Mercurial > hg > graal-jvmci-8
diff src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | 6432c3bb6240 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,748 @@ +/* + * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +// Classes in support of keeping track of promotions into a non-Contiguous +// space, in this case a CompactibleFreeListSpace. + +#define CFLS_LAB_REFILL_STATS 0 + +// Forward declarations +class CompactibleFreeListSpace; +class BlkClosure; +class BlkClosureCareful; +class UpwardsObjectClosure; +class ObjectClosureCareful; +class Klass; + +class PromotedObject VALUE_OBJ_CLASS_SPEC { + private: + enum { + promoted_mask = right_n_bits(2), // i.e. 0x3 + displaced_mark = nth_bit(2), // i.e. 0x4 + next_mask = ~(right_n_bits(3)) // i.e. ~(0x7) + }; + intptr_t _next; + public: + inline PromotedObject* next() const { + return (PromotedObject*)(_next & next_mask); + } + inline void setNext(PromotedObject* x) { + assert(((intptr_t)x & ~next_mask) == 0, + "Conflict in bit usage, " + " or insufficient alignment of objects"); + _next |= (intptr_t)x; + } + inline void setPromotedMark() { + _next |= promoted_mask; + } + inline bool hasPromotedMark() const { + return (_next & promoted_mask) == promoted_mask; + } + inline void setDisplacedMark() { + _next |= displaced_mark; + } + inline bool hasDisplacedMark() const { + return (_next & displaced_mark) != 0; + } + inline void clearNext() { _next = 0; } + debug_only(void *next_addr() { return (void *) &_next; }) +}; + +class SpoolBlock: public FreeChunk { + friend class PromotionInfo; + protected: + SpoolBlock* nextSpoolBlock; + size_t bufferSize; // number of usable words in this block + markOop* displacedHdr; // the displaced headers start here + + // Note about bufferSize: it denotes the number of entries available plus 1; + // legal indices range from 1 through BufferSize - 1. See the verification + // code verify() that counts the number of displaced headers spooled. + size_t computeBufferSize() { + return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop); + } + + public: + void init() { + bufferSize = computeBufferSize(); + displacedHdr = (markOop*)&displacedHdr; + nextSpoolBlock = NULL; + } +}; + +class PromotionInfo VALUE_OBJ_CLASS_SPEC { + bool _tracking; // set if tracking + CompactibleFreeListSpace* _space; // the space to which this belongs + PromotedObject* _promoHead; // head of list of promoted objects + PromotedObject* _promoTail; // tail of list of promoted objects + SpoolBlock* _spoolHead; // first spooling block + SpoolBlock* _spoolTail; // last non-full spooling block or null + SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail + SpoolBlock* _spareSpool; // free spool buffer + size_t _firstIndex; // first active index in + // first spooling block (_spoolHead) + size_t _nextIndex; // last active index + 1 in last + // spooling block (_spoolTail) + private: + // ensure that spooling space exists; return true if there is spooling space + bool ensure_spooling_space_work(); + + public: + PromotionInfo() : + _tracking(0), _space(NULL), + _promoHead(NULL), _promoTail(NULL), + _spoolHead(NULL), _spoolTail(NULL), + _spareSpool(NULL), _firstIndex(1), + _nextIndex(1) {} + + bool noPromotions() const { + assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency"); + return _promoHead == NULL; + } + void startTrackingPromotions(); + void stopTrackingPromotions(); + bool tracking() const { return _tracking; } + void track(PromotedObject* trackOop); // keep track of a promoted oop + // The following variant must be used when trackOop is not fully + // initialized and has a NULL klass: + void track(PromotedObject* trackOop, klassOop klassOfOop); // keep track of a promoted oop + void setSpace(CompactibleFreeListSpace* sp) { _space = sp; } + CompactibleFreeListSpace* space() const { return _space; } + markOop nextDisplacedHeader(); // get next header & forward spool pointer + void saveDisplacedHeader(markOop hdr); + // save header and forward spool + + inline size_t refillSize() const; + + SpoolBlock* getSpoolBlock(); // return a free spooling block + inline bool has_spooling_space() { + return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex; + } + // ensure that spooling space exists + bool ensure_spooling_space() { + return has_spooling_space() || ensure_spooling_space_work(); + } + #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \ + void promoted_oops_iterate##nv_suffix(OopClosureType* cl); + ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL) + #undef PROMOTED_OOPS_ITERATE_DECL + void promoted_oops_iterate(OopsInGenClosure* cl) { + promoted_oops_iterate_v(cl); + } + void verify() const; + void reset() { + _promoHead = NULL; + _promoTail = NULL; + _spoolHead = NULL; + _spoolTail = NULL; + _spareSpool = NULL; + _firstIndex = 0; + _nextIndex = 0; + + } +}; + +class LinearAllocBlock VALUE_OBJ_CLASS_SPEC { + public: + LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0), + _allocation_size_limit(0) {} + void set(HeapWord* ptr, size_t word_size, size_t refill_size, + size_t allocation_size_limit) { + _ptr = ptr; + _word_size = word_size; + _refillSize = refill_size; + _allocation_size_limit = allocation_size_limit; + } + HeapWord* _ptr; + size_t _word_size; + size_t _refillSize; + size_t _allocation_size_limit; // largest size that will be allocated +}; + +// Concrete subclass of CompactibleSpace that implements +// a free list space, such as used in the concurrent mark sweep +// generation. + +class CompactibleFreeListSpace: public CompactibleSpace { + friend class VMStructs; + friend class ConcurrentMarkSweepGeneration; + friend class ASConcurrentMarkSweepGeneration; + friend class CMSCollector; + friend class CMSPermGenGen; + // Local alloc buffer for promotion into this space. + friend class CFLS_LAB; + + // "Size" of chunks of work (executed during parallel remark phases + // of CMS collection); this probably belongs in CMSCollector, although + // it's cached here because it's used in + // initialize_sequential_subtasks_for_rescan() which modifies + // par_seq_tasks which also lives in Space. XXX + const size_t _rescan_task_size; + const size_t _marking_task_size; + + // Yet another sequential tasks done structure. This supports + // CMS GC, where we have threads dynamically + // claiming sub-tasks from a larger parallel task. + SequentialSubTasksDone _conc_par_seq_tasks; + + BlockOffsetArrayNonContigSpace _bt; + + CMSCollector* _collector; + ConcurrentMarkSweepGeneration* _gen; + + // Data structures for free blocks (used during allocation/sweeping) + + // Allocation is done linearly from two different blocks depending on + // whether the request is small or large, in an effort to reduce + // fragmentation. We assume that any locking for allocation is done + // by the containing generation. Thus, none of the methods in this + // space are re-entrant. + enum SomeConstants { + SmallForLinearAlloc = 16, // size < this then use _sLAB + SmallForDictionary = 257, // size < this then use _indexedFreeList + IndexSetSize = SmallForDictionary, // keep this odd-sized + IndexSetStart = MinObjAlignment, + IndexSetStride = MinObjAlignment + }; + + private: + enum FitStrategyOptions { + FreeBlockStrategyNone = 0, + FreeBlockBestFitFirst + }; + + PromotionInfo _promoInfo; + + // helps to impose a global total order on freelistLock ranks; + // assumes that CFLSpace's are allocated in global total order + static int _lockRank; + + // a lock protecting the free lists and free blocks; + // mutable because of ubiquity of locking even for otherwise const methods + mutable Mutex _freelistLock; + // locking verifier convenience function + void assert_locked() const PRODUCT_RETURN; + + // Linear allocation blocks + LinearAllocBlock _smallLinearAllocBlock; + + FreeBlockDictionary::DictionaryChoice _dictionaryChoice; + FreeBlockDictionary* _dictionary; // ptr to dictionary for large size blocks + + FreeList _indexedFreeList[IndexSetSize]; + // indexed array for small size blocks + // allocation stategy + bool _fitStrategy; // Use best fit strategy. + bool _adaptive_freelists; // Use adaptive freelists + + // This is an address close to the largest free chunk in the heap. + // It is currently assumed to be at the end of the heap. Free + // chunks with addresses greater than nearLargestChunk are coalesced + // in an effort to maintain a large chunk at the end of the heap. + HeapWord* _nearLargestChunk; + + // Used to keep track of limit of sweep for the space + HeapWord* _sweep_limit; + + // Support for compacting cms + HeapWord* cross_threshold(HeapWord* start, HeapWord* end); + HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top); + + // Initialization helpers. + void initializeIndexedFreeListArray(); + + // Extra stuff to manage promotion parallelism. + + // a lock protecting the dictionary during par promotion allocation. + mutable Mutex _parDictionaryAllocLock; + Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; } + + // Locks protecting the exact lists during par promotion allocation. + Mutex* _indexedFreeListParLocks[IndexSetSize]; + +#if CFLS_LAB_REFILL_STATS + // Some statistics. + jint _par_get_chunk_from_small; + jint _par_get_chunk_from_large; +#endif + + + // Attempt to obtain up to "n" blocks of the size "word_sz" (which is + // required to be smaller than "IndexSetSize".) If successful, + // adds them to "fl", which is required to be an empty free list. + // If the count of "fl" is negative, it's absolute value indicates a + // number of free chunks that had been previously "borrowed" from global + // list of size "word_sz", and must now be decremented. + void par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl); + + // Allocation helper functions + // Allocate using a strategy that takes from the indexed free lists + // first. This allocation strategy assumes a companion sweeping + // strategy that attempts to keep the needed number of chunks in each + // indexed free lists. + HeapWord* allocate_adaptive_freelists(size_t size); + // Allocate from the linear allocation buffers first. This allocation + // strategy assumes maximal coalescing can maintain chunks large enough + // to be used as linear allocation buffers. + HeapWord* allocate_non_adaptive_freelists(size_t size); + + // Gets a chunk from the linear allocation block (LinAB). If there + // is not enough space in the LinAB, refills it. + HeapWord* getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size); + HeapWord* getChunkFromSmallLinearAllocBlock(size_t size); + // Get a chunk from the space remaining in the linear allocation block. Do + // not attempt to refill if the space is not available, return NULL. Do the + // repairs on the linear allocation block as appropriate. + HeapWord* getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size); + inline HeapWord* getChunkFromSmallLinearAllocBlockRemainder(size_t size); + + // Helper function for getChunkFromIndexedFreeList. + // Replenish the indexed free list for this "size". Do not take from an + // underpopulated size. + FreeChunk* getChunkFromIndexedFreeListHelper(size_t size); + + // Get a chunk from the indexed free list. If the indexed free list + // does not have a free chunk, try to replenish the indexed free list + // then get the free chunk from the replenished indexed free list. + inline FreeChunk* getChunkFromIndexedFreeList(size_t size); + + // The returned chunk may be larger than requested (or null). + FreeChunk* getChunkFromDictionary(size_t size); + // The returned chunk is the exact size requested (or null). + FreeChunk* getChunkFromDictionaryExact(size_t size); + + // Find a chunk in the indexed free list that is the best + // fit for size "numWords". + FreeChunk* bestFitSmall(size_t numWords); + // For free list "fl" of chunks of size > numWords, + // remove a chunk, split off a chunk of size numWords + // and return it. The split off remainder is returned to + // the free lists. The old name for getFromListGreater + // was lookInListGreater. + FreeChunk* getFromListGreater(FreeList* fl, size_t numWords); + // Get a chunk in the indexed free list or dictionary, + // by considering a larger chunk and splitting it. + FreeChunk* getChunkFromGreater(size_t numWords); + // Verify that the given chunk is in the indexed free lists. + bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const; + // Remove the specified chunk from the indexed free lists. + void removeChunkFromIndexedFreeList(FreeChunk* fc); + // Remove the specified chunk from the dictionary. + void removeChunkFromDictionary(FreeChunk* fc); + // Split a free chunk into a smaller free chunk of size "new_size". + // Return the smaller free chunk and return the remainder to the + // free lists. + FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size); + // Add a chunk to the free lists. + void addChunkToFreeLists(HeapWord* chunk, size_t size); + // Add a chunk to the free lists, preferring to suffix it + // to the last free chunk at end of space if possible, and + // updating the block census stats as well as block offset table. + // Take any locks as appropriate if we are multithreaded. + void addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size); + // Add a free chunk to the indexed free lists. + void returnChunkToFreeList(FreeChunk* chunk); + // Add a free chunk to the dictionary. + void returnChunkToDictionary(FreeChunk* chunk); + + // Functions for maintaining the linear allocation buffers (LinAB). + // Repairing a linear allocation block refers to operations + // performed on the remainder of a LinAB after an allocation + // has been made from it. + void repairLinearAllocationBlocks(); + void repairLinearAllocBlock(LinearAllocBlock* blk); + void refillLinearAllocBlock(LinearAllocBlock* blk); + void refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk); + void refillLinearAllocBlocksIfNeeded(); + + void verify_objects_initialized() const; + + // Statistics reporting helper functions + void reportFreeListStatistics() const; + void reportIndexedFreeListStatistics() const; + size_t maxChunkSizeInIndexedFreeLists() const; + size_t numFreeBlocksInIndexedFreeLists() const; + // Accessor + HeapWord* unallocated_block() const { + HeapWord* ub = _bt.unallocated_block(); + assert(ub >= bottom() && + ub <= end(), "space invariant"); + return ub; + } + void freed(HeapWord* start, size_t size) { + _bt.freed(start, size); + } + + protected: + // reset the indexed free list to its initial empty condition. + void resetIndexedFreeListArray(); + // reset to an initial state with a single free block described + // by the MemRegion parameter. + void reset(MemRegion mr); + // Return the total number of words in the indexed free lists. + size_t totalSizeInIndexedFreeLists() const; + + public: + // Constructor... + CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr, + bool use_adaptive_freelists, + FreeBlockDictionary::DictionaryChoice); + // accessors + bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; } + FreeBlockDictionary* dictionary() const { return _dictionary; } + HeapWord* nearLargestChunk() const { return _nearLargestChunk; } + void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; } + + // Return the free chunk at the end of the space. If no such + // chunk exists, return NULL. + FreeChunk* find_chunk_at_end(); + + bool adaptive_freelists() { return _adaptive_freelists; } + + void set_collector(CMSCollector* collector) { _collector = collector; } + + // Support for parallelization of rescan and marking + const size_t rescan_task_size() const { return _rescan_task_size; } + const size_t marking_task_size() const { return _marking_task_size; } + SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; } + void initialize_sequential_subtasks_for_rescan(int n_threads); + void initialize_sequential_subtasks_for_marking(int n_threads, + HeapWord* low = NULL); + +#if CFLS_LAB_REFILL_STATS + void print_par_alloc_stats(); +#endif + + // Space enquiries + size_t used() const; + size_t free() const; + size_t max_alloc_in_words() const; + // XXX: should have a less conservative used_region() than that of + // Space; we could consider keeping track of highest allocated + // address and correcting that at each sweep, as the sweeper + // goes through the entire allocated part of the generation. We + // could also use that information to keep the sweeper from + // sweeping more than is necessary. The allocator and sweeper will + // of course need to synchronize on this, since the sweeper will + // try to bump down the address and the allocator will try to bump it up. + // For now, however, we'll just use the default used_region() + // which overestimates the region by returning the entire + // committed region (this is safe, but inefficient). + + // Returns a subregion of the space containing all the objects in + // the space. + MemRegion used_region() const { + return MemRegion(bottom(), + BlockOffsetArrayUseUnallocatedBlock ? + unallocated_block() : end()); + } + + // This is needed because the default implementation uses block_start() + // which can;t be used at certain times (for example phase 3 of mark-sweep). + // A better fix is to change the assertions in phase 3 of mark-sweep to + // use is_in_reserved(), but that is deferred since the is_in() assertions + // are buried through several layers of callers and are used elsewhere + // as well. + bool is_in(const void* p) const { + return used_region().contains(p); + } + + virtual bool is_free_block(const HeapWord* p) const; + + // Resizing support + void set_end(HeapWord* value); // override + + // mutual exclusion support + Mutex* freelistLock() const { return &_freelistLock; } + + // Iteration support + void oop_iterate(MemRegion mr, OopClosure* cl); + void oop_iterate(OopClosure* cl); + + void object_iterate(ObjectClosure* blk); + void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl); + + // Requires that "mr" be entirely within the space. + // Apply "cl->do_object" to all objects that intersect with "mr". + // If the iteration encounters an unparseable portion of the region, + // terminate the iteration and return the address of the start of the + // subregion that isn't done. Return of "NULL" indicates that the + // interation completed. + virtual HeapWord* + object_iterate_careful_m(MemRegion mr, + ObjectClosureCareful* cl); + virtual HeapWord* + object_iterate_careful(ObjectClosureCareful* cl); + + // Override: provides a DCTO_CL specific to this kind of space. + DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl, + CardTableModRefBS::PrecisionStyle precision, + HeapWord* boundary); + + void blk_iterate(BlkClosure* cl); + void blk_iterate_careful(BlkClosureCareful* cl); + HeapWord* block_start(const void* p) const; + HeapWord* block_start_careful(const void* p) const; + size_t block_size(const HeapWord* p) const; + size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const; + bool block_is_obj(const HeapWord* p) const; + bool obj_is_alive(const HeapWord* p) const; + size_t block_size_nopar(const HeapWord* p) const; + bool block_is_obj_nopar(const HeapWord* p) const; + + // iteration support for promotion + void save_marks(); + bool no_allocs_since_save_marks(); + void object_iterate_since_last_GC(ObjectClosure* cl); + + // iteration support for sweeping + void save_sweep_limit() { + _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ? + unallocated_block() : end(); + } + NOT_PRODUCT( + void clear_sweep_limit() { _sweep_limit = NULL; } + ) + HeapWord* sweep_limit() { return _sweep_limit; } + + // Apply "blk->do_oop" to the addresses of all reference fields in objects + // promoted into this generation since the most recent save_marks() call. + // Fields in objects allocated by applications of the closure + // *are* included in the iteration. Thus, when the iteration completes + // there should be no further such objects remaining. + #define CFLS_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ + void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk); + ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DECL) + #undef CFLS_OOP_SINCE_SAVE_MARKS_DECL + + // Allocation support + HeapWord* allocate(size_t size); + HeapWord* par_allocate(size_t size); + + oop promote(oop obj, size_t obj_size, oop* ref); + void gc_prologue(); + void gc_epilogue(); + + // This call is used by a containing CMS generation / collector + // to inform the CFLS space that a sweep has been completed + // and that the space can do any related house-keeping functions. + void sweep_completed(); + + // For an object in this space, the mark-word's two + // LSB's having the value [11] indicates that it has been + // promoted since the most recent call to save_marks() on + // this generation and has not subsequently been iterated + // over (using oop_since_save_marks_iterate() above). + bool obj_allocated_since_save_marks(const oop obj) const { + assert(is_in_reserved(obj), "Wrong space?"); + return ((PromotedObject*)obj)->hasPromotedMark(); + } + + // A worst-case estimate of the space required (in HeapWords) to expand the + // heap when promoting an obj of size obj_size. + size_t expansionSpaceRequired(size_t obj_size) const; + + FreeChunk* allocateScratch(size_t size); + + // returns true if either the small or large linear allocation buffer is empty. + bool linearAllocationWouldFail(); + + // Adjust the chunk for the minimum size. This version is called in + // most cases in CompactibleFreeListSpace methods. + inline static size_t adjustObjectSize(size_t size) { + return (size_t) align_object_size(MAX2(size, (size_t)MinChunkSize)); + } + // This is a virtual version of adjustObjectSize() that is called + // only occasionally when the compaction space changes and the type + // of the new compaction space is is only known to be CompactibleSpace. + size_t adjust_object_size_v(size_t size) const { + return adjustObjectSize(size); + } + // Minimum size of a free block. + virtual size_t minimum_free_block_size() const { return MinChunkSize; } + void removeFreeChunkFromFreeLists(FreeChunk* chunk); + void addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size, + bool coalesced); + + // Support for compaction + void prepare_for_compaction(CompactPoint* cp); + void adjust_pointers(); + void compact(); + // reset the space to reflect the fact that a compaction of the + // space has been done. + virtual void reset_after_compaction(); + + // Debugging support + void print() const; + void prepare_for_verify(); + void verify(bool allow_dirty) const; + void verifyFreeLists() const PRODUCT_RETURN; + void verifyIndexedFreeLists() const; + void verifyIndexedFreeList(size_t size) const; + // verify that the given chunk is in the free lists. + bool verifyChunkInFreeLists(FreeChunk* fc) const; + // Do some basic checks on the the free lists. + void checkFreeListConsistency() const PRODUCT_RETURN; + + NOT_PRODUCT ( + void initializeIndexedFreeListArrayReturnedBytes(); + size_t sumIndexedFreeListArrayReturnedBytes(); + // Return the total number of chunks in the indexed free lists. + size_t totalCountInIndexedFreeLists() const; + // Return the total numberof chunks in the space. + size_t totalCount(); + ) + + // The census consists of counts of the quantities such as + // the current count of the free chunks, number of chunks + // created as a result of the split of a larger chunk or + // coalescing of smaller chucks, etc. The counts in the + // census is used to make decisions on splitting and + // coalescing of chunks during the sweep of garbage. + + // Print the statistics for the free lists. + void printFLCensus(int sweepCt) const; + + // Statistics functions + // Initialize census for lists before the sweep. + void beginSweepFLCensus(float sweep_current, + float sweep_estimate); + // Set the surplus for each of the free lists. + void setFLSurplus(); + // Set the hint for each of the free lists. + void setFLHints(); + // Clear the census for each of the free lists. + void clearFLCensus(); + // Perform functions for the census after the end of the sweep. + void endSweepFLCensus(int sweepCt); + // Return true if the count of free chunks is greater + // than the desired number of free chunks. + bool coalOverPopulated(size_t size); + + +// Record (for each size): +// +// split-births = #chunks added due to splits in (prev-sweep-end, +// this-sweep-start) +// split-deaths = #chunks removed for splits in (prev-sweep-end, +// this-sweep-start) +// num-curr = #chunks at start of this sweep +// num-prev = #chunks at end of previous sweep +// +// The above are quantities that are measured. Now define: +// +// num-desired := num-prev + split-births - split-deaths - num-curr +// +// Roughly, num-prev + split-births is the supply, +// split-deaths is demand due to other sizes +// and num-curr is what we have left. +// +// Thus, num-desired is roughly speaking the "legitimate demand" +// for blocks of this size and what we are striving to reach at the +// end of the current sweep. +// +// For a given list, let num-len be its current population. +// Define, for a free list of a given size: +// +// coal-overpopulated := num-len >= num-desired * coal-surplus +// (coal-surplus is set to 1.05, i.e. we allow a little slop when +// coalescing -- we do not coalesce unless we think that the current +// supply has exceeded the estimated demand by more than 5%). +// +// For the set of sizes in the binary tree, which is neither dense nor +// closed, it may be the case that for a particular size we have never +// had, or do not now have, or did not have at the previous sweep, +// chunks of that size. We need to extend the definition of +// coal-overpopulated to such sizes as well: +// +// For a chunk in/not in the binary tree, extend coal-overpopulated +// defined above to include all sizes as follows: +// +// . a size that is non-existent is coal-overpopulated +// . a size that has a num-desired <= 0 as defined above is +// coal-overpopulated. +// +// Also define, for a chunk heap-offset C and mountain heap-offset M: +// +// close-to-mountain := C >= 0.99 * M +// +// Now, the coalescing strategy is: +// +// Coalesce left-hand chunk with right-hand chunk if and +// only if: +// +// EITHER +// . left-hand chunk is of a size that is coal-overpopulated +// OR +// . right-hand chunk is close-to-mountain + void smallCoalBirth(size_t size); + void smallCoalDeath(size_t size); + void coalBirth(size_t size); + void coalDeath(size_t size); + void smallSplitBirth(size_t size); + void smallSplitDeath(size_t size); + void splitBirth(size_t size); + void splitDeath(size_t size); + void split(size_t from, size_t to1); + + double flsFrag() const; +}; + +// A parallel-GC-thread-local allocation buffer for allocation into a +// CompactibleFreeListSpace. +class CFLS_LAB : public CHeapObj { + // The space that this buffer allocates into. + CompactibleFreeListSpace* _cfls; + + // Our local free lists. + FreeList _indexedFreeList[CompactibleFreeListSpace::IndexSetSize]; + + // Initialized from a command-line arg. + size_t _blocks_to_claim; + +#if CFLS_LAB_REFILL_STATS + // Some statistics. + int _refills; + int _blocksTaken; + static int _tot_refills; + static int _tot_blocksTaken; + static int _next_threshold; +#endif + +public: + CFLS_LAB(CompactibleFreeListSpace* cfls); + + // Allocate and return a block of the given size, or else return NULL. + HeapWord* alloc(size_t word_sz); + + // Return any unused portions of the buffer to the global pool. + void retire(); +}; + +size_t PromotionInfo::refillSize() const { + const size_t CMSSpoolBlockSize = 256; + const size_t sz = heap_word_size(sizeof(SpoolBlock) + sizeof(markOop) + * CMSSpoolBlockSize); + return CompactibleFreeListSpace::adjustObjectSize(sz); +}