1 /* 2 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * 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 assert((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 }