Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp @ 616:4f360ec815ba
6720309: G1: don't synchronously update RSet during evacuation pauses
6720334: G1: don't update RSets of collection set regions during an evacuation pause
Summary: Introduced a deferred update mechanism for delaying the rset updates during the collection pause
Reviewed-by: apetrusenko, tonyp
author | iveresov |
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date | Fri, 06 Mar 2009 13:50:14 -0800 |
parents | e9be0e04635a |
children | 0fbdb4381b99 |
rev | line source |
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0 | 1 /* |
196 | 2 * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved. |
0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 // Classes in support of keeping track of promotions into a non-Contiguous | |
26 // space, in this case a CompactibleFreeListSpace. | |
27 | |
28 #define CFLS_LAB_REFILL_STATS 0 | |
29 | |
30 // Forward declarations | |
31 class CompactibleFreeListSpace; | |
32 class BlkClosure; | |
33 class BlkClosureCareful; | |
34 class UpwardsObjectClosure; | |
35 class ObjectClosureCareful; | |
36 class Klass; | |
37 | |
38 class PromotedObject VALUE_OBJ_CLASS_SPEC { | |
39 private: | |
40 enum { | |
41 promoted_mask = right_n_bits(2), // i.e. 0x3 | |
42 displaced_mark = nth_bit(2), // i.e. 0x4 | |
43 next_mask = ~(right_n_bits(3)) // i.e. ~(0x7) | |
44 }; | |
45 intptr_t _next; | |
46 public: | |
47 inline PromotedObject* next() const { | |
48 return (PromotedObject*)(_next & next_mask); | |
49 } | |
50 inline void setNext(PromotedObject* x) { | |
51 assert(((intptr_t)x & ~next_mask) == 0, | |
52 "Conflict in bit usage, " | |
53 " or insufficient alignment of objects"); | |
54 _next |= (intptr_t)x; | |
55 } | |
56 inline void setPromotedMark() { | |
57 _next |= promoted_mask; | |
58 } | |
59 inline bool hasPromotedMark() const { | |
60 return (_next & promoted_mask) == promoted_mask; | |
61 } | |
62 inline void setDisplacedMark() { | |
63 _next |= displaced_mark; | |
64 } | |
65 inline bool hasDisplacedMark() const { | |
66 return (_next & displaced_mark) != 0; | |
67 } | |
68 inline void clearNext() { _next = 0; } | |
69 debug_only(void *next_addr() { return (void *) &_next; }) | |
70 }; | |
71 | |
72 class SpoolBlock: public FreeChunk { | |
73 friend class PromotionInfo; | |
74 protected: | |
75 SpoolBlock* nextSpoolBlock; | |
76 size_t bufferSize; // number of usable words in this block | |
77 markOop* displacedHdr; // the displaced headers start here | |
78 | |
79 // Note about bufferSize: it denotes the number of entries available plus 1; | |
80 // legal indices range from 1 through BufferSize - 1. See the verification | |
81 // code verify() that counts the number of displaced headers spooled. | |
82 size_t computeBufferSize() { | |
83 return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop); | |
84 } | |
85 | |
86 public: | |
87 void init() { | |
88 bufferSize = computeBufferSize(); | |
89 displacedHdr = (markOop*)&displacedHdr; | |
90 nextSpoolBlock = NULL; | |
91 } | |
92 }; | |
93 | |
94 class PromotionInfo VALUE_OBJ_CLASS_SPEC { | |
95 bool _tracking; // set if tracking | |
96 CompactibleFreeListSpace* _space; // the space to which this belongs | |
97 PromotedObject* _promoHead; // head of list of promoted objects | |
98 PromotedObject* _promoTail; // tail of list of promoted objects | |
99 SpoolBlock* _spoolHead; // first spooling block | |
100 SpoolBlock* _spoolTail; // last non-full spooling block or null | |
101 SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail | |
102 SpoolBlock* _spareSpool; // free spool buffer | |
103 size_t _firstIndex; // first active index in | |
104 // first spooling block (_spoolHead) | |
105 size_t _nextIndex; // last active index + 1 in last | |
106 // spooling block (_spoolTail) | |
107 private: | |
108 // ensure that spooling space exists; return true if there is spooling space | |
109 bool ensure_spooling_space_work(); | |
110 | |
111 public: | |
112 PromotionInfo() : | |
113 _tracking(0), _space(NULL), | |
114 _promoHead(NULL), _promoTail(NULL), | |
115 _spoolHead(NULL), _spoolTail(NULL), | |
116 _spareSpool(NULL), _firstIndex(1), | |
117 _nextIndex(1) {} | |
118 | |
119 bool noPromotions() const { | |
120 assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency"); | |
121 return _promoHead == NULL; | |
122 } | |
123 void startTrackingPromotions(); | |
124 void stopTrackingPromotions(); | |
125 bool tracking() const { return _tracking; } | |
126 void track(PromotedObject* trackOop); // keep track of a promoted oop | |
127 // The following variant must be used when trackOop is not fully | |
128 // initialized and has a NULL klass: | |
129 void track(PromotedObject* trackOop, klassOop klassOfOop); // keep track of a promoted oop | |
130 void setSpace(CompactibleFreeListSpace* sp) { _space = sp; } | |
131 CompactibleFreeListSpace* space() const { return _space; } | |
132 markOop nextDisplacedHeader(); // get next header & forward spool pointer | |
133 void saveDisplacedHeader(markOop hdr); | |
134 // save header and forward spool | |
135 | |
136 inline size_t refillSize() const; | |
137 | |
138 SpoolBlock* getSpoolBlock(); // return a free spooling block | |
139 inline bool has_spooling_space() { | |
140 return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex; | |
141 } | |
142 // ensure that spooling space exists | |
143 bool ensure_spooling_space() { | |
144 return has_spooling_space() || ensure_spooling_space_work(); | |
145 } | |
146 #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \ | |
147 void promoted_oops_iterate##nv_suffix(OopClosureType* cl); | |
148 ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL) | |
149 #undef PROMOTED_OOPS_ITERATE_DECL | |
150 void promoted_oops_iterate(OopsInGenClosure* cl) { | |
151 promoted_oops_iterate_v(cl); | |
152 } | |
153 void verify() const; | |
154 void reset() { | |
155 _promoHead = NULL; | |
156 _promoTail = NULL; | |
157 _spoolHead = NULL; | |
158 _spoolTail = NULL; | |
159 _spareSpool = NULL; | |
160 _firstIndex = 0; | |
161 _nextIndex = 0; | |
162 | |
163 } | |
164 }; | |
165 | |
166 class LinearAllocBlock VALUE_OBJ_CLASS_SPEC { | |
167 public: | |
168 LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0), | |
169 _allocation_size_limit(0) {} | |
170 void set(HeapWord* ptr, size_t word_size, size_t refill_size, | |
171 size_t allocation_size_limit) { | |
172 _ptr = ptr; | |
173 _word_size = word_size; | |
174 _refillSize = refill_size; | |
175 _allocation_size_limit = allocation_size_limit; | |
176 } | |
177 HeapWord* _ptr; | |
178 size_t _word_size; | |
179 size_t _refillSize; | |
180 size_t _allocation_size_limit; // largest size that will be allocated | |
181 }; | |
182 | |
183 // Concrete subclass of CompactibleSpace that implements | |
184 // a free list space, such as used in the concurrent mark sweep | |
185 // generation. | |
186 | |
187 class CompactibleFreeListSpace: public CompactibleSpace { | |
188 friend class VMStructs; | |
189 friend class ConcurrentMarkSweepGeneration; | |
190 friend class ASConcurrentMarkSweepGeneration; | |
191 friend class CMSCollector; | |
192 friend class CMSPermGenGen; | |
193 // Local alloc buffer for promotion into this space. | |
194 friend class CFLS_LAB; | |
195 | |
196 // "Size" of chunks of work (executed during parallel remark phases | |
197 // of CMS collection); this probably belongs in CMSCollector, although | |
198 // it's cached here because it's used in | |
199 // initialize_sequential_subtasks_for_rescan() which modifies | |
200 // par_seq_tasks which also lives in Space. XXX | |
201 const size_t _rescan_task_size; | |
202 const size_t _marking_task_size; | |
203 | |
204 // Yet another sequential tasks done structure. This supports | |
205 // CMS GC, where we have threads dynamically | |
206 // claiming sub-tasks from a larger parallel task. | |
207 SequentialSubTasksDone _conc_par_seq_tasks; | |
208 | |
209 BlockOffsetArrayNonContigSpace _bt; | |
210 | |
211 CMSCollector* _collector; | |
212 ConcurrentMarkSweepGeneration* _gen; | |
213 | |
214 // Data structures for free blocks (used during allocation/sweeping) | |
215 | |
216 // Allocation is done linearly from two different blocks depending on | |
217 // whether the request is small or large, in an effort to reduce | |
218 // fragmentation. We assume that any locking for allocation is done | |
219 // by the containing generation. Thus, none of the methods in this | |
220 // space are re-entrant. | |
221 enum SomeConstants { | |
222 SmallForLinearAlloc = 16, // size < this then use _sLAB | |
223 SmallForDictionary = 257, // size < this then use _indexedFreeList | |
224 IndexSetSize = SmallForDictionary, // keep this odd-sized | |
225 IndexSetStart = MinObjAlignment, | |
226 IndexSetStride = MinObjAlignment | |
227 }; | |
228 | |
229 private: | |
230 enum FitStrategyOptions { | |
231 FreeBlockStrategyNone = 0, | |
232 FreeBlockBestFitFirst | |
233 }; | |
234 | |
235 PromotionInfo _promoInfo; | |
236 | |
237 // helps to impose a global total order on freelistLock ranks; | |
238 // assumes that CFLSpace's are allocated in global total order | |
239 static int _lockRank; | |
240 | |
241 // a lock protecting the free lists and free blocks; | |
242 // mutable because of ubiquity of locking even for otherwise const methods | |
243 mutable Mutex _freelistLock; | |
244 // locking verifier convenience function | |
245 void assert_locked() const PRODUCT_RETURN; | |
246 | |
247 // Linear allocation blocks | |
248 LinearAllocBlock _smallLinearAllocBlock; | |
249 | |
250 FreeBlockDictionary::DictionaryChoice _dictionaryChoice; | |
251 FreeBlockDictionary* _dictionary; // ptr to dictionary for large size blocks | |
252 | |
253 FreeList _indexedFreeList[IndexSetSize]; | |
254 // indexed array for small size blocks | |
255 // allocation stategy | |
256 bool _fitStrategy; // Use best fit strategy. | |
257 bool _adaptive_freelists; // Use adaptive freelists | |
258 | |
259 // This is an address close to the largest free chunk in the heap. | |
260 // It is currently assumed to be at the end of the heap. Free | |
261 // chunks with addresses greater than nearLargestChunk are coalesced | |
262 // in an effort to maintain a large chunk at the end of the heap. | |
263 HeapWord* _nearLargestChunk; | |
264 | |
265 // Used to keep track of limit of sweep for the space | |
266 HeapWord* _sweep_limit; | |
267 | |
268 // Support for compacting cms | |
269 HeapWord* cross_threshold(HeapWord* start, HeapWord* end); | |
270 HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top); | |
271 | |
272 // Initialization helpers. | |
273 void initializeIndexedFreeListArray(); | |
274 | |
275 // Extra stuff to manage promotion parallelism. | |
276 | |
277 // a lock protecting the dictionary during par promotion allocation. | |
278 mutable Mutex _parDictionaryAllocLock; | |
279 Mutex* parDictionaryAllocLock() const { return &_parDictionaryAllocLock; } | |
280 | |
281 // Locks protecting the exact lists during par promotion allocation. | |
282 Mutex* _indexedFreeListParLocks[IndexSetSize]; | |
283 | |
284 #if CFLS_LAB_REFILL_STATS | |
285 // Some statistics. | |
286 jint _par_get_chunk_from_small; | |
287 jint _par_get_chunk_from_large; | |
288 #endif | |
289 | |
290 | |
291 // Attempt to obtain up to "n" blocks of the size "word_sz" (which is | |
292 // required to be smaller than "IndexSetSize".) If successful, | |
293 // adds them to "fl", which is required to be an empty free list. | |
294 // If the count of "fl" is negative, it's absolute value indicates a | |
295 // number of free chunks that had been previously "borrowed" from global | |
296 // list of size "word_sz", and must now be decremented. | |
297 void par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl); | |
298 | |
299 // Allocation helper functions | |
300 // Allocate using a strategy that takes from the indexed free lists | |
301 // first. This allocation strategy assumes a companion sweeping | |
302 // strategy that attempts to keep the needed number of chunks in each | |
303 // indexed free lists. | |
304 HeapWord* allocate_adaptive_freelists(size_t size); | |
305 // Allocate from the linear allocation buffers first. This allocation | |
306 // strategy assumes maximal coalescing can maintain chunks large enough | |
307 // to be used as linear allocation buffers. | |
308 HeapWord* allocate_non_adaptive_freelists(size_t size); | |
309 | |
310 // Gets a chunk from the linear allocation block (LinAB). If there | |
311 // is not enough space in the LinAB, refills it. | |
312 HeapWord* getChunkFromLinearAllocBlock(LinearAllocBlock* blk, size_t size); | |
313 HeapWord* getChunkFromSmallLinearAllocBlock(size_t size); | |
314 // Get a chunk from the space remaining in the linear allocation block. Do | |
315 // not attempt to refill if the space is not available, return NULL. Do the | |
316 // repairs on the linear allocation block as appropriate. | |
317 HeapWord* getChunkFromLinearAllocBlockRemainder(LinearAllocBlock* blk, size_t size); | |
318 inline HeapWord* getChunkFromSmallLinearAllocBlockRemainder(size_t size); | |
319 | |
320 // Helper function for getChunkFromIndexedFreeList. | |
321 // Replenish the indexed free list for this "size". Do not take from an | |
322 // underpopulated size. | |
323 FreeChunk* getChunkFromIndexedFreeListHelper(size_t size); | |
324 | |
325 // Get a chunk from the indexed free list. If the indexed free list | |
326 // does not have a free chunk, try to replenish the indexed free list | |
327 // then get the free chunk from the replenished indexed free list. | |
328 inline FreeChunk* getChunkFromIndexedFreeList(size_t size); | |
329 | |
330 // The returned chunk may be larger than requested (or null). | |
331 FreeChunk* getChunkFromDictionary(size_t size); | |
332 // The returned chunk is the exact size requested (or null). | |
333 FreeChunk* getChunkFromDictionaryExact(size_t size); | |
334 | |
335 // Find a chunk in the indexed free list that is the best | |
336 // fit for size "numWords". | |
337 FreeChunk* bestFitSmall(size_t numWords); | |
338 // For free list "fl" of chunks of size > numWords, | |
339 // remove a chunk, split off a chunk of size numWords | |
340 // and return it. The split off remainder is returned to | |
341 // the free lists. The old name for getFromListGreater | |
342 // was lookInListGreater. | |
343 FreeChunk* getFromListGreater(FreeList* fl, size_t numWords); | |
344 // Get a chunk in the indexed free list or dictionary, | |
345 // by considering a larger chunk and splitting it. | |
346 FreeChunk* getChunkFromGreater(size_t numWords); | |
347 // Verify that the given chunk is in the indexed free lists. | |
348 bool verifyChunkInIndexedFreeLists(FreeChunk* fc) const; | |
349 // Remove the specified chunk from the indexed free lists. | |
350 void removeChunkFromIndexedFreeList(FreeChunk* fc); | |
351 // Remove the specified chunk from the dictionary. | |
352 void removeChunkFromDictionary(FreeChunk* fc); | |
353 // Split a free chunk into a smaller free chunk of size "new_size". | |
354 // Return the smaller free chunk and return the remainder to the | |
355 // free lists. | |
356 FreeChunk* splitChunkAndReturnRemainder(FreeChunk* chunk, size_t new_size); | |
357 // Add a chunk to the free lists. | |
358 void addChunkToFreeLists(HeapWord* chunk, size_t size); | |
359 // Add a chunk to the free lists, preferring to suffix it | |
360 // to the last free chunk at end of space if possible, and | |
361 // updating the block census stats as well as block offset table. | |
362 // Take any locks as appropriate if we are multithreaded. | |
363 void addChunkToFreeListsAtEndRecordingStats(HeapWord* chunk, size_t size); | |
364 // Add a free chunk to the indexed free lists. | |
365 void returnChunkToFreeList(FreeChunk* chunk); | |
366 // Add a free chunk to the dictionary. | |
367 void returnChunkToDictionary(FreeChunk* chunk); | |
368 | |
369 // Functions for maintaining the linear allocation buffers (LinAB). | |
370 // Repairing a linear allocation block refers to operations | |
371 // performed on the remainder of a LinAB after an allocation | |
372 // has been made from it. | |
373 void repairLinearAllocationBlocks(); | |
374 void repairLinearAllocBlock(LinearAllocBlock* blk); | |
375 void refillLinearAllocBlock(LinearAllocBlock* blk); | |
376 void refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk); | |
377 void refillLinearAllocBlocksIfNeeded(); | |
378 | |
379 void verify_objects_initialized() const; | |
380 | |
381 // Statistics reporting helper functions | |
382 void reportFreeListStatistics() const; | |
383 void reportIndexedFreeListStatistics() const; | |
384 size_t maxChunkSizeInIndexedFreeLists() const; | |
385 size_t numFreeBlocksInIndexedFreeLists() const; | |
386 // Accessor | |
387 HeapWord* unallocated_block() const { | |
388 HeapWord* ub = _bt.unallocated_block(); | |
389 assert(ub >= bottom() && | |
390 ub <= end(), "space invariant"); | |
391 return ub; | |
392 } | |
393 void freed(HeapWord* start, size_t size) { | |
394 _bt.freed(start, size); | |
395 } | |
396 | |
397 protected: | |
398 // reset the indexed free list to its initial empty condition. | |
399 void resetIndexedFreeListArray(); | |
400 // reset to an initial state with a single free block described | |
401 // by the MemRegion parameter. | |
402 void reset(MemRegion mr); | |
403 // Return the total number of words in the indexed free lists. | |
404 size_t totalSizeInIndexedFreeLists() const; | |
405 | |
406 public: | |
407 // Constructor... | |
408 CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr, | |
409 bool use_adaptive_freelists, | |
410 FreeBlockDictionary::DictionaryChoice); | |
411 // accessors | |
412 bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; } | |
413 FreeBlockDictionary* dictionary() const { return _dictionary; } | |
414 HeapWord* nearLargestChunk() const { return _nearLargestChunk; } | |
415 void set_nearLargestChunk(HeapWord* v) { _nearLargestChunk = v; } | |
416 | |
417 // Return the free chunk at the end of the space. If no such | |
418 // chunk exists, return NULL. | |
419 FreeChunk* find_chunk_at_end(); | |
420 | |
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421 bool adaptive_freelists() const { return _adaptive_freelists; } |
0 | 422 |
423 void set_collector(CMSCollector* collector) { _collector = collector; } | |
424 | |
425 // Support for parallelization of rescan and marking | |
426 const size_t rescan_task_size() const { return _rescan_task_size; } | |
427 const size_t marking_task_size() const { return _marking_task_size; } | |
428 SequentialSubTasksDone* conc_par_seq_tasks() {return &_conc_par_seq_tasks; } | |
429 void initialize_sequential_subtasks_for_rescan(int n_threads); | |
430 void initialize_sequential_subtasks_for_marking(int n_threads, | |
431 HeapWord* low = NULL); | |
432 | |
433 #if CFLS_LAB_REFILL_STATS | |
434 void print_par_alloc_stats(); | |
435 #endif | |
436 | |
437 // Space enquiries | |
438 size_t used() const; | |
439 size_t free() const; | |
440 size_t max_alloc_in_words() const; | |
441 // XXX: should have a less conservative used_region() than that of | |
442 // Space; we could consider keeping track of highest allocated | |
443 // address and correcting that at each sweep, as the sweeper | |
444 // goes through the entire allocated part of the generation. We | |
445 // could also use that information to keep the sweeper from | |
446 // sweeping more than is necessary. The allocator and sweeper will | |
447 // of course need to synchronize on this, since the sweeper will | |
448 // try to bump down the address and the allocator will try to bump it up. | |
449 // For now, however, we'll just use the default used_region() | |
450 // which overestimates the region by returning the entire | |
451 // committed region (this is safe, but inefficient). | |
452 | |
453 // Returns a subregion of the space containing all the objects in | |
454 // the space. | |
455 MemRegion used_region() const { | |
456 return MemRegion(bottom(), | |
457 BlockOffsetArrayUseUnallocatedBlock ? | |
458 unallocated_block() : end()); | |
459 } | |
460 | |
461 // This is needed because the default implementation uses block_start() | |
462 // which can;t be used at certain times (for example phase 3 of mark-sweep). | |
463 // A better fix is to change the assertions in phase 3 of mark-sweep to | |
464 // use is_in_reserved(), but that is deferred since the is_in() assertions | |
465 // are buried through several layers of callers and are used elsewhere | |
466 // as well. | |
467 bool is_in(const void* p) const { | |
468 return used_region().contains(p); | |
469 } | |
470 | |
471 virtual bool is_free_block(const HeapWord* p) const; | |
472 | |
473 // Resizing support | |
474 void set_end(HeapWord* value); // override | |
475 | |
476 // mutual exclusion support | |
477 Mutex* freelistLock() const { return &_freelistLock; } | |
478 | |
479 // Iteration support | |
480 void oop_iterate(MemRegion mr, OopClosure* cl); | |
481 void oop_iterate(OopClosure* cl); | |
482 | |
483 void object_iterate(ObjectClosure* blk); | |
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484 // Apply the closure to each object in the space whose references |
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485 // point to objects in the heap. The usage of CompactibleFreeListSpace |
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486 // by the ConcurrentMarkSweepGeneration for concurrent GC's allows |
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487 // objects in the space with references to objects that are no longer |
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488 // valid. For example, an object may reference another object |
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489 // that has already been sweep up (collected). This method uses |
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490 // obj_is_alive() to determine whether it is safe to iterate of |
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491 // an object. |
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492 void safe_object_iterate(ObjectClosure* blk); |
0 | 493 void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl); |
494 | |
495 // Requires that "mr" be entirely within the space. | |
496 // Apply "cl->do_object" to all objects that intersect with "mr". | |
497 // If the iteration encounters an unparseable portion of the region, | |
498 // terminate the iteration and return the address of the start of the | |
499 // subregion that isn't done. Return of "NULL" indicates that the | |
500 // interation completed. | |
501 virtual HeapWord* | |
502 object_iterate_careful_m(MemRegion mr, | |
503 ObjectClosureCareful* cl); | |
504 virtual HeapWord* | |
505 object_iterate_careful(ObjectClosureCareful* cl); | |
506 | |
507 // Override: provides a DCTO_CL specific to this kind of space. | |
508 DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl, | |
509 CardTableModRefBS::PrecisionStyle precision, | |
510 HeapWord* boundary); | |
511 | |
512 void blk_iterate(BlkClosure* cl); | |
513 void blk_iterate_careful(BlkClosureCareful* cl); | |
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514 HeapWord* block_start_const(const void* p) const; |
0 | 515 HeapWord* block_start_careful(const void* p) const; |
516 size_t block_size(const HeapWord* p) const; | |
517 size_t block_size_no_stall(HeapWord* p, const CMSCollector* c) const; | |
518 bool block_is_obj(const HeapWord* p) const; | |
519 bool obj_is_alive(const HeapWord* p) const; | |
520 size_t block_size_nopar(const HeapWord* p) const; | |
521 bool block_is_obj_nopar(const HeapWord* p) const; | |
522 | |
523 // iteration support for promotion | |
524 void save_marks(); | |
525 bool no_allocs_since_save_marks(); | |
526 void object_iterate_since_last_GC(ObjectClosure* cl); | |
527 | |
528 // iteration support for sweeping | |
529 void save_sweep_limit() { | |
530 _sweep_limit = BlockOffsetArrayUseUnallocatedBlock ? | |
531 unallocated_block() : end(); | |
532 } | |
533 NOT_PRODUCT( | |
534 void clear_sweep_limit() { _sweep_limit = NULL; } | |
535 ) | |
536 HeapWord* sweep_limit() { return _sweep_limit; } | |
537 | |
538 // Apply "blk->do_oop" to the addresses of all reference fields in objects | |
539 // promoted into this generation since the most recent save_marks() call. | |
540 // Fields in objects allocated by applications of the closure | |
541 // *are* included in the iteration. Thus, when the iteration completes | |
542 // there should be no further such objects remaining. | |
543 #define CFLS_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
544 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk); | |
545 ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DECL) | |
546 #undef CFLS_OOP_SINCE_SAVE_MARKS_DECL | |
547 | |
548 // Allocation support | |
549 HeapWord* allocate(size_t size); | |
550 HeapWord* par_allocate(size_t size); | |
551 | |
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552 oop promote(oop obj, size_t obj_size); |
0 | 553 void gc_prologue(); |
554 void gc_epilogue(); | |
555 | |
556 // This call is used by a containing CMS generation / collector | |
557 // to inform the CFLS space that a sweep has been completed | |
558 // and that the space can do any related house-keeping functions. | |
559 void sweep_completed(); | |
560 | |
561 // For an object in this space, the mark-word's two | |
562 // LSB's having the value [11] indicates that it has been | |
563 // promoted since the most recent call to save_marks() on | |
564 // this generation and has not subsequently been iterated | |
565 // over (using oop_since_save_marks_iterate() above). | |
566 bool obj_allocated_since_save_marks(const oop obj) const { | |
567 assert(is_in_reserved(obj), "Wrong space?"); | |
568 return ((PromotedObject*)obj)->hasPromotedMark(); | |
569 } | |
570 | |
571 // A worst-case estimate of the space required (in HeapWords) to expand the | |
572 // heap when promoting an obj of size obj_size. | |
573 size_t expansionSpaceRequired(size_t obj_size) const; | |
574 | |
575 FreeChunk* allocateScratch(size_t size); | |
576 | |
577 // returns true if either the small or large linear allocation buffer is empty. | |
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578 bool linearAllocationWouldFail() const; |
0 | 579 |
580 // Adjust the chunk for the minimum size. This version is called in | |
581 // most cases in CompactibleFreeListSpace methods. | |
582 inline static size_t adjustObjectSize(size_t size) { | |
583 return (size_t) align_object_size(MAX2(size, (size_t)MinChunkSize)); | |
584 } | |
585 // This is a virtual version of adjustObjectSize() that is called | |
586 // only occasionally when the compaction space changes and the type | |
587 // of the new compaction space is is only known to be CompactibleSpace. | |
588 size_t adjust_object_size_v(size_t size) const { | |
589 return adjustObjectSize(size); | |
590 } | |
591 // Minimum size of a free block. | |
592 virtual size_t minimum_free_block_size() const { return MinChunkSize; } | |
593 void removeFreeChunkFromFreeLists(FreeChunk* chunk); | |
594 void addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size, | |
595 bool coalesced); | |
596 | |
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597 // Support for decisions regarding concurrent collection policy |
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598 bool should_concurrent_collect() const; |
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599 |
0 | 600 // Support for compaction |
601 void prepare_for_compaction(CompactPoint* cp); | |
602 void adjust_pointers(); | |
603 void compact(); | |
604 // reset the space to reflect the fact that a compaction of the | |
605 // space has been done. | |
606 virtual void reset_after_compaction(); | |
607 | |
608 // Debugging support | |
609 void print() const; | |
610 void prepare_for_verify(); | |
611 void verify(bool allow_dirty) const; | |
612 void verifyFreeLists() const PRODUCT_RETURN; | |
613 void verifyIndexedFreeLists() const; | |
614 void verifyIndexedFreeList(size_t size) const; | |
615 // verify that the given chunk is in the free lists. | |
616 bool verifyChunkInFreeLists(FreeChunk* fc) const; | |
617 // Do some basic checks on the the free lists. | |
618 void checkFreeListConsistency() const PRODUCT_RETURN; | |
619 | |
620 NOT_PRODUCT ( | |
621 void initializeIndexedFreeListArrayReturnedBytes(); | |
622 size_t sumIndexedFreeListArrayReturnedBytes(); | |
623 // Return the total number of chunks in the indexed free lists. | |
624 size_t totalCountInIndexedFreeLists() const; | |
625 // Return the total numberof chunks in the space. | |
626 size_t totalCount(); | |
627 ) | |
628 | |
629 // The census consists of counts of the quantities such as | |
630 // the current count of the free chunks, number of chunks | |
631 // created as a result of the split of a larger chunk or | |
632 // coalescing of smaller chucks, etc. The counts in the | |
633 // census is used to make decisions on splitting and | |
634 // coalescing of chunks during the sweep of garbage. | |
635 | |
636 // Print the statistics for the free lists. | |
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637 void printFLCensus(size_t sweep_count) const; |
0 | 638 |
639 // Statistics functions | |
640 // Initialize census for lists before the sweep. | |
641 void beginSweepFLCensus(float sweep_current, | |
642 float sweep_estimate); | |
643 // Set the surplus for each of the free lists. | |
644 void setFLSurplus(); | |
645 // Set the hint for each of the free lists. | |
646 void setFLHints(); | |
647 // Clear the census for each of the free lists. | |
648 void clearFLCensus(); | |
649 // Perform functions for the census after the end of the sweep. | |
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650 void endSweepFLCensus(size_t sweep_count); |
0 | 651 // Return true if the count of free chunks is greater |
652 // than the desired number of free chunks. | |
653 bool coalOverPopulated(size_t size); | |
654 | |
655 // Record (for each size): | |
656 // | |
657 // split-births = #chunks added due to splits in (prev-sweep-end, | |
658 // this-sweep-start) | |
659 // split-deaths = #chunks removed for splits in (prev-sweep-end, | |
660 // this-sweep-start) | |
661 // num-curr = #chunks at start of this sweep | |
662 // num-prev = #chunks at end of previous sweep | |
663 // | |
664 // The above are quantities that are measured. Now define: | |
665 // | |
666 // num-desired := num-prev + split-births - split-deaths - num-curr | |
667 // | |
668 // Roughly, num-prev + split-births is the supply, | |
669 // split-deaths is demand due to other sizes | |
670 // and num-curr is what we have left. | |
671 // | |
672 // Thus, num-desired is roughly speaking the "legitimate demand" | |
673 // for blocks of this size and what we are striving to reach at the | |
674 // end of the current sweep. | |
675 // | |
676 // For a given list, let num-len be its current population. | |
677 // Define, for a free list of a given size: | |
678 // | |
679 // coal-overpopulated := num-len >= num-desired * coal-surplus | |
680 // (coal-surplus is set to 1.05, i.e. we allow a little slop when | |
681 // coalescing -- we do not coalesce unless we think that the current | |
682 // supply has exceeded the estimated demand by more than 5%). | |
683 // | |
684 // For the set of sizes in the binary tree, which is neither dense nor | |
685 // closed, it may be the case that for a particular size we have never | |
686 // had, or do not now have, or did not have at the previous sweep, | |
687 // chunks of that size. We need to extend the definition of | |
688 // coal-overpopulated to such sizes as well: | |
689 // | |
690 // For a chunk in/not in the binary tree, extend coal-overpopulated | |
691 // defined above to include all sizes as follows: | |
692 // | |
693 // . a size that is non-existent is coal-overpopulated | |
694 // . a size that has a num-desired <= 0 as defined above is | |
695 // coal-overpopulated. | |
696 // | |
697 // Also define, for a chunk heap-offset C and mountain heap-offset M: | |
698 // | |
699 // close-to-mountain := C >= 0.99 * M | |
700 // | |
701 // Now, the coalescing strategy is: | |
702 // | |
703 // Coalesce left-hand chunk with right-hand chunk if and | |
704 // only if: | |
705 // | |
706 // EITHER | |
707 // . left-hand chunk is of a size that is coal-overpopulated | |
708 // OR | |
709 // . right-hand chunk is close-to-mountain | |
710 void smallCoalBirth(size_t size); | |
711 void smallCoalDeath(size_t size); | |
712 void coalBirth(size_t size); | |
713 void coalDeath(size_t size); | |
714 void smallSplitBirth(size_t size); | |
715 void smallSplitDeath(size_t size); | |
716 void splitBirth(size_t size); | |
717 void splitDeath(size_t size); | |
718 void split(size_t from, size_t to1); | |
719 | |
720 double flsFrag() const; | |
721 }; | |
722 | |
723 // A parallel-GC-thread-local allocation buffer for allocation into a | |
724 // CompactibleFreeListSpace. | |
725 class CFLS_LAB : public CHeapObj { | |
726 // The space that this buffer allocates into. | |
727 CompactibleFreeListSpace* _cfls; | |
728 | |
729 // Our local free lists. | |
730 FreeList _indexedFreeList[CompactibleFreeListSpace::IndexSetSize]; | |
731 | |
732 // Initialized from a command-line arg. | |
733 size_t _blocks_to_claim; | |
734 | |
735 #if CFLS_LAB_REFILL_STATS | |
736 // Some statistics. | |
737 int _refills; | |
738 int _blocksTaken; | |
739 static int _tot_refills; | |
740 static int _tot_blocksTaken; | |
741 static int _next_threshold; | |
742 #endif | |
743 | |
744 public: | |
745 CFLS_LAB(CompactibleFreeListSpace* cfls); | |
746 | |
747 // Allocate and return a block of the given size, or else return NULL. | |
748 HeapWord* alloc(size_t word_sz); | |
749 | |
750 // Return any unused portions of the buffer to the global pool. | |
751 void retire(); | |
752 }; | |
753 | |
754 size_t PromotionInfo::refillSize() const { | |
755 const size_t CMSSpoolBlockSize = 256; | |
756 const size_t sz = heap_word_size(sizeof(SpoolBlock) + sizeof(markOop) | |
757 * CMSSpoolBlockSize); | |
758 return CompactibleFreeListSpace::adjustObjectSize(sz); | |
759 } |