Mercurial > hg > graal-compiler
annotate src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp @ 1571:2d127394260e
6916623: Align object to 16 bytes to use Compressed Oops with java heap up to 64Gb
Summary: Added new product ObjectAlignmentInBytes flag to control object alignment.
Reviewed-by: twisti, ysr, iveresov
| author | kvn |
|---|---|
| date | Thu, 27 May 2010 18:01:56 -0700 |
| parents | a8127dc669ba |
| children | e9ff18c4ace7 |
| 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 LinearAllocBlock VALUE_OBJ_CLASS_SPEC { | |
| 37 public: | |
| 38 LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0), | |
| 39 _allocation_size_limit(0) {} | |
| 40 void set(HeapWord* ptr, size_t word_size, size_t refill_size, | |
| 41 size_t allocation_size_limit) { | |
| 42 _ptr = ptr; | |
| 43 _word_size = word_size; | |
| 44 _refillSize = refill_size; | |
| 45 _allocation_size_limit = allocation_size_limit; | |
| 46 } | |
| 47 HeapWord* _ptr; | |
| 48 size_t _word_size; | |
| 49 size_t _refillSize; | |
| 50 size_t _allocation_size_limit; // largest size that will be allocated | |
| 51 }; | |
| 52 | |
| 53 // Concrete subclass of CompactibleSpace that implements | |
| 54 // a free list space, such as used in the concurrent mark sweep | |
| 55 // generation. | |
| 56 | |
| 57 class CompactibleFreeListSpace: public CompactibleSpace { | |
| 58 friend class VMStructs; | |
| 59 friend class ConcurrentMarkSweepGeneration; | |
| 60 friend class ASConcurrentMarkSweepGeneration; | |
| 61 friend class CMSCollector; | |
| 62 friend class CMSPermGenGen; | |
| 63 // Local alloc buffer for promotion into this space. | |
| 64 friend class CFLS_LAB; | |
| 65 | |
| 66 // "Size" of chunks of work (executed during parallel remark phases | |
| 67 // of CMS collection); this probably belongs in CMSCollector, although | |
| 68 // it's cached here because it's used in | |
| 69 // initialize_sequential_subtasks_for_rescan() which modifies | |
| 70 // par_seq_tasks which also lives in Space. XXX | |
| 71 const size_t _rescan_task_size; | |
| 72 const size_t _marking_task_size; | |
| 73 | |
| 74 // Yet another sequential tasks done structure. This supports | |
| 75 // CMS GC, where we have threads dynamically | |
| 76 // claiming sub-tasks from a larger parallel task. | |
| 77 SequentialSubTasksDone _conc_par_seq_tasks; | |
| 78 | |
| 79 BlockOffsetArrayNonContigSpace _bt; | |
| 80 | |
| 81 CMSCollector* _collector; | |
| 82 ConcurrentMarkSweepGeneration* _gen; | |
| 83 | |
| 84 // Data structures for free blocks (used during allocation/sweeping) | |
| 85 | |
| 86 // Allocation is done linearly from two different blocks depending on | |
| 87 // whether the request is small or large, in an effort to reduce | |
| 88 // fragmentation. We assume that any locking for allocation is done | |
| 89 // by the containing generation. Thus, none of the methods in this | |
| 90 // space are re-entrant. | |
| 91 enum SomeConstants { | |
| 92 SmallForLinearAlloc = 16, // size < this then use _sLAB | |
| 93 SmallForDictionary = 257, // size < this then use _indexedFreeList | |
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94 IndexSetSize = SmallForDictionary // keep this odd-sized |
| 0 | 95 }; |
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96 static int IndexSetStart; |
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97 static int IndexSetStride; |
| 0 | 98 |
| 99 private: | |
| 100 enum FitStrategyOptions { | |
| 101 FreeBlockStrategyNone = 0, | |
| 102 FreeBlockBestFitFirst | |
| 103 }; | |
| 104 | |
| 105 PromotionInfo _promoInfo; | |
| 106 | |
| 107 // helps to impose a global total order on freelistLock ranks; | |
| 108 // assumes that CFLSpace's are allocated in global total order | |
| 109 static int _lockRank; | |
| 110 | |
| 111 // a lock protecting the free lists and free blocks; | |
| 112 // mutable because of ubiquity of locking even for otherwise const methods | |
| 113 mutable Mutex _freelistLock; | |
| 114 // locking verifier convenience function | |
| 115 void assert_locked() const PRODUCT_RETURN; | |
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116 void assert_locked(const Mutex* lock) const PRODUCT_RETURN; |
| 0 | 117 |
| 118 // Linear allocation blocks | |
| 119 LinearAllocBlock _smallLinearAllocBlock; | |
| 120 | |
| 121 FreeBlockDictionary::DictionaryChoice _dictionaryChoice; | |
| 122 FreeBlockDictionary* _dictionary; // ptr to dictionary for large size blocks | |
| 123 | |
| 124 FreeList _indexedFreeList[IndexSetSize]; | |
| 125 // indexed array for small size blocks | |
| 126 // allocation stategy | |
| 127 bool _fitStrategy; // Use best fit strategy. | |
| 128 bool _adaptive_freelists; // Use adaptive freelists | |
| 129 | |
| 130 // This is an address close to the largest free chunk in the heap. | |
| 131 // It is currently assumed to be at the end of the heap. Free | |
| 132 // chunks with addresses greater than nearLargestChunk are coalesced | |
| 133 // in an effort to maintain a large chunk at the end of the heap. | |
| 134 HeapWord* _nearLargestChunk; | |
| 135 | |
| 136 // Used to keep track of limit of sweep for the space | |
| 137 HeapWord* _sweep_limit; | |
| 138 | |
| 139 // Support for compacting cms | |
| 140 HeapWord* cross_threshold(HeapWord* start, HeapWord* end); | |
| 141 HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top); | |
| 142 | |
| 143 // Initialization helpers. | |
| 144 void initializeIndexedFreeListArray(); | |
| 145 | |
| 146 // Extra stuff to manage promotion parallelism. | |
| 147 | |
| 148 // a lock protecting the dictionary during par promotion allocation. | |
| 149 mutable Mutex _parDictionaryAllocLock; | |
| 150 Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; } | |
| 151 | |
| 152 // Locks protecting the exact lists during par promotion allocation. | |
| 153 Mutex* _indexedFreeListParLocks[IndexSetSize]; | |
| 154 | |
| 155 // Attempt to obtain up to "n" blocks of the size "word_sz" (which is | |
| 156 // required to be smaller than "IndexSetSize".) If successful, | |
| 157 // adds them to "fl", which is required to be an empty free list. | |
| 158 // If the count of "fl" is negative, it's absolute value indicates a | |
| 159 // number of free chunks that had been previously "borrowed" from global | |
| 160 // list of size "word_sz", and must now be decremented. | |
| 161 void par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl); | |
| 162 | |
| 163 // Allocation helper functions | |
| 164 // Allocate using a strategy that takes from the indexed free lists | |
| 165 // first. This allocation strategy assumes a companion sweeping | |
| 166 // strategy that attempts to keep the needed number of chunks in each | |
| 167 // indexed free lists. | |
| 168 HeapWord* allocate_adaptive_freelists(size_t size); | |
| 169 // Allocate from the linear allocation buffers first. This allocation | |
| 170 // strategy assumes maximal coalescing can maintain chunks large enough | |
| 171 // to be used as linear allocation buffers. | |
| 172 HeapWord* allocate_non_adaptive_freelists(size_t size); | |
| 173 | |
| 174 // Gets a chunk from the linear allocation block (LinAB). If there | |
| 175 // is not enough space in the LinAB, refills it. | |
| 176 HeapWord* getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size); | |
| 177 HeapWord* getChunkFromSmallLinearAllocBlock(size_t size); | |
| 178 // Get a chunk from the space remaining in the linear allocation block. Do | |
| 179 // not attempt to refill if the space is not available, return NULL. Do the | |
| 180 // repairs on the linear allocation block as appropriate. | |
| 181 HeapWord* getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size); | |
| 182 inline HeapWord* getChunkFromSmallLinearAllocBlockRemainder(size_t size); | |
| 183 | |
| 184 // Helper function for getChunkFromIndexedFreeList. | |
| 185 // Replenish the indexed free list for this "size". Do not take from an | |
| 186 // underpopulated size. | |
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187 FreeChunk* getChunkFromIndexedFreeListHelper(size_t size, bool replenish = true); |
| 0 | 188 |
| 189 // Get a chunk from the indexed free list. If the indexed free list | |
| 190 // does not have a free chunk, try to replenish the indexed free list | |
| 191 // then get the free chunk from the replenished indexed free list. | |
| 192 inline FreeChunk* getChunkFromIndexedFreeList(size_t size); | |
| 193 | |
| 194 // The returned chunk may be larger than requested (or null). | |
| 195 FreeChunk* getChunkFromDictionary(size_t size); | |
| 196 // The returned chunk is the exact size requested (or null). | |
| 197 FreeChunk* getChunkFromDictionaryExact(size_t size); | |
| 198 | |
| 199 // Find a chunk in the indexed free list that is the best | |
| 200 // fit for size "numWords". | |
| 201 FreeChunk* bestFitSmall(size_t numWords); | |
| 202 // For free list "fl" of chunks of size > numWords, | |
| 203 // remove a chunk, split off a chunk of size numWords | |
| 204 // and return it. The split off remainder is returned to | |
| 205 // the free lists. The old name for getFromListGreater | |
| 206 // was lookInListGreater. | |
| 207 FreeChunk* getFromListGreater(FreeList* fl, size_t numWords); | |
| 208 // Get a chunk in the indexed free list or dictionary, | |
| 209 // by considering a larger chunk and splitting it. | |
| 210 FreeChunk* getChunkFromGreater(size_t numWords); | |
| 211 // Verify that the given chunk is in the indexed free lists. | |
| 212 bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const; | |
| 213 // Remove the specified chunk from the indexed free lists. | |
| 214 void removeChunkFromIndexedFreeList(FreeChunk* fc); | |
| 215 // Remove the specified chunk from the dictionary. | |
| 216 void removeChunkFromDictionary(FreeChunk* fc); | |
| 217 // Split a free chunk into a smaller free chunk of size "new_size". | |
| 218 // Return the smaller free chunk and return the remainder to the | |
| 219 // free lists. | |
| 220 FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size); | |
| 221 // Add a chunk to the free lists. | |
| 222 void addChunkToFreeLists(HeapWord* chunk, size_t size); | |
| 223 // Add a chunk to the free lists, preferring to suffix it | |
| 224 // to the last free chunk at end of space if possible, and | |
| 225 // updating the block census stats as well as block offset table. | |
| 226 // Take any locks as appropriate if we are multithreaded. | |
| 227 void addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size); | |
| 228 // Add a free chunk to the indexed free lists. | |
| 229 void returnChunkToFreeList(FreeChunk* chunk); | |
| 230 // Add a free chunk to the dictionary. | |
| 231 void returnChunkToDictionary(FreeChunk* chunk); | |
| 232 | |
| 233 // Functions for maintaining the linear allocation buffers (LinAB). | |
| 234 // Repairing a linear allocation block refers to operations | |
| 235 // performed on the remainder of a LinAB after an allocation | |
| 236 // has been made from it. | |
| 237 void repairLinearAllocationBlocks(); | |
| 238 void repairLinearAllocBlock(LinearAllocBlock* blk); | |
| 239 void refillLinearAllocBlock(LinearAllocBlock* blk); | |
| 240 void refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk); | |
| 241 void refillLinearAllocBlocksIfNeeded(); | |
| 242 | |
| 243 void verify_objects_initialized() const; | |
| 244 | |
| 245 // Statistics reporting helper functions | |
| 246 void reportFreeListStatistics() const; | |
| 247 void reportIndexedFreeListStatistics() const; | |
| 248 size_t maxChunkSizeInIndexedFreeLists() const; | |
| 249 size_t numFreeBlocksInIndexedFreeLists() const; | |
| 250 // Accessor | |
| 251 HeapWord* unallocated_block() const { | |
| 252 HeapWord* ub = _bt.unallocated_block(); | |
| 253 assert(ub >= bottom() && | |
| 254 ub <= end(), "space invariant"); | |
| 255 return ub; | |
| 256 } | |
| 257 void freed(HeapWord* start, size_t size) { | |
| 258 _bt.freed(start, size); | |
| 259 } | |
| 260 | |
| 261 protected: | |
| 262 // reset the indexed free list to its initial empty condition. | |
| 263 void resetIndexedFreeListArray(); | |
| 264 // reset to an initial state with a single free block described | |
| 265 // by the MemRegion parameter. | |
| 266 void reset(MemRegion mr); | |
| 267 // Return the total number of words in the indexed free lists. | |
| 268 size_t totalSizeInIndexedFreeLists() const; | |
| 269 | |
| 270 public: | |
| 271 // Constructor... | |
| 272 CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr, | |
| 273 bool use_adaptive_freelists, | |
| 274 FreeBlockDictionary::DictionaryChoice); | |
| 275 // accessors | |
| 276 bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; } | |
| 277 FreeBlockDictionary* dictionary() const { return _dictionary; } | |
| 278 HeapWord* nearLargestChunk() const { return _nearLargestChunk; } | |
| 279 void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; } | |
| 280 | |
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281 // Set CMS global values |
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282 static void set_cms_values(); |
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283 |
| 0 | 284 // Return the free chunk at the end of the space. If no such |
| 285 // chunk exists, return NULL. | |
| 286 FreeChunk* find_chunk_at_end(); | |
| 287 | |
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288 bool adaptive_freelists() const { return _adaptive_freelists; } |
| 0 | 289 |
| 290 void set_collector(CMSCollector* collector) { _collector = collector; } | |
| 291 | |
| 292 // Support for parallelization of rescan and marking | |
| 293 const size_t rescan_task_size() const { return _rescan_task_size; } | |
| 294 const size_t marking_task_size() const { return _marking_task_size; } | |
| 295 SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; } | |
| 296 void initialize_sequential_subtasks_for_rescan(int n_threads); | |
| 297 void initialize_sequential_subtasks_for_marking(int n_threads, | |
| 298 HeapWord* low = NULL); | |
| 299 | |
| 300 // Space enquiries | |
| 301 size_t used() const; | |
| 302 size_t free() const; | |
| 303 size_t max_alloc_in_words() const; | |
| 304 // XXX: should have a less conservative used_region() than that of | |
| 305 // Space; we could consider keeping track of highest allocated | |
| 306 // address and correcting that at each sweep, as the sweeper | |
| 307 // goes through the entire allocated part of the generation. We | |
| 308 // could also use that information to keep the sweeper from | |
| 309 // sweeping more than is necessary. The allocator and sweeper will | |
| 310 // of course need to synchronize on this, since the sweeper will | |
| 311 // try to bump down the address and the allocator will try to bump it up. | |
| 312 // For now, however, we'll just use the default used_region() | |
| 313 // which overestimates the region by returning the entire | |
| 314 // committed region (this is safe, but inefficient). | |
| 315 | |
| 316 // Returns a subregion of the space containing all the objects in | |
| 317 // the space. | |
| 318 MemRegion used_region() const { | |
| 319 return MemRegion(bottom(), | |
| 320 BlockOffsetArrayUseUnallocatedBlock ? | |
| 321 unallocated_block() : end()); | |
| 322 } | |
| 323 | |
| 324 // This is needed because the default implementation uses block_start() | |
| 325 // which can;t be used at certain times (for example phase 3 of mark-sweep). | |
| 326 // A better fix is to change the assertions in phase 3 of mark-sweep to | |
| 327 // use is_in_reserved(), but that is deferred since the is_in() assertions | |
| 328 // are buried through several layers of callers and are used elsewhere | |
| 329 // as well. | |
| 330 bool is_in(const void* p) const { | |
| 331 return used_region().contains(p); | |
| 332 } | |
| 333 | |
| 334 virtual bool is_free_block(const HeapWord* p) const; | |
| 335 | |
| 336 // Resizing support | |
| 337 void set_end(HeapWord* value); // override | |
| 338 | |
| 339 // mutual exclusion support | |
| 340 Mutex* freelistLock() const { return &_freelistLock; } | |
| 341 | |
| 342 // Iteration support | |
| 343 void oop_iterate(MemRegion mr, OopClosure* cl); | |
| 344 void oop_iterate(OopClosure* cl); | |
| 345 | |
| 346 void object_iterate(ObjectClosure* blk); | |
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347 // Apply the closure to each object in the space whose references |
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348 // point to objects in the heap. The usage of CompactibleFreeListSpace |
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349 // by the ConcurrentMarkSweepGeneration for concurrent GC's allows |
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350 // objects in the space with references to objects that are no longer |
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351 // valid. For example, an object may reference another object |
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352 // that has already been sweep up (collected). This method uses |
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353 // obj_is_alive() to determine whether it is safe to iterate of |
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354 // an object. |
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355 void safe_object_iterate(ObjectClosure* blk); |
| 0 | 356 void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl); |
| 357 | |
| 358 // Requires that "mr" be entirely within the space. | |
| 359 // Apply "cl->do_object" to all objects that intersect with "mr". | |
| 360 // If the iteration encounters an unparseable portion of the region, | |
| 361 // terminate the iteration and return the address of the start of the | |
| 362 // subregion that isn't done. Return of "NULL" indicates that the | |
| 363 // interation completed. | |
| 364 virtual HeapWord* | |
| 365 object_iterate_careful_m(MemRegion mr, | |
| 366 ObjectClosureCareful* cl); | |
| 367 virtual HeapWord* | |
| 368 object_iterate_careful(ObjectClosureCareful* cl); | |
| 369 | |
| 370 // Override: provides a DCTO_CL specific to this kind of space. | |
| 371 DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl, | |
| 372 CardTableModRefBS::PrecisionStyle precision, | |
| 373 HeapWord* boundary); | |
| 374 | |
| 375 void blk_iterate(BlkClosure* cl); | |
| 376 void blk_iterate_careful(BlkClosureCareful* cl); | |
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377 HeapWord* block_start_const(const void* p) const; |
| 0 | 378 HeapWord* block_start_careful(const void* p) const; |
| 379 size_t block_size(const HeapWord* p) const; | |
| 380 size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const; | |
| 381 bool block_is_obj(const HeapWord* p) const; | |
| 382 bool obj_is_alive(const HeapWord* p) const; | |
| 383 size_t block_size_nopar(const HeapWord* p) const; | |
| 384 bool block_is_obj_nopar(const HeapWord* p) const; | |
| 385 | |
| 386 // iteration support for promotion | |
| 387 void save_marks(); | |
| 388 bool no_allocs_since_save_marks(); | |
| 389 void object_iterate_since_last_GC(ObjectClosure* cl); | |
| 390 | |
| 391 // iteration support for sweeping | |
| 392 void save_sweep_limit() { | |
| 393 _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ? | |
| 394 unallocated_block() : end(); | |
| 395 } | |
| 396 NOT_PRODUCT( | |
| 397 void clear_sweep_limit() { _sweep_limit = NULL; } | |
| 398 ) | |
| 399 HeapWord* sweep_limit() { return _sweep_limit; } | |
| 400 | |
| 401 // Apply "blk->do_oop" to the addresses of all reference fields in objects | |
| 402 // promoted into this generation since the most recent save_marks() call. | |
| 403 // Fields in objects allocated by applications of the closure | |
| 404 // *are* included in the iteration. Thus, when the iteration completes | |
| 405 // there should be no further such objects remaining. | |
| 406 #define CFLS_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
| 407 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk); | |
| 408 ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DECL) | |
| 409 #undef CFLS_OOP_SINCE_SAVE_MARKS_DECL | |
| 410 | |
| 411 // Allocation support | |
| 412 HeapWord* allocate(size_t size); | |
| 413 HeapWord* par_allocate(size_t size); | |
| 414 | |
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415 oop promote(oop obj, size_t obj_size); |
| 0 | 416 void gc_prologue(); |
| 417 void gc_epilogue(); | |
| 418 | |
| 419 // This call is used by a containing CMS generation / collector | |
| 420 // to inform the CFLS space that a sweep has been completed | |
| 421 // and that the space can do any related house-keeping functions. | |
| 422 void sweep_completed(); | |
| 423 | |
| 424 // For an object in this space, the mark-word's two | |
| 425 // LSB's having the value [11] indicates that it has been | |
| 426 // promoted since the most recent call to save_marks() on | |
| 427 // this generation and has not subsequently been iterated | |
| 428 // over (using oop_since_save_marks_iterate() above). | |
| 1521 | 429 // This property holds only for single-threaded collections, |
| 430 // and is typically used for Cheney scans; for MT scavenges, | |
| 431 // the property holds for all objects promoted during that | |
| 432 // scavenge for the duration of the scavenge and is used | |
| 433 // by card-scanning to avoid scanning objects (being) promoted | |
| 434 // during that scavenge. | |
| 0 | 435 bool obj_allocated_since_save_marks(const oop obj) const { |
| 436 assert(is_in_reserved(obj), "Wrong space?"); | |
| 437 return ((PromotedObject*)obj)->hasPromotedMark(); | |
| 438 } | |
| 439 | |
| 440 // A worst-case estimate of the space required (in HeapWords) to expand the | |
| 441 // heap when promoting an obj of size obj_size. | |
| 442 size_t expansionSpaceRequired(size_t obj_size) const; | |
| 443 | |
| 444 FreeChunk* allocateScratch(size_t size); | |
| 445 | |
| 446 // returns true if either the small or large linear allocation buffer is empty. | |
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447 bool linearAllocationWouldFail() const; |
| 0 | 448 |
| 449 // Adjust the chunk for the minimum size. This version is called in | |
| 450 // most cases in CompactibleFreeListSpace methods. | |
| 451 inline static size_t adjustObjectSize(size_t size) { | |
| 452 return (size_t) align_object_size(MAX2(size, (size_t)MinChunkSize)); | |
| 453 } | |
| 454 // This is a virtual version of adjustObjectSize() that is called | |
| 455 // only occasionally when the compaction space changes and the type | |
| 456 // of the new compaction space is is only known to be CompactibleSpace. | |
| 457 size_t adjust_object_size_v(size_t size) const { | |
| 458 return adjustObjectSize(size); | |
| 459 } | |
| 460 // Minimum size of a free block. | |
| 461 virtual size_t minimum_free_block_size() const { return MinChunkSize; } | |
| 462 void removeFreeChunkFromFreeLists(FreeChunk* chunk); | |
| 463 void addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size, | |
| 464 bool coalesced); | |
| 465 | |
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466 // Support for decisions regarding concurrent collection policy |
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467 bool should_concurrent_collect() const; |
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468 |
| 0 | 469 // Support for compaction |
| 470 void prepare_for_compaction(CompactPoint* cp); | |
| 471 void adjust_pointers(); | |
| 472 void compact(); | |
| 473 // reset the space to reflect the fact that a compaction of the | |
| 474 // space has been done. | |
| 475 virtual void reset_after_compaction(); | |
| 476 | |
| 477 // Debugging support | |
| 478 void print() const; | |
| 479 void prepare_for_verify(); | |
| 480 void verify(bool allow_dirty) const; | |
| 481 void verifyFreeLists() const PRODUCT_RETURN; | |
| 482 void verifyIndexedFreeLists() const; | |
| 483 void verifyIndexedFreeList(size_t size) const; | |
| 484 // verify that the given chunk is in the free lists. | |
| 485 bool verifyChunkInFreeLists(FreeChunk* fc) const; | |
| 486 // Do some basic checks on the the free lists. | |
| 487 void checkFreeListConsistency() const PRODUCT_RETURN; | |
| 488 | |
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489 // Printing support |
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490 void dump_at_safepoint_with_locks(CMSCollector* c, outputStream* st); |
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491 void print_indexed_free_lists(outputStream* st) const; |
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492 void print_dictionary_free_lists(outputStream* st) const; |
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493 void print_promo_info_blocks(outputStream* st) const; |
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494 |
| 0 | 495 NOT_PRODUCT ( |
| 496 void initializeIndexedFreeListArrayReturnedBytes(); | |
| 497 size_t sumIndexedFreeListArrayReturnedBytes(); | |
| 498 // Return the total number of chunks in the indexed free lists. | |
| 499 size_t totalCountInIndexedFreeLists() const; | |
| 500 // Return the total numberof chunks in the space. | |
| 501 size_t totalCount(); | |
| 502 ) | |
| 503 | |
| 504 // The census consists of counts of the quantities such as | |
| 505 // the current count of the free chunks, number of chunks | |
| 506 // created as a result of the split of a larger chunk or | |
| 507 // coalescing of smaller chucks, etc. The counts in the | |
| 508 // census is used to make decisions on splitting and | |
| 509 // coalescing of chunks during the sweep of garbage. | |
| 510 | |
| 511 // Print the statistics for the free lists. | |
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512 void printFLCensus(size_t sweep_count) const; |
| 0 | 513 |
| 514 // Statistics functions | |
| 515 // Initialize census for lists before the sweep. | |
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516 void beginSweepFLCensus(float inter_sweep_current, |
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517 float inter_sweep_estimate, |
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518 float intra_sweep_estimate); |
| 0 | 519 // Set the surplus for each of the free lists. |
| 520 void setFLSurplus(); | |
| 521 // Set the hint for each of the free lists. | |
| 522 void setFLHints(); | |
| 523 // Clear the census for each of the free lists. | |
| 524 void clearFLCensus(); | |
| 525 // Perform functions for the census after the end of the sweep. | |
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526 void endSweepFLCensus(size_t sweep_count); |
| 0 | 527 // Return true if the count of free chunks is greater |
| 528 // than the desired number of free chunks. | |
| 529 bool coalOverPopulated(size_t size); | |
| 530 | |
| 531 // Record (for each size): | |
| 532 // | |
| 533 // split-births = #chunks added due to splits in (prev-sweep-end, | |
| 534 // this-sweep-start) | |
| 535 // split-deaths = #chunks removed for splits in (prev-sweep-end, | |
| 536 // this-sweep-start) | |
| 537 // num-curr = #chunks at start of this sweep | |
| 538 // num-prev = #chunks at end of previous sweep | |
| 539 // | |
| 540 // The above are quantities that are measured. Now define: | |
| 541 // | |
| 542 // num-desired := num-prev + split-births - split-deaths - num-curr | |
| 543 // | |
| 544 // Roughly, num-prev + split-births is the supply, | |
| 545 // split-deaths is demand due to other sizes | |
| 546 // and num-curr is what we have left. | |
| 547 // | |
| 548 // Thus, num-desired is roughly speaking the "legitimate demand" | |
| 549 // for blocks of this size and what we are striving to reach at the | |
| 550 // end of the current sweep. | |
| 551 // | |
| 552 // For a given list, let num-len be its current population. | |
| 553 // Define, for a free list of a given size: | |
| 554 // | |
| 555 // coal-overpopulated := num-len >= num-desired * coal-surplus | |
| 556 // (coal-surplus is set to 1.05, i.e. we allow a little slop when | |
| 557 // coalescing -- we do not coalesce unless we think that the current | |
| 558 // supply has exceeded the estimated demand by more than 5%). | |
| 559 // | |
| 560 // For the set of sizes in the binary tree, which is neither dense nor | |
| 561 // closed, it may be the case that for a particular size we have never | |
| 562 // had, or do not now have, or did not have at the previous sweep, | |
| 563 // chunks of that size. We need to extend the definition of | |
| 564 // coal-overpopulated to such sizes as well: | |
| 565 // | |
| 566 // For a chunk in/not in the binary tree, extend coal-overpopulated | |
| 567 // defined above to include all sizes as follows: | |
| 568 // | |
| 569 // . a size that is non-existent is coal-overpopulated | |
| 570 // . a size that has a num-desired <= 0 as defined above is | |
| 571 // coal-overpopulated. | |
| 572 // | |
| 573 // Also define, for a chunk heap-offset C and mountain heap-offset M: | |
| 574 // | |
| 575 // close-to-mountain := C >= 0.99 * M | |
| 576 // | |
| 577 // Now, the coalescing strategy is: | |
| 578 // | |
| 579 // Coalesce left-hand chunk with right-hand chunk if and | |
| 580 // only if: | |
| 581 // | |
| 582 // EITHER | |
| 583 // . left-hand chunk is of a size that is coal-overpopulated | |
| 584 // OR | |
| 585 // . right-hand chunk is close-to-mountain | |
| 586 void smallCoalBirth(size_t size); | |
| 587 void smallCoalDeath(size_t size); | |
| 588 void coalBirth(size_t size); | |
| 589 void coalDeath(size_t size); | |
| 590 void smallSplitBirth(size_t size); | |
| 591 void smallSplitDeath(size_t size); | |
| 592 void splitBirth(size_t size); | |
| 593 void splitDeath(size_t size); | |
| 594 void split(size_t from, size_t to1); | |
| 595 | |
| 596 double flsFrag() const; | |
| 597 }; | |
| 598 | |
| 599 // A parallel-GC-thread-local allocation buffer for allocation into a | |
| 600 // CompactibleFreeListSpace. | |
| 601 class CFLS_LAB : public CHeapObj { | |
| 602 // The space that this buffer allocates into. | |
| 603 CompactibleFreeListSpace* _cfls; | |
| 604 | |
| 605 // Our local free lists. | |
| 606 FreeList _indexedFreeList[CompactibleFreeListSpace::IndexSetSize]; | |
| 607 | |
| 608 // Initialized from a command-line arg. | |
| 609 | |
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610 // Allocation statistics in support of dynamic adjustment of |
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611 // #blocks to claim per get_from_global_pool() call below. |
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612 static AdaptiveWeightedAverage |
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613 _blocks_to_claim [CompactibleFreeListSpace::IndexSetSize]; |
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614 static size_t _global_num_blocks [CompactibleFreeListSpace::IndexSetSize]; |
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615 static int _global_num_workers[CompactibleFreeListSpace::IndexSetSize]; |
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616 size_t _num_blocks [CompactibleFreeListSpace::IndexSetSize]; |
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617 |
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618 // Internal work method |
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619 void get_from_global_pool(size_t word_sz, FreeList* fl); |
| 0 | 620 |
| 621 public: | |
| 622 CFLS_LAB(CompactibleFreeListSpace* cfls); | |
| 623 | |
| 624 // Allocate and return a block of the given size, or else return NULL. | |
| 625 HeapWord* alloc(size_t word_sz); | |
| 626 | |
| 627 // Return any unused portions of the buffer to the global pool. | |
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628 void retire(int tid); |
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629 |
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630 // Dynamic OldPLABSize sizing |
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631 static void compute_desired_plab_size(); |
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632 // When the settings are modified from default static initialization |
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633 static void modify_initialization(size_t n, unsigned wt); |
| 0 | 634 }; |
| 635 | |
| 636 size_t PromotionInfo::refillSize() const { | |
| 637 const size_t CMSSpoolBlockSize = 256; | |
| 638 const size_t sz = heap_word_size(sizeof(SpoolBlock) + sizeof(markOop) | |
| 639 * CMSSpoolBlockSize); | |
| 640 return CompactibleFreeListSpace::adjustObjectSize(sz); | |
| 641 } |