1521
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1 /*
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2 * Copyright 2001-2009 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/_promotionInfo.cpp.incl"
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27
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28 /////////////////////////////////////////////////////////////////////////
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29 //// PromotionInfo
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30 /////////////////////////////////////////////////////////////////////////
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31
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32
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33 //////////////////////////////////////////////////////////////////////////////
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34 // We go over the list of promoted objects, removing each from the list,
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35 // and applying the closure (this may, in turn, add more elements to
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36 // the tail of the promoted list, and these newly added objects will
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37 // also be processed) until the list is empty.
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38 // To aid verification and debugging, in the non-product builds
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39 // we actually forward _promoHead each time we process a promoted oop.
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40 // Note that this is not necessary in general (i.e. when we don't need to
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41 // call PromotionInfo::verify()) because oop_iterate can only add to the
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42 // end of _promoTail, and never needs to look at _promoHead.
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43
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44 #define PROMOTED_OOPS_ITERATE_DEFN(OopClosureType, nv_suffix) \
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45 \
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46 void PromotionInfo::promoted_oops_iterate##nv_suffix(OopClosureType* cl) { \
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47 NOT_PRODUCT(verify()); \
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48 PromotedObject *curObj, *nextObj; \
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49 for (curObj = _promoHead; curObj != NULL; curObj = nextObj) { \
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50 if ((nextObj = curObj->next()) == NULL) { \
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51 /* protect ourselves against additions due to closure application \
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52 below by resetting the list. */ \
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53 assert(_promoTail == curObj, "Should have been the tail"); \
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54 _promoHead = _promoTail = NULL; \
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55 } \
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56 if (curObj->hasDisplacedMark()) { \
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57 /* restore displaced header */ \
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58 oop(curObj)->set_mark(nextDisplacedHeader()); \
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59 } else { \
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60 /* restore prototypical header */ \
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61 oop(curObj)->init_mark(); \
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62 } \
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63 /* The "promoted_mark" should now not be set */ \
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64 assert(!curObj->hasPromotedMark(), \
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65 "Should have been cleared by restoring displaced mark-word"); \
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66 NOT_PRODUCT(_promoHead = nextObj); \
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67 if (cl != NULL) oop(curObj)->oop_iterate(cl); \
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68 if (nextObj == NULL) { /* start at head of list reset above */ \
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69 nextObj = _promoHead; \
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70 } \
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71 } \
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72 assert(noPromotions(), "post-condition violation"); \
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73 assert(_promoHead == NULL && _promoTail == NULL, "emptied promoted list");\
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74 assert(_spoolHead == _spoolTail, "emptied spooling buffers"); \
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75 assert(_firstIndex == _nextIndex, "empty buffer"); \
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76 }
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77
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78 // This should have been ALL_SINCE_...() just like the others,
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79 // but, because the body of the method above is somehwat longer,
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80 // the MSVC compiler cannot cope; as a workaround, we split the
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81 // macro into its 3 constituent parts below (see original macro
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82 // definition in specializedOopClosures.hpp).
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83 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG(PROMOTED_OOPS_ITERATE_DEFN)
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84 PROMOTED_OOPS_ITERATE_DEFN(OopsInGenClosure,_v)
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85
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86
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87 // Return the next displaced header, incrementing the pointer and
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88 // recycling spool area as necessary.
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89 markOop PromotionInfo::nextDisplacedHeader() {
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90 assert(_spoolHead != NULL, "promotionInfo inconsistency");
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91 assert(_spoolHead != _spoolTail || _firstIndex < _nextIndex,
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92 "Empty spool space: no displaced header can be fetched");
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93 assert(_spoolHead->bufferSize > _firstIndex, "Off by one error at head?");
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94 markOop hdr = _spoolHead->displacedHdr[_firstIndex];
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95 // Spool forward
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96 if (++_firstIndex == _spoolHead->bufferSize) { // last location in this block
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97 // forward to next block, recycling this block into spare spool buffer
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98 SpoolBlock* tmp = _spoolHead->nextSpoolBlock;
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99 assert(_spoolHead != _spoolTail, "Spooling storage mix-up");
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100 _spoolHead->nextSpoolBlock = _spareSpool;
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101 _spareSpool = _spoolHead;
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102 _spoolHead = tmp;
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103 _firstIndex = 1;
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104 NOT_PRODUCT(
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105 if (_spoolHead == NULL) { // all buffers fully consumed
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106 assert(_spoolTail == NULL && _nextIndex == 1,
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107 "spool buffers processing inconsistency");
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108 }
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109 )
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110 }
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111 return hdr;
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112 }
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113
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114 void PromotionInfo::track(PromotedObject* trackOop) {
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115 track(trackOop, oop(trackOop)->klass());
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116 }
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117
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118 void PromotionInfo::track(PromotedObject* trackOop, klassOop klassOfOop) {
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119 // make a copy of header as it may need to be spooled
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120 markOop mark = oop(trackOop)->mark();
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121 trackOop->clearNext();
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122 if (mark->must_be_preserved_for_cms_scavenge(klassOfOop)) {
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123 // save non-prototypical header, and mark oop
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124 saveDisplacedHeader(mark);
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125 trackOop->setDisplacedMark();
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126 } else {
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127 // we'd like to assert something like the following:
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128 // assert(mark == markOopDesc::prototype(), "consistency check");
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129 // ... but the above won't work because the age bits have not (yet) been
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130 // cleared. The remainder of the check would be identical to the
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131 // condition checked in must_be_preserved() above, so we don't really
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132 // have anything useful to check here!
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133 }
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134 if (_promoTail != NULL) {
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135 assert(_promoHead != NULL, "List consistency");
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136 _promoTail->setNext(trackOop);
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137 _promoTail = trackOop;
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138 } else {
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139 assert(_promoHead == NULL, "List consistency");
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140 _promoHead = _promoTail = trackOop;
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141 }
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142 // Mask as newly promoted, so we can skip over such objects
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143 // when scanning dirty cards
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144 assert(!trackOop->hasPromotedMark(), "Should not have been marked");
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145 trackOop->setPromotedMark();
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146 }
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147
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148 // Save the given displaced header, incrementing the pointer and
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149 // obtaining more spool area as necessary.
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150 void PromotionInfo::saveDisplacedHeader(markOop hdr) {
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151 assert(_spoolHead != NULL && _spoolTail != NULL,
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152 "promotionInfo inconsistency");
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153 assert(_spoolTail->bufferSize > _nextIndex, "Off by one error at tail?");
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154 _spoolTail->displacedHdr[_nextIndex] = hdr;
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155 // Spool forward
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156 if (++_nextIndex == _spoolTail->bufferSize) { // last location in this block
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157 // get a new spooling block
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158 assert(_spoolTail->nextSpoolBlock == NULL, "tail should terminate spool list");
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159 _splice_point = _spoolTail; // save for splicing
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160 _spoolTail->nextSpoolBlock = getSpoolBlock(); // might fail
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161 _spoolTail = _spoolTail->nextSpoolBlock; // might become NULL ...
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162 // ... but will attempt filling before next promotion attempt
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163 _nextIndex = 1;
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164 }
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165 }
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166
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167 // Ensure that spooling space exists. Return false if spooling space
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168 // could not be obtained.
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169 bool PromotionInfo::ensure_spooling_space_work() {
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170 assert(!has_spooling_space(), "Only call when there is no spooling space");
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171 // Try and obtain more spooling space
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172 SpoolBlock* newSpool = getSpoolBlock();
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173 assert(newSpool == NULL ||
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174 (newSpool->bufferSize != 0 && newSpool->nextSpoolBlock == NULL),
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175 "getSpoolBlock() sanity check");
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176 if (newSpool == NULL) {
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177 return false;
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178 }
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179 _nextIndex = 1;
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180 if (_spoolTail == NULL) {
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181 _spoolTail = newSpool;
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182 if (_spoolHead == NULL) {
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183 _spoolHead = newSpool;
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184 _firstIndex = 1;
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185 } else {
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186 assert(_splice_point != NULL && _splice_point->nextSpoolBlock == NULL,
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187 "Splice point invariant");
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188 // Extra check that _splice_point is connected to list
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189 #ifdef ASSERT
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190 {
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191 SpoolBlock* blk = _spoolHead;
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192 for (; blk->nextSpoolBlock != NULL;
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193 blk = blk->nextSpoolBlock);
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194 assert(blk != NULL && blk == _splice_point,
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195 "Splice point incorrect");
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196 }
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197 #endif // ASSERT
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198 _splice_point->nextSpoolBlock = newSpool;
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199 }
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200 } else {
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201 assert(_spoolHead != NULL, "spool list consistency");
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202 _spoolTail->nextSpoolBlock = newSpool;
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203 _spoolTail = newSpool;
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204 }
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205 return true;
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206 }
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207
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208 // Get a free spool buffer from the free pool, getting a new block
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209 // from the heap if necessary.
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210 SpoolBlock* PromotionInfo::getSpoolBlock() {
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211 SpoolBlock* res;
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212 if ((res = _spareSpool) != NULL) {
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213 _spareSpool = _spareSpool->nextSpoolBlock;
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214 res->nextSpoolBlock = NULL;
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215 } else { // spare spool exhausted, get some from heap
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216 res = (SpoolBlock*)(space()->allocateScratch(refillSize()));
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217 if (res != NULL) {
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218 res->init();
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219 }
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220 }
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221 assert(res == NULL || res->nextSpoolBlock == NULL, "postcondition");
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222 return res;
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223 }
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224
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225 void PromotionInfo::startTrackingPromotions() {
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226 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
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227 "spooling inconsistency?");
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228 _firstIndex = _nextIndex = 1;
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229 _tracking = true;
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230 }
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231
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232 #define CMSPrintPromoBlockInfo 1
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233
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234 void PromotionInfo::stopTrackingPromotions(uint worker_id) {
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235 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
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236 "spooling inconsistency?");
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237 _firstIndex = _nextIndex = 1;
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238 _tracking = false;
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239 if (CMSPrintPromoBlockInfo > 1) {
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240 print_statistics(worker_id);
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241 }
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242 }
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243
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244 void PromotionInfo::print_statistics(uint worker_id) const {
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245 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
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246 "Else will undercount");
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247 assert(CMSPrintPromoBlockInfo > 0, "Else unnecessary call");
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248 // Count the number of blocks and slots in the free pool
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249 size_t slots = 0;
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250 size_t blocks = 0;
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251 for (SpoolBlock* cur_spool = _spareSpool;
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252 cur_spool != NULL;
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253 cur_spool = cur_spool->nextSpoolBlock) {
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254 // the first entry is just a self-pointer; indices 1 through
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255 // bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
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256 guarantee((void*)cur_spool->displacedHdr == (void*)&cur_spool->displacedHdr,
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257 "first entry of displacedHdr should be self-referential");
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258 slots += cur_spool->bufferSize - 1;
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259 blocks++;
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260 }
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261 if (_spoolHead != NULL) {
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262 slots += _spoolHead->bufferSize - 1;
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263 blocks++;
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264 }
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265 gclog_or_tty->print_cr(" [worker %d] promo_blocks = %d, promo_slots = %d ",
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266 worker_id, blocks, slots);
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267 }
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268
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269 // When _spoolTail is not NULL, then the slot <_spoolTail, _nextIndex>
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270 // points to the next slot available for filling.
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271 // The set of slots holding displaced headers are then all those in the
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272 // right-open interval denoted by:
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273 //
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274 // [ <_spoolHead, _firstIndex>, <_spoolTail, _nextIndex> )
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275 //
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276 // When _spoolTail is NULL, then the set of slots with displaced headers
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277 // is all those starting at the slot <_spoolHead, _firstIndex> and
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278 // going up to the last slot of last block in the linked list.
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279 // In this lartter case, _splice_point points to the tail block of
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280 // this linked list of blocks holding displaced headers.
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281 void PromotionInfo::verify() const {
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282 // Verify the following:
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283 // 1. the number of displaced headers matches the number of promoted
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284 // objects that have displaced headers
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285 // 2. each promoted object lies in this space
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286 debug_only(
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287 PromotedObject* junk = NULL;
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288 assert(junk->next_addr() == (void*)(oop(junk)->mark_addr()),
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289 "Offset of PromotedObject::_next is expected to align with "
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290 " the OopDesc::_mark within OopDesc");
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291 )
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292 // FIXME: guarantee????
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293 guarantee(_spoolHead == NULL || _spoolTail != NULL ||
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294 _splice_point != NULL, "list consistency");
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295 guarantee(_promoHead == NULL || _promoTail != NULL, "list consistency");
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296 // count the number of objects with displaced headers
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297 size_t numObjsWithDisplacedHdrs = 0;
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298 for (PromotedObject* curObj = _promoHead; curObj != NULL; curObj = curObj->next()) {
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299 guarantee(space()->is_in_reserved((HeapWord*)curObj), "Containment");
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300 // the last promoted object may fail the mark() != NULL test of is_oop().
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301 guarantee(curObj->next() == NULL || oop(curObj)->is_oop(), "must be an oop");
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302 if (curObj->hasDisplacedMark()) {
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303 numObjsWithDisplacedHdrs++;
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304 }
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305 }
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306 // Count the number of displaced headers
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307 size_t numDisplacedHdrs = 0;
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308 for (SpoolBlock* curSpool = _spoolHead;
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309 curSpool != _spoolTail && curSpool != NULL;
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310 curSpool = curSpool->nextSpoolBlock) {
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311 // the first entry is just a self-pointer; indices 1 through
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312 // bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
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313 guarantee((void*)curSpool->displacedHdr == (void*)&curSpool->displacedHdr,
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314 "first entry of displacedHdr should be self-referential");
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315 numDisplacedHdrs += curSpool->bufferSize - 1;
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316 }
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317 guarantee((_spoolHead == _spoolTail) == (numDisplacedHdrs == 0),
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318 "internal consistency");
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319 guarantee(_spoolTail != NULL || _nextIndex == 1,
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320 "Inconsistency between _spoolTail and _nextIndex");
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321 // We overcounted (_firstIndex-1) worth of slots in block
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322 // _spoolHead and we undercounted (_nextIndex-1) worth of
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323 // slots in block _spoolTail. We make an appropriate
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324 // adjustment by subtracting the first and adding the
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325 // second: - (_firstIndex - 1) + (_nextIndex - 1)
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326 numDisplacedHdrs += (_nextIndex - _firstIndex);
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327 guarantee(numDisplacedHdrs == numObjsWithDisplacedHdrs, "Displaced hdr count");
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328 }
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329
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330 void PromotionInfo::print_on(outputStream* st) const {
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331 SpoolBlock* curSpool = NULL;
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332 size_t i = 0;
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333 st->print_cr("start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")",
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334 _firstIndex, _nextIndex);
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335 for (curSpool = _spoolHead; curSpool != _spoolTail && curSpool != NULL;
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336 curSpool = curSpool->nextSpoolBlock) {
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337 curSpool->print_on(st);
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338 st->print_cr(" active ");
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339 i++;
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340 }
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341 for (curSpool = _spoolTail; curSpool != NULL;
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342 curSpool = curSpool->nextSpoolBlock) {
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343 curSpool->print_on(st);
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344 st->print_cr(" inactive ");
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345 i++;
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346 }
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347 for (curSpool = _spareSpool; curSpool != NULL;
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348 curSpool = curSpool->nextSpoolBlock) {
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349 curSpool->print_on(st);
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350 st->print_cr(" free ");
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351 i++;
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352 }
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353 st->print_cr(SIZE_FORMAT " header spooling blocks", i);
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354 }
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355
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356 void SpoolBlock::print_on(outputStream* st) const {
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357 st->print("[" PTR_FORMAT "," PTR_FORMAT "), " SIZE_FORMAT " HeapWords -> " PTR_FORMAT,
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358 this, (HeapWord*)displacedHdr + bufferSize,
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359 bufferSize, nextSpoolBlock);
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360 }
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