly promoted objects on the card will then result in
|
|
497 // its keeping the value cur_younger_gen_and_prev_non_clean
|
|
498 // value, which we have dealt with in Case 3 here. [End Case 3b]
|
|
499 // [End Case 3]
|
|
500 //
|
|
501 // (Please refer to the code in the helper class
|
|
502 // ClearNonCleanCardWrapper and in CardTableModRefBS for details.)
|
|
503 //
|
|
504 // The informal arguments above can be tightened into a formal
|
|
505 // correctness proof and it behooves us to write up such a proof,
|
|
506 // or to use model checking to prove that there are no lingering
|
|
507 // concerns.
|
|
508 //
|
|
509 // Clearly because of Case 3b one cannot bound the time for
|
|
510 // which a card will retain what we have called a "stale" value.
|
|
511 // However, one can obtain a Loose upper bound on the redundant
|
|
512 // work as a result of such stale values. Note first that any
|
|
513 // time a stale card lies in the occupied part of the space at
|
|
514 // the start of the collection, it is scanned by younger refs
|
|
515 // code and we can define a rank function on card values that
|
|
516 // declines when this is so. Note also that when a card does not
|
|
517 // lie in the occupied part of the space at the beginning of a
|
|
518 // young collection, its rank can either decline or stay unchanged.
|
|
519 // In this case, no extra work is done in terms of redundant
|
|
520 // younger refs scanning of that card.
|
|
521 // Then, the case analysis above reveals that, in the worst case,
|
|
522 // any such stale card will be scanned unnecessarily at most twice.
|
|
523 //
|
|
524 // It is nonethelss advisable to try and get rid of some of this
|
|
525 // redundant work in a subsequent (low priority) re-design of
|
|
526 // the card-scanning code, if only to simplify the underlying
|
|
527 // state machine analysis/proof. ysr 1/28/2002. XXX
|
|
528 cur_entry++;
|
|
529 }
|
|
530 }
|
|
531 }
|
|
532
|
|
533 void CardTableRS::verify() {
|
|
534 // At present, we only know how to verify the card table RS for
|
|
535 // generational heaps.
|
|
536 VerifyCTGenClosure blk(this);
|
|
537 CollectedHeap* ch = Universe::heap();
|
|
538 // We will do the perm-gen portion of the card table, too.
|
|
539 Generation* pg = SharedHeap::heap()->perm_gen();
|
|
540 HeapWord* pg_boundary = pg->reserved().start();
|
|
541
|
|
542 if (ch->kind() == CollectedHeap::GenCollectedHeap) {
|
|
543 GenCollectedHeap::heap()->generation_iterate(&blk, false);
|
|
544 _ct_bs.verify();
|
|
545
|
|
546 // If the old gen collections also collect perm, then we are only
|
|
547 // interested in perm-to-young pointers, not perm-to-old pointers.
|
|
548 GenCollectedHeap* gch = GenCollectedHeap::heap();
|
|
549 CollectorPolicy* cp = gch->collector_policy();
|
|
550 if (cp->is_mark_sweep_policy() || cp->is_concurrent_mark_sweep_policy()) {
|
|
551 pg_boundary = gch->get_gen(1)->reserved().start();
|
|
552 }
|
|
553 }
|
|
554 VerifyCTSpaceClosure perm_space_blk(this, pg_boundary);
|
|
555 SharedHeap::heap()->perm_gen()->space_iterate(&perm_space_blk, true);
|
|
556 }
|
|
557
|
|
558
|
|
559 void CardTableRS::verify_empty(MemRegion mr) {
|
|
560 if (!mr.is_empty()) {
|
|
561 jbyte* cur_entry = byte_for(mr.start());
|
|
562 jbyte* limit = byte_after(mr.last());
|
|
563 for (;cur_entry < limit; cur_entry++) {
|
|
564 guarantee(*cur_entry == CardTableModRefBS::clean_card,
|
|
565 "Unexpected dirty card found");
|
|
566 }
|
|
567 }
|
|
568 }
|