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1 /* |
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2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. |
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8 * |
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9 * This code is distributed in the hope that it will be useful, but WITHOUT |
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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12 * version 2 for more details (a copy is included in the LICENSE file that |
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13 * accompanied this code). |
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14 * |
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15 * You should have received a copy of the GNU General Public License version |
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16 * 2 along with this work; if not, write to the Free Software Foundation, |
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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18 * |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #include "precompiled.hpp" |
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26 #include "gc/g1/g1BlockOffsetTable.inline.hpp" |
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27 #include "gc/g1/g1CollectedHeap.inline.hpp" |
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28 #include "gc/g1/heapRegion.hpp" |
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29 #include "gc/shared/space.hpp" |
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30 #include "logging/log.hpp" |
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31 #include "oops/oop.inline.hpp" |
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32 #include "runtime/java.hpp" |
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33 #include "services/memTracker.hpp" |
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34 |
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35 |
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36 |
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37 ////////////////////////////////////////////////////////////////////// |
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38 // G1BlockOffsetTable |
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39 ////////////////////////////////////////////////////////////////////// |
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40 |
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41 G1BlockOffsetTable::G1BlockOffsetTable(MemRegion heap, G1RegionToSpaceMapper* storage) : |
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42 _reserved(heap), _offset_array(NULL) { |
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43 |
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44 MemRegion bot_reserved = storage->reserved(); |
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45 |
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46 _offset_array = (u_char*)bot_reserved.start(); |
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47 |
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48 log_trace(gc, bot)("G1BlockOffsetTable::G1BlockOffsetTable: "); |
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49 log_trace(gc, bot)(" rs.base(): " PTR_FORMAT " rs.size(): " SIZE_FORMAT " rs end(): " PTR_FORMAT, |
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50 p2i(bot_reserved.start()), bot_reserved.byte_size(), p2i(bot_reserved.end())); |
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51 } |
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52 |
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53 bool G1BlockOffsetTable::is_card_boundary(HeapWord* p) const { |
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54 assert(p >= _reserved.start(), "just checking"); |
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55 size_t delta = pointer_delta(p, _reserved.start()); |
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56 return (delta & right_n_bits((int)BOTConstants::LogN_words)) == (size_t)NoBits; |
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57 } |
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58 |
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59 #ifdef ASSERT |
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60 void G1BlockOffsetTable::check_index(size_t index, const char* msg) const { |
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61 assert((index) < (_reserved.word_size() >> BOTConstants::LogN_words), |
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62 "%s - index: " SIZE_FORMAT ", _vs.committed_size: " SIZE_FORMAT, |
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63 msg, (index), (_reserved.word_size() >> BOTConstants::LogN_words)); |
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64 assert(G1CollectedHeap::heap()->is_in_exact(address_for_index_raw(index)), |
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65 "Index " SIZE_FORMAT " corresponding to " PTR_FORMAT |
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66 " (%u) is not in committed area.", |
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67 (index), |
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68 p2i(address_for_index_raw(index)), |
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69 G1CollectedHeap::heap()->addr_to_region(address_for_index_raw(index))); |
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70 } |
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71 #endif // ASSERT |
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72 |
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73 ////////////////////////////////////////////////////////////////////// |
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74 // G1BlockOffsetTablePart |
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75 ////////////////////////////////////////////////////////////////////// |
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76 |
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77 G1BlockOffsetTablePart::G1BlockOffsetTablePart(G1BlockOffsetTable* array, G1ContiguousSpace* gsp) : |
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78 _bot(array), |
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79 _space(gsp), |
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80 _next_offset_threshold(NULL), |
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81 _next_offset_index(0) |
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82 { |
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83 debug_only(_object_can_span = false;) |
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84 } |
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85 |
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86 // The arguments follow the normal convention of denoting |
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87 // a right-open interval: [start, end) |
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88 void G1BlockOffsetTablePart:: set_remainder_to_point_to_start(HeapWord* start, HeapWord* end) { |
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89 |
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90 if (start >= end) { |
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91 // The start address is equal to the end address (or to |
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92 // the right of the end address) so there are not cards |
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93 // that need to be updated.. |
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94 return; |
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95 } |
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96 |
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97 // Write the backskip value for each region. |
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98 // |
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99 // offset |
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100 // card 2nd 3rd |
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101 // | +- 1st | | |
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102 // v v v v |
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103 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+- |
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104 // |x|0|0|0|0|0|0|0|1|1|1|1|1|1| ... |1|1|1|1|2|2|2|2|2|2| ... |
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105 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+- |
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106 // 11 19 75 |
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107 // 12 |
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108 // |
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109 // offset card is the card that points to the start of an object |
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110 // x - offset value of offset card |
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111 // 1st - start of first logarithmic region |
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112 // 0 corresponds to logarithmic value N_words + 0 and 2**(3 * 0) = 1 |
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113 // 2nd - start of second logarithmic region |
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114 // 1 corresponds to logarithmic value N_words + 1 and 2**(3 * 1) = 8 |
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115 // 3rd - start of third logarithmic region |
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116 // 2 corresponds to logarithmic value N_words + 2 and 2**(3 * 2) = 64 |
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117 // |
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118 // integer below the block offset entry is an example of |
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119 // the index of the entry |
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120 // |
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121 // Given an address, |
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122 // Find the index for the address |
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123 // Find the block offset table entry |
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124 // Convert the entry to a back slide |
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125 // (e.g., with today's, offset = 0x81 => |
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126 // back slip = 2**(3*(0x81 - N_words)) = 2**3) = 8 |
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127 // Move back N (e.g., 8) entries and repeat with the |
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128 // value of the new entry |
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129 // |
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130 size_t start_card = _bot->index_for(start); |
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131 size_t end_card = _bot->index_for(end-1); |
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132 assert(start ==_bot->address_for_index(start_card), "Precondition"); |
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133 assert(end ==_bot->address_for_index(end_card)+BOTConstants::N_words, "Precondition"); |
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134 set_remainder_to_point_to_start_incl(start_card, end_card); // closed interval |
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135 } |
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136 |
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137 // Unlike the normal convention in this code, the argument here denotes |
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138 // a closed, inclusive interval: [start_card, end_card], cf set_remainder_to_point_to_start() |
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139 // above. |
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140 void G1BlockOffsetTablePart::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card) { |
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141 if (start_card > end_card) { |
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142 return; |
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143 } |
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144 assert(start_card > _bot->index_for(_space->bottom()), "Cannot be first card"); |
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145 assert(_bot->offset_array(start_card-1) <= BOTConstants::N_words, |
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146 "Offset card has an unexpected value"); |
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147 size_t start_card_for_region = start_card; |
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148 u_char offset = max_jubyte; |
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149 for (uint i = 0; i < BOTConstants::N_powers; i++) { |
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150 // -1 so that the the card with the actual offset is counted. Another -1 |
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151 // so that the reach ends in this region and not at the start |
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152 // of the next. |
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153 size_t reach = start_card - 1 + (BOTConstants::power_to_cards_back(i+1) - 1); |
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154 offset = BOTConstants::N_words + i; |
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155 if (reach >= end_card) { |
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156 _bot->set_offset_array(start_card_for_region, end_card, offset); |
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157 start_card_for_region = reach + 1; |
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158 break; |
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159 } |
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160 _bot->set_offset_array(start_card_for_region, reach, offset); |
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161 start_card_for_region = reach + 1; |
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162 } |
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163 assert(start_card_for_region > end_card, "Sanity check"); |
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164 DEBUG_ONLY(check_all_cards(start_card, end_card);) |
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165 } |
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166 |
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167 // The card-interval [start_card, end_card] is a closed interval; this |
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168 // is an expensive check -- use with care and only under protection of |
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169 // suitable flag. |
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170 void G1BlockOffsetTablePart::check_all_cards(size_t start_card, size_t end_card) const { |
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171 |
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172 if (end_card < start_card) { |
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173 return; |
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174 } |
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175 guarantee(_bot->offset_array(start_card) == BOTConstants::N_words, "Wrong value in second card"); |
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176 for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) { |
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177 u_char entry = _bot->offset_array(c); |
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178 if (c - start_card > BOTConstants::power_to_cards_back(1)) { |
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179 guarantee(entry > BOTConstants::N_words, |
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180 "Should be in logarithmic region - " |
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181 "entry: %u, " |
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182 "_array->offset_array(c): %u, " |
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183 "N_words: %u", |
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184 (uint)entry, (uint)_bot->offset_array(c), BOTConstants::N_words); |
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185 } |
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186 size_t backskip = BOTConstants::entry_to_cards_back(entry); |
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187 size_t landing_card = c - backskip; |
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188 guarantee(landing_card >= (start_card - 1), "Inv"); |
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189 if (landing_card >= start_card) { |
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190 guarantee(_bot->offset_array(landing_card) <= entry, |
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191 "Monotonicity - landing_card offset: %u, " |
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192 "entry: %u", |
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193 (uint)_bot->offset_array(landing_card), (uint)entry); |
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194 } else { |
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195 guarantee(landing_card == start_card - 1, "Tautology"); |
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196 // Note that N_words is the maximum offset value |
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197 guarantee(_bot->offset_array(landing_card) <= BOTConstants::N_words, |
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198 "landing card offset: %u, " |
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199 "N_words: %u", |
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200 (uint)_bot->offset_array(landing_card), (uint)BOTConstants::N_words); |
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201 } |
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202 } |
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203 } |
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204 |
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205 HeapWord* G1BlockOffsetTablePart::forward_to_block_containing_addr_slow(HeapWord* q, |
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206 HeapWord* n, |
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207 const void* addr) { |
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208 // We're not in the normal case. We need to handle an important subcase |
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209 // here: LAB allocation. An allocation previously recorded in the |
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210 // offset table was actually a lab allocation, and was divided into |
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211 // several objects subsequently. Fix this situation as we answer the |
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212 // query, by updating entries as we cross them. |
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213 |
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214 // If the fist object's end q is at the card boundary. Start refining |
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215 // with the corresponding card (the value of the entry will be basically |
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216 // set to 0). If the object crosses the boundary -- start from the next card. |
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217 size_t n_index = _bot->index_for(n); |
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218 size_t next_index = _bot->index_for(n) + !_bot->is_card_boundary(n); |
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219 // Calculate a consistent next boundary. If "n" is not at the boundary |
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220 // already, step to the boundary. |
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221 HeapWord* next_boundary = _bot->address_for_index(n_index) + |
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222 (n_index == next_index ? 0 : BOTConstants::N_words); |
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223 assert(next_boundary <= _bot->_reserved.end(), |
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224 "next_boundary is beyond the end of the covered region " |
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225 " next_boundary " PTR_FORMAT " _array->_end " PTR_FORMAT, |
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226 p2i(next_boundary), p2i(_bot->_reserved.end())); |
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227 if (addr >= _space->top()) return _space->top(); |
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228 while (next_boundary < addr) { |
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229 while (n <= next_boundary) { |
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230 q = n; |
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231 oop obj = oop(q); |
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232 if (obj->klass_or_null_acquire() == NULL) return q; |
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233 n += block_size(q); |
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234 } |
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235 assert(q <= next_boundary && n > next_boundary, "Consequence of loop"); |
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236 // [q, n) is the block that crosses the boundary. |
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237 alloc_block_work(&next_boundary, &next_index, q, n); |
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238 } |
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239 return forward_to_block_containing_addr_const(q, n, addr); |
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240 } |
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241 |
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242 // |
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243 // threshold_ |
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244 // | _index_ |
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245 // v v |
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246 // +-------+-------+-------+-------+-------+ |
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247 // | i-1 | i | i+1 | i+2 | i+3 | |
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248 // +-------+-------+-------+-------+-------+ |
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249 // ( ^ ] |
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250 // block-start |
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251 // |
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252 void G1BlockOffsetTablePart::alloc_block_work(HeapWord** threshold_, size_t* index_, |
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253 HeapWord* blk_start, HeapWord* blk_end) { |
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254 // For efficiency, do copy-in/copy-out. |
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255 HeapWord* threshold = *threshold_; |
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256 size_t index = *index_; |
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257 |
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258 assert(blk_start != NULL && blk_end > blk_start, |
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259 "phantom block"); |
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260 assert(blk_end > threshold, "should be past threshold"); |
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261 assert(blk_start <= threshold, "blk_start should be at or before threshold"); |
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262 assert(pointer_delta(threshold, blk_start) <= BOTConstants::N_words, |
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263 "offset should be <= BlockOffsetSharedArray::N"); |
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264 assert(G1CollectedHeap::heap()->is_in_reserved(blk_start), |
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265 "reference must be into the heap"); |
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266 assert(G1CollectedHeap::heap()->is_in_reserved(blk_end-1), |
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267 "limit must be within the heap"); |
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268 assert(threshold == _bot->_reserved.start() + index*BOTConstants::N_words, |
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269 "index must agree with threshold"); |
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270 |
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271 DEBUG_ONLY(size_t orig_index = index;) |
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272 |
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273 // Mark the card that holds the offset into the block. Note |
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274 // that _next_offset_index and _next_offset_threshold are not |
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275 // updated until the end of this method. |
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276 _bot->set_offset_array(index, threshold, blk_start); |
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277 |
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278 // We need to now mark the subsequent cards that this blk spans. |
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279 |
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280 // Index of card on which blk ends. |
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281 size_t end_index = _bot->index_for(blk_end - 1); |
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282 |
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283 // Are there more cards left to be updated? |
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284 if (index + 1 <= end_index) { |
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285 HeapWord* rem_st = _bot->address_for_index(index + 1); |
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286 // Calculate rem_end this way because end_index |
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287 // may be the last valid index in the covered region. |
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288 HeapWord* rem_end = _bot->address_for_index(end_index) + BOTConstants::N_words; |
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289 set_remainder_to_point_to_start(rem_st, rem_end); |
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290 } |
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291 |
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292 index = end_index + 1; |
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293 // Calculate threshold_ this way because end_index |
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294 // may be the last valid index in the covered region. |
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295 threshold = _bot->address_for_index(end_index) + BOTConstants::N_words; |
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296 assert(threshold >= blk_end, "Incorrect offset threshold"); |
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297 |
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298 // index_ and threshold_ updated here. |
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299 *threshold_ = threshold; |
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300 *index_ = index; |
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301 |
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302 #ifdef ASSERT |
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303 // The offset can be 0 if the block starts on a boundary. That |
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304 // is checked by an assertion above. |
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305 size_t start_index = _bot->index_for(blk_start); |
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306 HeapWord* boundary = _bot->address_for_index(start_index); |
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307 assert((_bot->offset_array(orig_index) == 0 && blk_start == boundary) || |
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308 (_bot->offset_array(orig_index) > 0 && _bot->offset_array(orig_index) <= BOTConstants::N_words), |
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309 "offset array should have been set - " |
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310 "orig_index offset: %u, " |
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311 "blk_start: " PTR_FORMAT ", " |
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312 "boundary: " PTR_FORMAT, |
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313 (uint)_bot->offset_array(orig_index), |
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314 p2i(blk_start), p2i(boundary)); |
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315 for (size_t j = orig_index + 1; j <= end_index; j++) { |
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316 assert(_bot->offset_array(j) > 0 && |
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317 _bot->offset_array(j) <= |
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318 (u_char) (BOTConstants::N_words+BOTConstants::N_powers-1), |
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319 "offset array should have been set - " |
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320 "%u not > 0 OR %u not <= %u", |
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321 (uint) _bot->offset_array(j), |
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322 (uint) _bot->offset_array(j), |
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323 (uint) (BOTConstants::N_words+BOTConstants::N_powers-1)); |
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324 } |
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325 #endif |
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326 } |
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327 |
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328 void G1BlockOffsetTablePart::verify() const { |
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329 assert(_space->bottom() < _space->top(), "Only non-empty regions should be verified."); |
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330 size_t start_card = _bot->index_for(_space->bottom()); |
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331 size_t end_card = _bot->index_for(_space->top() - 1); |
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332 |
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333 for (size_t current_card = start_card; current_card < end_card; current_card++) { |
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334 u_char entry = _bot->offset_array(current_card); |
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335 if (entry < BOTConstants::N_words) { |
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336 // The entry should point to an object before the current card. Verify that |
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337 // it is possible to walk from that object in to the current card by just |
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338 // iterating over the objects following it. |
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339 HeapWord* card_address = _bot->address_for_index(current_card); |
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340 HeapWord* obj_end = card_address - entry; |
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341 while (obj_end < card_address) { |
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342 HeapWord* obj = obj_end; |
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343 size_t obj_size = block_size(obj); |
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344 obj_end = obj + obj_size; |
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345 guarantee(obj_end > obj && obj_end <= _space->top(), |
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346 "Invalid object end. obj: " PTR_FORMAT " obj_size: " SIZE_FORMAT " obj_end: " PTR_FORMAT " top: " PTR_FORMAT, |
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347 p2i(obj), obj_size, p2i(obj_end), p2i(_space->top())); |
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348 } |
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349 } else { |
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350 // Because we refine the BOT based on which cards are dirty there is not much we can verify here. |
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351 // We need to make sure that we are going backwards and that we don't pass the start of the |
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352 // corresponding heap region. But that is about all we can verify. |
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353 size_t backskip = BOTConstants::entry_to_cards_back(entry); |
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354 guarantee(backskip >= 1, "Must be going back at least one card."); |
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355 |
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356 size_t max_backskip = current_card - start_card; |
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357 guarantee(backskip <= max_backskip, |
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358 "Going backwards beyond the start_card. start_card: " SIZE_FORMAT " current_card: " SIZE_FORMAT " backskip: " SIZE_FORMAT, |
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359 start_card, current_card, backskip); |
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360 |
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361 HeapWord* backskip_address = _bot->address_for_index(current_card - backskip); |
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362 guarantee(backskip_address >= _space->bottom(), |
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363 "Going backwards beyond bottom of the region: bottom: " PTR_FORMAT ", backskip_address: " PTR_FORMAT, |
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364 p2i(_space->bottom()), p2i(backskip_address)); |
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365 } |
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366 } |
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367 } |
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368 |
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369 #ifdef ASSERT |
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370 void G1BlockOffsetTablePart::set_object_can_span(bool can_span) { |
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371 _object_can_span = can_span; |
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372 } |
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373 #endif |
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374 |
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375 #ifndef PRODUCT |
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376 void |
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377 G1BlockOffsetTablePart::print_on(outputStream* out) { |
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378 size_t from_index = _bot->index_for(_space->bottom()); |
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379 size_t to_index = _bot->index_for(_space->end()); |
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380 out->print_cr(">> BOT for area [" PTR_FORMAT "," PTR_FORMAT ") " |
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381 "cards [" SIZE_FORMAT "," SIZE_FORMAT ")", |
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382 p2i(_space->bottom()), p2i(_space->end()), from_index, to_index); |
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383 for (size_t i = from_index; i < to_index; ++i) { |
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384 out->print_cr(" entry " SIZE_FORMAT_W(8) " | " PTR_FORMAT " : %3u", |
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385 i, p2i(_bot->address_for_index(i)), |
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386 (uint) _bot->offset_array(i)); |
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387 } |
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388 out->print_cr(" next offset threshold: " PTR_FORMAT, p2i(_next_offset_threshold)); |
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389 out->print_cr(" next offset index: " SIZE_FORMAT, _next_offset_index); |
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390 } |
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391 #endif // !PRODUCT |
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392 |
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393 HeapWord* G1BlockOffsetTablePart::initialize_threshold_raw() { |
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394 assert(!G1CollectedHeap::heap()->is_in_reserved(_bot->_offset_array), |
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395 "just checking"); |
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396 _next_offset_index = _bot->index_for_raw(_space->bottom()); |
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397 _next_offset_index++; |
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398 _next_offset_threshold = |
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399 _bot->address_for_index_raw(_next_offset_index); |
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400 return _next_offset_threshold; |
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401 } |
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402 |
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403 void G1BlockOffsetTablePart::zero_bottom_entry_raw() { |
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404 assert(!G1CollectedHeap::heap()->is_in_reserved(_bot->_offset_array), |
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405 "just checking"); |
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406 size_t bottom_index = _bot->index_for_raw(_space->bottom()); |
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407 assert(_bot->address_for_index_raw(bottom_index) == _space->bottom(), |
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408 "Precondition of call"); |
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409 _bot->set_offset_array_raw(bottom_index, 0); |
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410 } |
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411 |
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412 HeapWord* G1BlockOffsetTablePart::initialize_threshold() { |
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413 assert(!G1CollectedHeap::heap()->is_in_reserved(_bot->_offset_array), |
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414 "just checking"); |
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415 _next_offset_index = _bot->index_for(_space->bottom()); |
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416 _next_offset_index++; |
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417 _next_offset_threshold = |
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418 _bot->address_for_index(_next_offset_index); |
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419 return _next_offset_threshold; |
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420 } |
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421 |
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422 void G1BlockOffsetTablePart::set_for_starts_humongous(HeapWord* obj_top, size_t fill_size) { |
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423 // The first BOT entry should have offset 0. |
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424 reset_bot(); |
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425 alloc_block(_space->bottom(), obj_top); |
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426 if (fill_size > 0) { |
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427 alloc_block(obj_top, fill_size); |
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428 } |
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429 } |