1 /* 2 * Copyright (c) 2001, 2015, 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 #ifndef SHARE_VM_GC_CMS_COMPACTIBLEFREELISTSPACE_HPP 26 #define SHARE_VM_GC_CMS_COMPACTIBLEFREELISTSPACE_HPP 27 28 #include "gc/cms/adaptiveFreeList.hpp" 29 #include "gc/cms/promotionInfo.hpp" 30 #include "gc/shared/blockOffsetTable.hpp" 31 #include "gc/shared/space.hpp" 32 #include "logging/log.hpp" 33 #include "memory/binaryTreeDictionary.hpp" 34 #include "memory/freeList.hpp" 35 36 // Classes in support of keeping track of promotions into a non-Contiguous 37 // space, in this case a CompactibleFreeListSpace. 38 39 // Forward declarations 40 class CMSCollector; 41 class CompactibleFreeListSpace; 42 class ConcurrentMarkSweepGeneration; 43 class BlkClosure; 44 class BlkClosureCareful; 45 class FreeChunk; 46 class UpwardsObjectClosure; 47 class ObjectClosureCareful; 48 class Klass; 49 50 class LinearAllocBlock VALUE_OBJ_CLASS_SPEC { 51 public: 52 LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0), 53 _allocation_size_limit(0) {} 54 void set(HeapWord* ptr, size_t word_size, size_t refill_size, 55 size_t allocation_size_limit) { 56 _ptr = ptr; 57 _word_size = word_size; 58 _refillSize = refill_size; 59 _allocation_size_limit = allocation_size_limit; 60 } 61 HeapWord* _ptr; 62 size_t _word_size; 63 size_t _refillSize; 64 size_t _allocation_size_limit; // Largest size that will be allocated 65 66 void print_on(outputStream* st) const; 67 }; 68 69 // Concrete subclass of CompactibleSpace that implements 70 // a free list space, such as used in the concurrent mark sweep 71 // generation. 72 73 class CompactibleFreeListSpace: public CompactibleSpace { 74 friend class VMStructs; 75 friend class ConcurrentMarkSweepGeneration; 76 friend class CMSCollector; 77 // Local alloc buffer for promotion into this space. 78 friend class CFLS_LAB; 79 // Allow scan_and_* functions to call (private) overrides of the auxiliary functions on this class 80 template <typename SpaceType> 81 friend void CompactibleSpace::scan_and_adjust_pointers(SpaceType* space); 82 template <typename SpaceType> 83 friend void CompactibleSpace::scan_and_compact(SpaceType* space); 84 template <typename SpaceType> 85 friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp); 86 87 // "Size" of chunks of work (executed during parallel remark phases 88 // of CMS collection); this probably belongs in CMSCollector, although 89 // it's cached here because it's used in 90 // initialize_sequential_subtasks_for_rescan() which modifies 91 // par_seq_tasks which also lives in Space. XXX 92 const size_t _rescan_task_size; 93 const size_t _marking_task_size; 94 95 // Yet another sequential tasks done structure. This supports 96 // CMS GC, where we have threads dynamically 97 // claiming sub-tasks from a larger parallel task. 98 SequentialSubTasksDone _conc_par_seq_tasks; 99 100 BlockOffsetArrayNonContigSpace _bt; 101 102 CMSCollector* _collector; 103 ConcurrentMarkSweepGeneration* _old_gen; 104 105 // Data structures for free blocks (used during allocation/sweeping) 106 107 // Allocation is done linearly from two different blocks depending on 108 // whether the request is small or large, in an effort to reduce 109 // fragmentation. We assume that any locking for allocation is done 110 // by the containing generation. Thus, none of the methods in this 111 // space are re-entrant. 112 enum SomeConstants { 113 SmallForLinearAlloc = 16, // size < this then use _sLAB 114 SmallForDictionary = 257, // size < this then use _indexedFreeList 115 IndexSetSize = SmallForDictionary // keep this odd-sized 116 }; 117 static size_t IndexSetStart; 118 static size_t IndexSetStride; 119 120 private: 121 enum FitStrategyOptions { 122 FreeBlockStrategyNone = 0, 123 FreeBlockBestFitFirst 124 }; 125 126 PromotionInfo _promoInfo; 127 128 // Helps to impose a global total order on freelistLock ranks; 129 // assumes that CFLSpace's are allocated in global total order 130 static int _lockRank; 131 132 // A lock protecting the free lists and free blocks; 133 // mutable because of ubiquity of locking even for otherwise const methods 134 mutable Mutex _freelistLock; 135 // Locking verifier convenience function 136 void assert_locked() const PRODUCT_RETURN; 137 void assert_locked(const Mutex* lock) const PRODUCT_RETURN; 138 139 // Linear allocation blocks 140 LinearAllocBlock _smallLinearAllocBlock; 141 142 AFLBinaryTreeDictionary* _dictionary; // Pointer to dictionary for large size blocks 143 144 // Indexed array for small size blocks 145 AdaptiveFreeList<FreeChunk> _indexedFreeList[IndexSetSize]; 146 147 // Allocation strategy 148 bool _fitStrategy; // Use best fit strategy 149 150 // This is an address close to the largest free chunk in the heap. 151 // It is currently assumed to be at the end of the heap. Free 152 // chunks with addresses greater than nearLargestChunk are coalesced 153 // in an effort to maintain a large chunk at the end of the heap. 154 HeapWord* _nearLargestChunk; 155 156 // Used to keep track of limit of sweep for the space 157 HeapWord* _sweep_limit; 158 159 // Used to make the young collector update the mod union table 160 MemRegionClosure* _preconsumptionDirtyCardClosure; 161 162 // Support for compacting cms 163 HeapWord* cross_threshold(HeapWord* start, HeapWord* end); 164 HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top); 165 166 // Initialization helpers. 167 void initializeIndexedFreeListArray(); 168 169 // Extra stuff to manage promotion parallelism. 170 171 // A lock protecting the dictionary during par promotion allocation. 172 mutable Mutex _parDictionaryAllocLock; 173 Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; } 174 175 // Locks protecting the exact lists during par promotion allocation. 176 Mutex* _indexedFreeListParLocks[IndexSetSize]; 177 178 // Attempt to obtain up to "n" blocks of the size "word_sz" (which is 179 // required to be smaller than "IndexSetSize".) If successful, 180 // adds them to "fl", which is required to be an empty free list. 181 // If the count of "fl" is negative, it's absolute value indicates a 182 // number of free chunks that had been previously "borrowed" from global 183 // list of size "word_sz", and must now be decremented. 184 void par_get_chunk_of_blocks(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl); 185 186 // Used by par_get_chunk_of_blocks() for the chunks from the 187 // indexed_free_lists. 188 bool par_get_chunk_of_blocks_IFL(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl); 189 190 // Used by par_get_chunk_of_blocks_dictionary() to get a chunk 191 // evenly splittable into "n" "word_sz" chunks. Returns that 192 // evenly splittable chunk. May split a larger chunk to get the 193 // evenly splittable chunk. 194 FreeChunk* get_n_way_chunk_to_split(size_t word_sz, size_t n); 195 196 // Used by par_get_chunk_of_blocks() for the chunks from the 197 // dictionary. 198 void par_get_chunk_of_blocks_dictionary(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl); 199 200 // Allocation helper functions 201 // Allocate using a strategy that takes from the indexed free lists 202 // first. This allocation strategy assumes a companion sweeping 203 // strategy that attempts to keep the needed number of chunks in each 204 // indexed free lists. 205 HeapWord* allocate_adaptive_freelists(size_t size); 206 207 // Gets a chunk from the linear allocation block (LinAB). If there 208 // is not enough space in the LinAB, refills it. 209 HeapWord* getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size); 210 HeapWord* getChunkFromSmallLinearAllocBlock(size_t size); 211 // Get a chunk from the space remaining in the linear allocation block. Do 212 // not attempt to refill if the space is not available, return NULL. Do the 213 // repairs on the linear allocation block as appropriate. 214 HeapWord* getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size); 215 inline HeapWord* getChunkFromSmallLinearAllocBlockRemainder(size_t size); 216 217 // Helper function for getChunkFromIndexedFreeList. 218 // Replenish the indexed free list for this "size". Do not take from an 219 // underpopulated size. 220 FreeChunk* getChunkFromIndexedFreeListHelper(size_t size, bool replenish = true); 221 222 // Get a chunk from the indexed free list. If the indexed free list 223 // does not have a free chunk, try to replenish the indexed free list 224 // then get the free chunk from the replenished indexed free list. 225 inline FreeChunk* getChunkFromIndexedFreeList(size_t size); 226 227 // The returned chunk may be larger than requested (or null). 228 FreeChunk* getChunkFromDictionary(size_t size); 229 // The returned chunk is the exact size requested (or null). 230 FreeChunk* getChunkFromDictionaryExact(size_t size); 231 232 // Find a chunk in the indexed free list that is the best 233 // fit for size "numWords". 234 FreeChunk* bestFitSmall(size_t numWords); 235 // For free list "fl" of chunks of size > numWords, 236 // remove a chunk, split off a chunk of size numWords 237 // and return it. The split off remainder is returned to 238 // the free lists. The old name for getFromListGreater 239 // was lookInListGreater. 240 FreeChunk* getFromListGreater(AdaptiveFreeList<FreeChunk>* fl, size_t numWords); 241 // Get a chunk in the indexed free list or dictionary, 242 // by considering a larger chunk and splitting it. 243 FreeChunk* getChunkFromGreater(size_t numWords); 244 // Verify that the given chunk is in the indexed free lists. 245 bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const; 246 // Remove the specified chunk from the indexed free lists. 247 void removeChunkFromIndexedFreeList(FreeChunk* fc); 248 // Remove the specified chunk from the dictionary. 249 void removeChunkFromDictionary(FreeChunk* fc); 250 // Split a free chunk into a smaller free chunk of size "new_size". 251 // Return the smaller free chunk and return the remainder to the 252 // free lists. 253 FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size); 254 // Add a chunk to the free lists. 255 void addChunkToFreeLists(HeapWord* chunk, size_t size); 256 // Add a chunk to the free lists, preferring to suffix it 257 // to the last free chunk at end of space if possible, and 258 // updating the block census stats as well as block offset table. 259 // Take any locks as appropriate if we are multithreaded. 260 void addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size); 261 // Add a free chunk to the indexed free lists. 262 void returnChunkToFreeList(FreeChunk* chunk); 263 // Add a free chunk to the dictionary. 264 void returnChunkToDictionary(FreeChunk* chunk); 265 266 // Functions for maintaining the linear allocation buffers (LinAB). 267 // Repairing a linear allocation block refers to operations 268 // performed on the remainder of a LinAB after an allocation 269 // has been made from it. 270 void repairLinearAllocationBlocks(); 271 void repairLinearAllocBlock(LinearAllocBlock* blk); 272 void refillLinearAllocBlock(LinearAllocBlock* blk); 273 void refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk); 274 void refillLinearAllocBlocksIfNeeded(); 275 276 void verify_objects_initialized() const; 277 278 // Statistics reporting helper functions 279 void reportFreeListStatistics(const char* title) const; 280 void reportIndexedFreeListStatistics(outputStream* st) const; 281 size_t maxChunkSizeInIndexedFreeLists() const; 282 size_t numFreeBlocksInIndexedFreeLists() const; 283 // Accessor 284 HeapWord* unallocated_block() const { 285 if (BlockOffsetArrayUseUnallocatedBlock) { 286 HeapWord* ub = _bt.unallocated_block(); 287 assert(ub >= bottom() && 288 ub <= end(), "space invariant"); 289 return ub; 290 } else { 291 return end(); 292 } 293 } 294 void freed(HeapWord* start, size_t size) { 295 _bt.freed(start, size); 296 } 297 298 // Auxiliary functions for scan_and_{forward,adjust_pointers,compact} support. 299 // See comments for CompactibleSpace for more information. 300 inline HeapWord* scan_limit() const { 301 return end(); 302 } 303 304 inline bool scanned_block_is_obj(const HeapWord* addr) const { 305 return CompactibleFreeListSpace::block_is_obj(addr); // Avoid virtual call 306 } 307 308 inline size_t scanned_block_size(const HeapWord* addr) const { 309 return CompactibleFreeListSpace::block_size(addr); // Avoid virtual call 310 } 311 312 inline size_t adjust_obj_size(size_t size) const { 313 return adjustObjectSize(size); 314 } 315 316 inline size_t obj_size(const HeapWord* addr) const { 317 return adjustObjectSize(oop(addr)->size()); 318 } 319 320 protected: 321 // Reset the indexed free list to its initial empty condition. 322 void resetIndexedFreeListArray(); 323 // Reset to an initial state with a single free block described 324 // by the MemRegion parameter. 325 void reset(MemRegion mr); 326 // Return the total number of words in the indexed free lists. 327 size_t totalSizeInIndexedFreeLists() const; 328 329 public: 330 // Constructor 331 CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr); 332 // Accessors 333 bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; } 334 FreeBlockDictionary<FreeChunk>* dictionary() const { return _dictionary; } 335 HeapWord* nearLargestChunk() const { return _nearLargestChunk; } 336 void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; } 337 338 // Set CMS global values. 339 static void set_cms_values(); 340 341 // Return the free chunk at the end of the space. If no such 342 // chunk exists, return NULL. 343 FreeChunk* find_chunk_at_end(); 344 345 void set_collector(CMSCollector* collector) { _collector = collector; } 346 347 // Support for parallelization of rescan and marking. 348 const size_t rescan_task_size() const { return _rescan_task_size; } 349 const size_t marking_task_size() const { return _marking_task_size; } 350 SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; } 351 void initialize_sequential_subtasks_for_rescan(int n_threads); 352 void initialize_sequential_subtasks_for_marking(int n_threads, 353 HeapWord* low = NULL); 354 355 virtual MemRegionClosure* preconsumptionDirtyCardClosure() const { 356 return _preconsumptionDirtyCardClosure; 357 } 358 359 void setPreconsumptionDirtyCardClosure(MemRegionClosure* cl) { 360 _preconsumptionDirtyCardClosure = cl; 361 } 362 363 // Space enquiries 364 size_t used() const; 365 size_t free() const; 366 size_t max_alloc_in_words() const; 367 // XXX: should have a less conservative used_region() than that of 368 // Space; we could consider keeping track of highest allocated 369 // address and correcting that at each sweep, as the sweeper 370 // goes through the entire allocated part of the generation. We 371 // could also use that information to keep the sweeper from 372 // sweeping more than is necessary. The allocator and sweeper will 373 // of course need to synchronize on this, since the sweeper will 374 // try to bump down the address and the allocator will try to bump it up. 375 // For now, however, we'll just use the default used_region() 376 // which overestimates the region by returning the entire 377 // committed region (this is safe, but inefficient). 378 379 // Returns a subregion of the space containing all the objects in 380 // the space. 381 MemRegion used_region() const { 382 return MemRegion(bottom(), 383 BlockOffsetArrayUseUnallocatedBlock ? 384 unallocated_block() : end()); 385 } 386 387 virtual bool is_free_block(const HeapWord* p) const; 388 389 // Resizing support 390 void set_end(HeapWord* value); // override 391 392 // Never mangle CompactibleFreeListSpace 393 void mangle_unused_area() {} 394 void mangle_unused_area_complete() {} 395 396 // Mutual exclusion support 397 Mutex* freelistLock() const { return &_freelistLock; } 398 399 // Iteration support 400 void oop_iterate(ExtendedOopClosure* cl); 401 402 void object_iterate(ObjectClosure* blk); 403 // Apply the closure to each object in the space whose references 404 // point to objects in the heap. The usage of CompactibleFreeListSpace 405 // by the ConcurrentMarkSweepGeneration for concurrent GC's allows 406 // objects in the space with references to objects that are no longer 407 // valid. For example, an object may reference another object 408 // that has already been sweep up (collected). This method uses 409 // obj_is_alive() to determine whether it is safe to iterate of 410 // an object. 411 void safe_object_iterate(ObjectClosure* blk); 412 413 // Iterate over all objects that intersect with mr, calling "cl->do_object" 414 // on each. There is an exception to this: if this closure has already 415 // been invoked on an object, it may skip such objects in some cases. This is 416 // Most likely to happen in an "upwards" (ascending address) iteration of 417 // MemRegions. 418 void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl); 419 420 // Requires that "mr" be entirely within the space. 421 // Apply "cl->do_object" to all objects that intersect with "mr". 422 // If the iteration encounters an unparseable portion of the region, 423 // terminate the iteration and return the address of the start of the 424 // subregion that isn't done. Return of "NULL" indicates that the 425 // iteration completed. 426 HeapWord* object_iterate_careful_m(MemRegion mr, 427 ObjectClosureCareful* cl); 428 429 // Override: provides a DCTO_CL specific to this kind of space. 430 DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl, 431 CardTableModRefBS::PrecisionStyle precision, 432 HeapWord* boundary, 433 bool parallel); 434 435 void blk_iterate(BlkClosure* cl); 436 void blk_iterate_careful(BlkClosureCareful* cl); 437 HeapWord* block_start_const(const void* p) const; 438 HeapWord* block_start_careful(const void* p) const; 439 size_t block_size(const HeapWord* p) const; 440 size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const; 441 bool block_is_obj(const HeapWord* p) const; 442 bool obj_is_alive(const HeapWord* p) const; 443 size_t block_size_nopar(const HeapWord* p) const; 444 bool block_is_obj_nopar(const HeapWord* p) const; 445 446 // Iteration support for promotion 447 void save_marks(); 448 bool no_allocs_since_save_marks(); 449 450 // Iteration support for sweeping 451 void save_sweep_limit() { 452 _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ? 453 unallocated_block() : end(); 454 log_develop(gc, sweep)(">>>>> Saving sweep limit " PTR_FORMAT 455 " for space [" PTR_FORMAT "," PTR_FORMAT ") <<<<<<", 456 p2i(_sweep_limit), p2i(bottom()), p2i(end())); 457 } 458 NOT_PRODUCT( 459 void clear_sweep_limit() { _sweep_limit = NULL; } 460 ) 461 HeapWord* sweep_limit() { return _sweep_limit; } 462 463 // Apply "blk->do_oop" to the addresses of all reference fields in objects 464 // promoted into this generation since the most recent save_marks() call. 465 // Fields in objects allocated by applications of the closure 466 // *are* included in the iteration. Thus, when the iteration completes 467 // there should be no further such objects remaining. 468 #define CFLS_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ 469 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk); 470 ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DECL) 471 #undef CFLS_OOP_SINCE_SAVE_MARKS_DECL 472 473 // Allocation support 474 HeapWord* allocate(size_t size); 475 HeapWord* par_allocate(size_t size); 476 477 oop promote(oop obj, size_t obj_size); 478 void gc_prologue(); 479 void gc_epilogue(); 480 481 // This call is used by a containing CMS generation / collector 482 // to inform the CFLS space that a sweep has been completed 483 // and that the space can do any related house-keeping functions. 484 void sweep_completed(); 485 486 // For an object in this space, the mark-word's two 487 // LSB's having the value [11] indicates that it has been 488 // promoted since the most recent call to save_marks() on 489 // this generation and has not subsequently been iterated 490 // over (using oop_since_save_marks_iterate() above). 491 // This property holds only for single-threaded collections, 492 // and is typically used for Cheney scans; for MT scavenges, 493 // the property holds for all objects promoted during that 494 // scavenge for the duration of the scavenge and is used 495 // by card-scanning to avoid scanning objects (being) promoted 496 // during that scavenge. 497 bool obj_allocated_since_save_marks(const oop obj) const { 498 assert(is_in_reserved(obj), "Wrong space?"); 499 return ((PromotedObject*)obj)->hasPromotedMark(); 500 } 501 502 // A worst-case estimate of the space required (in HeapWords) to expand the 503 // heap when promoting an obj of size obj_size. 504 size_t expansionSpaceRequired(size_t obj_size) const; 505 506 FreeChunk* allocateScratch(size_t size); 507 508 // Returns true if either the small or large linear allocation buffer is empty. 509 bool linearAllocationWouldFail() const; 510 511 // Adjust the chunk for the minimum size. This version is called in 512 // most cases in CompactibleFreeListSpace methods. 513 inline static size_t adjustObjectSize(size_t size) { 514 return (size_t) align_object_size(MAX2(size, (size_t)MinChunkSize)); 515 } 516 // This is a virtual version of adjustObjectSize() that is called 517 // only occasionally when the compaction space changes and the type 518 // of the new compaction space is is only known to be CompactibleSpace. 519 size_t adjust_object_size_v(size_t size) const { 520 return adjustObjectSize(size); 521 } 522 // Minimum size of a free block. 523 virtual size_t minimum_free_block_size() const { return MinChunkSize; } 524 void removeFreeChunkFromFreeLists(FreeChunk* chunk); 525 void addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size, 526 bool coalesced); 527 528 // Support for compaction. 529 void prepare_for_compaction(CompactPoint* cp); 530 void adjust_pointers(); 531 void compact(); 532 // Reset the space to reflect the fact that a compaction of the 533 // space has been done. 534 virtual void reset_after_compaction(); 535 536 // Debugging support. 537 void print() const; 538 void print_on(outputStream* st) const; 539 void prepare_for_verify(); 540 void verify() const; 541 void verifyFreeLists() const PRODUCT_RETURN; 542 void verifyIndexedFreeLists() const; 543 void verifyIndexedFreeList(size_t size) const; 544 // Verify that the given chunk is in the free lists: 545 // i.e. either the binary tree dictionary, the indexed free lists 546 // or the linear allocation block. 547 bool verify_chunk_in_free_list(FreeChunk* fc) const; 548 // Verify that the given chunk is the linear allocation block. 549 bool verify_chunk_is_linear_alloc_block(FreeChunk* fc) const; 550 // Do some basic checks on the the free lists. 551 void check_free_list_consistency() const PRODUCT_RETURN; 552 553 // Printing support 554 void dump_at_safepoint_with_locks(CMSCollector* c, outputStream* st); 555 void print_indexed_free_lists(outputStream* st) const; 556 void print_dictionary_free_lists(outputStream* st) const; 557 void print_promo_info_blocks(outputStream* st) const; 558 559 NOT_PRODUCT ( 560 void initializeIndexedFreeListArrayReturnedBytes(); 561 size_t sumIndexedFreeListArrayReturnedBytes(); 562 // Return the total number of chunks in the indexed free lists. 563 size_t totalCountInIndexedFreeLists() const; 564 // Return the total number of chunks in the space. 565 size_t totalCount(); 566 ) 567 568 // The census consists of counts of the quantities such as 569 // the current count of the free chunks, number of chunks 570 // created as a result of the split of a larger chunk or 571 // coalescing of smaller chucks, etc. The counts in the 572 // census is used to make decisions on splitting and 573 // coalescing of chunks during the sweep of garbage. 574 575 // Print the statistics for the free lists. 576 void printFLCensus(size_t sweep_count) const; 577 578 // Statistics functions 579 // Initialize census for lists before the sweep. 580 void beginSweepFLCensus(float inter_sweep_current, 581 float inter_sweep_estimate, 582 float intra_sweep_estimate); 583 // Set the surplus for each of the free lists. 584 void setFLSurplus(); 585 // Set the hint for each of the free lists. 586 void setFLHints(); 587 // Clear the census for each of the free lists. 588 void clearFLCensus(); 589 // Perform functions for the census after the end of the sweep. 590 void endSweepFLCensus(size_t sweep_count); 591 // Return true if the count of free chunks is greater 592 // than the desired number of free chunks. 593 bool coalOverPopulated(size_t size); 594 595 // Record (for each size): 596 // 597 // split-births = #chunks added due to splits in (prev-sweep-end, 598 // this-sweep-start) 599 // split-deaths = #chunks removed for splits in (prev-sweep-end, 600 // this-sweep-start) 601 // num-curr = #chunks at start of this sweep 602 // num-prev = #chunks at end of previous sweep 603 // 604 // The above are quantities that are measured. Now define: 605 // 606 // num-desired := num-prev + split-births - split-deaths - num-curr 607 // 608 // Roughly, num-prev + split-births is the supply, 609 // split-deaths is demand due to other sizes 610 // and num-curr is what we have left. 611 // 612 // Thus, num-desired is roughly speaking the "legitimate demand" 613 // for blocks of this size and what we are striving to reach at the 614 // end of the current sweep. 615 // 616 // For a given list, let num-len be its current population. 617 // Define, for a free list of a given size: 618 // 619 // coal-overpopulated := num-len >= num-desired * coal-surplus 620 // (coal-surplus is set to 1.05, i.e. we allow a little slop when 621 // coalescing -- we do not coalesce unless we think that the current 622 // supply has exceeded the estimated demand by more than 5%). 623 // 624 // For the set of sizes in the binary tree, which is neither dense nor 625 // closed, it may be the case that for a particular size we have never 626 // had, or do not now have, or did not have at the previous sweep, 627 // chunks of that size. We need to extend the definition of 628 // coal-overpopulated to such sizes as well: 629 // 630 // For a chunk in/not in the binary tree, extend coal-overpopulated 631 // defined above to include all sizes as follows: 632 // 633 // . a size that is non-existent is coal-overpopulated 634 // . a size that has a num-desired <= 0 as defined above is 635 // coal-overpopulated. 636 // 637 // Also define, for a chunk heap-offset C and mountain heap-offset M: 638 // 639 // close-to-mountain := C >= 0.99 * M 640 // 641 // Now, the coalescing strategy is: 642 // 643 // Coalesce left-hand chunk with right-hand chunk if and 644 // only if: 645 // 646 // EITHER 647 // . left-hand chunk is of a size that is coal-overpopulated 648 // OR 649 // . right-hand chunk is close-to-mountain 650 void smallCoalBirth(size_t size); 651 void smallCoalDeath(size_t size); 652 void coalBirth(size_t size); 653 void coalDeath(size_t size); 654 void smallSplitBirth(size_t size); 655 void smallSplitDeath(size_t size); 656 void split_birth(size_t size); 657 void splitDeath(size_t size); 658 void split(size_t from, size_t to1); 659 660 double flsFrag() const; 661 }; 662 663 // A parallel-GC-thread-local allocation buffer for allocation into a 664 // CompactibleFreeListSpace. 665 class CFLS_LAB : public CHeapObj<mtGC> { 666 // The space that this buffer allocates into. 667 CompactibleFreeListSpace* _cfls; 668 669 // Our local free lists. 670 AdaptiveFreeList<FreeChunk> _indexedFreeList[CompactibleFreeListSpace::IndexSetSize]; 671 672 // Initialized from a command-line arg. 673 674 // Allocation statistics in support of dynamic adjustment of 675 // #blocks to claim per get_from_global_pool() call below. 676 static AdaptiveWeightedAverage 677 _blocks_to_claim [CompactibleFreeListSpace::IndexSetSize]; 678 static size_t _global_num_blocks [CompactibleFreeListSpace::IndexSetSize]; 679 static uint _global_num_workers[CompactibleFreeListSpace::IndexSetSize]; 680 size_t _num_blocks [CompactibleFreeListSpace::IndexSetSize]; 681 682 // Internal work method 683 void get_from_global_pool(size_t word_sz, AdaptiveFreeList<FreeChunk>* fl); 684 685 public: 686 static const int _default_dynamic_old_plab_size = 16; 687 static const int _default_static_old_plab_size = 50; 688 689 CFLS_LAB(CompactibleFreeListSpace* cfls); 690 691 // Allocate and return a block of the given size, or else return NULL. 692 HeapWord* alloc(size_t word_sz); 693 694 // Return any unused portions of the buffer to the global pool. 695 void retire(int tid); 696 697 // Dynamic OldPLABSize sizing 698 static void compute_desired_plab_size(); 699 // When the settings are modified from default static initialization 700 static void modify_initialization(size_t n, unsigned wt); 701 }; 702 703 size_t PromotionInfo::refillSize() const { 704 const size_t CMSSpoolBlockSize = 256; 705 const size_t sz = heap_word_size(sizeof(SpoolBlock) + sizeof(markOop) 706 * CMSSpoolBlockSize); 707 return CompactibleFreeListSpace::adjustObjectSize(sz); 708 } 709 710 #endif // SHARE_VM_GC_CMS_COMPACTIBLEFREELISTSPACE_HPP