truffle: src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp comparison

comparison src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
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children	6432c3bb6240

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+:a61af66fc99e
+/*
+* 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);
+}

Mercurial > hg > truffle

comparison src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp @ 0:a61af66fc99e jdk7-b24