Wed, 03 Jul 2013 17:26:59 -0400
7133260: AllocationProfiler uses space in metadata and doesn't seem to do anything useful.
Summary: Remove -Xaprof and Klass::_alloc_count & ArrayKlass::_alloc_size.
Reviewed-by: stefank, coleenp
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_COMPACTIBLEFREELISTSPACE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_COMPACTIBLEFREELISTSPACE_HPP
28 #include "gc_implementation/concurrentMarkSweep/adaptiveFreeList.hpp"
29 #include "gc_implementation/concurrentMarkSweep/promotionInfo.hpp"
30 #include "memory/binaryTreeDictionary.hpp"
31 #include "memory/blockOffsetTable.inline.hpp"
32 #include "memory/freeList.hpp"
33 #include "memory/space.hpp"
35 // Classes in support of keeping track of promotions into a non-Contiguous
36 // space, in this case a CompactibleFreeListSpace.
38 // Forward declarations
39 class CompactibleFreeListSpace;
40 class BlkClosure;
41 class BlkClosureCareful;
42 class FreeChunk;
43 class UpwardsObjectClosure;
44 class ObjectClosureCareful;
45 class Klass;
47 class LinearAllocBlock VALUE_OBJ_CLASS_SPEC {
48 public:
49 LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0),
50 _allocation_size_limit(0) {}
51 void set(HeapWord* ptr, size_t word_size, size_t refill_size,
52 size_t allocation_size_limit) {
53 _ptr = ptr;
54 _word_size = word_size;
55 _refillSize = refill_size;
56 _allocation_size_limit = allocation_size_limit;
57 }
58 HeapWord* _ptr;
59 size_t _word_size;
60 size_t _refillSize;
61 size_t _allocation_size_limit; // largest size that will be allocated
63 void print_on(outputStream* st) const;
64 };
66 // Concrete subclass of CompactibleSpace that implements
67 // a free list space, such as used in the concurrent mark sweep
68 // generation.
70 class CompactibleFreeListSpace: public CompactibleSpace {
71 friend class VMStructs;
72 friend class ConcurrentMarkSweepGeneration;
73 friend class ASConcurrentMarkSweepGeneration;
74 friend class CMSCollector;
75 // Local alloc buffer for promotion into this space.
76 friend class CFLS_LAB;
78 // "Size" of chunks of work (executed during parallel remark phases
79 // of CMS collection); this probably belongs in CMSCollector, although
80 // it's cached here because it's used in
81 // initialize_sequential_subtasks_for_rescan() which modifies
82 // par_seq_tasks which also lives in Space. XXX
83 const size_t _rescan_task_size;
84 const size_t _marking_task_size;
86 // Yet another sequential tasks done structure. This supports
87 // CMS GC, where we have threads dynamically
88 // claiming sub-tasks from a larger parallel task.
89 SequentialSubTasksDone _conc_par_seq_tasks;
91 BlockOffsetArrayNonContigSpace _bt;
93 CMSCollector* _collector;
94 ConcurrentMarkSweepGeneration* _gen;
96 // Data structures for free blocks (used during allocation/sweeping)
98 // Allocation is done linearly from two different blocks depending on
99 // whether the request is small or large, in an effort to reduce
100 // fragmentation. We assume that any locking for allocation is done
101 // by the containing generation. Thus, none of the methods in this
102 // space are re-entrant.
103 enum SomeConstants {
104 SmallForLinearAlloc = 16, // size < this then use _sLAB
105 SmallForDictionary = 257, // size < this then use _indexedFreeList
106 IndexSetSize = SmallForDictionary // keep this odd-sized
107 };
108 static size_t IndexSetStart;
109 static size_t IndexSetStride;
111 private:
112 enum FitStrategyOptions {
113 FreeBlockStrategyNone = 0,
114 FreeBlockBestFitFirst
115 };
117 PromotionInfo _promoInfo;
119 // helps to impose a global total order on freelistLock ranks;
120 // assumes that CFLSpace's are allocated in global total order
121 static int _lockRank;
123 // a lock protecting the free lists and free blocks;
124 // mutable because of ubiquity of locking even for otherwise const methods
125 mutable Mutex _freelistLock;
126 // locking verifier convenience function
127 void assert_locked() const PRODUCT_RETURN;
128 void assert_locked(const Mutex* lock) const PRODUCT_RETURN;
130 // Linear allocation blocks
131 LinearAllocBlock _smallLinearAllocBlock;
133 FreeBlockDictionary<FreeChunk>::DictionaryChoice _dictionaryChoice;
134 AFLBinaryTreeDictionary* _dictionary; // ptr to dictionary for large size blocks
136 AdaptiveFreeList<FreeChunk> _indexedFreeList[IndexSetSize];
137 // indexed array for small size blocks
138 // allocation stategy
139 bool _fitStrategy; // Use best fit strategy.
140 bool _adaptive_freelists; // Use adaptive freelists
142 // This is an address close to the largest free chunk in the heap.
143 // It is currently assumed to be at the end of the heap. Free
144 // chunks with addresses greater than nearLargestChunk are coalesced
145 // in an effort to maintain a large chunk at the end of the heap.
146 HeapWord* _nearLargestChunk;
148 // Used to keep track of limit of sweep for the space
149 HeapWord* _sweep_limit;
151 // Support for compacting cms
152 HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
153 HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top);
155 // Initialization helpers.
156 void initializeIndexedFreeListArray();
158 // Extra stuff to manage promotion parallelism.
160 // a lock protecting the dictionary during par promotion allocation.
161 mutable Mutex _parDictionaryAllocLock;
162 Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; }
164 // Locks protecting the exact lists during par promotion allocation.
165 Mutex* _indexedFreeListParLocks[IndexSetSize];
167 // Attempt to obtain up to "n" blocks of the size "word_sz" (which is
168 // required to be smaller than "IndexSetSize".) If successful,
169 // adds them to "fl", which is required to be an empty free list.
170 // If the count of "fl" is negative, it's absolute value indicates a
171 // number of free chunks that had been previously "borrowed" from global
172 // list of size "word_sz", and must now be decremented.
173 void par_get_chunk_of_blocks(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl);
175 // Allocation helper functions
176 // Allocate using a strategy that takes from the indexed free lists
177 // first. This allocation strategy assumes a companion sweeping
178 // strategy that attempts to keep the needed number of chunks in each
179 // indexed free lists.
180 HeapWord* allocate_adaptive_freelists(size_t size);
181 // Allocate from the linear allocation buffers first. This allocation
182 // strategy assumes maximal coalescing can maintain chunks large enough
183 // to be used as linear allocation buffers.
184 HeapWord* allocate_non_adaptive_freelists(size_t size);
186 // Gets a chunk from the linear allocation block (LinAB). If there
187 // is not enough space in the LinAB, refills it.
188 HeapWord* getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size);
189 HeapWord* getChunkFromSmallLinearAllocBlock(size_t size);
190 // Get a chunk from the space remaining in the linear allocation block. Do
191 // not attempt to refill if the space is not available, return NULL. Do the
192 // repairs on the linear allocation block as appropriate.
193 HeapWord* getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size);
194 inline HeapWord* getChunkFromSmallLinearAllocBlockRemainder(size_t size);
196 // Helper function for getChunkFromIndexedFreeList.
197 // Replenish the indexed free list for this "size". Do not take from an
198 // underpopulated size.
199 FreeChunk* getChunkFromIndexedFreeListHelper(size_t size, bool replenish = true);
201 // Get a chunk from the indexed free list. If the indexed free list
202 // does not have a free chunk, try to replenish the indexed free list
203 // then get the free chunk from the replenished indexed free list.
204 inline FreeChunk* getChunkFromIndexedFreeList(size_t size);
206 // The returned chunk may be larger than requested (or null).
207 FreeChunk* getChunkFromDictionary(size_t size);
208 // The returned chunk is the exact size requested (or null).
209 FreeChunk* getChunkFromDictionaryExact(size_t size);
211 // Find a chunk in the indexed free list that is the best
212 // fit for size "numWords".
213 FreeChunk* bestFitSmall(size_t numWords);
214 // For free list "fl" of chunks of size > numWords,
215 // remove a chunk, split off a chunk of size numWords
216 // and return it. The split off remainder is returned to
217 // the free lists. The old name for getFromListGreater
218 // was lookInListGreater.
219 FreeChunk* getFromListGreater(AdaptiveFreeList<FreeChunk>* fl, size_t numWords);
220 // Get a chunk in the indexed free list or dictionary,
221 // by considering a larger chunk and splitting it.
222 FreeChunk* getChunkFromGreater(size_t numWords);
223 // Verify that the given chunk is in the indexed free lists.
224 bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const;
225 // Remove the specified chunk from the indexed free lists.
226 void removeChunkFromIndexedFreeList(FreeChunk* fc);
227 // Remove the specified chunk from the dictionary.
228 void removeChunkFromDictionary(FreeChunk* fc);
229 // Split a free chunk into a smaller free chunk of size "new_size".
230 // Return the smaller free chunk and return the remainder to the
231 // free lists.
232 FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size);
233 // Add a chunk to the free lists.
234 void addChunkToFreeLists(HeapWord* chunk, size_t size);
235 // Add a chunk to the free lists, preferring to suffix it
236 // to the last free chunk at end of space if possible, and
237 // updating the block census stats as well as block offset table.
238 // Take any locks as appropriate if we are multithreaded.
239 void addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size);
240 // Add a free chunk to the indexed free lists.
241 void returnChunkToFreeList(FreeChunk* chunk);
242 // Add a free chunk to the dictionary.
243 void returnChunkToDictionary(FreeChunk* chunk);
245 // Functions for maintaining the linear allocation buffers (LinAB).
246 // Repairing a linear allocation block refers to operations
247 // performed on the remainder of a LinAB after an allocation
248 // has been made from it.
249 void repairLinearAllocationBlocks();
250 void repairLinearAllocBlock(LinearAllocBlock* blk);
251 void refillLinearAllocBlock(LinearAllocBlock* blk);
252 void refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk);
253 void refillLinearAllocBlocksIfNeeded();
255 void verify_objects_initialized() const;
257 // Statistics reporting helper functions
258 void reportFreeListStatistics() const;
259 void reportIndexedFreeListStatistics() const;
260 size_t maxChunkSizeInIndexedFreeLists() const;
261 size_t numFreeBlocksInIndexedFreeLists() const;
262 // Accessor
263 HeapWord* unallocated_block() const {
264 if (BlockOffsetArrayUseUnallocatedBlock) {
265 HeapWord* ub = _bt.unallocated_block();
266 assert(ub >= bottom() &&
267 ub <= end(), "space invariant");
268 return ub;
269 } else {
270 return end();
271 }
272 }
273 void freed(HeapWord* start, size_t size) {
274 _bt.freed(start, size);
275 }
277 protected:
278 // reset the indexed free list to its initial empty condition.
279 void resetIndexedFreeListArray();
280 // reset to an initial state with a single free block described
281 // by the MemRegion parameter.
282 void reset(MemRegion mr);
283 // Return the total number of words in the indexed free lists.
284 size_t totalSizeInIndexedFreeLists() const;
286 public:
287 // Constructor...
288 CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr,
289 bool use_adaptive_freelists,
290 FreeBlockDictionary<FreeChunk>::DictionaryChoice);
291 // accessors
292 bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; }
293 FreeBlockDictionary<FreeChunk>* dictionary() const { return _dictionary; }
294 HeapWord* nearLargestChunk() const { return _nearLargestChunk; }
295 void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; }
297 // Set CMS global values
298 static void set_cms_values();
300 // Return the free chunk at the end of the space. If no such
301 // chunk exists, return NULL.
302 FreeChunk* find_chunk_at_end();
304 bool adaptive_freelists() const { return _adaptive_freelists; }
306 void set_collector(CMSCollector* collector) { _collector = collector; }
308 // Support for parallelization of rescan and marking
309 const size_t rescan_task_size() const { return _rescan_task_size; }
310 const size_t marking_task_size() const { return _marking_task_size; }
311 SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; }
312 void initialize_sequential_subtasks_for_rescan(int n_threads);
313 void initialize_sequential_subtasks_for_marking(int n_threads,
314 HeapWord* low = NULL);
316 // Space enquiries
317 size_t used() const;
318 size_t free() const;
319 size_t max_alloc_in_words() const;
320 // XXX: should have a less conservative used_region() than that of
321 // Space; we could consider keeping track of highest allocated
322 // address and correcting that at each sweep, as the sweeper
323 // goes through the entire allocated part of the generation. We
324 // could also use that information to keep the sweeper from
325 // sweeping more than is necessary. The allocator and sweeper will
326 // of course need to synchronize on this, since the sweeper will
327 // try to bump down the address and the allocator will try to bump it up.
328 // For now, however, we'll just use the default used_region()
329 // which overestimates the region by returning the entire
330 // committed region (this is safe, but inefficient).
332 // Returns a subregion of the space containing all the objects in
333 // the space.
334 MemRegion used_region() const {
335 return MemRegion(bottom(),
336 BlockOffsetArrayUseUnallocatedBlock ?
337 unallocated_block() : end());
338 }
340 bool is_in(const void* p) const {
341 return used_region().contains(p);
342 }
344 virtual bool is_free_block(const HeapWord* p) const;
346 // Resizing support
347 void set_end(HeapWord* value); // override
349 // mutual exclusion support
350 Mutex* freelistLock() const { return &_freelistLock; }
352 // Iteration support
353 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
354 void oop_iterate(ExtendedOopClosure* cl);
356 void object_iterate(ObjectClosure* blk);
357 // Apply the closure to each object in the space whose references
358 // point to objects in the heap. The usage of CompactibleFreeListSpace
359 // by the ConcurrentMarkSweepGeneration for concurrent GC's allows
360 // objects in the space with references to objects that are no longer
361 // valid. For example, an object may reference another object
362 // that has already been sweep up (collected). This method uses
363 // obj_is_alive() to determine whether it is safe to iterate of
364 // an object.
365 void safe_object_iterate(ObjectClosure* blk);
366 void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl);
368 // Requires that "mr" be entirely within the space.
369 // Apply "cl->do_object" to all objects that intersect with "mr".
370 // If the iteration encounters an unparseable portion of the region,
371 // terminate the iteration and return the address of the start of the
372 // subregion that isn't done. Return of "NULL" indicates that the
373 // interation completed.
374 virtual HeapWord*
375 object_iterate_careful_m(MemRegion mr,
376 ObjectClosureCareful* cl);
377 virtual HeapWord*
378 object_iterate_careful(ObjectClosureCareful* cl);
380 // Override: provides a DCTO_CL specific to this kind of space.
381 DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl,
382 CardTableModRefBS::PrecisionStyle precision,
383 HeapWord* boundary);
385 void blk_iterate(BlkClosure* cl);
386 void blk_iterate_careful(BlkClosureCareful* cl);
387 HeapWord* block_start_const(const void* p) const;
388 HeapWord* block_start_careful(const void* p) const;
389 size_t block_size(const HeapWord* p) const;
390 size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const;
391 bool block_is_obj(const HeapWord* p) const;
392 bool obj_is_alive(const HeapWord* p) const;
393 size_t block_size_nopar(const HeapWord* p) const;
394 bool block_is_obj_nopar(const HeapWord* p) const;
396 // iteration support for promotion
397 void save_marks();
398 bool no_allocs_since_save_marks();
400 // iteration support for sweeping
401 void save_sweep_limit() {
402 _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ?
403 unallocated_block() : end();
404 if (CMSTraceSweeper) {
405 gclog_or_tty->print_cr(">>>>> Saving sweep limit " PTR_FORMAT
406 " for space [" PTR_FORMAT "," PTR_FORMAT ") <<<<<<",
407 _sweep_limit, bottom(), end());
408 }
409 }
410 NOT_PRODUCT(
411 void clear_sweep_limit() { _sweep_limit = NULL; }
412 )
413 HeapWord* sweep_limit() { return _sweep_limit; }
415 // Apply "blk->do_oop" to the addresses of all reference fields in objects
416 // promoted into this generation since the most recent save_marks() call.
417 // Fields in objects allocated by applications of the closure
418 // *are* included in the iteration. Thus, when the iteration completes
419 // there should be no further such objects remaining.
420 #define CFLS_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
421 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk);
422 ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DECL)
423 #undef CFLS_OOP_SINCE_SAVE_MARKS_DECL
425 // Allocation support
426 HeapWord* allocate(size_t size);
427 HeapWord* par_allocate(size_t size);
429 oop promote(oop obj, size_t obj_size);
430 void gc_prologue();
431 void gc_epilogue();
433 // This call is used by a containing CMS generation / collector
434 // to inform the CFLS space that a sweep has been completed
435 // and that the space can do any related house-keeping functions.
436 void sweep_completed();
438 // For an object in this space, the mark-word's two
439 // LSB's having the value [11] indicates that it has been
440 // promoted since the most recent call to save_marks() on
441 // this generation and has not subsequently been iterated
442 // over (using oop_since_save_marks_iterate() above).
443 // This property holds only for single-threaded collections,
444 // and is typically used for Cheney scans; for MT scavenges,
445 // the property holds for all objects promoted during that
446 // scavenge for the duration of the scavenge and is used
447 // by card-scanning to avoid scanning objects (being) promoted
448 // during that scavenge.
449 bool obj_allocated_since_save_marks(const oop obj) const {
450 assert(is_in_reserved(obj), "Wrong space?");
451 return ((PromotedObject*)obj)->hasPromotedMark();
452 }
454 // A worst-case estimate of the space required (in HeapWords) to expand the
455 // heap when promoting an obj of size obj_size.
456 size_t expansionSpaceRequired(size_t obj_size) const;
458 FreeChunk* allocateScratch(size_t size);
460 // returns true if either the small or large linear allocation buffer is empty.
461 bool linearAllocationWouldFail() const;
463 // Adjust the chunk for the minimum size. This version is called in
464 // most cases in CompactibleFreeListSpace methods.
465 inline static size_t adjustObjectSize(size_t size) {
466 return (size_t) align_object_size(MAX2(size, (size_t)MinChunkSize));
467 }
468 // This is a virtual version of adjustObjectSize() that is called
469 // only occasionally when the compaction space changes and the type
470 // of the new compaction space is is only known to be CompactibleSpace.
471 size_t adjust_object_size_v(size_t size) const {
472 return adjustObjectSize(size);
473 }
474 // Minimum size of a free block.
475 virtual size_t minimum_free_block_size() const { return MinChunkSize; }
476 void removeFreeChunkFromFreeLists(FreeChunk* chunk);
477 void addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size,
478 bool coalesced);
480 // Support for decisions regarding concurrent collection policy
481 bool should_concurrent_collect() const;
483 // Support for compaction
484 void prepare_for_compaction(CompactPoint* cp);
485 void adjust_pointers();
486 void compact();
487 // reset the space to reflect the fact that a compaction of the
488 // space has been done.
489 virtual void reset_after_compaction();
491 // Debugging support
492 void print() const;
493 void print_on(outputStream* st) const;
494 void prepare_for_verify();
495 void verify() const;
496 void verifyFreeLists() const PRODUCT_RETURN;
497 void verifyIndexedFreeLists() const;
498 void verifyIndexedFreeList(size_t size) const;
499 // Verify that the given chunk is in the free lists:
500 // i.e. either the binary tree dictionary, the indexed free lists
501 // or the linear allocation block.
502 bool verify_chunk_in_free_list(FreeChunk* fc) const;
503 // Verify that the given chunk is the linear allocation block
504 bool verify_chunk_is_linear_alloc_block(FreeChunk* fc) const;
505 // Do some basic checks on the the free lists.
506 void check_free_list_consistency() const PRODUCT_RETURN;
508 // Printing support
509 void dump_at_safepoint_with_locks(CMSCollector* c, outputStream* st);
510 void print_indexed_free_lists(outputStream* st) const;
511 void print_dictionary_free_lists(outputStream* st) const;
512 void print_promo_info_blocks(outputStream* st) const;
514 NOT_PRODUCT (
515 void initializeIndexedFreeListArrayReturnedBytes();
516 size_t sumIndexedFreeListArrayReturnedBytes();
517 // Return the total number of chunks in the indexed free lists.
518 size_t totalCountInIndexedFreeLists() const;
519 // Return the total numberof chunks in the space.
520 size_t totalCount();
521 )
523 // The census consists of counts of the quantities such as
524 // the current count of the free chunks, number of chunks
525 // created as a result of the split of a larger chunk or
526 // coalescing of smaller chucks, etc. The counts in the
527 // census is used to make decisions on splitting and
528 // coalescing of chunks during the sweep of garbage.
530 // Print the statistics for the free lists.
531 void printFLCensus(size_t sweep_count) const;
533 // Statistics functions
534 // Initialize census for lists before the sweep.
535 void beginSweepFLCensus(float inter_sweep_current,
536 float inter_sweep_estimate,
537 float intra_sweep_estimate);
538 // Set the surplus for each of the free lists.
539 void setFLSurplus();
540 // Set the hint for each of the free lists.
541 void setFLHints();
542 // Clear the census for each of the free lists.
543 void clearFLCensus();
544 // Perform functions for the census after the end of the sweep.
545 void endSweepFLCensus(size_t sweep_count);
546 // Return true if the count of free chunks is greater
547 // than the desired number of free chunks.
548 bool coalOverPopulated(size_t size);
550 // Record (for each size):
551 //
552 // split-births = #chunks added due to splits in (prev-sweep-end,
553 // this-sweep-start)
554 // split-deaths = #chunks removed for splits in (prev-sweep-end,
555 // this-sweep-start)
556 // num-curr = #chunks at start of this sweep
557 // num-prev = #chunks at end of previous sweep
558 //
559 // The above are quantities that are measured. Now define:
560 //
561 // num-desired := num-prev + split-births - split-deaths - num-curr
562 //
563 // Roughly, num-prev + split-births is the supply,
564 // split-deaths is demand due to other sizes
565 // and num-curr is what we have left.
566 //
567 // Thus, num-desired is roughly speaking the "legitimate demand"
568 // for blocks of this size and what we are striving to reach at the
569 // end of the current sweep.
570 //
571 // For a given list, let num-len be its current population.
572 // Define, for a free list of a given size:
573 //
574 // coal-overpopulated := num-len >= num-desired * coal-surplus
575 // (coal-surplus is set to 1.05, i.e. we allow a little slop when
576 // coalescing -- we do not coalesce unless we think that the current
577 // supply has exceeded the estimated demand by more than 5%).
578 //
579 // For the set of sizes in the binary tree, which is neither dense nor
580 // closed, it may be the case that for a particular size we have never
581 // had, or do not now have, or did not have at the previous sweep,
582 // chunks of that size. We need to extend the definition of
583 // coal-overpopulated to such sizes as well:
584 //
585 // For a chunk in/not in the binary tree, extend coal-overpopulated
586 // defined above to include all sizes as follows:
587 //
588 // . a size that is non-existent is coal-overpopulated
589 // . a size that has a num-desired <= 0 as defined above is
590 // coal-overpopulated.
591 //
592 // Also define, for a chunk heap-offset C and mountain heap-offset M:
593 //
594 // close-to-mountain := C >= 0.99 * M
595 //
596 // Now, the coalescing strategy is:
597 //
598 // Coalesce left-hand chunk with right-hand chunk if and
599 // only if:
600 //
601 // EITHER
602 // . left-hand chunk is of a size that is coal-overpopulated
603 // OR
604 // . right-hand chunk is close-to-mountain
605 void smallCoalBirth(size_t size);
606 void smallCoalDeath(size_t size);
607 void coalBirth(size_t size);
608 void coalDeath(size_t size);
609 void smallSplitBirth(size_t size);
610 void smallSplitDeath(size_t size);
611 void split_birth(size_t size);
612 void splitDeath(size_t size);
613 void split(size_t from, size_t to1);
615 double flsFrag() const;
616 };
618 // A parallel-GC-thread-local allocation buffer for allocation into a
619 // CompactibleFreeListSpace.
620 class CFLS_LAB : public CHeapObj<mtGC> {
621 // The space that this buffer allocates into.
622 CompactibleFreeListSpace* _cfls;
624 // Our local free lists.
625 AdaptiveFreeList<FreeChunk> _indexedFreeList[CompactibleFreeListSpace::IndexSetSize];
627 // Initialized from a command-line arg.
629 // Allocation statistics in support of dynamic adjustment of
630 // #blocks to claim per get_from_global_pool() call below.
631 static AdaptiveWeightedAverage
632 _blocks_to_claim [CompactibleFreeListSpace::IndexSetSize];
633 static size_t _global_num_blocks [CompactibleFreeListSpace::IndexSetSize];
634 static uint _global_num_workers[CompactibleFreeListSpace::IndexSetSize];
635 size_t _num_blocks [CompactibleFreeListSpace::IndexSetSize];
637 // Internal work method
638 void get_from_global_pool(size_t word_sz, AdaptiveFreeList<FreeChunk>* fl);
640 public:
641 CFLS_LAB(CompactibleFreeListSpace* cfls);
643 // Allocate and return a block of the given size, or else return NULL.
644 HeapWord* alloc(size_t word_sz);
646 // Return any unused portions of the buffer to the global pool.
647 void retire(int tid);
649 // Dynamic OldPLABSize sizing
650 static void compute_desired_plab_size();
651 // When the settings are modified from default static initialization
652 static void modify_initialization(size_t n, unsigned wt);
653 };
655 size_t PromotionInfo::refillSize() const {
656 const size_t CMSSpoolBlockSize = 256;
657 const size_t sz = heap_word_size(sizeof(SpoolBlock) + sizeof(markOop)
658 * CMSSpoolBlockSize);
659 return CompactibleFreeListSpace::adjustObjectSize(sz);
660 }
662 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_COMPACTIBLEFREELISTSPACE_HPP