Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/promotionInfo.cpp @ 1546:a00b51b2dda4
6948539: CMS+UseCompressedOops: placement of cms_free bit interferes with promoted object link
Summary: When using compressed oops, use compressed promoted pointers in b63:b31 of the mark word, so as not to interfere with the CMS "freeness bit" at b7. Updated mark-word layout documentation.
Reviewed-by: minqi, poonam, jmasa, coleenp
| author | ysr |
|---|---|
| date | Mon, 17 May 2010 00:47:28 -0700 |
| parents | a8127dc669ba |
| children | c18cbe5936b8 |
| rev | line source |
|---|---|
| 1521 | 1 /* |
|
1546
a00b51b2dda4
6948539: CMS+UseCompressedOops: placement of cms_free bit interferes with promoted object link
ysr
parents:
1521
diff
changeset
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2 * Copyright 2010 Sun Microsystems, Inc. All Rights Reserved. |
| 1521 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
| 19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
| 20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
| 21 * have any questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 # include "incls/_precompiled.incl" | |
| 26 # include "incls/_promotionInfo.cpp.incl" | |
| 27 | |
| 28 ///////////////////////////////////////////////////////////////////////// | |
| 29 //// PromotionInfo | |
| 30 ///////////////////////////////////////////////////////////////////////// | |
| 31 | |
| 32 | |
| 33 ////////////////////////////////////////////////////////////////////////////// | |
| 34 // We go over the list of promoted objects, removing each from the list, | |
| 35 // and applying the closure (this may, in turn, add more elements to | |
| 36 // the tail of the promoted list, and these newly added objects will | |
| 37 // also be processed) until the list is empty. | |
| 38 // To aid verification and debugging, in the non-product builds | |
| 39 // we actually forward _promoHead each time we process a promoted oop. | |
| 40 // Note that this is not necessary in general (i.e. when we don't need to | |
| 41 // call PromotionInfo::verify()) because oop_iterate can only add to the | |
| 42 // end of _promoTail, and never needs to look at _promoHead. | |
| 43 | |
| 44 #define PROMOTED_OOPS_ITERATE_DEFN(OopClosureType, nv_suffix) \ | |
| 45 \ | |
| 46 void PromotionInfo::promoted_oops_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 47 NOT_PRODUCT(verify()); \ | |
| 48 PromotedObject *curObj, *nextObj; \ | |
| 49 for (curObj = _promoHead; curObj != NULL; curObj = nextObj) { \ | |
| 50 if ((nextObj = curObj->next()) == NULL) { \ | |
| 51 /* protect ourselves against additions due to closure application \ | |
| 52 below by resetting the list. */ \ | |
| 53 assert(_promoTail == curObj, "Should have been the tail"); \ | |
| 54 _promoHead = _promoTail = NULL; \ | |
| 55 } \ | |
| 56 if (curObj->hasDisplacedMark()) { \ | |
| 57 /* restore displaced header */ \ | |
| 58 oop(curObj)->set_mark(nextDisplacedHeader()); \ | |
| 59 } else { \ | |
| 60 /* restore prototypical header */ \ | |
| 61 oop(curObj)->init_mark(); \ | |
| 62 } \ | |
| 63 /* The "promoted_mark" should now not be set */ \ | |
| 64 assert(!curObj->hasPromotedMark(), \ | |
| 65 "Should have been cleared by restoring displaced mark-word"); \ | |
| 66 NOT_PRODUCT(_promoHead = nextObj); \ | |
| 67 if (cl != NULL) oop(curObj)->oop_iterate(cl); \ | |
| 68 if (nextObj == NULL) { /* start at head of list reset above */ \ | |
| 69 nextObj = _promoHead; \ | |
| 70 } \ | |
| 71 } \ | |
| 72 assert(noPromotions(), "post-condition violation"); \ | |
| 73 assert(_promoHead == NULL && _promoTail == NULL, "emptied promoted list");\ | |
| 74 assert(_spoolHead == _spoolTail, "emptied spooling buffers"); \ | |
| 75 assert(_firstIndex == _nextIndex, "empty buffer"); \ | |
| 76 } | |
| 77 | |
| 78 // This should have been ALL_SINCE_...() just like the others, | |
| 79 // but, because the body of the method above is somehwat longer, | |
| 80 // the MSVC compiler cannot cope; as a workaround, we split the | |
| 81 // macro into its 3 constituent parts below (see original macro | |
| 82 // definition in specializedOopClosures.hpp). | |
| 83 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG(PROMOTED_OOPS_ITERATE_DEFN) | |
| 84 PROMOTED_OOPS_ITERATE_DEFN(OopsInGenClosure,_v) | |
| 85 | |
| 86 | |
| 87 // Return the next displaced header, incrementing the pointer and | |
| 88 // recycling spool area as necessary. | |
| 89 markOop PromotionInfo::nextDisplacedHeader() { | |
| 90 assert(_spoolHead != NULL, "promotionInfo inconsistency"); | |
| 91 assert(_spoolHead != _spoolTail || _firstIndex < _nextIndex, | |
| 92 "Empty spool space: no displaced header can be fetched"); | |
| 93 assert(_spoolHead->bufferSize > _firstIndex, "Off by one error at head?"); | |
| 94 markOop hdr = _spoolHead->displacedHdr[_firstIndex]; | |
| 95 // Spool forward | |
| 96 if (++_firstIndex == _spoolHead->bufferSize) { // last location in this block | |
| 97 // forward to next block, recycling this block into spare spool buffer | |
| 98 SpoolBlock* tmp = _spoolHead->nextSpoolBlock; | |
| 99 assert(_spoolHead != _spoolTail, "Spooling storage mix-up"); | |
| 100 _spoolHead->nextSpoolBlock = _spareSpool; | |
| 101 _spareSpool = _spoolHead; | |
| 102 _spoolHead = tmp; | |
| 103 _firstIndex = 1; | |
| 104 NOT_PRODUCT( | |
| 105 if (_spoolHead == NULL) { // all buffers fully consumed | |
| 106 assert(_spoolTail == NULL && _nextIndex == 1, | |
| 107 "spool buffers processing inconsistency"); | |
| 108 } | |
| 109 ) | |
| 110 } | |
| 111 return hdr; | |
| 112 } | |
| 113 | |
| 114 void PromotionInfo::track(PromotedObject* trackOop) { | |
| 115 track(trackOop, oop(trackOop)->klass()); | |
| 116 } | |
| 117 | |
| 118 void PromotionInfo::track(PromotedObject* trackOop, klassOop klassOfOop) { | |
| 119 // make a copy of header as it may need to be spooled | |
| 120 markOop mark = oop(trackOop)->mark(); | |
| 121 trackOop->clearNext(); | |
| 122 if (mark->must_be_preserved_for_cms_scavenge(klassOfOop)) { | |
| 123 // save non-prototypical header, and mark oop | |
| 124 saveDisplacedHeader(mark); | |
| 125 trackOop->setDisplacedMark(); | |
| 126 } else { | |
| 127 // we'd like to assert something like the following: | |
| 128 // assert(mark == markOopDesc::prototype(), "consistency check"); | |
| 129 // ... but the above won't work because the age bits have not (yet) been | |
| 130 // cleared. The remainder of the check would be identical to the | |
| 131 // condition checked in must_be_preserved() above, so we don't really | |
| 132 // have anything useful to check here! | |
| 133 } | |
| 134 if (_promoTail != NULL) { | |
| 135 assert(_promoHead != NULL, "List consistency"); | |
| 136 _promoTail->setNext(trackOop); | |
| 137 _promoTail = trackOop; | |
| 138 } else { | |
| 139 assert(_promoHead == NULL, "List consistency"); | |
| 140 _promoHead = _promoTail = trackOop; | |
| 141 } | |
| 142 // Mask as newly promoted, so we can skip over such objects | |
| 143 // when scanning dirty cards | |
| 144 assert(!trackOop->hasPromotedMark(), "Should not have been marked"); | |
| 145 trackOop->setPromotedMark(); | |
| 146 } | |
| 147 | |
| 148 // Save the given displaced header, incrementing the pointer and | |
| 149 // obtaining more spool area as necessary. | |
| 150 void PromotionInfo::saveDisplacedHeader(markOop hdr) { | |
| 151 assert(_spoolHead != NULL && _spoolTail != NULL, | |
| 152 "promotionInfo inconsistency"); | |
| 153 assert(_spoolTail->bufferSize > _nextIndex, "Off by one error at tail?"); | |
| 154 _spoolTail->displacedHdr[_nextIndex] = hdr; | |
| 155 // Spool forward | |
| 156 if (++_nextIndex == _spoolTail->bufferSize) { // last location in this block | |
| 157 // get a new spooling block | |
| 158 assert(_spoolTail->nextSpoolBlock == NULL, "tail should terminate spool list"); | |
| 159 _splice_point = _spoolTail; // save for splicing | |
| 160 _spoolTail->nextSpoolBlock = getSpoolBlock(); // might fail | |
| 161 _spoolTail = _spoolTail->nextSpoolBlock; // might become NULL ... | |
| 162 // ... but will attempt filling before next promotion attempt | |
| 163 _nextIndex = 1; | |
| 164 } | |
| 165 } | |
| 166 | |
| 167 // Ensure that spooling space exists. Return false if spooling space | |
| 168 // could not be obtained. | |
| 169 bool PromotionInfo::ensure_spooling_space_work() { | |
| 170 assert(!has_spooling_space(), "Only call when there is no spooling space"); | |
| 171 // Try and obtain more spooling space | |
| 172 SpoolBlock* newSpool = getSpoolBlock(); | |
| 173 assert(newSpool == NULL || | |
| 174 (newSpool->bufferSize != 0 && newSpool->nextSpoolBlock == NULL), | |
| 175 "getSpoolBlock() sanity check"); | |
| 176 if (newSpool == NULL) { | |
| 177 return false; | |
| 178 } | |
| 179 _nextIndex = 1; | |
| 180 if (_spoolTail == NULL) { | |
| 181 _spoolTail = newSpool; | |
| 182 if (_spoolHead == NULL) { | |
| 183 _spoolHead = newSpool; | |
| 184 _firstIndex = 1; | |
| 185 } else { | |
| 186 assert(_splice_point != NULL && _splice_point->nextSpoolBlock == NULL, | |
| 187 "Splice point invariant"); | |
| 188 // Extra check that _splice_point is connected to list | |
| 189 #ifdef ASSERT | |
| 190 { | |
| 191 SpoolBlock* blk = _spoolHead; | |
| 192 for (; blk->nextSpoolBlock != NULL; | |
| 193 blk = blk->nextSpoolBlock); | |
| 194 assert(blk != NULL && blk == _splice_point, | |
| 195 "Splice point incorrect"); | |
| 196 } | |
| 197 #endif // ASSERT | |
| 198 _splice_point->nextSpoolBlock = newSpool; | |
| 199 } | |
| 200 } else { | |
| 201 assert(_spoolHead != NULL, "spool list consistency"); | |
| 202 _spoolTail->nextSpoolBlock = newSpool; | |
| 203 _spoolTail = newSpool; | |
| 204 } | |
| 205 return true; | |
| 206 } | |
| 207 | |
| 208 // Get a free spool buffer from the free pool, getting a new block | |
| 209 // from the heap if necessary. | |
| 210 SpoolBlock* PromotionInfo::getSpoolBlock() { | |
| 211 SpoolBlock* res; | |
| 212 if ((res = _spareSpool) != NULL) { | |
| 213 _spareSpool = _spareSpool->nextSpoolBlock; | |
| 214 res->nextSpoolBlock = NULL; | |
| 215 } else { // spare spool exhausted, get some from heap | |
| 216 res = (SpoolBlock*)(space()->allocateScratch(refillSize())); | |
| 217 if (res != NULL) { | |
| 218 res->init(); | |
| 219 } | |
| 220 } | |
| 221 assert(res == NULL || res->nextSpoolBlock == NULL, "postcondition"); | |
| 222 return res; | |
| 223 } | |
| 224 | |
| 225 void PromotionInfo::startTrackingPromotions() { | |
| 226 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex, | |
| 227 "spooling inconsistency?"); | |
| 228 _firstIndex = _nextIndex = 1; | |
| 229 _tracking = true; | |
| 230 } | |
| 231 | |
| 232 #define CMSPrintPromoBlockInfo 1 | |
| 233 | |
| 234 void PromotionInfo::stopTrackingPromotions(uint worker_id) { | |
| 235 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex, | |
| 236 "spooling inconsistency?"); | |
| 237 _firstIndex = _nextIndex = 1; | |
| 238 _tracking = false; | |
| 239 if (CMSPrintPromoBlockInfo > 1) { | |
| 240 print_statistics(worker_id); | |
| 241 } | |
| 242 } | |
| 243 | |
| 244 void PromotionInfo::print_statistics(uint worker_id) const { | |
| 245 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex, | |
| 246 "Else will undercount"); | |
| 247 assert(CMSPrintPromoBlockInfo > 0, "Else unnecessary call"); | |
| 248 // Count the number of blocks and slots in the free pool | |
| 249 size_t slots = 0; | |
| 250 size_t blocks = 0; | |
| 251 for (SpoolBlock* cur_spool = _spareSpool; | |
| 252 cur_spool != NULL; | |
| 253 cur_spool = cur_spool->nextSpoolBlock) { | |
| 254 // the first entry is just a self-pointer; indices 1 through | |
| 255 // bufferSize - 1 are occupied (thus, bufferSize - 1 slots). | |
| 256 guarantee((void*)cur_spool->displacedHdr == (void*)&cur_spool->displacedHdr, | |
| 257 "first entry of displacedHdr should be self-referential"); | |
| 258 slots += cur_spool->bufferSize - 1; | |
| 259 blocks++; | |
| 260 } | |
| 261 if (_spoolHead != NULL) { | |
| 262 slots += _spoolHead->bufferSize - 1; | |
| 263 blocks++; | |
| 264 } | |
| 265 gclog_or_tty->print_cr(" [worker %d] promo_blocks = %d, promo_slots = %d ", | |
| 266 worker_id, blocks, slots); | |
| 267 } | |
| 268 | |
| 269 // When _spoolTail is not NULL, then the slot <_spoolTail, _nextIndex> | |
| 270 // points to the next slot available for filling. | |
| 271 // The set of slots holding displaced headers are then all those in the | |
| 272 // right-open interval denoted by: | |
| 273 // | |
| 274 // [ <_spoolHead, _firstIndex>, <_spoolTail, _nextIndex> ) | |
| 275 // | |
| 276 // When _spoolTail is NULL, then the set of slots with displaced headers | |
| 277 // is all those starting at the slot <_spoolHead, _firstIndex> and | |
| 278 // going up to the last slot of last block in the linked list. | |
| 279 // In this lartter case, _splice_point points to the tail block of | |
| 280 // this linked list of blocks holding displaced headers. | |
| 281 void PromotionInfo::verify() const { | |
| 282 // Verify the following: | |
| 283 // 1. the number of displaced headers matches the number of promoted | |
| 284 // objects that have displaced headers | |
| 285 // 2. each promoted object lies in this space | |
| 286 debug_only( | |
| 287 PromotedObject* junk = NULL; | |
| 288 assert(junk->next_addr() == (void*)(oop(junk)->mark_addr()), | |
| 289 "Offset of PromotedObject::_next is expected to align with " | |
| 290 " the OopDesc::_mark within OopDesc"); | |
| 291 ) | |
| 292 // FIXME: guarantee???? | |
| 293 guarantee(_spoolHead == NULL || _spoolTail != NULL || | |
| 294 _splice_point != NULL, "list consistency"); | |
| 295 guarantee(_promoHead == NULL || _promoTail != NULL, "list consistency"); | |
| 296 // count the number of objects with displaced headers | |
| 297 size_t numObjsWithDisplacedHdrs = 0; | |
| 298 for (PromotedObject* curObj = _promoHead; curObj != NULL; curObj = curObj->next()) { | |
| 299 guarantee(space()->is_in_reserved((HeapWord*)curObj), "Containment"); | |
| 300 // the last promoted object may fail the mark() != NULL test of is_oop(). | |
| 301 guarantee(curObj->next() == NULL || oop(curObj)->is_oop(), "must be an oop"); | |
| 302 if (curObj->hasDisplacedMark()) { | |
| 303 numObjsWithDisplacedHdrs++; | |
| 304 } | |
| 305 } | |
| 306 // Count the number of displaced headers | |
| 307 size_t numDisplacedHdrs = 0; | |
| 308 for (SpoolBlock* curSpool = _spoolHead; | |
| 309 curSpool != _spoolTail && curSpool != NULL; | |
| 310 curSpool = curSpool->nextSpoolBlock) { | |
| 311 // the first entry is just a self-pointer; indices 1 through | |
| 312 // bufferSize - 1 are occupied (thus, bufferSize - 1 slots). | |
| 313 guarantee((void*)curSpool->displacedHdr == (void*)&curSpool->displacedHdr, | |
| 314 "first entry of displacedHdr should be self-referential"); | |
| 315 numDisplacedHdrs += curSpool->bufferSize - 1; | |
| 316 } | |
| 317 guarantee((_spoolHead == _spoolTail) == (numDisplacedHdrs == 0), | |
| 318 "internal consistency"); | |
| 319 guarantee(_spoolTail != NULL || _nextIndex == 1, | |
| 320 "Inconsistency between _spoolTail and _nextIndex"); | |
| 321 // We overcounted (_firstIndex-1) worth of slots in block | |
| 322 // _spoolHead and we undercounted (_nextIndex-1) worth of | |
| 323 // slots in block _spoolTail. We make an appropriate | |
| 324 // adjustment by subtracting the first and adding the | |
| 325 // second: - (_firstIndex - 1) + (_nextIndex - 1) | |
| 326 numDisplacedHdrs += (_nextIndex - _firstIndex); | |
| 327 guarantee(numDisplacedHdrs == numObjsWithDisplacedHdrs, "Displaced hdr count"); | |
| 328 } | |
| 329 | |
| 330 void PromotionInfo::print_on(outputStream* st) const { | |
| 331 SpoolBlock* curSpool = NULL; | |
| 332 size_t i = 0; | |
| 333 st->print_cr("start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")", | |
| 334 _firstIndex, _nextIndex); | |
| 335 for (curSpool = _spoolHead; curSpool != _spoolTail && curSpool != NULL; | |
| 336 curSpool = curSpool->nextSpoolBlock) { | |
| 337 curSpool->print_on(st); | |
| 338 st->print_cr(" active "); | |
| 339 i++; | |
| 340 } | |
| 341 for (curSpool = _spoolTail; curSpool != NULL; | |
| 342 curSpool = curSpool->nextSpoolBlock) { | |
| 343 curSpool->print_on(st); | |
| 344 st->print_cr(" inactive "); | |
| 345 i++; | |
| 346 } | |
| 347 for (curSpool = _spareSpool; curSpool != NULL; | |
| 348 curSpool = curSpool->nextSpoolBlock) { | |
| 349 curSpool->print_on(st); | |
| 350 st->print_cr(" free "); | |
| 351 i++; | |
| 352 } | |
| 353 st->print_cr(SIZE_FORMAT " header spooling blocks", i); | |
| 354 } | |
| 355 | |
| 356 void SpoolBlock::print_on(outputStream* st) const { | |
| 357 st->print("[" PTR_FORMAT "," PTR_FORMAT "), " SIZE_FORMAT " HeapWords -> " PTR_FORMAT, | |
| 358 this, (HeapWord*)displacedHdr + bufferSize, | |
| 359 bufferSize, nextSpoolBlock); | |
| 360 } |