--- old/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp 2015-05-13 13:54:23.467002202 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,723 +0,0 @@ -/* - * Copyright (c) 2001, 2015, 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.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 CMSCollector; -class CompactibleFreeListSpace; -class ConcurrentMarkSweepGeneration; -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 CMSCollector; - // Local alloc buffer for promotion into this space. - friend class CFLS_LAB; - // Allow scan_and_* functions to call (private) overrides of the auxiliary functions on this class - template - friend void CompactibleSpace::scan_and_adjust_pointers(SpaceType* space); - template - friend void CompactibleSpace::scan_and_compact(SpaceType* space); - template - friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp); - - // "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::DictionaryChoice _dictionaryChoice; - AFLBinaryTreeDictionary* _dictionary; // Pointer to dictionary for large size blocks - - // Indexed array for small size blocks - AdaptiveFreeList _indexedFreeList[IndexSetSize]; - - // Allocation strategy - 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; - - // Used to make the young collector update the mod union table - MemRegionClosure* _preconsumptionDirtyCardClosure; - - // 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* 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* 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* 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* 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); - } - - // Auxiliary functions for scan_and_{forward,adjust_pointers,compact} support. - // See comments for CompactibleSpace for more information. - inline HeapWord* scan_limit() const { - return end(); - } - - inline bool scanned_block_is_obj(const HeapWord* addr) const { - return CompactibleFreeListSpace::block_is_obj(addr); // Avoid virtual call - } - - inline size_t scanned_block_size(const HeapWord* addr) const { - return CompactibleFreeListSpace::block_size(addr); // Avoid virtual call - } - - inline size_t adjust_obj_size(size_t size) const { - return adjustObjectSize(size); - } - - inline size_t obj_size(const HeapWord* addr) const { - return adjustObjectSize(oop(addr)->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; } - - // 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); - - virtual MemRegionClosure* preconsumptionDirtyCardClosure() const { - return _preconsumptionDirtyCardClosure; - } - - void setPreconsumptionDirtyCardClosure(MemRegionClosure* cl) { - _preconsumptionDirtyCardClosure = cl; - } - - // 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 - - // Never mangle CompactibleFreeListSpace - void mangle_unused_area() {} - void mangle_unused_area_complete() {} - - // 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 - // iteration 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 number of 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 { - // The space that this buffer allocates into. - CompactibleFreeListSpace* _cfls; - - // Our local free lists. - AdaptiveFreeList _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* fl); - -public: - static const int _default_dynamic_old_plab_size = 16; - static const int _default_static_old_plab_size = 50; - - 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 --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/cms/compactibleFreeListSpace.hpp 2015-05-13 13:54:23.267993944 +0200 @@ -0,0 +1,723 @@ +/* + * Copyright (c) 2001, 2015, 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_CMS_COMPACTIBLEFREELISTSPACE_HPP +#define SHARE_VM_GC_CMS_COMPACTIBLEFREELISTSPACE_HPP + +#include "gc/cms/adaptiveFreeList.hpp" +#include "gc/cms/promotionInfo.hpp" +#include "gc/shared/blockOffsetTable.hpp" +#include "gc/shared/space.hpp" +#include "memory/binaryTreeDictionary.hpp" +#include "memory/freeList.hpp" + +// Classes in support of keeping track of promotions into a non-Contiguous +// space, in this case a CompactibleFreeListSpace. + +// Forward declarations +class CMSCollector; +class CompactibleFreeListSpace; +class ConcurrentMarkSweepGeneration; +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 CMSCollector; + // Local alloc buffer for promotion into this space. + friend class CFLS_LAB; + // Allow scan_and_* functions to call (private) overrides of the auxiliary functions on this class + template + friend void CompactibleSpace::scan_and_adjust_pointers(SpaceType* space); + template + friend void CompactibleSpace::scan_and_compact(SpaceType* space); + template + friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp); + + // "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::DictionaryChoice _dictionaryChoice; + AFLBinaryTreeDictionary* _dictionary; // Pointer to dictionary for large size blocks + + // Indexed array for small size blocks + AdaptiveFreeList _indexedFreeList[IndexSetSize]; + + // Allocation strategy + 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; + + // Used to make the young collector update the mod union table + MemRegionClosure* _preconsumptionDirtyCardClosure; + + // 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* 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* 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* 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* 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); + } + + // Auxiliary functions for scan_and_{forward,adjust_pointers,compact} support. + // See comments for CompactibleSpace for more information. + inline HeapWord* scan_limit() const { + return end(); + } + + inline bool scanned_block_is_obj(const HeapWord* addr) const { + return CompactibleFreeListSpace::block_is_obj(addr); // Avoid virtual call + } + + inline size_t scanned_block_size(const HeapWord* addr) const { + return CompactibleFreeListSpace::block_size(addr); // Avoid virtual call + } + + inline size_t adjust_obj_size(size_t size) const { + return adjustObjectSize(size); + } + + inline size_t obj_size(const HeapWord* addr) const { + return adjustObjectSize(oop(addr)->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; } + + // 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); + + virtual MemRegionClosure* preconsumptionDirtyCardClosure() const { + return _preconsumptionDirtyCardClosure; + } + + void setPreconsumptionDirtyCardClosure(MemRegionClosure* cl) { + _preconsumptionDirtyCardClosure = cl; + } + + // 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 + + // Never mangle CompactibleFreeListSpace + void mangle_unused_area() {} + void mangle_unused_area_complete() {} + + // 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 + // iteration 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 number of 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 { + // The space that this buffer allocates into. + CompactibleFreeListSpace* _cfls; + + // Our local free lists. + AdaptiveFreeList _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* fl); + +public: + static const int _default_dynamic_old_plab_size = 16; + static const int _default_static_old_plab_size = 50; + + 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_CMS_COMPACTIBLEFREELISTSPACE_HPP