1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,748 @@
1.4 +/*
1.5 + * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +// Classes in support of keeping track of promotions into a non-Contiguous
1.29 +// space, in this case a CompactibleFreeListSpace.
1.30 +
1.31 +#define CFLS_LAB_REFILL_STATS 0
1.32 +
1.33 +// Forward declarations
1.34 +class CompactibleFreeListSpace;
1.35 +class BlkClosure;
1.36 +class BlkClosureCareful;
1.37 +class UpwardsObjectClosure;
1.38 +class ObjectClosureCareful;
1.39 +class Klass;
1.40 +
1.41 +class PromotedObject VALUE_OBJ_CLASS_SPEC {
1.42 + private:
1.43 + enum {
1.44 + promoted_mask = right_n_bits(2), // i.e. 0x3
1.45 + displaced_mark = nth_bit(2), // i.e. 0x4
1.46 + next_mask = ~(right_n_bits(3)) // i.e. ~(0x7)
1.47 + };
1.48 + intptr_t _next;
1.49 + public:
1.50 + inline PromotedObject* next() const {
1.51 + return (PromotedObject*)(_next & next_mask);
1.52 + }
1.53 + inline void setNext(PromotedObject* x) {
1.54 + assert(((intptr_t)x & ~next_mask) == 0,
1.55 + "Conflict in bit usage, "
1.56 + " or insufficient alignment of objects");
1.57 + _next |= (intptr_t)x;
1.58 + }
1.59 + inline void setPromotedMark() {
1.60 + _next |= promoted_mask;
1.61 + }
1.62 + inline bool hasPromotedMark() const {
1.63 + return (_next & promoted_mask) == promoted_mask;
1.64 + }
1.65 + inline void setDisplacedMark() {
1.66 + _next |= displaced_mark;
1.67 + }
1.68 + inline bool hasDisplacedMark() const {
1.69 + return (_next & displaced_mark) != 0;
1.70 + }
1.71 + inline void clearNext() { _next = 0; }
1.72 + debug_only(void *next_addr() { return (void *) &_next; })
1.73 +};
1.74 +
1.75 +class SpoolBlock: public FreeChunk {
1.76 + friend class PromotionInfo;
1.77 + protected:
1.78 + SpoolBlock* nextSpoolBlock;
1.79 + size_t bufferSize; // number of usable words in this block
1.80 + markOop* displacedHdr; // the displaced headers start here
1.81 +
1.82 + // Note about bufferSize: it denotes the number of entries available plus 1;
1.83 + // legal indices range from 1 through BufferSize - 1. See the verification
1.84 + // code verify() that counts the number of displaced headers spooled.
1.85 + size_t computeBufferSize() {
1.86 + return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop);
1.87 + }
1.88 +
1.89 + public:
1.90 + void init() {
1.91 + bufferSize = computeBufferSize();
1.92 + displacedHdr = (markOop*)&displacedHdr;
1.93 + nextSpoolBlock = NULL;
1.94 + }
1.95 +};
1.96 +
1.97 +class PromotionInfo VALUE_OBJ_CLASS_SPEC {
1.98 + bool _tracking; // set if tracking
1.99 + CompactibleFreeListSpace* _space; // the space to which this belongs
1.100 + PromotedObject* _promoHead; // head of list of promoted objects
1.101 + PromotedObject* _promoTail; // tail of list of promoted objects
1.102 + SpoolBlock* _spoolHead; // first spooling block
1.103 + SpoolBlock* _spoolTail; // last non-full spooling block or null
1.104 + SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail
1.105 + SpoolBlock* _spareSpool; // free spool buffer
1.106 + size_t _firstIndex; // first active index in
1.107 + // first spooling block (_spoolHead)
1.108 + size_t _nextIndex; // last active index + 1 in last
1.109 + // spooling block (_spoolTail)
1.110 + private:
1.111 + // ensure that spooling space exists; return true if there is spooling space
1.112 + bool ensure_spooling_space_work();
1.113 +
1.114 + public:
1.115 + PromotionInfo() :
1.116 + _tracking(0), _space(NULL),
1.117 + _promoHead(NULL), _promoTail(NULL),
1.118 + _spoolHead(NULL), _spoolTail(NULL),
1.119 + _spareSpool(NULL), _firstIndex(1),
1.120 + _nextIndex(1) {}
1.121 +
1.122 + bool noPromotions() const {
1.123 + assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency");
1.124 + return _promoHead == NULL;
1.125 + }
1.126 + void startTrackingPromotions();
1.127 + void stopTrackingPromotions();
1.128 + bool tracking() const { return _tracking; }
1.129 + void track(PromotedObject* trackOop); // keep track of a promoted oop
1.130 + // The following variant must be used when trackOop is not fully
1.131 + // initialized and has a NULL klass:
1.132 + void track(PromotedObject* trackOop, klassOop klassOfOop); // keep track of a promoted oop
1.133 + void setSpace(CompactibleFreeListSpace* sp) { _space = sp; }
1.134 + CompactibleFreeListSpace* space() const { return _space; }
1.135 + markOop nextDisplacedHeader(); // get next header & forward spool pointer
1.136 + void saveDisplacedHeader(markOop hdr);
1.137 + // save header and forward spool
1.138 +
1.139 + inline size_t refillSize() const;
1.140 +
1.141 + SpoolBlock* getSpoolBlock(); // return a free spooling block
1.142 + inline bool has_spooling_space() {
1.143 + return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex;
1.144 + }
1.145 + // ensure that spooling space exists
1.146 + bool ensure_spooling_space() {
1.147 + return has_spooling_space() || ensure_spooling_space_work();
1.148 + }
1.149 + #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \
1.150 + void promoted_oops_iterate##nv_suffix(OopClosureType* cl);
1.151 + ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL)
1.152 + #undef PROMOTED_OOPS_ITERATE_DECL
1.153 + void promoted_oops_iterate(OopsInGenClosure* cl) {
1.154 + promoted_oops_iterate_v(cl);
1.155 + }
1.156 + void verify() const;
1.157 + void reset() {
1.158 + _promoHead = NULL;
1.159 + _promoTail = NULL;
1.160 + _spoolHead = NULL;
1.161 + _spoolTail = NULL;
1.162 + _spareSpool = NULL;
1.163 + _firstIndex = 0;
1.164 + _nextIndex = 0;
1.165 +
1.166 + }
1.167 +};
1.168 +
1.169 +class LinearAllocBlock VALUE_OBJ_CLASS_SPEC {
1.170 + public:
1.171 + LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0),
1.172 + _allocation_size_limit(0) {}
1.173 + void set(HeapWord* ptr, size_t word_size, size_t refill_size,
1.174 + size_t allocation_size_limit) {
1.175 + _ptr = ptr;
1.176 + _word_size = word_size;
1.177 + _refillSize = refill_size;
1.178 + _allocation_size_limit = allocation_size_limit;
1.179 + }
1.180 + HeapWord* _ptr;
1.181 + size_t _word_size;
1.182 + size_t _refillSize;
1.183 + size_t _allocation_size_limit; // largest size that will be allocated
1.184 +};
1.185 +
1.186 +// Concrete subclass of CompactibleSpace that implements
1.187 +// a free list space, such as used in the concurrent mark sweep
1.188 +// generation.
1.189 +
1.190 +class CompactibleFreeListSpace: public CompactibleSpace {
1.191 + friend class VMStructs;
1.192 + friend class ConcurrentMarkSweepGeneration;
1.193 + friend class ASConcurrentMarkSweepGeneration;
1.194 + friend class CMSCollector;
1.195 + friend class CMSPermGenGen;
1.196 + // Local alloc buffer for promotion into this space.
1.197 + friend class CFLS_LAB;
1.198 +
1.199 + // "Size" of chunks of work (executed during parallel remark phases
1.200 + // of CMS collection); this probably belongs in CMSCollector, although
1.201 + // it's cached here because it's used in
1.202 + // initialize_sequential_subtasks_for_rescan() which modifies
1.203 + // par_seq_tasks which also lives in Space. XXX
1.204 + const size_t _rescan_task_size;
1.205 + const size_t _marking_task_size;
1.206 +
1.207 + // Yet another sequential tasks done structure. This supports
1.208 + // CMS GC, where we have threads dynamically
1.209 + // claiming sub-tasks from a larger parallel task.
1.210 + SequentialSubTasksDone _conc_par_seq_tasks;
1.211 +
1.212 + BlockOffsetArrayNonContigSpace _bt;
1.213 +
1.214 + CMSCollector* _collector;
1.215 + ConcurrentMarkSweepGeneration* _gen;
1.216 +
1.217 + // Data structures for free blocks (used during allocation/sweeping)
1.218 +
1.219 + // Allocation is done linearly from two different blocks depending on
1.220 + // whether the request is small or large, in an effort to reduce
1.221 + // fragmentation. We assume that any locking for allocation is done
1.222 + // by the containing generation. Thus, none of the methods in this
1.223 + // space are re-entrant.
1.224 + enum SomeConstants {
1.225 + SmallForLinearAlloc = 16, // size < this then use _sLAB
1.226 + SmallForDictionary = 257, // size < this then use _indexedFreeList
1.227 + IndexSetSize = SmallForDictionary, // keep this odd-sized
1.228 + IndexSetStart = MinObjAlignment,
1.229 + IndexSetStride = MinObjAlignment
1.230 + };
1.231 +
1.232 + private:
1.233 + enum FitStrategyOptions {
1.234 + FreeBlockStrategyNone = 0,
1.235 + FreeBlockBestFitFirst
1.236 + };
1.237 +
1.238 + PromotionInfo _promoInfo;
1.239 +
1.240 + // helps to impose a global total order on freelistLock ranks;
1.241 + // assumes that CFLSpace's are allocated in global total order
1.242 + static int _lockRank;
1.243 +
1.244 + // a lock protecting the free lists and free blocks;
1.245 + // mutable because of ubiquity of locking even for otherwise const methods
1.246 + mutable Mutex _freelistLock;
1.247 + // locking verifier convenience function
1.248 + void assert_locked() const PRODUCT_RETURN;
1.249 +
1.250 + // Linear allocation blocks
1.251 + LinearAllocBlock _smallLinearAllocBlock;
1.252 +
1.253 + FreeBlockDictionary::DictionaryChoice _dictionaryChoice;
1.254 + FreeBlockDictionary* _dictionary; // ptr to dictionary for large size blocks
1.255 +
1.256 + FreeList _indexedFreeList[IndexSetSize];
1.257 + // indexed array for small size blocks
1.258 + // allocation stategy
1.259 + bool _fitStrategy; // Use best fit strategy.
1.260 + bool _adaptive_freelists; // Use adaptive freelists
1.261 +
1.262 + // This is an address close to the largest free chunk in the heap.
1.263 + // It is currently assumed to be at the end of the heap. Free
1.264 + // chunks with addresses greater than nearLargestChunk are coalesced
1.265 + // in an effort to maintain a large chunk at the end of the heap.
1.266 + HeapWord* _nearLargestChunk;
1.267 +
1.268 + // Used to keep track of limit of sweep for the space
1.269 + HeapWord* _sweep_limit;
1.270 +
1.271 + // Support for compacting cms
1.272 + HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
1.273 + HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top);
1.274 +
1.275 + // Initialization helpers.
1.276 + void initializeIndexedFreeListArray();
1.277 +
1.278 + // Extra stuff to manage promotion parallelism.
1.279 +
1.280 + // a lock protecting the dictionary during par promotion allocation.
1.281 + mutable Mutex _parDictionaryAllocLock;
1.282 + Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; }
1.283 +
1.284 + // Locks protecting the exact lists during par promotion allocation.
1.285 + Mutex* _indexedFreeListParLocks[IndexSetSize];
1.286 +
1.287 +#if CFLS_LAB_REFILL_STATS
1.288 + // Some statistics.
1.289 + jint _par_get_chunk_from_small;
1.290 + jint _par_get_chunk_from_large;
1.291 +#endif
1.292 +
1.293 +
1.294 + // Attempt to obtain up to "n" blocks of the size "word_sz" (which is
1.295 + // required to be smaller than "IndexSetSize".) If successful,
1.296 + // adds them to "fl", which is required to be an empty free list.
1.297 + // If the count of "fl" is negative, it's absolute value indicates a
1.298 + // number of free chunks that had been previously "borrowed" from global
1.299 + // list of size "word_sz", and must now be decremented.
1.300 + void par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl);
1.301 +
1.302 + // Allocation helper functions
1.303 + // Allocate using a strategy that takes from the indexed free lists
1.304 + // first. This allocation strategy assumes a companion sweeping
1.305 + // strategy that attempts to keep the needed number of chunks in each
1.306 + // indexed free lists.
1.307 + HeapWord* allocate_adaptive_freelists(size_t size);
1.308 + // Allocate from the linear allocation buffers first. This allocation
1.309 + // strategy assumes maximal coalescing can maintain chunks large enough
1.310 + // to be used as linear allocation buffers.
1.311 + HeapWord* allocate_non_adaptive_freelists(size_t size);
1.312 +
1.313 + // Gets a chunk from the linear allocation block (LinAB). If there
1.314 + // is not enough space in the LinAB, refills it.
1.315 + HeapWord* getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size);
1.316 + HeapWord* getChunkFromSmallLinearAllocBlock(size_t size);
1.317 + // Get a chunk from the space remaining in the linear allocation block. Do
1.318 + // not attempt to refill if the space is not available, return NULL. Do the
1.319 + // repairs on the linear allocation block as appropriate.
1.320 + HeapWord* getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size);
1.321 + inline HeapWord* getChunkFromSmallLinearAllocBlockRemainder(size_t size);
1.322 +
1.323 + // Helper function for getChunkFromIndexedFreeList.
1.324 + // Replenish the indexed free list for this "size". Do not take from an
1.325 + // underpopulated size.
1.326 + FreeChunk* getChunkFromIndexedFreeListHelper(size_t size);
1.327 +
1.328 + // Get a chunk from the indexed free list. If the indexed free list
1.329 + // does not have a free chunk, try to replenish the indexed free list
1.330 + // then get the free chunk from the replenished indexed free list.
1.331 + inline FreeChunk* getChunkFromIndexedFreeList(size_t size);
1.332 +
1.333 + // The returned chunk may be larger than requested (or null).
1.334 + FreeChunk* getChunkFromDictionary(size_t size);
1.335 + // The returned chunk is the exact size requested (or null).
1.336 + FreeChunk* getChunkFromDictionaryExact(size_t size);
1.337 +
1.338 + // Find a chunk in the indexed free list that is the best
1.339 + // fit for size "numWords".
1.340 + FreeChunk* bestFitSmall(size_t numWords);
1.341 + // For free list "fl" of chunks of size > numWords,
1.342 + // remove a chunk, split off a chunk of size numWords
1.343 + // and return it. The split off remainder is returned to
1.344 + // the free lists. The old name for getFromListGreater
1.345 + // was lookInListGreater.
1.346 + FreeChunk* getFromListGreater(FreeList* fl, size_t numWords);
1.347 + // Get a chunk in the indexed free list or dictionary,
1.348 + // by considering a larger chunk and splitting it.
1.349 + FreeChunk* getChunkFromGreater(size_t numWords);
1.350 + // Verify that the given chunk is in the indexed free lists.
1.351 + bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const;
1.352 + // Remove the specified chunk from the indexed free lists.
1.353 + void removeChunkFromIndexedFreeList(FreeChunk* fc);
1.354 + // Remove the specified chunk from the dictionary.
1.355 + void removeChunkFromDictionary(FreeChunk* fc);
1.356 + // Split a free chunk into a smaller free chunk of size "new_size".
1.357 + // Return the smaller free chunk and return the remainder to the
1.358 + // free lists.
1.359 + FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size);
1.360 + // Add a chunk to the free lists.
1.361 + void addChunkToFreeLists(HeapWord* chunk, size_t size);
1.362 + // Add a chunk to the free lists, preferring to suffix it
1.363 + // to the last free chunk at end of space if possible, and
1.364 + // updating the block census stats as well as block offset table.
1.365 + // Take any locks as appropriate if we are multithreaded.
1.366 + void addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size);
1.367 + // Add a free chunk to the indexed free lists.
1.368 + void returnChunkToFreeList(FreeChunk* chunk);
1.369 + // Add a free chunk to the dictionary.
1.370 + void returnChunkToDictionary(FreeChunk* chunk);
1.371 +
1.372 + // Functions for maintaining the linear allocation buffers (LinAB).
1.373 + // Repairing a linear allocation block refers to operations
1.374 + // performed on the remainder of a LinAB after an allocation
1.375 + // has been made from it.
1.376 + void repairLinearAllocationBlocks();
1.377 + void repairLinearAllocBlock(LinearAllocBlock* blk);
1.378 + void refillLinearAllocBlock(LinearAllocBlock* blk);
1.379 + void refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk);
1.380 + void refillLinearAllocBlocksIfNeeded();
1.381 +
1.382 + void verify_objects_initialized() const;
1.383 +
1.384 + // Statistics reporting helper functions
1.385 + void reportFreeListStatistics() const;
1.386 + void reportIndexedFreeListStatistics() const;
1.387 + size_t maxChunkSizeInIndexedFreeLists() const;
1.388 + size_t numFreeBlocksInIndexedFreeLists() const;
1.389 + // Accessor
1.390 + HeapWord* unallocated_block() const {
1.391 + HeapWord* ub = _bt.unallocated_block();
1.392 + assert(ub >= bottom() &&
1.393 + ub <= end(), "space invariant");
1.394 + return ub;
1.395 + }
1.396 + void freed(HeapWord* start, size_t size) {
1.397 + _bt.freed(start, size);
1.398 + }
1.399 +
1.400 + protected:
1.401 + // reset the indexed free list to its initial empty condition.
1.402 + void resetIndexedFreeListArray();
1.403 + // reset to an initial state with a single free block described
1.404 + // by the MemRegion parameter.
1.405 + void reset(MemRegion mr);
1.406 + // Return the total number of words in the indexed free lists.
1.407 + size_t totalSizeInIndexedFreeLists() const;
1.408 +
1.409 + public:
1.410 + // Constructor...
1.411 + CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr,
1.412 + bool use_adaptive_freelists,
1.413 + FreeBlockDictionary::DictionaryChoice);
1.414 + // accessors
1.415 + bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; }
1.416 + FreeBlockDictionary* dictionary() const { return _dictionary; }
1.417 + HeapWord* nearLargestChunk() const { return _nearLargestChunk; }
1.418 + void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; }
1.419 +
1.420 + // Return the free chunk at the end of the space. If no such
1.421 + // chunk exists, return NULL.
1.422 + FreeChunk* find_chunk_at_end();
1.423 +
1.424 + bool adaptive_freelists() { return _adaptive_freelists; }
1.425 +
1.426 + void set_collector(CMSCollector* collector) { _collector = collector; }
1.427 +
1.428 + // Support for parallelization of rescan and marking
1.429 + const size_t rescan_task_size() const { return _rescan_task_size; }
1.430 + const size_t marking_task_size() const { return _marking_task_size; }
1.431 + SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; }
1.432 + void initialize_sequential_subtasks_for_rescan(int n_threads);
1.433 + void initialize_sequential_subtasks_for_marking(int n_threads,
1.434 + HeapWord* low = NULL);
1.435 +
1.436 +#if CFLS_LAB_REFILL_STATS
1.437 + void print_par_alloc_stats();
1.438 +#endif
1.439 +
1.440 + // Space enquiries
1.441 + size_t used() const;
1.442 + size_t free() const;
1.443 + size_t max_alloc_in_words() const;
1.444 + // XXX: should have a less conservative used_region() than that of
1.445 + // Space; we could consider keeping track of highest allocated
1.446 + // address and correcting that at each sweep, as the sweeper
1.447 + // goes through the entire allocated part of the generation. We
1.448 + // could also use that information to keep the sweeper from
1.449 + // sweeping more than is necessary. The allocator and sweeper will
1.450 + // of course need to synchronize on this, since the sweeper will
1.451 + // try to bump down the address and the allocator will try to bump it up.
1.452 + // For now, however, we'll just use the default used_region()
1.453 + // which overestimates the region by returning the entire
1.454 + // committed region (this is safe, but inefficient).
1.455 +
1.456 + // Returns a subregion of the space containing all the objects in
1.457 + // the space.
1.458 + MemRegion used_region() const {
1.459 + return MemRegion(bottom(),
1.460 + BlockOffsetArrayUseUnallocatedBlock ?
1.461 + unallocated_block() : end());
1.462 + }
1.463 +
1.464 + // This is needed because the default implementation uses block_start()
1.465 + // which can;t be used at certain times (for example phase 3 of mark-sweep).
1.466 + // A better fix is to change the assertions in phase 3 of mark-sweep to
1.467 + // use is_in_reserved(), but that is deferred since the is_in() assertions
1.468 + // are buried through several layers of callers and are used elsewhere
1.469 + // as well.
1.470 + bool is_in(const void* p) const {
1.471 + return used_region().contains(p);
1.472 + }
1.473 +
1.474 + virtual bool is_free_block(const HeapWord* p) const;
1.475 +
1.476 + // Resizing support
1.477 + void set_end(HeapWord* value); // override
1.478 +
1.479 + // mutual exclusion support
1.480 + Mutex* freelistLock() const { return &_freelistLock; }
1.481 +
1.482 + // Iteration support
1.483 + void oop_iterate(MemRegion mr, OopClosure* cl);
1.484 + void oop_iterate(OopClosure* cl);
1.485 +
1.486 + void object_iterate(ObjectClosure* blk);
1.487 + void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl);
1.488 +
1.489 + // Requires that "mr" be entirely within the space.
1.490 + // Apply "cl->do_object" to all objects that intersect with "mr".
1.491 + // If the iteration encounters an unparseable portion of the region,
1.492 + // terminate the iteration and return the address of the start of the
1.493 + // subregion that isn't done. Return of "NULL" indicates that the
1.494 + // interation completed.
1.495 + virtual HeapWord*
1.496 + object_iterate_careful_m(MemRegion mr,
1.497 + ObjectClosureCareful* cl);
1.498 + virtual HeapWord*
1.499 + object_iterate_careful(ObjectClosureCareful* cl);
1.500 +
1.501 + // Override: provides a DCTO_CL specific to this kind of space.
1.502 + DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl,
1.503 + CardTableModRefBS::PrecisionStyle precision,
1.504 + HeapWord* boundary);
1.505 +
1.506 + void blk_iterate(BlkClosure* cl);
1.507 + void blk_iterate_careful(BlkClosureCareful* cl);
1.508 + HeapWord* block_start(const void* p) const;
1.509 + HeapWord* block_start_careful(const void* p) const;
1.510 + size_t block_size(const HeapWord* p) const;
1.511 + size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const;
1.512 + bool block_is_obj(const HeapWord* p) const;
1.513 + bool obj_is_alive(const HeapWord* p) const;
1.514 + size_t block_size_nopar(const HeapWord* p) const;
1.515 + bool block_is_obj_nopar(const HeapWord* p) const;
1.516 +
1.517 + // iteration support for promotion
1.518 + void save_marks();
1.519 + bool no_allocs_since_save_marks();
1.520 + void object_iterate_since_last_GC(ObjectClosure* cl);
1.521 +
1.522 + // iteration support for sweeping
1.523 + void save_sweep_limit() {
1.524 + _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ?
1.525 + unallocated_block() : end();
1.526 + }
1.527 + NOT_PRODUCT(
1.528 + void clear_sweep_limit() { _sweep_limit = NULL; }
1.529 + )
1.530 + HeapWord* sweep_limit() { return _sweep_limit; }
1.531 +
1.532 + // Apply "blk->do_oop" to the addresses of all reference fields in objects
1.533 + // promoted into this generation since the most recent save_marks() call.
1.534 + // Fields in objects allocated by applications of the closure
1.535 + // *are* included in the iteration. Thus, when the iteration completes
1.536 + // there should be no further such objects remaining.
1.537 + #define CFLS_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
1.538 + void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk);
1.539 + ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DECL)
1.540 + #undef CFLS_OOP_SINCE_SAVE_MARKS_DECL
1.541 +
1.542 + // Allocation support
1.543 + HeapWord* allocate(size_t size);
1.544 + HeapWord* par_allocate(size_t size);
1.545 +
1.546 + oop promote(oop obj, size_t obj_size, oop* ref);
1.547 + void gc_prologue();
1.548 + void gc_epilogue();
1.549 +
1.550 + // This call is used by a containing CMS generation / collector
1.551 + // to inform the CFLS space that a sweep has been completed
1.552 + // and that the space can do any related house-keeping functions.
1.553 + void sweep_completed();
1.554 +
1.555 + // For an object in this space, the mark-word's two
1.556 + // LSB's having the value [11] indicates that it has been
1.557 + // promoted since the most recent call to save_marks() on
1.558 + // this generation and has not subsequently been iterated
1.559 + // over (using oop_since_save_marks_iterate() above).
1.560 + bool obj_allocated_since_save_marks(const oop obj) const {
1.561 + assert(is_in_reserved(obj), "Wrong space?");
1.562 + return ((PromotedObject*)obj)->hasPromotedMark();
1.563 + }
1.564 +
1.565 + // A worst-case estimate of the space required (in HeapWords) to expand the
1.566 + // heap when promoting an obj of size obj_size.
1.567 + size_t expansionSpaceRequired(size_t obj_size) const;
1.568 +
1.569 + FreeChunk* allocateScratch(size_t size);
1.570 +
1.571 + // returns true if either the small or large linear allocation buffer is empty.
1.572 + bool linearAllocationWouldFail();
1.573 +
1.574 + // Adjust the chunk for the minimum size. This version is called in
1.575 + // most cases in CompactibleFreeListSpace methods.
1.576 + inline static size_t adjustObjectSize(size_t size) {
1.577 + return (size_t) align_object_size(MAX2(size, (size_t)MinChunkSize));
1.578 + }
1.579 + // This is a virtual version of adjustObjectSize() that is called
1.580 + // only occasionally when the compaction space changes and the type
1.581 + // of the new compaction space is is only known to be CompactibleSpace.
1.582 + size_t adjust_object_size_v(size_t size) const {
1.583 + return adjustObjectSize(size);
1.584 + }
1.585 + // Minimum size of a free block.
1.586 + virtual size_t minimum_free_block_size() const { return MinChunkSize; }
1.587 + void removeFreeChunkFromFreeLists(FreeChunk* chunk);
1.588 + void addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size,
1.589 + bool coalesced);
1.590 +
1.591 + // Support for compaction
1.592 + void prepare_for_compaction(CompactPoint* cp);
1.593 + void adjust_pointers();
1.594 + void compact();
1.595 + // reset the space to reflect the fact that a compaction of the
1.596 + // space has been done.
1.597 + virtual void reset_after_compaction();
1.598 +
1.599 + // Debugging support
1.600 + void print() const;
1.601 + void prepare_for_verify();
1.602 + void verify(bool allow_dirty) const;
1.603 + void verifyFreeLists() const PRODUCT_RETURN;
1.604 + void verifyIndexedFreeLists() const;
1.605 + void verifyIndexedFreeList(size_t size) const;
1.606 + // verify that the given chunk is in the free lists.
1.607 + bool verifyChunkInFreeLists(FreeChunk* fc) const;
1.608 + // Do some basic checks on the the free lists.
1.609 + void checkFreeListConsistency() const PRODUCT_RETURN;
1.610 +
1.611 + NOT_PRODUCT (
1.612 + void initializeIndexedFreeListArrayReturnedBytes();
1.613 + size_t sumIndexedFreeListArrayReturnedBytes();
1.614 + // Return the total number of chunks in the indexed free lists.
1.615 + size_t totalCountInIndexedFreeLists() const;
1.616 + // Return the total numberof chunks in the space.
1.617 + size_t totalCount();
1.618 + )
1.619 +
1.620 + // The census consists of counts of the quantities such as
1.621 + // the current count of the free chunks, number of chunks
1.622 + // created as a result of the split of a larger chunk or
1.623 + // coalescing of smaller chucks, etc. The counts in the
1.624 + // census is used to make decisions on splitting and
1.625 + // coalescing of chunks during the sweep of garbage.
1.626 +
1.627 + // Print the statistics for the free lists.
1.628 + void printFLCensus(int sweepCt) const;
1.629 +
1.630 + // Statistics functions
1.631 + // Initialize census for lists before the sweep.
1.632 + void beginSweepFLCensus(float sweep_current,
1.633 + float sweep_estimate);
1.634 + // Set the surplus for each of the free lists.
1.635 + void setFLSurplus();
1.636 + // Set the hint for each of the free lists.
1.637 + void setFLHints();
1.638 + // Clear the census for each of the free lists.
1.639 + void clearFLCensus();
1.640 + // Perform functions for the census after the end of the sweep.
1.641 + void endSweepFLCensus(int sweepCt);
1.642 + // Return true if the count of free chunks is greater
1.643 + // than the desired number of free chunks.
1.644 + bool coalOverPopulated(size_t size);
1.645 +
1.646 +
1.647 +// Record (for each size):
1.648 +//
1.649 +// split-births = #chunks added due to splits in (prev-sweep-end,
1.650 +// this-sweep-start)
1.651 +// split-deaths = #chunks removed for splits in (prev-sweep-end,
1.652 +// this-sweep-start)
1.653 +// num-curr = #chunks at start of this sweep
1.654 +// num-prev = #chunks at end of previous sweep
1.655 +//
1.656 +// The above are quantities that are measured. Now define:
1.657 +//
1.658 +// num-desired := num-prev + split-births - split-deaths - num-curr
1.659 +//
1.660 +// Roughly, num-prev + split-births is the supply,
1.661 +// split-deaths is demand due to other sizes
1.662 +// and num-curr is what we have left.
1.663 +//
1.664 +// Thus, num-desired is roughly speaking the "legitimate demand"
1.665 +// for blocks of this size and what we are striving to reach at the
1.666 +// end of the current sweep.
1.667 +//
1.668 +// For a given list, let num-len be its current population.
1.669 +// Define, for a free list of a given size:
1.670 +//
1.671 +// coal-overpopulated := num-len >= num-desired * coal-surplus
1.672 +// (coal-surplus is set to 1.05, i.e. we allow a little slop when
1.673 +// coalescing -- we do not coalesce unless we think that the current
1.674 +// supply has exceeded the estimated demand by more than 5%).
1.675 +//
1.676 +// For the set of sizes in the binary tree, which is neither dense nor
1.677 +// closed, it may be the case that for a particular size we have never
1.678 +// had, or do not now have, or did not have at the previous sweep,
1.679 +// chunks of that size. We need to extend the definition of
1.680 +// coal-overpopulated to such sizes as well:
1.681 +//
1.682 +// For a chunk in/not in the binary tree, extend coal-overpopulated
1.683 +// defined above to include all sizes as follows:
1.684 +//
1.685 +// . a size that is non-existent is coal-overpopulated
1.686 +// . a size that has a num-desired <= 0 as defined above is
1.687 +// coal-overpopulated.
1.688 +//
1.689 +// Also define, for a chunk heap-offset C and mountain heap-offset M:
1.690 +//
1.691 +// close-to-mountain := C >= 0.99 * M
1.692 +//
1.693 +// Now, the coalescing strategy is:
1.694 +//
1.695 +// Coalesce left-hand chunk with right-hand chunk if and
1.696 +// only if:
1.697 +//
1.698 +// EITHER
1.699 +// . left-hand chunk is of a size that is coal-overpopulated
1.700 +// OR
1.701 +// . right-hand chunk is close-to-mountain
1.702 + void smallCoalBirth(size_t size);
1.703 + void smallCoalDeath(size_t size);
1.704 + void coalBirth(size_t size);
1.705 + void coalDeath(size_t size);
1.706 + void smallSplitBirth(size_t size);
1.707 + void smallSplitDeath(size_t size);
1.708 + void splitBirth(size_t size);
1.709 + void splitDeath(size_t size);
1.710 + void split(size_t from, size_t to1);
1.711 +
1.712 + double flsFrag() const;
1.713 +};
1.714 +
1.715 +// A parallel-GC-thread-local allocation buffer for allocation into a
1.716 +// CompactibleFreeListSpace.
1.717 +class CFLS_LAB : public CHeapObj {
1.718 + // The space that this buffer allocates into.
1.719 + CompactibleFreeListSpace* _cfls;
1.720 +
1.721 + // Our local free lists.
1.722 + FreeList _indexedFreeList[CompactibleFreeListSpace::IndexSetSize];
1.723 +
1.724 + // Initialized from a command-line arg.
1.725 + size_t _blocks_to_claim;
1.726 +
1.727 +#if CFLS_LAB_REFILL_STATS
1.728 + // Some statistics.
1.729 + int _refills;
1.730 + int _blocksTaken;
1.731 + static int _tot_refills;
1.732 + static int _tot_blocksTaken;
1.733 + static int _next_threshold;
1.734 +#endif
1.735 +
1.736 +public:
1.737 + CFLS_LAB(CompactibleFreeListSpace* cfls);
1.738 +
1.739 + // Allocate and return a block of the given size, or else return NULL.
1.740 + HeapWord* alloc(size_t word_sz);
1.741 +
1.742 + // Return any unused portions of the buffer to the global pool.
1.743 + void retire();
1.744 +};
1.745 +
1.746 +size_t PromotionInfo::refillSize() const {
1.747 + const size_t CMSSpoolBlockSize = 256;
1.748 + const size_t sz = heap_word_size(sizeof(SpoolBlock) + sizeof(markOop)
1.749 + * CMSSpoolBlockSize);
1.750 + return CompactibleFreeListSpace::adjustObjectSize(sz);
1.751 +}
