Mercurial > hg > graal-compiler
annotate src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp @ 1518:3bfae429e2cf
6948537: CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT
Summary: On sun4v/CMT avoid use of memset() in BOT updates so as to prevent concurrent BOT readers from seeing the phantom zeros arising from memset()'s use of BIS.
Reviewed-by: jmasa, johnc, minqi, poonam, tonyp
| author | ysr |
|---|---|
| date | Mon, 03 May 2010 10:24:51 -0700 |
| parents | e018e6884bd8 |
| children | a8127dc669ba |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 579 | 2 * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved. |
| 0 | 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 // Classes in support of keeping track of promotions into a non-Contiguous | |
| 26 // space, in this case a CompactibleFreeListSpace. | |
| 27 | |
| 28 // Forward declarations | |
| 29 class CompactibleFreeListSpace; | |
| 30 class BlkClosure; | |
| 31 class BlkClosureCareful; | |
| 32 class UpwardsObjectClosure; | |
| 33 class ObjectClosureCareful; | |
| 34 class Klass; | |
| 35 | |
| 36 class PromotedObject VALUE_OBJ_CLASS_SPEC { | |
| 37 private: | |
| 38 enum { | |
| 39 promoted_mask = right_n_bits(2), // i.e. 0x3 | |
| 40 displaced_mark = nth_bit(2), // i.e. 0x4 | |
| 41 next_mask = ~(right_n_bits(3)) // i.e. ~(0x7) | |
| 42 }; | |
| 43 intptr_t _next; | |
| 44 public: | |
| 45 inline PromotedObject* next() const { | |
| 46 return (PromotedObject*)(_next & next_mask); | |
| 47 } | |
| 48 inline void setNext(PromotedObject* x) { | |
| 49 assert(((intptr_t)x & ~next_mask) == 0, | |
| 50 "Conflict in bit usage, " | |
| 51 " or insufficient alignment of objects"); | |
| 52 _next |= (intptr_t)x; | |
| 53 } | |
| 54 inline void setPromotedMark() { | |
| 55 _next |= promoted_mask; | |
| 56 } | |
| 57 inline bool hasPromotedMark() const { | |
| 58 return (_next & promoted_mask) == promoted_mask; | |
| 59 } | |
| 60 inline void setDisplacedMark() { | |
| 61 _next |= displaced_mark; | |
| 62 } | |
| 63 inline bool hasDisplacedMark() const { | |
| 64 return (_next & displaced_mark) != 0; | |
| 65 } | |
| 66 inline void clearNext() { _next = 0; } | |
| 67 debug_only(void *next_addr() { return (void *) &_next; }) | |
| 68 }; | |
| 69 | |
| 70 class SpoolBlock: public FreeChunk { | |
| 71 friend class PromotionInfo; | |
| 72 protected: | |
| 73 SpoolBlock* nextSpoolBlock; | |
| 74 size_t bufferSize; // number of usable words in this block | |
| 75 markOop* displacedHdr; // the displaced headers start here | |
| 76 | |
| 77 // Note about bufferSize: it denotes the number of entries available plus 1; | |
| 78 // legal indices range from 1 through BufferSize - 1. See the verification | |
| 79 // code verify() that counts the number of displaced headers spooled. | |
| 80 size_t computeBufferSize() { | |
| 81 return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop); | |
| 82 } | |
| 83 | |
| 84 public: | |
| 85 void init() { | |
| 86 bufferSize = computeBufferSize(); | |
| 87 displacedHdr = (markOop*)&displacedHdr; | |
| 88 nextSpoolBlock = NULL; | |
| 89 } | |
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90 |
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91 void print_on(outputStream* st) const; |
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92 void print() const { print_on(gclog_or_tty); } |
| 0 | 93 }; |
| 94 | |
| 95 class PromotionInfo VALUE_OBJ_CLASS_SPEC { | |
| 96 bool _tracking; // set if tracking | |
| 97 CompactibleFreeListSpace* _space; // the space to which this belongs | |
| 98 PromotedObject* _promoHead; // head of list of promoted objects | |
| 99 PromotedObject* _promoTail; // tail of list of promoted objects | |
| 100 SpoolBlock* _spoolHead; // first spooling block | |
| 101 SpoolBlock* _spoolTail; // last non-full spooling block or null | |
| 102 SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail | |
| 103 SpoolBlock* _spareSpool; // free spool buffer | |
| 104 size_t _firstIndex; // first active index in | |
| 105 // first spooling block (_spoolHead) | |
| 106 size_t _nextIndex; // last active index + 1 in last | |
| 107 // spooling block (_spoolTail) | |
| 108 private: | |
| 109 // ensure that spooling space exists; return true if there is spooling space | |
| 110 bool ensure_spooling_space_work(); | |
| 111 | |
| 112 public: | |
| 113 PromotionInfo() : | |
| 114 _tracking(0), _space(NULL), | |
| 115 _promoHead(NULL), _promoTail(NULL), | |
| 116 _spoolHead(NULL), _spoolTail(NULL), | |
| 117 _spareSpool(NULL), _firstIndex(1), | |
| 118 _nextIndex(1) {} | |
| 119 | |
| 120 bool noPromotions() const { | |
| 121 assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency"); | |
| 122 return _promoHead == NULL; | |
| 123 } | |
| 124 void startTrackingPromotions(); | |
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125 void stopTrackingPromotions(uint worker_id = 0); |
| 0 | 126 bool tracking() const { return _tracking; } |
| 127 void track(PromotedObject* trackOop); // keep track of a promoted oop | |
| 128 // The following variant must be used when trackOop is not fully | |
| 129 // initialized and has a NULL klass: | |
| 130 void track(PromotedObject* trackOop, klassOop klassOfOop); // keep track of a promoted oop | |
| 131 void setSpace(CompactibleFreeListSpace* sp) { _space = sp; } | |
| 132 CompactibleFreeListSpace* space() const { return _space; } | |
| 133 markOop nextDisplacedHeader(); // get next header & forward spool pointer | |
| 134 void saveDisplacedHeader(markOop hdr); | |
| 135 // save header and forward spool | |
| 136 | |
| 137 inline size_t refillSize() const; | |
| 138 | |
| 139 SpoolBlock* getSpoolBlock(); // return a free spooling block | |
| 140 inline bool has_spooling_space() { | |
| 141 return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex; | |
| 142 } | |
| 143 // ensure that spooling space exists | |
| 144 bool ensure_spooling_space() { | |
| 145 return has_spooling_space() || ensure_spooling_space_work(); | |
| 146 } | |
| 147 #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \ | |
| 148 void promoted_oops_iterate##nv_suffix(OopClosureType* cl); | |
| 149 ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL) | |
| 150 #undef PROMOTED_OOPS_ITERATE_DECL | |
| 151 void promoted_oops_iterate(OopsInGenClosure* cl) { | |
| 152 promoted_oops_iterate_v(cl); | |
| 153 } | |
| 154 void verify() const; | |
| 155 void reset() { | |
| 156 _promoHead = NULL; | |
| 157 _promoTail = NULL; | |
| 158 _spoolHead = NULL; | |
| 159 _spoolTail = NULL; | |
| 160 _spareSpool = NULL; | |
| 161 _firstIndex = 0; | |
| 162 _nextIndex = 0; | |
| 163 | |
| 164 } | |
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165 |
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166 void print_on(outputStream* st) const; |
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167 void print_statistics(uint worker_id) const; |
| 0 | 168 }; |
| 169 | |
| 170 class LinearAllocBlock VALUE_OBJ_CLASS_SPEC { | |
| 171 public: | |
| 172 LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0), | |
| 173 _allocation_size_limit(0) {} | |
| 174 void set(HeapWord* ptr, size_t word_size, size_t refill_size, | |
| 175 size_t allocation_size_limit) { | |
| 176 _ptr = ptr; | |
| 177 _word_size = word_size; | |
| 178 _refillSize = refill_size; | |
| 179 _allocation_size_limit = allocation_size_limit; | |
| 180 } | |
| 181 HeapWord* _ptr; | |
| 182 size_t _word_size; | |
| 183 size_t _refillSize; | |
| 184 size_t _allocation_size_limit; // largest size that will be allocated | |
| 185 }; | |
| 186 | |
| 187 // Concrete subclass of CompactibleSpace that implements | |
| 188 // a free list space, such as used in the concurrent mark sweep | |
| 189 // generation. | |
| 190 | |
| 191 class CompactibleFreeListSpace: public CompactibleSpace { | |
| 192 friend class VMStructs; | |
| 193 friend class ConcurrentMarkSweepGeneration; | |
| 194 friend class ASConcurrentMarkSweepGeneration; | |
| 195 friend class CMSCollector; | |
| 196 friend class CMSPermGenGen; | |
| 197 // Local alloc buffer for promotion into this space. | |
| 198 friend class CFLS_LAB; | |
| 199 | |
| 200 // "Size" of chunks of work (executed during parallel remark phases | |
| 201 // of CMS collection); this probably belongs in CMSCollector, although | |
| 202 // it's cached here because it's used in | |
| 203 // initialize_sequential_subtasks_for_rescan() which modifies | |
| 204 // par_seq_tasks which also lives in Space. XXX | |
| 205 const size_t _rescan_task_size; | |
| 206 const size_t _marking_task_size; | |
| 207 | |
| 208 // Yet another sequential tasks done structure. This supports | |
| 209 // CMS GC, where we have threads dynamically | |
| 210 // claiming sub-tasks from a larger parallel task. | |
| 211 SequentialSubTasksDone _conc_par_seq_tasks; | |
| 212 | |
| 213 BlockOffsetArrayNonContigSpace _bt; | |
| 214 | |
| 215 CMSCollector* _collector; | |
| 216 ConcurrentMarkSweepGeneration* _gen; | |
| 217 | |
| 218 // Data structures for free blocks (used during allocation/sweeping) | |
| 219 | |
| 220 // Allocation is done linearly from two different blocks depending on | |
| 221 // whether the request is small or large, in an effort to reduce | |
| 222 // fragmentation. We assume that any locking for allocation is done | |
| 223 // by the containing generation. Thus, none of the methods in this | |
| 224 // space are re-entrant. | |
| 225 enum SomeConstants { | |
| 226 SmallForLinearAlloc = 16, // size < this then use _sLAB | |
| 227 SmallForDictionary = 257, // size < this then use _indexedFreeList | |
| 228 IndexSetSize = SmallForDictionary, // keep this odd-sized | |
| 229 IndexSetStart = MinObjAlignment, | |
| 230 IndexSetStride = MinObjAlignment | |
| 231 }; | |
| 232 | |
| 233 private: | |
| 234 enum FitStrategyOptions { | |
| 235 FreeBlockStrategyNone = 0, | |
| 236 FreeBlockBestFitFirst | |
| 237 }; | |
| 238 | |
| 239 PromotionInfo _promoInfo; | |
| 240 | |
| 241 // helps to impose a global total order on freelistLock ranks; | |
| 242 // assumes that CFLSpace's are allocated in global total order | |
| 243 static int _lockRank; | |
| 244 | |
| 245 // a lock protecting the free lists and free blocks; | |
| 246 // mutable because of ubiquity of locking even for otherwise const methods | |
| 247 mutable Mutex _freelistLock; | |
| 248 // locking verifier convenience function | |
| 249 void assert_locked() const PRODUCT_RETURN; | |
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250 void assert_locked(const Mutex* lock) const PRODUCT_RETURN; |
| 0 | 251 |
| 252 // Linear allocation blocks | |
| 253 LinearAllocBlock _smallLinearAllocBlock; | |
| 254 | |
| 255 FreeBlockDictionary::DictionaryChoice _dictionaryChoice; | |
| 256 FreeBlockDictionary* _dictionary; // ptr to dictionary for large size blocks | |
| 257 | |
| 258 FreeList _indexedFreeList[IndexSetSize]; | |
| 259 // indexed array for small size blocks | |
| 260 // allocation stategy | |
| 261 bool _fitStrategy; // Use best fit strategy. | |
| 262 bool _adaptive_freelists; // Use adaptive freelists | |
| 263 | |
| 264 // This is an address close to the largest free chunk in the heap. | |
| 265 // It is currently assumed to be at the end of the heap. Free | |
| 266 // chunks with addresses greater than nearLargestChunk are coalesced | |
| 267 // in an effort to maintain a large chunk at the end of the heap. | |
| 268 HeapWord* _nearLargestChunk; | |
| 269 | |
| 270 // Used to keep track of limit of sweep for the space | |
| 271 HeapWord* _sweep_limit; | |
| 272 | |
| 273 // Support for compacting cms | |
| 274 HeapWord* cross_threshold(HeapWord* start, HeapWord* end); | |
| 275 HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top); | |
| 276 | |
| 277 // Initialization helpers. | |
| 278 void initializeIndexedFreeListArray(); | |
| 279 | |
| 280 // Extra stuff to manage promotion parallelism. | |
| 281 | |
| 282 // a lock protecting the dictionary during par promotion allocation. | |
| 283 mutable Mutex _parDictionaryAllocLock; | |
| 284 Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; } | |
| 285 | |
| 286 // Locks protecting the exact lists during par promotion allocation. | |
| 287 Mutex* _indexedFreeListParLocks[IndexSetSize]; | |
| 288 | |
| 289 // Attempt to obtain up to "n" blocks of the size "word_sz" (which is | |
| 290 // required to be smaller than "IndexSetSize".) If successful, | |
| 291 // adds them to "fl", which is required to be an empty free list. | |
| 292 // If the count of "fl" is negative, it's absolute value indicates a | |
| 293 // number of free chunks that had been previously "borrowed" from global | |
| 294 // list of size "word_sz", and must now be decremented. | |
| 295 void par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl); | |
| 296 | |
| 297 // Allocation helper functions | |
| 298 // Allocate using a strategy that takes from the indexed free lists | |
| 299 // first. This allocation strategy assumes a companion sweeping | |
| 300 // strategy that attempts to keep the needed number of chunks in each | |
| 301 // indexed free lists. | |
| 302 HeapWord* allocate_adaptive_freelists(size_t size); | |
| 303 // Allocate from the linear allocation buffers first. This allocation | |
| 304 // strategy assumes maximal coalescing can maintain chunks large enough | |
| 305 // to be used as linear allocation buffers. | |
| 306 HeapWord* allocate_non_adaptive_freelists(size_t size); | |
| 307 | |
| 308 // Gets a chunk from the linear allocation block (LinAB). If there | |
| 309 // is not enough space in the LinAB, refills it. | |
| 310 HeapWord* getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size); | |
| 311 HeapWord* getChunkFromSmallLinearAllocBlock(size_t size); | |
| 312 // Get a chunk from the space remaining in the linear allocation block. Do | |
| 313 // not attempt to refill if the space is not available, return NULL. Do the | |
| 314 // repairs on the linear allocation block as appropriate. | |
| 315 HeapWord* getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size); | |
| 316 inline HeapWord* getChunkFromSmallLinearAllocBlockRemainder(size_t size); | |
| 317 | |
| 318 // Helper function for getChunkFromIndexedFreeList. | |
| 319 // Replenish the indexed free list for this "size". Do not take from an | |
| 320 // underpopulated size. | |
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321 FreeChunk* getChunkFromIndexedFreeListHelper(size_t size, bool replenish = true); |
| 0 | 322 |
| 323 // Get a chunk from the indexed free list. If the indexed free list | |
| 324 // does not have a free chunk, try to replenish the indexed free list | |
| 325 // then get the free chunk from the replenished indexed free list. | |
| 326 inline FreeChunk* getChunkFromIndexedFreeList(size_t size); | |
| 327 | |
| 328 // The returned chunk may be larger than requested (or null). | |
| 329 FreeChunk* getChunkFromDictionary(size_t size); | |
| 330 // The returned chunk is the exact size requested (or null). | |
| 331 FreeChunk* getChunkFromDictionaryExact(size_t size); | |
| 332 | |
| 333 // Find a chunk in the indexed free list that is the best | |
| 334 // fit for size "numWords". | |
| 335 FreeChunk* bestFitSmall(size_t numWords); | |
| 336 // For free list "fl" of chunks of size > numWords, | |
| 337 // remove a chunk, split off a chunk of size numWords | |
| 338 // and return it. The split off remainder is returned to | |
| 339 // the free lists. The old name for getFromListGreater | |
| 340 // was lookInListGreater. | |
| 341 FreeChunk* getFromListGreater(FreeList* fl, size_t numWords); | |
| 342 // Get a chunk in the indexed free list or dictionary, | |
| 343 // by considering a larger chunk and splitting it. | |
| 344 FreeChunk* getChunkFromGreater(size_t numWords); | |
| 345 // Verify that the given chunk is in the indexed free lists. | |
| 346 bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const; | |
| 347 // Remove the specified chunk from the indexed free lists. | |
| 348 void removeChunkFromIndexedFreeList(FreeChunk* fc); | |
| 349 // Remove the specified chunk from the dictionary. | |
| 350 void removeChunkFromDictionary(FreeChunk* fc); | |
| 351 // Split a free chunk into a smaller free chunk of size "new_size". | |
| 352 // Return the smaller free chunk and return the remainder to the | |
| 353 // free lists. | |
| 354 FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size); | |
| 355 // Add a chunk to the free lists. | |
| 356 void addChunkToFreeLists(HeapWord* chunk, size_t size); | |
| 357 // Add a chunk to the free lists, preferring to suffix it | |
| 358 // to the last free chunk at end of space if possible, and | |
| 359 // updating the block census stats as well as block offset table. | |
| 360 // Take any locks as appropriate if we are multithreaded. | |
| 361 void addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size); | |
| 362 // Add a free chunk to the indexed free lists. | |
| 363 void returnChunkToFreeList(FreeChunk* chunk); | |
| 364 // Add a free chunk to the dictionary. | |
| 365 void returnChunkToDictionary(FreeChunk* chunk); | |
| 366 | |
| 367 // Functions for maintaining the linear allocation buffers (LinAB). | |
| 368 // Repairing a linear allocation block refers to operations | |
| 369 // performed on the remainder of a LinAB after an allocation | |
| 370 // has been made from it. | |
| 371 void repairLinearAllocationBlocks(); | |
| 372 void repairLinearAllocBlock(LinearAllocBlock* blk); | |
| 373 void refillLinearAllocBlock(LinearAllocBlock* blk); | |
| 374 void refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk); | |
| 375 void refillLinearAllocBlocksIfNeeded(); | |
| 376 | |
| 377 void verify_objects_initialized() const; | |
| 378 | |
| 379 // Statistics reporting helper functions | |
| 380 void reportFreeListStatistics() const; | |
| 381 void reportIndexedFreeListStatistics() const; | |
| 382 size_t maxChunkSizeInIndexedFreeLists() const; | |
| 383 size_t numFreeBlocksInIndexedFreeLists() const; | |
| 384 // Accessor | |
| 385 HeapWord* unallocated_block() const { | |
| 386 HeapWord* ub = _bt.unallocated_block(); | |
| 387 assert(ub >= bottom() && | |
| 388 ub <= end(), "space invariant"); | |
| 389 return ub; | |
| 390 } | |
| 391 void freed(HeapWord* start, size_t size) { | |
| 392 _bt.freed(start, size); | |
| 393 } | |
| 394 | |
| 395 protected: | |
| 396 // reset the indexed free list to its initial empty condition. | |
| 397 void resetIndexedFreeListArray(); | |
| 398 // reset to an initial state with a single free block described | |
| 399 // by the MemRegion parameter. | |
| 400 void reset(MemRegion mr); | |
| 401 // Return the total number of words in the indexed free lists. | |
| 402 size_t totalSizeInIndexedFreeLists() const; | |
| 403 | |
| 404 public: | |
| 405 // Constructor... | |
| 406 CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr, | |
| 407 bool use_adaptive_freelists, | |
| 408 FreeBlockDictionary::DictionaryChoice); | |
| 409 // accessors | |
| 410 bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; } | |
| 411 FreeBlockDictionary* dictionary() const { return _dictionary; } | |
| 412 HeapWord* nearLargestChunk() const { return _nearLargestChunk; } | |
| 413 void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; } | |
| 414 | |
| 415 // Return the free chunk at the end of the space. If no such | |
| 416 // chunk exists, return NULL. | |
| 417 FreeChunk* find_chunk_at_end(); | |
| 418 | |
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419 bool adaptive_freelists() const { return _adaptive_freelists; } |
| 0 | 420 |
| 421 void set_collector(CMSCollector* collector) { _collector = collector; } | |
| 422 | |
| 423 // Support for parallelization of rescan and marking | |
| 424 const size_t rescan_task_size() const { return _rescan_task_size; } | |
| 425 const size_t marking_task_size() const { return _marking_task_size; } | |
| 426 SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; } | |
| 427 void initialize_sequential_subtasks_for_rescan(int n_threads); | |
| 428 void initialize_sequential_subtasks_for_marking(int n_threads, | |
| 429 HeapWord* low = NULL); | |
| 430 | |
| 431 // Space enquiries | |
| 432 size_t used() const; | |
| 433 size_t free() const; | |
| 434 size_t max_alloc_in_words() const; | |
| 435 // XXX: should have a less conservative used_region() than that of | |
| 436 // Space; we could consider keeping track of highest allocated | |
| 437 // address and correcting that at each sweep, as the sweeper | |
| 438 // goes through the entire allocated part of the generation. We | |
| 439 // could also use that information to keep the sweeper from | |
| 440 // sweeping more than is necessary. The allocator and sweeper will | |
| 441 // of course need to synchronize on this, since the sweeper will | |
| 442 // try to bump down the address and the allocator will try to bump it up. | |
| 443 // For now, however, we'll just use the default used_region() | |
| 444 // which overestimates the region by returning the entire | |
| 445 // committed region (this is safe, but inefficient). | |
| 446 | |
| 447 // Returns a subregion of the space containing all the objects in | |
| 448 // the space. | |
| 449 MemRegion used_region() const { | |
| 450 return MemRegion(bottom(), | |
| 451 BlockOffsetArrayUseUnallocatedBlock ? | |
| 452 unallocated_block() : end()); | |
| 453 } | |
| 454 | |
| 455 // This is needed because the default implementation uses block_start() | |
| 456 // which can;t be used at certain times (for example phase 3 of mark-sweep). | |
| 457 // A better fix is to change the assertions in phase 3 of mark-sweep to | |
| 458 // use is_in_reserved(), but that is deferred since the is_in() assertions | |
| 459 // are buried through several layers of callers and are used elsewhere | |
| 460 // as well. | |
| 461 bool is_in(const void* p) const { | |
| 462 return used_region().contains(p); | |
| 463 } | |
| 464 | |
| 465 virtual bool is_free_block(const HeapWord* p) const; | |
| 466 | |
| 467 // Resizing support | |
| 468 void set_end(HeapWord* value); // override | |
| 469 | |
| 470 // mutual exclusion support | |
| 471 Mutex* freelistLock() const { return &_freelistLock; } | |
| 472 | |
| 473 // Iteration support | |
| 474 void oop_iterate(MemRegion mr, OopClosure* cl); | |
| 475 void oop_iterate(OopClosure* cl); | |
| 476 | |
| 477 void object_iterate(ObjectClosure* blk); | |
|
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478 // Apply the closure to each object in the space whose references |
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479 // point to objects in the heap. The usage of CompactibleFreeListSpace |
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480 // by the ConcurrentMarkSweepGeneration for concurrent GC's allows |
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481 // objects in the space with references to objects that are no longer |
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482 // valid. For example, an object may reference another object |
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483 // that has already been sweep up (collected). This method uses |
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484 // obj_is_alive() to determine whether it is safe to iterate of |
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485 // an object. |
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486 void safe_object_iterate(ObjectClosure* blk); |
| 0 | 487 void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl); |
| 488 | |
| 489 // Requires that "mr" be entirely within the space. | |
| 490 // Apply "cl->do_object" to all objects that intersect with "mr". | |
| 491 // If the iteration encounters an unparseable portion of the region, | |
| 492 // terminate the iteration and return the address of the start of the | |
| 493 // subregion that isn't done. Return of "NULL" indicates that the | |
| 494 // interation completed. | |
| 495 virtual HeapWord* | |
| 496 object_iterate_careful_m(MemRegion mr, | |
| 497 ObjectClosureCareful* cl); | |
| 498 virtual HeapWord* | |
| 499 object_iterate_careful(ObjectClosureCareful* cl); | |
| 500 | |
| 501 // Override: provides a DCTO_CL specific to this kind of space. | |
| 502 DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl, | |
| 503 CardTableModRefBS::PrecisionStyle precision, | |
| 504 HeapWord* boundary); | |
| 505 | |
| 506 void blk_iterate(BlkClosure* cl); | |
| 507 void blk_iterate_careful(BlkClosureCareful* cl); | |
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508 HeapWord* block_start_const(const void* p) const; |
| 0 | 509 HeapWord* block_start_careful(const void* p) const; |
| 510 size_t block_size(const HeapWord* p) const; | |
| 511 size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const; | |
| 512 bool block_is_obj(const HeapWord* p) const; | |
| 513 bool obj_is_alive(const HeapWord* p) const; | |
| 514 size_t block_size_nopar(const HeapWord* p) const; | |
| 515 bool block_is_obj_nopar(const HeapWord* p) const; | |
| 516 | |
| 517 // iteration support for promotion | |
| 518 void save_marks(); | |
| 519 bool no_allocs_since_save_marks(); | |
| 520 void object_iterate_since_last_GC(ObjectClosure* cl); | |
| 521 | |
| 522 // iteration support for sweeping | |
| 523 void save_sweep_limit() { | |
| 524 _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ? | |
| 525 unallocated_block() : end(); | |
| 526 } | |
| 527 NOT_PRODUCT( | |
| 528 void clear_sweep_limit() { _sweep_limit = NULL; } | |
| 529 ) | |
| 530 HeapWord* sweep_limit() { return _sweep_limit; } | |
| 531 | |
| 532 // Apply "blk->do_oop" to the addresses of all reference fields in objects | |
| 533 // promoted into this generation since the most recent save_marks() call. | |
| 534 // Fields in objects allocated by applications of the closure | |
| 535 // *are* included in the iteration. Thus, when the iteration completes | |
| 536 // there should be no further such objects remaining. | |
| 537 #define CFLS_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
| 538 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk); | |
| 539 ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DECL) | |
| 540 #undef CFLS_OOP_SINCE_SAVE_MARKS_DECL | |
| 541 | |
| 542 // Allocation support | |
| 543 HeapWord* allocate(size_t size); | |
| 544 HeapWord* par_allocate(size_t size); | |
| 545 | |
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546 oop promote(oop obj, size_t obj_size); |
| 0 | 547 void gc_prologue(); |
| 548 void gc_epilogue(); | |
| 549 | |
| 550 // This call is used by a containing CMS generation / collector | |
| 551 // to inform the CFLS space that a sweep has been completed | |
| 552 // and that the space can do any related house-keeping functions. | |
| 553 void sweep_completed(); | |
| 554 | |
| 555 // For an object in this space, the mark-word's two | |
| 556 // LSB's having the value [11] indicates that it has been | |
| 557 // promoted since the most recent call to save_marks() on | |
| 558 // this generation and has not subsequently been iterated | |
| 559 // over (using oop_since_save_marks_iterate() above). | |
| 560 bool obj_allocated_since_save_marks(const oop obj) const { | |
| 561 assert(is_in_reserved(obj), "Wrong space?"); | |
| 562 return ((PromotedObject*)obj)->hasPromotedMark(); | |
| 563 } | |
| 564 | |
| 565 // A worst-case estimate of the space required (in HeapWords) to expand the | |
| 566 // heap when promoting an obj of size obj_size. | |
| 567 size_t expansionSpaceRequired(size_t obj_size) const; | |
| 568 | |
| 569 FreeChunk* allocateScratch(size_t size); | |
| 570 | |
| 571 // returns true if either the small or large linear allocation buffer is empty. | |
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572 bool linearAllocationWouldFail() const; |
| 0 | 573 |
| 574 // Adjust the chunk for the minimum size. This version is called in | |
| 575 // most cases in CompactibleFreeListSpace methods. | |
| 576 inline static size_t adjustObjectSize(size_t size) { | |
| 577 return (size_t) align_object_size(MAX2(size, (size_t)MinChunkSize)); | |
| 578 } | |
| 579 // This is a virtual version of adjustObjectSize() that is called | |
| 580 // only occasionally when the compaction space changes and the type | |
| 581 // of the new compaction space is is only known to be CompactibleSpace. | |
| 582 size_t adjust_object_size_v(size_t size) const { | |
| 583 return adjustObjectSize(size); | |
| 584 } | |
| 585 // Minimum size of a free block. | |
| 586 virtual size_t minimum_free_block_size() const { return MinChunkSize; } | |
| 587 void removeFreeChunkFromFreeLists(FreeChunk* chunk); | |
| 588 void addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size, | |
| 589 bool coalesced); | |
| 590 | |
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591 // Support for decisions regarding concurrent collection policy |
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592 bool should_concurrent_collect() const; |
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593 |
| 0 | 594 // Support for compaction |
| 595 void prepare_for_compaction(CompactPoint* cp); | |
| 596 void adjust_pointers(); | |
| 597 void compact(); | |
| 598 // reset the space to reflect the fact that a compaction of the | |
| 599 // space has been done. | |
| 600 virtual void reset_after_compaction(); | |
| 601 | |
| 602 // Debugging support | |
| 603 void print() const; | |
| 604 void prepare_for_verify(); | |
| 605 void verify(bool allow_dirty) const; | |
| 606 void verifyFreeLists() const PRODUCT_RETURN; | |
| 607 void verifyIndexedFreeLists() const; | |
| 608 void verifyIndexedFreeList(size_t size) const; | |
| 609 // verify that the given chunk is in the free lists. | |
| 610 bool verifyChunkInFreeLists(FreeChunk* fc) const; | |
| 611 // Do some basic checks on the the free lists. | |
| 612 void checkFreeListConsistency() const PRODUCT_RETURN; | |
| 613 | |
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614 // Printing support |
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615 void dump_at_safepoint_with_locks(CMSCollector* c, outputStream* st); |
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616 void print_indexed_free_lists(outputStream* st) const; |
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617 void print_dictionary_free_lists(outputStream* st) const; |
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618 void print_promo_info_blocks(outputStream* st) const; |
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619 |
| 0 | 620 NOT_PRODUCT ( |
| 621 void initializeIndexedFreeListArrayReturnedBytes(); | |
| 622 size_t sumIndexedFreeListArrayReturnedBytes(); | |
| 623 // Return the total number of chunks in the indexed free lists. | |
| 624 size_t totalCountInIndexedFreeLists() const; | |
| 625 // Return the total numberof chunks in the space. | |
| 626 size_t totalCount(); | |
| 627 ) | |
| 628 | |
| 629 // The census consists of counts of the quantities such as | |
| 630 // the current count of the free chunks, number of chunks | |
| 631 // created as a result of the split of a larger chunk or | |
| 632 // coalescing of smaller chucks, etc. The counts in the | |
| 633 // census is used to make decisions on splitting and | |
| 634 // coalescing of chunks during the sweep of garbage. | |
| 635 | |
| 636 // Print the statistics for the free lists. | |
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637 void printFLCensus(size_t sweep_count) const; |
| 0 | 638 |
| 639 // Statistics functions | |
| 640 // Initialize census for lists before the sweep. | |
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641 void beginSweepFLCensus(float inter_sweep_current, |
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642 float inter_sweep_estimate, |
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643 float intra_sweep_estimate); |
| 0 | 644 // Set the surplus for each of the free lists. |
| 645 void setFLSurplus(); | |
| 646 // Set the hint for each of the free lists. | |
| 647 void setFLHints(); | |
| 648 // Clear the census for each of the free lists. | |
| 649 void clearFLCensus(); | |
| 650 // Perform functions for the census after the end of the sweep. | |
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651 void endSweepFLCensus(size_t sweep_count); |
| 0 | 652 // Return true if the count of free chunks is greater |
| 653 // than the desired number of free chunks. | |
| 654 bool coalOverPopulated(size_t size); | |
| 655 | |
| 656 // Record (for each size): | |
| 657 // | |
| 658 // split-births = #chunks added due to splits in (prev-sweep-end, | |
| 659 // this-sweep-start) | |
| 660 // split-deaths = #chunks removed for splits in (prev-sweep-end, | |
| 661 // this-sweep-start) | |
| 662 // num-curr = #chunks at start of this sweep | |
| 663 // num-prev = #chunks at end of previous sweep | |
| 664 // | |
| 665 // The above are quantities that are measured. Now define: | |
| 666 // | |
| 667 // num-desired := num-prev + split-births - split-deaths - num-curr | |
| 668 // | |
| 669 // Roughly, num-prev + split-births is the supply, | |
| 670 // split-deaths is demand due to other sizes | |
| 671 // and num-curr is what we have left. | |
| 672 // | |
| 673 // Thus, num-desired is roughly speaking the "legitimate demand" | |
| 674 // for blocks of this size and what we are striving to reach at the | |
| 675 // end of the current sweep. | |
| 676 // | |
| 677 // For a given list, let num-len be its current population. | |
| 678 // Define, for a free list of a given size: | |
| 679 // | |
| 680 // coal-overpopulated := num-len >= num-desired * coal-surplus | |
| 681 // (coal-surplus is set to 1.05, i.e. we allow a little slop when | |
| 682 // coalescing -- we do not coalesce unless we think that the current | |
| 683 // supply has exceeded the estimated demand by more than 5%). | |
| 684 // | |
| 685 // For the set of sizes in the binary tree, which is neither dense nor | |
| 686 // closed, it may be the case that for a particular size we have never | |
| 687 // had, or do not now have, or did not have at the previous sweep, | |
| 688 // chunks of that size. We need to extend the definition of | |
| 689 // coal-overpopulated to such sizes as well: | |
| 690 // | |
| 691 // For a chunk in/not in the binary tree, extend coal-overpopulated | |
| 692 // defined above to include all sizes as follows: | |
| 693 // | |
| 694 // . a size that is non-existent is coal-overpopulated | |
| 695 // . a size that has a num-desired <= 0 as defined above is | |
| 696 // coal-overpopulated. | |
| 697 // | |
| 698 // Also define, for a chunk heap-offset C and mountain heap-offset M: | |
| 699 // | |
| 700 // close-to-mountain := C >= 0.99 * M | |
| 701 // | |
| 702 // Now, the coalescing strategy is: | |
| 703 // | |
| 704 // Coalesce left-hand chunk with right-hand chunk if and | |
| 705 // only if: | |
| 706 // | |
| 707 // EITHER | |
| 708 // . left-hand chunk is of a size that is coal-overpopulated | |
| 709 // OR | |
| 710 // . right-hand chunk is close-to-mountain | |
| 711 void smallCoalBirth(size_t size); | |
| 712 void smallCoalDeath(size_t size); | |
| 713 void coalBirth(size_t size); | |
| 714 void coalDeath(size_t size); | |
| 715 void smallSplitBirth(size_t size); | |
| 716 void smallSplitDeath(size_t size); | |
| 717 void splitBirth(size_t size); | |
| 718 void splitDeath(size_t size); | |
| 719 void split(size_t from, size_t to1); | |
| 720 | |
| 721 double flsFrag() const; | |
| 722 }; | |
| 723 | |
| 724 // A parallel-GC-thread-local allocation buffer for allocation into a | |
| 725 // CompactibleFreeListSpace. | |
| 726 class CFLS_LAB : public CHeapObj { | |
| 727 // The space that this buffer allocates into. | |
| 728 CompactibleFreeListSpace* _cfls; | |
| 729 | |
| 730 // Our local free lists. | |
| 731 FreeList _indexedFreeList[CompactibleFreeListSpace::IndexSetSize]; | |
| 732 | |
| 733 // Initialized from a command-line arg. | |
| 734 | |
|
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735 // Allocation statistics in support of dynamic adjustment of |
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736 // #blocks to claim per get_from_global_pool() call below. |
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737 static AdaptiveWeightedAverage |
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738 _blocks_to_claim [CompactibleFreeListSpace::IndexSetSize]; |
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739 static size_t _global_num_blocks [CompactibleFreeListSpace::IndexSetSize]; |
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740 static int _global_num_workers[CompactibleFreeListSpace::IndexSetSize]; |
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741 size_t _num_blocks [CompactibleFreeListSpace::IndexSetSize]; |
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742 |
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743 // Internal work method |
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744 void get_from_global_pool(size_t word_sz, FreeList* fl); |
| 0 | 745 |
| 746 public: | |
| 747 CFLS_LAB(CompactibleFreeListSpace* cfls); | |
| 748 | |
| 749 // Allocate and return a block of the given size, or else return NULL. | |
| 750 HeapWord* alloc(size_t word_sz); | |
| 751 | |
| 752 // Return any unused portions of the buffer to the global pool. | |
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753 void retire(int tid); |
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754 |
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755 // Dynamic OldPLABSize sizing |
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756 static void compute_desired_plab_size(); |
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757 // When the settings are modified from default static initialization |
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758 static void modify_initialization(size_t n, unsigned wt); |
| 0 | 759 }; |
| 760 | |
| 761 size_t PromotionInfo::refillSize() const { | |
| 762 const size_t CMSSpoolBlockSize = 256; | |
| 763 const size_t sz = heap_word_size(sizeof(SpoolBlock) + sizeof(markOop) | |
| 764 * CMSSpoolBlockSize); | |
| 765 return CompactibleFreeListSpace::adjustObjectSize(sz); | |
| 766 } |