--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/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);
+}