| /* |
| * Copyright (c) 2001, 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #ifndef SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_COMPACTIBLEFREELISTSPACE_HPP |
| #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_COMPACTIBLEFREELISTSPACE_HPP |
| |
| #include "gc_implementation/concurrentMarkSweep/adaptiveFreeList.hpp" |
| #include "gc_implementation/concurrentMarkSweep/promotionInfo.hpp" |
| #include "memory/binaryTreeDictionary.hpp" |
| #include "memory/blockOffsetTable.inline.hpp" |
| #include "memory/freeList.hpp" |
| #include "memory/space.hpp" |
| |
| // Classes in support of keeping track of promotions into a non-Contiguous |
| // space, in this case a CompactibleFreeListSpace. |
| |
| // Forward declarations |
| class CompactibleFreeListSpace; |
| class BlkClosure; |
| class BlkClosureCareful; |
| class FreeChunk; |
| class UpwardsObjectClosure; |
| class ObjectClosureCareful; |
| class Klass; |
| |
| 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 |
| |
| void print_on(outputStream* st) const; |
| }; |
| |
| // 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; |
| // 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 |
| }; |
| static size_t IndexSetStart; |
| static size_t IndexSetStride; |
| |
| 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; |
| void assert_locked(const Mutex* lock) const PRODUCT_RETURN; |
| |
| // Linear allocation blocks |
| LinearAllocBlock _smallLinearAllocBlock; |
| |
| FreeBlockDictionary<FreeChunk>::DictionaryChoice _dictionaryChoice; |
| AFLBinaryTreeDictionary* _dictionary; // ptr to dictionary for large size blocks |
| |
| AdaptiveFreeList<FreeChunk> _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]; |
| |
| // 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, AdaptiveFreeList<FreeChunk>* fl); |
| |
| // Used by par_get_chunk_of_blocks() for the chunks from the |
| // indexed_free_lists. |
| bool par_get_chunk_of_blocks_IFL(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl); |
| |
| // Used by par_get_chunk_of_blocks_dictionary() to get a chunk |
| // evenly splittable into "n" "word_sz" chunks. Returns that |
| // evenly splittable chunk. May split a larger chunk to get the |
| // evenly splittable chunk. |
| FreeChunk* get_n_way_chunk_to_split(size_t word_sz, size_t n); |
| |
| // Used by par_get_chunk_of_blocks() for the chunks from the |
| // dictionary. |
| void par_get_chunk_of_blocks_dictionary(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* 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, bool replenish = true); |
| |
| // 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(AdaptiveFreeList<FreeChunk>* 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 { |
| if (BlockOffsetArrayUseUnallocatedBlock) { |
| HeapWord* ub = _bt.unallocated_block(); |
| assert(ub >= bottom() && |
| ub <= end(), "space invariant"); |
| return ub; |
| } else { |
| return end(); |
| } |
| } |
| 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<FreeChunk>::DictionaryChoice); |
| // accessors |
| bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; } |
| FreeBlockDictionary<FreeChunk>* dictionary() const { return _dictionary; } |
| HeapWord* nearLargestChunk() const { return _nearLargestChunk; } |
| void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; } |
| |
| // Set CMS global values |
| static void set_cms_values(); |
| |
| // 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() const { 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); |
| |
| // 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()); |
| } |
| |
| 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(ExtendedOopClosure* cl); |
| |
| void object_iterate(ObjectClosure* blk); |
| // Apply the closure to each object in the space whose references |
| // point to objects in the heap. The usage of CompactibleFreeListSpace |
| // by the ConcurrentMarkSweepGeneration for concurrent GC's allows |
| // objects in the space with references to objects that are no longer |
| // valid. For example, an object may reference another object |
| // that has already been sweep up (collected). This method uses |
| // obj_is_alive() to determine whether it is safe to iterate of |
| // an object. |
| void safe_object_iterate(ObjectClosure* blk); |
| |
| // Iterate over all objects that intersect with mr, calling "cl->do_object" |
| // on each. There is an exception to this: if this closure has already |
| // been invoked on an object, it may skip such objects in some cases. This is |
| // Most likely to happen in an "upwards" (ascending address) iteration of |
| // MemRegions. |
| 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. |
| HeapWord* object_iterate_careful_m(MemRegion mr, |
| ObjectClosureCareful* cl); |
| |
| // Override: provides a DCTO_CL specific to this kind of space. |
| DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl, |
| CardTableModRefBS::PrecisionStyle precision, |
| HeapWord* boundary); |
| |
| void blk_iterate(BlkClosure* cl); |
| void blk_iterate_careful(BlkClosureCareful* cl); |
| HeapWord* block_start_const(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(); |
| |
| // iteration support for sweeping |
| void save_sweep_limit() { |
| _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ? |
| unallocated_block() : end(); |
| if (CMSTraceSweeper) { |
| gclog_or_tty->print_cr(">>>>> Saving sweep limit " PTR_FORMAT |
| " for space [" PTR_FORMAT "," PTR_FORMAT ") <<<<<<", |
| p2i(_sweep_limit), p2i(bottom()), p2i(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); |
| 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). |
| // This property holds only for single-threaded collections, |
| // and is typically used for Cheney scans; for MT scavenges, |
| // the property holds for all objects promoted during that |
| // scavenge for the duration of the scavenge and is used |
| // by card-scanning to avoid scanning objects (being) promoted |
| // during that scavenge. |
| 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() const; |
| |
| // 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 decisions regarding concurrent collection policy |
| bool should_concurrent_collect() const; |
| |
| // 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 print_on(outputStream* st) const; |
| void prepare_for_verify(); |
| void verify() 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: |
| // i.e. either the binary tree dictionary, the indexed free lists |
| // or the linear allocation block. |
| bool verify_chunk_in_free_list(FreeChunk* fc) const; |
| // Verify that the given chunk is the linear allocation block |
| bool verify_chunk_is_linear_alloc_block(FreeChunk* fc) const; |
| // Do some basic checks on the the free lists. |
| void check_free_list_consistency() const PRODUCT_RETURN; |
| |
| // Printing support |
| void dump_at_safepoint_with_locks(CMSCollector* c, outputStream* st); |
| void print_indexed_free_lists(outputStream* st) const; |
| void print_dictionary_free_lists(outputStream* st) const; |
| void print_promo_info_blocks(outputStream* st) const; |
| |
| 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(size_t sweep_count) const; |
| |
| // Statistics functions |
| // Initialize census for lists before the sweep. |
| void beginSweepFLCensus(float inter_sweep_current, |
| float inter_sweep_estimate, |
| float intra_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(size_t sweep_count); |
| // 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 split_birth(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<mtGC> { |
| // The space that this buffer allocates into. |
| CompactibleFreeListSpace* _cfls; |
| |
| // Our local free lists. |
| AdaptiveFreeList<FreeChunk> _indexedFreeList[CompactibleFreeListSpace::IndexSetSize]; |
| |
| // Initialized from a command-line arg. |
| |
| // Allocation statistics in support of dynamic adjustment of |
| // #blocks to claim per get_from_global_pool() call below. |
| static AdaptiveWeightedAverage |
| _blocks_to_claim [CompactibleFreeListSpace::IndexSetSize]; |
| static size_t _global_num_blocks [CompactibleFreeListSpace::IndexSetSize]; |
| static uint _global_num_workers[CompactibleFreeListSpace::IndexSetSize]; |
| size_t _num_blocks [CompactibleFreeListSpace::IndexSetSize]; |
| |
| // Internal work method |
| void get_from_global_pool(size_t word_sz, AdaptiveFreeList<FreeChunk>* fl); |
| |
| 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(int tid); |
| |
| // Dynamic OldPLABSize sizing |
| static void compute_desired_plab_size(); |
| // When the settings are modified from default static initialization |
| static void modify_initialization(size_t n, unsigned wt); |
| }; |
| |
| 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); |
| } |
| |
| #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_COMPACTIBLEFREELISTSPACE_HPP |