rev 7084 : [mq]: demacro

   1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
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  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).
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_COMPACTIBLEFREELISTSPACE_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_COMPACTIBLEFREELISTSPACE_HPP
  27 
  28 #include "gc_implementation/concurrentMarkSweep/adaptiveFreeList.hpp"
  29 #include "gc_implementation/concurrentMarkSweep/promotionInfo.hpp"
  30 #include "memory/binaryTreeDictionary.hpp"
  31 #include "memory/blockOffsetTable.inline.hpp"
  32 #include "memory/freeList.hpp"
  33 #include "memory/space.hpp"
  34 
  35 // Classes in support of keeping track of promotions into a non-Contiguous
  36 // space, in this case a CompactibleFreeListSpace.
  37 
  38 // Forward declarations
  39 class CompactibleFreeListSpace;
  40 class BlkClosure;
  41 class BlkClosureCareful;
  42 class FreeChunk;
  43 class UpwardsObjectClosure;
  44 class ObjectClosureCareful;
  45 class Klass;
  46 
  47 class LinearAllocBlock VALUE_OBJ_CLASS_SPEC {
  48  public:
  49   LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0),
  50     _allocation_size_limit(0) {}
  51   void set(HeapWord* ptr, size_t word_size, size_t refill_size,
  52     size_t allocation_size_limit) {
  53     _ptr = ptr;
  54     _word_size = word_size;
  55     _refillSize = refill_size;
  56     _allocation_size_limit = allocation_size_limit;
  57   }
  58   HeapWord* _ptr;
  59   size_t    _word_size;
  60   size_t    _refillSize;
  61   size_t    _allocation_size_limit;  // Largest size that will be allocated
  62 
  63   void print_on(outputStream* st) const;
  64 };
  65 
  66 // Concrete subclass of CompactibleSpace that implements
  67 // a free list space, such as used in the concurrent mark sweep
  68 // generation.
  69 
  70 class CompactibleFreeListSpace: public CompactibleSpace {
  71   friend class VMStructs;
  72   friend class ConcurrentMarkSweepGeneration;
  73   friend class CMSCollector;
  74   // Local alloc buffer for promotion into this space.
  75   friend class CFLS_LAB;
  76 
  77   // "Size" of chunks of work (executed during parallel remark phases
  78   // of CMS collection); this probably belongs in CMSCollector, although
  79   // it's cached here because it's used in
  80   // initialize_sequential_subtasks_for_rescan() which modifies
  81   // par_seq_tasks which also lives in Space. XXX
  82   const size_t _rescan_task_size;
  83   const size_t _marking_task_size;
  84 
  85   // Yet another sequential tasks done structure. This supports
  86   // CMS GC, where we have threads dynamically
  87   // claiming sub-tasks from a larger parallel task.
  88   SequentialSubTasksDone _conc_par_seq_tasks;
  89 
  90   BlockOffsetArrayNonContigSpace _bt;
  91 
  92   CMSCollector* _collector;
  93   ConcurrentMarkSweepGeneration* _gen;
  94 
  95   // Data structures for free blocks (used during allocation/sweeping)
  96 
  97   // Allocation is done linearly from two different blocks depending on
  98   // whether the request is small or large, in an effort to reduce
  99   // fragmentation. We assume that any locking for allocation is done
 100   // by the containing generation. Thus, none of the methods in this
 101   // space are re-entrant.
 102   enum SomeConstants {
 103     SmallForLinearAlloc = 16,        // size < this then use _sLAB
 104     SmallForDictionary  = 257,       // size < this then use _indexedFreeList
 105     IndexSetSize        = SmallForDictionary  // keep this odd-sized
 106   };
 107   static size_t IndexSetStart;
 108   static size_t IndexSetStride;
 109 
 110  private:
 111   enum FitStrategyOptions {
 112     FreeBlockStrategyNone = 0,
 113     FreeBlockBestFitFirst
 114   };
 115 
 116   PromotionInfo _promoInfo;
 117 
 118   // Helps to impose a global total order on freelistLock ranks;
 119   // assumes that CFLSpace's are allocated in global total order
 120   static int   _lockRank;
 121 
 122   // A lock protecting the free lists and free blocks;
 123   // mutable because of ubiquity of locking even for otherwise const methods
 124   mutable Mutex _freelistLock;
 125   // Locking verifier convenience function
 126   void assert_locked() const PRODUCT_RETURN;
 127   void assert_locked(const Mutex* lock) const PRODUCT_RETURN;
 128 
 129   // Linear allocation blocks
 130   LinearAllocBlock _smallLinearAllocBlock;
 131 
 132   FreeBlockDictionary<FreeChunk>::DictionaryChoice _dictionaryChoice;
 133   AFLBinaryTreeDictionary* _dictionary;    // Pointer to dictionary for large size blocks
 134 
 135   // Indexed array for small size blocks
 136   AdaptiveFreeList<FreeChunk> _indexedFreeList[IndexSetSize];
 137 
 138   // Allocation strategy
 139   bool       _fitStrategy;        // Use best fit strategy
 140   bool       _adaptive_freelists; // Use adaptive freelists
 141 
 142   // This is an address close to the largest free chunk in the heap.
 143   // It is currently assumed to be at the end of the heap.  Free
 144   // chunks with addresses greater than nearLargestChunk are coalesced
 145   // in an effort to maintain a large chunk at the end of the heap.
 146   HeapWord*  _nearLargestChunk;
 147 
 148   // Used to keep track of limit of sweep for the space
 149   HeapWord* _sweep_limit;
 150 
 151   // Support for compacting cms
 152   HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
 153   HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top);
 154 
 155   // Initialization helpers.
 156   void initializeIndexedFreeListArray();
 157 
 158   // Extra stuff to manage promotion parallelism.
 159 
 160   // A lock protecting the dictionary during par promotion allocation.
 161   mutable Mutex _parDictionaryAllocLock;
 162   Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; }
 163 
 164   // Locks protecting the exact lists during par promotion allocation.
 165   Mutex* _indexedFreeListParLocks[IndexSetSize];
 166 
 167   // Attempt to obtain up to "n" blocks of the size "word_sz" (which is
 168   // required to be smaller than "IndexSetSize".)  If successful,
 169   // adds them to "fl", which is required to be an empty free list.
 170   // If the count of "fl" is negative, it's absolute value indicates a
 171   // number of free chunks that had been previously "borrowed" from global
 172   // list of size "word_sz", and must now be decremented.
 173   void par_get_chunk_of_blocks(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl);
 174 
 175   // Used by par_get_chunk_of_blocks() for the chunks from the
 176   // indexed_free_lists.
 177   bool par_get_chunk_of_blocks_IFL(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl);
 178 
 179   // Used by par_get_chunk_of_blocks_dictionary() to get a chunk
 180   // evenly splittable into "n" "word_sz" chunks.  Returns that
 181   // evenly splittable chunk.  May split a larger chunk to get the
 182   // evenly splittable chunk.
 183   FreeChunk* get_n_way_chunk_to_split(size_t word_sz, size_t n);
 184 
 185   // Used by par_get_chunk_of_blocks() for the chunks from the
 186   // dictionary.
 187   void par_get_chunk_of_blocks_dictionary(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl);
 188 
 189   // Allocation helper functions
 190   // Allocate using a strategy that takes from the indexed free lists
 191   // first.  This allocation strategy assumes a companion sweeping
 192   // strategy that attempts to keep the needed number of chunks in each
 193   // indexed free lists.
 194   HeapWord* allocate_adaptive_freelists(size_t size);
 195   // Allocate from the linear allocation buffers first.  This allocation
 196   // strategy assumes maximal coalescing can maintain chunks large enough
 197   // to be used as linear allocation buffers.
 198   HeapWord* allocate_non_adaptive_freelists(size_t size);
 199 
 200   // Gets a chunk from the linear allocation block (LinAB).  If there
 201   // is not enough space in the LinAB, refills it.
 202   HeapWord*  getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size);
 203   HeapWord*  getChunkFromSmallLinearAllocBlock(size_t size);
 204   // Get a chunk from the space remaining in the linear allocation block.  Do
 205   // not attempt to refill if the space is not available, return NULL.  Do the
 206   // repairs on the linear allocation block as appropriate.
 207   HeapWord*  getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size);
 208   inline HeapWord*  getChunkFromSmallLinearAllocBlockRemainder(size_t size);
 209 
 210   // Helper function for getChunkFromIndexedFreeList.
 211   // Replenish the indexed free list for this "size".  Do not take from an
 212   // underpopulated size.
 213   FreeChunk*  getChunkFromIndexedFreeListHelper(size_t size, bool replenish = true);
 214 
 215   // Get a chunk from the indexed free list.  If the indexed free list
 216   // does not have a free chunk, try to replenish the indexed free list
 217   // then get the free chunk from the replenished indexed free list.
 218   inline FreeChunk* getChunkFromIndexedFreeList(size_t size);
 219 
 220   // The returned chunk may be larger than requested (or null).
 221   FreeChunk* getChunkFromDictionary(size_t size);
 222   // The returned chunk is the exact size requested (or null).
 223   FreeChunk* getChunkFromDictionaryExact(size_t size);
 224 
 225   // Find a chunk in the indexed free list that is the best
 226   // fit for size "numWords".
 227   FreeChunk* bestFitSmall(size_t numWords);
 228   // For free list "fl" of chunks of size > numWords,
 229   // remove a chunk, split off a chunk of size numWords
 230   // and return it.  The split off remainder is returned to
 231   // the free lists.  The old name for getFromListGreater
 232   // was lookInListGreater.
 233   FreeChunk* getFromListGreater(AdaptiveFreeList<FreeChunk>* fl, size_t numWords);
 234   // Get a chunk in the indexed free list or dictionary,
 235   // by considering a larger chunk and splitting it.
 236   FreeChunk* getChunkFromGreater(size_t numWords);
 237   //  Verify that the given chunk is in the indexed free lists.
 238   bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const;
 239   // Remove the specified chunk from the indexed free lists.
 240   void       removeChunkFromIndexedFreeList(FreeChunk* fc);
 241   // Remove the specified chunk from the dictionary.
 242   void       removeChunkFromDictionary(FreeChunk* fc);
 243   // Split a free chunk into a smaller free chunk of size "new_size".
 244   // Return the smaller free chunk and return the remainder to the
 245   // free lists.
 246   FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size);
 247   // Add a chunk to the free lists.
 248   void       addChunkToFreeLists(HeapWord* chunk, size_t size);
 249   // Add a chunk to the free lists, preferring to suffix it
 250   // to the last free chunk at end of space if possible, and
 251   // updating the block census stats as well as block offset table.
 252   // Take any locks as appropriate if we are multithreaded.
 253   void       addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size);
 254   // Add a free chunk to the indexed free lists.
 255   void       returnChunkToFreeList(FreeChunk* chunk);
 256   // Add a free chunk to the dictionary.
 257   void       returnChunkToDictionary(FreeChunk* chunk);
 258 
 259   // Functions for maintaining the linear allocation buffers (LinAB).
 260   // Repairing a linear allocation block refers to operations
 261   // performed on the remainder of a LinAB after an allocation
 262   // has been made from it.
 263   void       repairLinearAllocationBlocks();
 264   void       repairLinearAllocBlock(LinearAllocBlock* blk);
 265   void       refillLinearAllocBlock(LinearAllocBlock* blk);
 266   void       refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk);
 267   void       refillLinearAllocBlocksIfNeeded();
 268 
 269   void       verify_objects_initialized() const;
 270 
 271   // Statistics reporting helper functions
 272   void       reportFreeListStatistics() const;
 273   void       reportIndexedFreeListStatistics() const;
 274   size_t     maxChunkSizeInIndexedFreeLists() const;
 275   size_t     numFreeBlocksInIndexedFreeLists() const;
 276   // Accessor
 277   HeapWord* unallocated_block() const {
 278     if (BlockOffsetArrayUseUnallocatedBlock) {
 279       HeapWord* ub = _bt.unallocated_block();
 280       assert(ub >= bottom() &&
 281              ub <= end(), "space invariant");
 282       return ub;
 283     } else {
 284       return end();
 285     }
 286   }
 287   void freed(HeapWord* start, size_t size) {
 288     _bt.freed(start, size);
 289   }
 290 
 291  protected:
 292   // Reset the indexed free list to its initial empty condition.
 293   void resetIndexedFreeListArray();
 294   // Reset to an initial state with a single free block described
 295   // by the MemRegion parameter.
 296   void reset(MemRegion mr);
 297   // Return the total number of words in the indexed free lists.
 298   size_t     totalSizeInIndexedFreeLists() const;
 299 
 300  public:
 301   // Constructor
 302   CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr,
 303                            bool use_adaptive_freelists,
 304                            FreeBlockDictionary<FreeChunk>::DictionaryChoice);
 305   // Accessors
 306   bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; }
 307   FreeBlockDictionary<FreeChunk>* dictionary() const { return _dictionary; }
 308   HeapWord* nearLargestChunk() const { return _nearLargestChunk; }
 309   void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; }
 310 
 311   // Set CMS global values.
 312   static void set_cms_values();
 313 
 314   // Return the free chunk at the end of the space.  If no such
 315   // chunk exists, return NULL.
 316   FreeChunk* find_chunk_at_end();
 317 
 318   bool adaptive_freelists() const { return _adaptive_freelists; }
 319 
 320   void set_collector(CMSCollector* collector) { _collector = collector; }
 321 
 322   // Support for parallelization of rescan and marking.
 323   const size_t rescan_task_size()  const { return _rescan_task_size;  }
 324   const size_t marking_task_size() const { return _marking_task_size; }
 325   SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; }
 326   void initialize_sequential_subtasks_for_rescan(int n_threads);
 327   void initialize_sequential_subtasks_for_marking(int n_threads,
 328          HeapWord* low = NULL);
 329 
 330   // Space enquiries
 331   size_t used() const;
 332   size_t free() const;
 333   size_t max_alloc_in_words() const;
 334   // XXX: should have a less conservative used_region() than that of
 335   // Space; we could consider keeping track of highest allocated
 336   // address and correcting that at each sweep, as the sweeper
 337   // goes through the entire allocated part of the generation. We
 338   // could also use that information to keep the sweeper from
 339   // sweeping more than is necessary. The allocator and sweeper will
 340   // of course need to synchronize on this, since the sweeper will
 341   // try to bump down the address and the allocator will try to bump it up.
 342   // For now, however, we'll just use the default used_region()
 343   // which overestimates the region by returning the entire
 344   // committed region (this is safe, but inefficient).
 345 
 346   // Returns a subregion of the space containing all the objects in
 347   // the space.
 348   MemRegion used_region() const {
 349     return MemRegion(bottom(),
 350                      BlockOffsetArrayUseUnallocatedBlock ?
 351                      unallocated_block() : end());
 352   }
 353 
 354   virtual bool is_free_block(const HeapWord* p) const;
 355 
 356   // Resizing support
 357   void set_end(HeapWord* value);  // override
 358 
 359   // Mutual exclusion support
 360   Mutex* freelistLock() const { return &_freelistLock; }
 361 
 362   // Iteration support
 363   void oop_iterate(ExtendedOopClosure* cl);
 364 
 365   void object_iterate(ObjectClosure* blk);
 366   // Apply the closure to each object in the space whose references
 367   // point to objects in the heap.  The usage of CompactibleFreeListSpace
 368   // by the ConcurrentMarkSweepGeneration for concurrent GC's allows
 369   // objects in the space with references to objects that are no longer
 370   // valid.  For example, an object may reference another object
 371   // that has already been sweep up (collected).  This method uses
 372   // obj_is_alive() to determine whether it is safe to iterate of
 373   // an object.
 374   void safe_object_iterate(ObjectClosure* blk);
 375 
 376   // Iterate over all objects that intersect with mr, calling "cl->do_object"
 377   // on each.  There is an exception to this: if this closure has already
 378   // been invoked on an object, it may skip such objects in some cases.  This is
 379   // Most likely to happen in an "upwards" (ascending address) iteration of
 380   // MemRegions.
 381   void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl);
 382 
 383   // Requires that "mr" be entirely within the space.
 384   // Apply "cl->do_object" to all objects that intersect with "mr".
 385   // If the iteration encounters an unparseable portion of the region,
 386   // terminate the iteration and return the address of the start of the
 387   // subregion that isn't done.  Return of "NULL" indicates that the
 388   // iteration completed.
 389   HeapWord* object_iterate_careful_m(MemRegion mr,
 390                                      ObjectClosureCareful* cl);
 391 
 392   // Override: provides a DCTO_CL specific to this kind of space.
 393   DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl,
 394                                      CardTableModRefBS::PrecisionStyle precision,
 395                                      HeapWord* boundary);
 396 
 397   void blk_iterate(BlkClosure* cl);
 398   void blk_iterate_careful(BlkClosureCareful* cl);
 399   HeapWord* block_start_const(const void* p) const;
 400   HeapWord* block_start_careful(const void* p) const;
 401   size_t block_size(const HeapWord* p) const;
 402   size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const;
 403   bool block_is_obj(const HeapWord* p) const;
 404   bool obj_is_alive(const HeapWord* p) const;
 405   size_t block_size_nopar(const HeapWord* p) const;
 406   bool block_is_obj_nopar(const HeapWord* p) const;
 407 
 408   // Functions for scan_and_{forward,adjust_pointers,compact} support.
 409   inline HeapWord* scan_limit() const {
 410     return end();
 411   }
 412 
 413   inline bool scanned_block_is_obj(const HeapWord* addr) const {
 414     return CompactibleFreeListSpace::block_is_obj(addr); // Avoid virtual call
 415   }
 416 
 417   inline size_t scanned_block_size(const HeapWord* addr) const {
 418     return CompactibleFreeListSpace::block_size(addr); // Avoid virtual call
 419   }
 420 
 421   inline size_t adjust_obj_size(size_t size) const {
 422     return adjustObjectSize(size);
 423   }
 424 
 425   inline size_t obj_size(const HeapWord* addr) const {
 426     return adjustObjectSize(oop(addr)->size());
 427   }
 428 
 429   // Iteration support for promotion
 430   void save_marks();
 431   bool no_allocs_since_save_marks();
 432 
 433   // Iteration support for sweeping
 434   void save_sweep_limit() {
 435     _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ?
 436                    unallocated_block() : end();
 437     if (CMSTraceSweeper) {
 438       gclog_or_tty->print_cr(">>>>> Saving sweep limit " PTR_FORMAT
 439                              "  for space [" PTR_FORMAT "," PTR_FORMAT ") <<<<<<",
 440                              p2i(_sweep_limit), p2i(bottom()), p2i(end()));
 441     }
 442   }
 443   NOT_PRODUCT(
 444     void clear_sweep_limit() { _sweep_limit = NULL; }
 445   )
 446   HeapWord* sweep_limit() { return _sweep_limit; }
 447 
 448   // Apply "blk->do_oop" to the addresses of all reference fields in objects
 449   // promoted into this generation since the most recent save_marks() call.
 450   // Fields in objects allocated by applications of the closure
 451   // *are* included in the iteration. Thus, when the iteration completes
 452   // there should be no further such objects remaining.
 453   #define CFLS_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)  \
 454     void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk);
 455   ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DECL)
 456   #undef CFLS_OOP_SINCE_SAVE_MARKS_DECL
 457 
 458   // Allocation support
 459   HeapWord* allocate(size_t size);
 460   HeapWord* par_allocate(size_t size);
 461 
 462   oop       promote(oop obj, size_t obj_size);
 463   void      gc_prologue();
 464   void      gc_epilogue();
 465 
 466   // This call is used by a containing CMS generation / collector
 467   // to inform the CFLS space that a sweep has been completed
 468   // and that the space can do any related house-keeping functions.
 469   void      sweep_completed();
 470 
 471   // For an object in this space, the mark-word's two
 472   // LSB's having the value [11] indicates that it has been
 473   // promoted since the most recent call to save_marks() on
 474   // this generation and has not subsequently been iterated
 475   // over (using oop_since_save_marks_iterate() above).
 476   // This property holds only for single-threaded collections,
 477   // and is typically used for Cheney scans; for MT scavenges,
 478   // the property holds for all objects promoted during that
 479   // scavenge for the duration of the scavenge and is used
 480   // by card-scanning to avoid scanning objects (being) promoted
 481   // during that scavenge.
 482   bool obj_allocated_since_save_marks(const oop obj) const {
 483     assert(is_in_reserved(obj), "Wrong space?");
 484     return ((PromotedObject*)obj)->hasPromotedMark();
 485   }
 486 
 487   // A worst-case estimate of the space required (in HeapWords) to expand the
 488   // heap when promoting an obj of size obj_size.
 489   size_t expansionSpaceRequired(size_t obj_size) const;
 490 
 491   FreeChunk* allocateScratch(size_t size);
 492 
 493   // Returns true if either the small or large linear allocation buffer is empty.
 494   bool       linearAllocationWouldFail() const;
 495 
 496   // Adjust the chunk for the minimum size.  This version is called in
 497   // most cases in CompactibleFreeListSpace methods.
 498   inline static size_t adjustObjectSize(size_t size) {
 499     return (size_t) align_object_size(MAX2(size, (size_t)MinChunkSize));
 500   }
 501   // This is a virtual version of adjustObjectSize() that is called
 502   // only occasionally when the compaction space changes and the type
 503   // of the new compaction space is is only known to be CompactibleSpace.
 504   size_t adjust_object_size_v(size_t size) const {
 505     return adjustObjectSize(size);
 506   }
 507   // Minimum size of a free block.
 508   virtual size_t minimum_free_block_size() const { return MinChunkSize; }
 509   void      removeFreeChunkFromFreeLists(FreeChunk* chunk);
 510   void      addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size,
 511               bool coalesced);
 512 
 513   // Support for decisions regarding concurrent collection policy.
 514   bool should_concurrent_collect() const;
 515 
 516   // Support for compaction.
 517   void prepare_for_compaction(CompactPoint* cp);
 518   void adjust_pointers();
 519   void compact();
 520   // Reset the space to reflect the fact that a compaction of the
 521   // space has been done.
 522   virtual void reset_after_compaction();
 523 
 524   // Debugging support.
 525   void print()                            const;
 526   void print_on(outputStream* st)         const;
 527   void prepare_for_verify();
 528   void verify()                           const;
 529   void verifyFreeLists()                  const PRODUCT_RETURN;
 530   void verifyIndexedFreeLists()           const;
 531   void verifyIndexedFreeList(size_t size) const;
 532   // Verify that the given chunk is in the free lists:
 533   // i.e. either the binary tree dictionary, the indexed free lists
 534   // or the linear allocation block.
 535   bool verify_chunk_in_free_list(FreeChunk* fc) const;
 536   // Verify that the given chunk is the linear allocation block.
 537   bool verify_chunk_is_linear_alloc_block(FreeChunk* fc) const;
 538   // Do some basic checks on the the free lists.
 539   void check_free_list_consistency()      const PRODUCT_RETURN;
 540 
 541   // Printing support
 542   void dump_at_safepoint_with_locks(CMSCollector* c, outputStream* st);
 543   void print_indexed_free_lists(outputStream* st) const;
 544   void print_dictionary_free_lists(outputStream* st) const;
 545   void print_promo_info_blocks(outputStream* st) const;
 546 
 547   NOT_PRODUCT (
 548     void initializeIndexedFreeListArrayReturnedBytes();
 549     size_t sumIndexedFreeListArrayReturnedBytes();
 550     // Return the total number of chunks in the indexed free lists.
 551     size_t totalCountInIndexedFreeLists() const;
 552     // Return the total number of chunks in the space.
 553     size_t totalCount();
 554   )
 555 
 556   // The census consists of counts of the quantities such as
 557   // the current count of the free chunks, number of chunks
 558   // created as a result of the split of a larger chunk or
 559   // coalescing of smaller chucks, etc.  The counts in the
 560   // census is used to make decisions on splitting and
 561   // coalescing of chunks during the sweep of garbage.
 562 
 563   // Print the statistics for the free lists.
 564   void printFLCensus(size_t sweep_count) const;
 565 
 566   // Statistics functions
 567   // Initialize census for lists before the sweep.
 568   void beginSweepFLCensus(float inter_sweep_current,
 569                           float inter_sweep_estimate,
 570                           float intra_sweep_estimate);
 571   // Set the surplus for each of the free lists.
 572   void setFLSurplus();
 573   // Set the hint for each of the free lists.
 574   void setFLHints();
 575   // Clear the census for each of the free lists.
 576   void clearFLCensus();
 577   // Perform functions for the census after the end of the sweep.
 578   void endSweepFLCensus(size_t sweep_count);
 579   // Return true if the count of free chunks is greater
 580   // than the desired number of free chunks.
 581   bool coalOverPopulated(size_t size);
 582 
 583 // Record (for each size):
 584 //
 585 //   split-births = #chunks added due to splits in (prev-sweep-end,
 586 //      this-sweep-start)
 587 //   split-deaths = #chunks removed for splits in (prev-sweep-end,
 588 //      this-sweep-start)
 589 //   num-curr     = #chunks at start of this sweep
 590 //   num-prev     = #chunks at end of previous sweep
 591 //
 592 // The above are quantities that are measured. Now define:
 593 //
 594 //   num-desired := num-prev + split-births - split-deaths - num-curr
 595 //
 596 // Roughly, num-prev + split-births is the supply,
 597 // split-deaths is demand due to other sizes
 598 // and num-curr is what we have left.
 599 //
 600 // Thus, num-desired is roughly speaking the "legitimate demand"
 601 // for blocks of this size and what we are striving to reach at the
 602 // end of the current sweep.
 603 //
 604 // For a given list, let num-len be its current population.
 605 // Define, for a free list of a given size:
 606 //
 607 //   coal-overpopulated := num-len >= num-desired * coal-surplus
 608 // (coal-surplus is set to 1.05, i.e. we allow a little slop when
 609 // coalescing -- we do not coalesce unless we think that the current
 610 // supply has exceeded the estimated demand by more than 5%).
 611 //
 612 // For the set of sizes in the binary tree, which is neither dense nor
 613 // closed, it may be the case that for a particular size we have never
 614 // had, or do not now have, or did not have at the previous sweep,
 615 // chunks of that size. We need to extend the definition of
 616 // coal-overpopulated to such sizes as well:
 617 //
 618 //   For a chunk in/not in the binary tree, extend coal-overpopulated
 619 //   defined above to include all sizes as follows:
 620 //
 621 //   . a size that is non-existent is coal-overpopulated
 622 //   . a size that has a num-desired <= 0 as defined above is
 623 //     coal-overpopulated.
 624 //
 625 // Also define, for a chunk heap-offset C and mountain heap-offset M:
 626 //
 627 //   close-to-mountain := C >= 0.99 * M
 628 //
 629 // Now, the coalescing strategy is:
 630 //
 631 //    Coalesce left-hand chunk with right-hand chunk if and
 632 //    only if:
 633 //
 634 //      EITHER
 635 //        . left-hand chunk is of a size that is coal-overpopulated
 636 //      OR
 637 //        . right-hand chunk is close-to-mountain
 638   void smallCoalBirth(size_t size);
 639   void smallCoalDeath(size_t size);
 640   void coalBirth(size_t size);
 641   void coalDeath(size_t size);
 642   void smallSplitBirth(size_t size);
 643   void smallSplitDeath(size_t size);
 644   void split_birth(size_t size);
 645   void splitDeath(size_t size);
 646   void split(size_t from, size_t to1);
 647 
 648   double flsFrag() const;
 649 };
 650 
 651 // A parallel-GC-thread-local allocation buffer for allocation into a
 652 // CompactibleFreeListSpace.
 653 class CFLS_LAB : public CHeapObj<mtGC> {
 654   // The space that this buffer allocates into.
 655   CompactibleFreeListSpace* _cfls;
 656 
 657   // Our local free lists.
 658   AdaptiveFreeList<FreeChunk> _indexedFreeList[CompactibleFreeListSpace::IndexSetSize];
 659 
 660   // Initialized from a command-line arg.
 661 
 662   // Allocation statistics in support of dynamic adjustment of
 663   // #blocks to claim per get_from_global_pool() call below.
 664   static AdaptiveWeightedAverage
 665                  _blocks_to_claim  [CompactibleFreeListSpace::IndexSetSize];
 666   static size_t _global_num_blocks [CompactibleFreeListSpace::IndexSetSize];
 667   static uint   _global_num_workers[CompactibleFreeListSpace::IndexSetSize];
 668   size_t        _num_blocks        [CompactibleFreeListSpace::IndexSetSize];
 669 
 670   // Internal work method
 671   void get_from_global_pool(size_t word_sz, AdaptiveFreeList<FreeChunk>* fl);
 672 
 673 public:
 674   CFLS_LAB(CompactibleFreeListSpace* cfls);
 675 
 676   // Allocate and return a block of the given size, or else return NULL.
 677   HeapWord* alloc(size_t word_sz);
 678 
 679   // Return any unused portions of the buffer to the global pool.
 680   void retire(int tid);
 681 
 682   // Dynamic OldPLABSize sizing
 683   static void compute_desired_plab_size();
 684   // When the settings are modified from default static initialization
 685   static void modify_initialization(size_t n, unsigned wt);
 686 };
 687 
 688 size_t PromotionInfo::refillSize() const {
 689   const size_t CMSSpoolBlockSize = 256;
 690   const size_t sz = heap_word_size(sizeof(SpoolBlock) + sizeof(markOop)
 691                                    * CMSSpoolBlockSize);
 692   return CompactibleFreeListSpace::adjustObjectSize(sz);
 693 }
 694 
 695 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_COMPACTIBLEFREELISTSPACE_HPP
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