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annotate src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp @ 3901:aa67216400d3
7085404: JSR 292: VolatileCallSites should have push notification too
Reviewed-by: never, kvn
author | twisti |
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date | Fri, 02 Sep 2011 00:36:18 -0700 |
parents | 1e3493ac2d11 |
children | c08412904149 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "gc_implementation/concurrentMarkSweep/cmsLockVerifier.hpp" | |
27 #include "gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp" | |
28 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp" | |
29 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
30 #include "gc_implementation/shared/liveRange.hpp" | |
31 #include "gc_implementation/shared/spaceDecorator.hpp" | |
32 #include "gc_interface/collectedHeap.hpp" | |
33 #include "memory/allocation.inline.hpp" | |
34 #include "memory/blockOffsetTable.inline.hpp" | |
35 #include "memory/resourceArea.hpp" | |
36 #include "memory/universe.inline.hpp" | |
37 #include "oops/oop.inline.hpp" | |
38 #include "runtime/globals.hpp" | |
39 #include "runtime/handles.inline.hpp" | |
40 #include "runtime/init.hpp" | |
41 #include "runtime/java.hpp" | |
42 #include "runtime/vmThread.hpp" | |
43 #include "utilities/copy.hpp" | |
0 | 44 |
45 ///////////////////////////////////////////////////////////////////////// | |
46 //// CompactibleFreeListSpace | |
47 ///////////////////////////////////////////////////////////////////////// | |
48 | |
49 // highest ranked free list lock rank | |
50 int CompactibleFreeListSpace::_lockRank = Mutex::leaf + 3; | |
51 | |
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52 // Defaults are 0 so things will break badly if incorrectly initialized. |
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53 int CompactibleFreeListSpace::IndexSetStart = 0; |
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54 int CompactibleFreeListSpace::IndexSetStride = 0; |
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55 |
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56 size_t MinChunkSize = 0; |
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57 |
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58 void CompactibleFreeListSpace::set_cms_values() { |
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59 // Set CMS global values |
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60 assert(MinChunkSize == 0, "already set"); |
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61 #define numQuanta(x,y) ((x+y-1)/y) |
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62 MinChunkSize = numQuanta(sizeof(FreeChunk), MinObjAlignmentInBytes) * MinObjAlignment; |
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63 |
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64 assert(IndexSetStart == 0 && IndexSetStride == 0, "already set"); |
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65 IndexSetStart = MinObjAlignment; |
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66 IndexSetStride = MinObjAlignment; |
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67 } |
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68 |
0 | 69 // Constructor |
70 CompactibleFreeListSpace::CompactibleFreeListSpace(BlockOffsetSharedArray* bs, | |
71 MemRegion mr, bool use_adaptive_freelists, | |
72 FreeBlockDictionary::DictionaryChoice dictionaryChoice) : | |
73 _dictionaryChoice(dictionaryChoice), | |
74 _adaptive_freelists(use_adaptive_freelists), | |
75 _bt(bs, mr), | |
76 // free list locks are in the range of values taken by _lockRank | |
77 // This range currently is [_leaf+2, _leaf+3] | |
78 // Note: this requires that CFLspace c'tors | |
79 // are called serially in the order in which the locks are | |
80 // are acquired in the program text. This is true today. | |
81 _freelistLock(_lockRank--, "CompactibleFreeListSpace._lock", true), | |
82 _parDictionaryAllocLock(Mutex::leaf - 1, // == rank(ExpandHeap_lock) - 1 | |
83 "CompactibleFreeListSpace._dict_par_lock", true), | |
84 _rescan_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord * | |
85 CMSRescanMultiple), | |
86 _marking_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord * | |
87 CMSConcMarkMultiple), | |
88 _collector(NULL) | |
89 { | |
90 _bt.set_space(this); | |
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91 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle); |
0 | 92 // We have all of "mr", all of which we place in the dictionary |
93 // as one big chunk. We'll need to decide here which of several | |
94 // possible alternative dictionary implementations to use. For | |
95 // now the choice is easy, since we have only one working | |
96 // implementation, namely, the simple binary tree (splaying | |
97 // temporarily disabled). | |
98 switch (dictionaryChoice) { | |
99 case FreeBlockDictionary::dictionarySplayTree: | |
100 case FreeBlockDictionary::dictionarySkipList: | |
101 default: | |
102 warning("dictionaryChoice: selected option not understood; using" | |
103 " default BinaryTreeDictionary implementation instead."); | |
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104 case FreeBlockDictionary::dictionaryBinaryTree: |
0 | 105 _dictionary = new BinaryTreeDictionary(mr); |
106 break; | |
107 } | |
108 assert(_dictionary != NULL, "CMS dictionary initialization"); | |
109 // The indexed free lists are initially all empty and are lazily | |
110 // filled in on demand. Initialize the array elements to NULL. | |
111 initializeIndexedFreeListArray(); | |
112 | |
113 // Not using adaptive free lists assumes that allocation is first | |
114 // from the linAB's. Also a cms perm gen which can be compacted | |
115 // has to have the klass's klassKlass allocated at a lower | |
116 // address in the heap than the klass so that the klassKlass is | |
117 // moved to its new location before the klass is moved. | |
118 // Set the _refillSize for the linear allocation blocks | |
119 if (!use_adaptive_freelists) { | |
120 FreeChunk* fc = _dictionary->getChunk(mr.word_size()); | |
121 // The small linAB initially has all the space and will allocate | |
122 // a chunk of any size. | |
123 HeapWord* addr = (HeapWord*) fc; | |
124 _smallLinearAllocBlock.set(addr, fc->size() , | |
125 1024*SmallForLinearAlloc, fc->size()); | |
126 // Note that _unallocated_block is not updated here. | |
127 // Allocations from the linear allocation block should | |
128 // update it. | |
129 } else { | |
130 _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc, | |
131 SmallForLinearAlloc); | |
132 } | |
133 // CMSIndexedFreeListReplenish should be at least 1 | |
134 CMSIndexedFreeListReplenish = MAX2((uintx)1, CMSIndexedFreeListReplenish); | |
135 _promoInfo.setSpace(this); | |
136 if (UseCMSBestFit) { | |
137 _fitStrategy = FreeBlockBestFitFirst; | |
138 } else { | |
139 _fitStrategy = FreeBlockStrategyNone; | |
140 } | |
141 checkFreeListConsistency(); | |
142 | |
143 // Initialize locks for parallel case. | |
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144 |
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145 if (CollectedHeap::use_parallel_gc_threads()) { |
0 | 146 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
147 _indexedFreeListParLocks[i] = new Mutex(Mutex::leaf - 1, // == ExpandHeap_lock - 1 | |
148 "a freelist par lock", | |
149 true); | |
150 if (_indexedFreeListParLocks[i] == NULL) | |
151 vm_exit_during_initialization("Could not allocate a par lock"); | |
152 DEBUG_ONLY( | |
153 _indexedFreeList[i].set_protecting_lock(_indexedFreeListParLocks[i]); | |
154 ) | |
155 } | |
156 _dictionary->set_par_lock(&_parDictionaryAllocLock); | |
157 } | |
158 } | |
159 | |
160 // Like CompactibleSpace forward() but always calls cross_threshold() to | |
161 // update the block offset table. Removed initialize_threshold call because | |
162 // CFLS does not use a block offset array for contiguous spaces. | |
163 HeapWord* CompactibleFreeListSpace::forward(oop q, size_t size, | |
164 CompactPoint* cp, HeapWord* compact_top) { | |
165 // q is alive | |
166 // First check if we should switch compaction space | |
167 assert(this == cp->space, "'this' should be current compaction space."); | |
168 size_t compaction_max_size = pointer_delta(end(), compact_top); | |
169 assert(adjustObjectSize(size) == cp->space->adjust_object_size_v(size), | |
170 "virtual adjustObjectSize_v() method is not correct"); | |
171 size_t adjusted_size = adjustObjectSize(size); | |
172 assert(compaction_max_size >= MinChunkSize || compaction_max_size == 0, | |
173 "no small fragments allowed"); | |
174 assert(minimum_free_block_size() == MinChunkSize, | |
175 "for de-virtualized reference below"); | |
176 // Can't leave a nonzero size, residual fragment smaller than MinChunkSize | |
177 if (adjusted_size + MinChunkSize > compaction_max_size && | |
178 adjusted_size != compaction_max_size) { | |
179 do { | |
180 // switch to next compaction space | |
181 cp->space->set_compaction_top(compact_top); | |
182 cp->space = cp->space->next_compaction_space(); | |
183 if (cp->space == NULL) { | |
184 cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen); | |
185 assert(cp->gen != NULL, "compaction must succeed"); | |
186 cp->space = cp->gen->first_compaction_space(); | |
187 assert(cp->space != NULL, "generation must have a first compaction space"); | |
188 } | |
189 compact_top = cp->space->bottom(); | |
190 cp->space->set_compaction_top(compact_top); | |
191 // The correct adjusted_size may not be the same as that for this method | |
192 // (i.e., cp->space may no longer be "this" so adjust the size again. | |
193 // Use the virtual method which is not used above to save the virtual | |
194 // dispatch. | |
195 adjusted_size = cp->space->adjust_object_size_v(size); | |
196 compaction_max_size = pointer_delta(cp->space->end(), compact_top); | |
197 assert(cp->space->minimum_free_block_size() == 0, "just checking"); | |
198 } while (adjusted_size > compaction_max_size); | |
199 } | |
200 | |
201 // store the forwarding pointer into the mark word | |
202 if ((HeapWord*)q != compact_top) { | |
203 q->forward_to(oop(compact_top)); | |
204 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark"); | |
205 } else { | |
206 // if the object isn't moving we can just set the mark to the default | |
207 // mark and handle it specially later on. | |
208 q->init_mark(); | |
209 assert(q->forwardee() == NULL, "should be forwarded to NULL"); | |
210 } | |
211 | |
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212 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(q, adjusted_size)); |
0 | 213 compact_top += adjusted_size; |
214 | |
215 // we need to update the offset table so that the beginnings of objects can be | |
216 // found during scavenge. Note that we are updating the offset table based on | |
217 // where the object will be once the compaction phase finishes. | |
218 | |
219 // Always call cross_threshold(). A contiguous space can only call it when | |
220 // the compaction_top exceeds the current threshold but not for an | |
221 // non-contiguous space. | |
222 cp->threshold = | |
223 cp->space->cross_threshold(compact_top - adjusted_size, compact_top); | |
224 return compact_top; | |
225 } | |
226 | |
227 // A modified copy of OffsetTableContigSpace::cross_threshold() with _offsets -> _bt | |
228 // and use of single_block instead of alloc_block. The name here is not really | |
229 // appropriate - maybe a more general name could be invented for both the | |
230 // contiguous and noncontiguous spaces. | |
231 | |
232 HeapWord* CompactibleFreeListSpace::cross_threshold(HeapWord* start, HeapWord* the_end) { | |
233 _bt.single_block(start, the_end); | |
234 return end(); | |
235 } | |
236 | |
237 // Initialize them to NULL. | |
238 void CompactibleFreeListSpace::initializeIndexedFreeListArray() { | |
239 for (size_t i = 0; i < IndexSetSize; i++) { | |
240 // Note that on platforms where objects are double word aligned, | |
241 // the odd array elements are not used. It is convenient, however, | |
242 // to map directly from the object size to the array element. | |
243 _indexedFreeList[i].reset(IndexSetSize); | |
244 _indexedFreeList[i].set_size(i); | |
245 assert(_indexedFreeList[i].count() == 0, "reset check failed"); | |
246 assert(_indexedFreeList[i].head() == NULL, "reset check failed"); | |
247 assert(_indexedFreeList[i].tail() == NULL, "reset check failed"); | |
248 assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed"); | |
249 } | |
250 } | |
251 | |
252 void CompactibleFreeListSpace::resetIndexedFreeListArray() { | |
253 for (int i = 1; i < IndexSetSize; i++) { | |
254 assert(_indexedFreeList[i].size() == (size_t) i, | |
255 "Indexed free list sizes are incorrect"); | |
256 _indexedFreeList[i].reset(IndexSetSize); | |
257 assert(_indexedFreeList[i].count() == 0, "reset check failed"); | |
258 assert(_indexedFreeList[i].head() == NULL, "reset check failed"); | |
259 assert(_indexedFreeList[i].tail() == NULL, "reset check failed"); | |
260 assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed"); | |
261 } | |
262 } | |
263 | |
264 void CompactibleFreeListSpace::reset(MemRegion mr) { | |
265 resetIndexedFreeListArray(); | |
266 dictionary()->reset(); | |
267 if (BlockOffsetArrayUseUnallocatedBlock) { | |
268 assert(end() == mr.end(), "We are compacting to the bottom of CMS gen"); | |
269 // Everything's allocated until proven otherwise. | |
270 _bt.set_unallocated_block(end()); | |
271 } | |
272 if (!mr.is_empty()) { | |
273 assert(mr.word_size() >= MinChunkSize, "Chunk size is too small"); | |
274 _bt.single_block(mr.start(), mr.word_size()); | |
275 FreeChunk* fc = (FreeChunk*) mr.start(); | |
276 fc->setSize(mr.word_size()); | |
277 if (mr.word_size() >= IndexSetSize ) { | |
278 returnChunkToDictionary(fc); | |
279 } else { | |
280 _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); | |
281 _indexedFreeList[mr.word_size()].returnChunkAtHead(fc); | |
282 } | |
283 } | |
284 _promoInfo.reset(); | |
285 _smallLinearAllocBlock._ptr = NULL; | |
286 _smallLinearAllocBlock._word_size = 0; | |
287 } | |
288 | |
289 void CompactibleFreeListSpace::reset_after_compaction() { | |
290 // Reset the space to the new reality - one free chunk. | |
291 MemRegion mr(compaction_top(), end()); | |
292 reset(mr); | |
293 // Now refill the linear allocation block(s) if possible. | |
294 if (_adaptive_freelists) { | |
295 refillLinearAllocBlocksIfNeeded(); | |
296 } else { | |
297 // Place as much of mr in the linAB as we can get, | |
298 // provided it was big enough to go into the dictionary. | |
299 FreeChunk* fc = dictionary()->findLargestDict(); | |
300 if (fc != NULL) { | |
301 assert(fc->size() == mr.word_size(), | |
302 "Why was the chunk broken up?"); | |
303 removeChunkFromDictionary(fc); | |
304 HeapWord* addr = (HeapWord*) fc; | |
305 _smallLinearAllocBlock.set(addr, fc->size() , | |
306 1024*SmallForLinearAlloc, fc->size()); | |
307 // Note that _unallocated_block is not updated here. | |
308 } | |
309 } | |
310 } | |
311 | |
312 // Walks the entire dictionary, returning a coterminal | |
313 // chunk, if it exists. Use with caution since it involves | |
314 // a potentially complete walk of a potentially large tree. | |
315 FreeChunk* CompactibleFreeListSpace::find_chunk_at_end() { | |
316 | |
317 assert_lock_strong(&_freelistLock); | |
318 | |
319 return dictionary()->find_chunk_ends_at(end()); | |
320 } | |
321 | |
322 | |
323 #ifndef PRODUCT | |
324 void CompactibleFreeListSpace::initializeIndexedFreeListArrayReturnedBytes() { | |
325 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
326 _indexedFreeList[i].allocation_stats()->set_returnedBytes(0); | |
327 } | |
328 } | |
329 | |
330 size_t CompactibleFreeListSpace::sumIndexedFreeListArrayReturnedBytes() { | |
331 size_t sum = 0; | |
332 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
333 sum += _indexedFreeList[i].allocation_stats()->returnedBytes(); | |
334 } | |
335 return sum; | |
336 } | |
337 | |
338 size_t CompactibleFreeListSpace::totalCountInIndexedFreeLists() const { | |
339 size_t count = 0; | |
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340 for (int i = (int)MinChunkSize; i < IndexSetSize; i++) { |
0 | 341 debug_only( |
342 ssize_t total_list_count = 0; | |
343 for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; | |
344 fc = fc->next()) { | |
345 total_list_count++; | |
346 } | |
347 assert(total_list_count == _indexedFreeList[i].count(), | |
348 "Count in list is incorrect"); | |
349 ) | |
350 count += _indexedFreeList[i].count(); | |
351 } | |
352 return count; | |
353 } | |
354 | |
355 size_t CompactibleFreeListSpace::totalCount() { | |
356 size_t num = totalCountInIndexedFreeLists(); | |
357 num += dictionary()->totalCount(); | |
358 if (_smallLinearAllocBlock._word_size != 0) { | |
359 num++; | |
360 } | |
361 return num; | |
362 } | |
363 #endif | |
364 | |
365 bool CompactibleFreeListSpace::is_free_block(const HeapWord* p) const { | |
366 FreeChunk* fc = (FreeChunk*) p; | |
367 return fc->isFree(); | |
368 } | |
369 | |
370 size_t CompactibleFreeListSpace::used() const { | |
371 return capacity() - free(); | |
372 } | |
373 | |
374 size_t CompactibleFreeListSpace::free() const { | |
375 // "MT-safe, but not MT-precise"(TM), if you will: i.e. | |
376 // if you do this while the structures are in flux you | |
377 // may get an approximate answer only; for instance | |
378 // because there is concurrent allocation either | |
379 // directly by mutators or for promotion during a GC. | |
380 // It's "MT-safe", however, in the sense that you are guaranteed | |
381 // not to crash and burn, for instance, because of walking | |
382 // pointers that could disappear as you were walking them. | |
383 // The approximation is because the various components | |
384 // that are read below are not read atomically (and | |
385 // further the computation of totalSizeInIndexedFreeLists() | |
386 // is itself a non-atomic computation. The normal use of | |
387 // this is during a resize operation at the end of GC | |
388 // and at that time you are guaranteed to get the | |
389 // correct actual value. However, for instance, this is | |
390 // also read completely asynchronously by the "perf-sampler" | |
391 // that supports jvmstat, and you are apt to see the values | |
392 // flicker in such cases. | |
393 assert(_dictionary != NULL, "No _dictionary?"); | |
394 return (_dictionary->totalChunkSize(DEBUG_ONLY(freelistLock())) + | |
395 totalSizeInIndexedFreeLists() + | |
396 _smallLinearAllocBlock._word_size) * HeapWordSize; | |
397 } | |
398 | |
399 size_t CompactibleFreeListSpace::max_alloc_in_words() const { | |
400 assert(_dictionary != NULL, "No _dictionary?"); | |
401 assert_locked(); | |
402 size_t res = _dictionary->maxChunkSize(); | |
403 res = MAX2(res, MIN2(_smallLinearAllocBlock._word_size, | |
404 (size_t) SmallForLinearAlloc - 1)); | |
405 // XXX the following could potentially be pretty slow; | |
406 // should one, pesimally for the rare cases when res | |
407 // caclulated above is less than IndexSetSize, | |
408 // just return res calculated above? My reasoning was that | |
409 // those cases will be so rare that the extra time spent doesn't | |
410 // really matter.... | |
411 // Note: do not change the loop test i >= res + IndexSetStride | |
412 // to i > res below, because i is unsigned and res may be zero. | |
413 for (size_t i = IndexSetSize - 1; i >= res + IndexSetStride; | |
414 i -= IndexSetStride) { | |
415 if (_indexedFreeList[i].head() != NULL) { | |
416 assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList"); | |
417 return i; | |
418 } | |
419 } | |
420 return res; | |
421 } | |
422 | |
1716
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423 void LinearAllocBlock::print_on(outputStream* st) const { |
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424 st->print_cr(" LinearAllocBlock: ptr = " PTR_FORMAT ", word_size = " SIZE_FORMAT |
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425 ", refillsize = " SIZE_FORMAT ", allocation_size_limit = " SIZE_FORMAT, |
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426 _ptr, _word_size, _refillSize, _allocation_size_limit); |
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427 } |
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428 |
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429 void CompactibleFreeListSpace::print_on(outputStream* st) const { |
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430 st->print_cr("COMPACTIBLE FREELIST SPACE"); |
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431 st->print_cr(" Space:"); |
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432 Space::print_on(st); |
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433 |
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434 st->print_cr("promoInfo:"); |
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435 _promoInfo.print_on(st); |
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436 |
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437 st->print_cr("_smallLinearAllocBlock"); |
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438 _smallLinearAllocBlock.print_on(st); |
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439 |
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440 // dump_memory_block(_smallLinearAllocBlock->_ptr, 128); |
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441 |
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442 st->print_cr(" _fitStrategy = %s, _adaptive_freelists = %s", |
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443 _fitStrategy?"true":"false", _adaptive_freelists?"true":"false"); |
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444 } |
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445 |
1145
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446 void CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st) |
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447 const { |
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448 reportIndexedFreeListStatistics(); |
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449 gclog_or_tty->print_cr("Layout of Indexed Freelists"); |
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450 gclog_or_tty->print_cr("---------------------------"); |
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451 FreeList::print_labels_on(st, "size"); |
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452 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
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453 _indexedFreeList[i].print_on(gclog_or_tty); |
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454 for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; |
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455 fc = fc->next()) { |
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456 gclog_or_tty->print_cr("\t[" PTR_FORMAT "," PTR_FORMAT ") %s", |
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457 fc, (HeapWord*)fc + i, |
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458 fc->cantCoalesce() ? "\t CC" : ""); |
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459 } |
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460 } |
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461 } |
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462 |
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463 void CompactibleFreeListSpace::print_promo_info_blocks(outputStream* st) |
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464 const { |
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465 _promoInfo.print_on(st); |
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466 } |
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467 |
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468 void CompactibleFreeListSpace::print_dictionary_free_lists(outputStream* st) |
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469 const { |
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470 _dictionary->reportStatistics(); |
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471 st->print_cr("Layout of Freelists in Tree"); |
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472 st->print_cr("---------------------------"); |
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473 _dictionary->print_free_lists(st); |
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474 } |
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475 |
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476 class BlkPrintingClosure: public BlkClosure { |
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477 const CMSCollector* _collector; |
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478 const CompactibleFreeListSpace* _sp; |
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479 const CMSBitMap* _live_bit_map; |
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480 const bool _post_remark; |
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481 outputStream* _st; |
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482 public: |
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483 BlkPrintingClosure(const CMSCollector* collector, |
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484 const CompactibleFreeListSpace* sp, |
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485 const CMSBitMap* live_bit_map, |
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486 outputStream* st): |
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487 _collector(collector), |
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488 _sp(sp), |
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489 _live_bit_map(live_bit_map), |
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490 _post_remark(collector->abstract_state() > CMSCollector::FinalMarking), |
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491 _st(st) { } |
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492 size_t do_blk(HeapWord* addr); |
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493 }; |
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494 |
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495 size_t BlkPrintingClosure::do_blk(HeapWord* addr) { |
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496 size_t sz = _sp->block_size_no_stall(addr, _collector); |
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497 assert(sz != 0, "Should always be able to compute a size"); |
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498 if (_sp->block_is_obj(addr)) { |
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499 const bool dead = _post_remark && !_live_bit_map->isMarked(addr); |
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500 _st->print_cr(PTR_FORMAT ": %s object of size " SIZE_FORMAT "%s", |
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501 addr, |
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502 dead ? "dead" : "live", |
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503 sz, |
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504 (!dead && CMSPrintObjectsInDump) ? ":" : "."); |
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505 if (CMSPrintObjectsInDump && !dead) { |
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506 oop(addr)->print_on(_st); |
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507 _st->print_cr("--------------------------------------"); |
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508 } |
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509 } else { // free block |
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510 _st->print_cr(PTR_FORMAT ": free block of size " SIZE_FORMAT "%s", |
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511 addr, sz, CMSPrintChunksInDump ? ":" : "."); |
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512 if (CMSPrintChunksInDump) { |
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513 ((FreeChunk*)addr)->print_on(_st); |
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514 _st->print_cr("--------------------------------------"); |
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515 } |
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516 } |
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517 return sz; |
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518 } |
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519 |
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520 void CompactibleFreeListSpace::dump_at_safepoint_with_locks(CMSCollector* c, |
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521 outputStream* st) { |
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522 st->print_cr("\n========================="); |
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523 st->print_cr("Block layout in CMS Heap:"); |
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524 st->print_cr("========================="); |
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525 BlkPrintingClosure bpcl(c, this, c->markBitMap(), st); |
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526 blk_iterate(&bpcl); |
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527 |
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528 st->print_cr("\n======================================="); |
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529 st->print_cr("Order & Layout of Promotion Info Blocks"); |
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530 st->print_cr("======================================="); |
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531 print_promo_info_blocks(st); |
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532 |
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533 st->print_cr("\n==========================="); |
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534 st->print_cr("Order of Indexed Free Lists"); |
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535 st->print_cr("========================="); |
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536 print_indexed_free_lists(st); |
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537 |
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538 st->print_cr("\n================================="); |
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539 st->print_cr("Order of Free Lists in Dictionary"); |
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540 st->print_cr("================================="); |
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541 print_dictionary_free_lists(st); |
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542 } |
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543 |
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544 |
0 | 545 void CompactibleFreeListSpace::reportFreeListStatistics() const { |
546 assert_lock_strong(&_freelistLock); | |
547 assert(PrintFLSStatistics != 0, "Reporting error"); | |
548 _dictionary->reportStatistics(); | |
549 if (PrintFLSStatistics > 1) { | |
550 reportIndexedFreeListStatistics(); | |
551 size_t totalSize = totalSizeInIndexedFreeLists() + | |
552 _dictionary->totalChunkSize(DEBUG_ONLY(freelistLock())); | |
553 gclog_or_tty->print(" free=%ld frag=%1.4f\n", totalSize, flsFrag()); | |
554 } | |
555 } | |
556 | |
557 void CompactibleFreeListSpace::reportIndexedFreeListStatistics() const { | |
558 assert_lock_strong(&_freelistLock); | |
559 gclog_or_tty->print("Statistics for IndexedFreeLists:\n" | |
560 "--------------------------------\n"); | |
561 size_t totalSize = totalSizeInIndexedFreeLists(); | |
562 size_t freeBlocks = numFreeBlocksInIndexedFreeLists(); | |
563 gclog_or_tty->print("Total Free Space: %d\n", totalSize); | |
564 gclog_or_tty->print("Max Chunk Size: %d\n", maxChunkSizeInIndexedFreeLists()); | |
565 gclog_or_tty->print("Number of Blocks: %d\n", freeBlocks); | |
566 if (freeBlocks != 0) { | |
567 gclog_or_tty->print("Av. Block Size: %d\n", totalSize/freeBlocks); | |
568 } | |
569 } | |
570 | |
571 size_t CompactibleFreeListSpace::numFreeBlocksInIndexedFreeLists() const { | |
572 size_t res = 0; | |
573 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
574 debug_only( | |
575 ssize_t recount = 0; | |
576 for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; | |
577 fc = fc->next()) { | |
578 recount += 1; | |
579 } | |
580 assert(recount == _indexedFreeList[i].count(), | |
581 "Incorrect count in list"); | |
582 ) | |
583 res += _indexedFreeList[i].count(); | |
584 } | |
585 return res; | |
586 } | |
587 | |
588 size_t CompactibleFreeListSpace::maxChunkSizeInIndexedFreeLists() const { | |
589 for (size_t i = IndexSetSize - 1; i != 0; i -= IndexSetStride) { | |
590 if (_indexedFreeList[i].head() != NULL) { | |
591 assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList"); | |
592 return (size_t)i; | |
593 } | |
594 } | |
595 return 0; | |
596 } | |
597 | |
598 void CompactibleFreeListSpace::set_end(HeapWord* value) { | |
599 HeapWord* prevEnd = end(); | |
600 assert(prevEnd != value, "unnecessary set_end call"); | |
1716
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601 assert(prevEnd == NULL || !BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(), |
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602 "New end is below unallocated block"); |
0 | 603 _end = value; |
604 if (prevEnd != NULL) { | |
605 // Resize the underlying block offset table. | |
606 _bt.resize(pointer_delta(value, bottom())); | |
1145
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607 if (value <= prevEnd) { |
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608 assert(!BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(), |
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609 "New end is below unallocated block"); |
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610 } else { |
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611 // Now, take this new chunk and add it to the free blocks. |
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612 // Note that the BOT has not yet been updated for this block. |
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613 size_t newFcSize = pointer_delta(value, prevEnd); |
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614 // XXX This is REALLY UGLY and should be fixed up. XXX |
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615 if (!_adaptive_freelists && _smallLinearAllocBlock._ptr == NULL) { |
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616 // Mark the boundary of the new block in BOT |
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617 _bt.mark_block(prevEnd, value); |
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618 // put it all in the linAB |
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619 if (ParallelGCThreads == 0) { |
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620 _smallLinearAllocBlock._ptr = prevEnd; |
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621 _smallLinearAllocBlock._word_size = newFcSize; |
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622 repairLinearAllocBlock(&_smallLinearAllocBlock); |
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623 } else { // ParallelGCThreads > 0 |
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624 MutexLockerEx x(parDictionaryAllocLock(), |
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625 Mutex::_no_safepoint_check_flag); |
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626 _smallLinearAllocBlock._ptr = prevEnd; |
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627 _smallLinearAllocBlock._word_size = newFcSize; |
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628 repairLinearAllocBlock(&_smallLinearAllocBlock); |
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629 } |
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630 // Births of chunks put into a LinAB are not recorded. Births |
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631 // of chunks as they are allocated out of a LinAB are. |
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632 } else { |
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633 // Add the block to the free lists, if possible coalescing it |
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634 // with the last free block, and update the BOT and census data. |
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635 addChunkToFreeListsAtEndRecordingStats(prevEnd, newFcSize); |
0 | 636 } |
637 } | |
638 } | |
639 } | |
640 | |
641 class FreeListSpace_DCTOC : public Filtering_DCTOC { | |
642 CompactibleFreeListSpace* _cfls; | |
643 CMSCollector* _collector; | |
644 protected: | |
645 // Override. | |
646 #define walk_mem_region_with_cl_DECL(ClosureType) \ | |
647 virtual void walk_mem_region_with_cl(MemRegion mr, \ | |
648 HeapWord* bottom, HeapWord* top, \ | |
649 ClosureType* cl); \ | |
650 void walk_mem_region_with_cl_par(MemRegion mr, \ | |
651 HeapWord* bottom, HeapWord* top, \ | |
652 ClosureType* cl); \ | |
653 void walk_mem_region_with_cl_nopar(MemRegion mr, \ | |
654 HeapWord* bottom, HeapWord* top, \ | |
655 ClosureType* cl) | |
656 walk_mem_region_with_cl_DECL(OopClosure); | |
657 walk_mem_region_with_cl_DECL(FilteringClosure); | |
658 | |
659 public: | |
660 FreeListSpace_DCTOC(CompactibleFreeListSpace* sp, | |
661 CMSCollector* collector, | |
662 OopClosure* cl, | |
663 CardTableModRefBS::PrecisionStyle precision, | |
664 HeapWord* boundary) : | |
665 Filtering_DCTOC(sp, cl, precision, boundary), | |
666 _cfls(sp), _collector(collector) {} | |
667 }; | |
668 | |
669 // We de-virtualize the block-related calls below, since we know that our | |
670 // space is a CompactibleFreeListSpace. | |
671 #define FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \ | |
672 void FreeListSpace_DCTOC::walk_mem_region_with_cl(MemRegion mr, \ | |
673 HeapWord* bottom, \ | |
674 HeapWord* top, \ | |
675 ClosureType* cl) { \ | |
676 if (SharedHeap::heap()->n_par_threads() > 0) { \ | |
677 walk_mem_region_with_cl_par(mr, bottom, top, cl); \ | |
678 } else { \ | |
679 walk_mem_region_with_cl_nopar(mr, bottom, top, cl); \ | |
680 } \ | |
681 } \ | |
682 void FreeListSpace_DCTOC::walk_mem_region_with_cl_par(MemRegion mr, \ | |
683 HeapWord* bottom, \ | |
684 HeapWord* top, \ | |
685 ClosureType* cl) { \ | |
686 /* Skip parts that are before "mr", in case "block_start" sent us \ | |
687 back too far. */ \ | |
688 HeapWord* mr_start = mr.start(); \ | |
689 size_t bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom); \ | |
690 HeapWord* next = bottom + bot_size; \ | |
691 while (next < mr_start) { \ | |
692 bottom = next; \ | |
693 bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom); \ | |
694 next = bottom + bot_size; \ | |
695 } \ | |
696 \ | |
697 while (bottom < top) { \ | |
698 if (_cfls->CompactibleFreeListSpace::block_is_obj(bottom) && \ | |
699 !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks( \ | |
700 oop(bottom)) && \ | |
701 !_collector->CMSCollector::is_dead_obj(oop(bottom))) { \ | |
702 size_t word_sz = oop(bottom)->oop_iterate(cl, mr); \ | |
703 bottom += _cfls->adjustObjectSize(word_sz); \ | |
704 } else { \ | |
705 bottom += _cfls->CompactibleFreeListSpace::block_size(bottom); \ | |
706 } \ | |
707 } \ | |
708 } \ | |
709 void FreeListSpace_DCTOC::walk_mem_region_with_cl_nopar(MemRegion mr, \ | |
710 HeapWord* bottom, \ | |
711 HeapWord* top, \ | |
712 ClosureType* cl) { \ | |
713 /* Skip parts that are before "mr", in case "block_start" sent us \ | |
714 back too far. */ \ | |
715 HeapWord* mr_start = mr.start(); \ | |
716 size_t bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom); \ | |
717 HeapWord* next = bottom + bot_size; \ | |
718 while (next < mr_start) { \ | |
719 bottom = next; \ | |
720 bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom); \ | |
721 next = bottom + bot_size; \ | |
722 } \ | |
723 \ | |
724 while (bottom < top) { \ | |
725 if (_cfls->CompactibleFreeListSpace::block_is_obj_nopar(bottom) && \ | |
726 !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks( \ | |
727 oop(bottom)) && \ | |
728 !_collector->CMSCollector::is_dead_obj(oop(bottom))) { \ | |
729 size_t word_sz = oop(bottom)->oop_iterate(cl, mr); \ | |
730 bottom += _cfls->adjustObjectSize(word_sz); \ | |
731 } else { \ | |
732 bottom += _cfls->CompactibleFreeListSpace::block_size_nopar(bottom); \ | |
733 } \ | |
734 } \ | |
735 } | |
736 | |
737 // (There are only two of these, rather than N, because the split is due | |
738 // only to the introduction of the FilteringClosure, a local part of the | |
739 // impl of this abstraction.) | |
740 FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(OopClosure) | |
741 FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure) | |
742 | |
743 DirtyCardToOopClosure* | |
744 CompactibleFreeListSpace::new_dcto_cl(OopClosure* cl, | |
745 CardTableModRefBS::PrecisionStyle precision, | |
746 HeapWord* boundary) { | |
747 return new FreeListSpace_DCTOC(this, _collector, cl, precision, boundary); | |
748 } | |
749 | |
750 | |
751 // Note on locking for the space iteration functions: | |
752 // since the collector's iteration activities are concurrent with | |
753 // allocation activities by mutators, absent a suitable mutual exclusion | |
754 // mechanism the iterators may go awry. For instace a block being iterated | |
755 // may suddenly be allocated or divided up and part of it allocated and | |
756 // so on. | |
757 | |
758 // Apply the given closure to each block in the space. | |
759 void CompactibleFreeListSpace::blk_iterate_careful(BlkClosureCareful* cl) { | |
760 assert_lock_strong(freelistLock()); | |
761 HeapWord *cur, *limit; | |
762 for (cur = bottom(), limit = end(); cur < limit; | |
763 cur += cl->do_blk_careful(cur)); | |
764 } | |
765 | |
766 // Apply the given closure to each block in the space. | |
767 void CompactibleFreeListSpace::blk_iterate(BlkClosure* cl) { | |
768 assert_lock_strong(freelistLock()); | |
769 HeapWord *cur, *limit; | |
770 for (cur = bottom(), limit = end(); cur < limit; | |
771 cur += cl->do_blk(cur)); | |
772 } | |
773 | |
774 // Apply the given closure to each oop in the space. | |
775 void CompactibleFreeListSpace::oop_iterate(OopClosure* cl) { | |
776 assert_lock_strong(freelistLock()); | |
777 HeapWord *cur, *limit; | |
778 size_t curSize; | |
779 for (cur = bottom(), limit = end(); cur < limit; | |
780 cur += curSize) { | |
781 curSize = block_size(cur); | |
782 if (block_is_obj(cur)) { | |
783 oop(cur)->oop_iterate(cl); | |
784 } | |
785 } | |
786 } | |
787 | |
788 // Apply the given closure to each oop in the space \intersect memory region. | |
789 void CompactibleFreeListSpace::oop_iterate(MemRegion mr, OopClosure* cl) { | |
790 assert_lock_strong(freelistLock()); | |
791 if (is_empty()) { | |
792 return; | |
793 } | |
794 MemRegion cur = MemRegion(bottom(), end()); | |
795 mr = mr.intersection(cur); | |
796 if (mr.is_empty()) { | |
797 return; | |
798 } | |
799 if (mr.equals(cur)) { | |
800 oop_iterate(cl); | |
801 return; | |
802 } | |
803 assert(mr.end() <= end(), "just took an intersection above"); | |
804 HeapWord* obj_addr = block_start(mr.start()); | |
805 HeapWord* t = mr.end(); | |
806 | |
807 SpaceMemRegionOopsIterClosure smr_blk(cl, mr); | |
808 if (block_is_obj(obj_addr)) { | |
809 // Handle first object specially. | |
810 oop obj = oop(obj_addr); | |
811 obj_addr += adjustObjectSize(obj->oop_iterate(&smr_blk)); | |
812 } else { | |
813 FreeChunk* fc = (FreeChunk*)obj_addr; | |
814 obj_addr += fc->size(); | |
815 } | |
816 while (obj_addr < t) { | |
817 HeapWord* obj = obj_addr; | |
818 obj_addr += block_size(obj_addr); | |
819 // If "obj_addr" is not greater than top, then the | |
820 // entire object "obj" is within the region. | |
821 if (obj_addr <= t) { | |
822 if (block_is_obj(obj)) { | |
823 oop(obj)->oop_iterate(cl); | |
824 } | |
825 } else { | |
826 // "obj" extends beyond end of region | |
827 if (block_is_obj(obj)) { | |
828 oop(obj)->oop_iterate(&smr_blk); | |
829 } | |
830 break; | |
831 } | |
832 } | |
833 } | |
834 | |
835 // NOTE: In the following methods, in order to safely be able to | |
836 // apply the closure to an object, we need to be sure that the | |
837 // object has been initialized. We are guaranteed that an object | |
838 // is initialized if we are holding the Heap_lock with the | |
839 // world stopped. | |
840 void CompactibleFreeListSpace::verify_objects_initialized() const { | |
841 if (is_init_completed()) { | |
842 assert_locked_or_safepoint(Heap_lock); | |
843 if (Universe::is_fully_initialized()) { | |
844 guarantee(SafepointSynchronize::is_at_safepoint(), | |
845 "Required for objects to be initialized"); | |
846 } | |
847 } // else make a concession at vm start-up | |
848 } | |
849 | |
850 // Apply the given closure to each object in the space | |
851 void CompactibleFreeListSpace::object_iterate(ObjectClosure* blk) { | |
852 assert_lock_strong(freelistLock()); | |
853 NOT_PRODUCT(verify_objects_initialized()); | |
854 HeapWord *cur, *limit; | |
855 size_t curSize; | |
856 for (cur = bottom(), limit = end(); cur < limit; | |
857 cur += curSize) { | |
858 curSize = block_size(cur); | |
859 if (block_is_obj(cur)) { | |
860 blk->do_object(oop(cur)); | |
861 } | |
862 } | |
863 } | |
864 | |
517
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865 // Apply the given closure to each live object in the space |
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866 // The usage of CompactibleFreeListSpace |
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867 // by the ConcurrentMarkSweepGeneration for concurrent GC's allows |
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868 // objects in the space with references to objects that are no longer |
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869 // valid. For example, an object may reference another object |
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870 // that has already been sweep up (collected). This method uses |
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871 // obj_is_alive() to determine whether it is safe to apply the closure to |
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872 // an object. See obj_is_alive() for details on how liveness of an |
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873 // object is decided. |
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874 |
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875 void CompactibleFreeListSpace::safe_object_iterate(ObjectClosure* blk) { |
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876 assert_lock_strong(freelistLock()); |
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877 NOT_PRODUCT(verify_objects_initialized()); |
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878 HeapWord *cur, *limit; |
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879 size_t curSize; |
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880 for (cur = bottom(), limit = end(); cur < limit; |
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881 cur += curSize) { |
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882 curSize = block_size(cur); |
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883 if (block_is_obj(cur) && obj_is_alive(cur)) { |
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884 blk->do_object(oop(cur)); |
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885 } |
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886 } |
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887 } |
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888 |
0 | 889 void CompactibleFreeListSpace::object_iterate_mem(MemRegion mr, |
890 UpwardsObjectClosure* cl) { | |
1145
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891 assert_locked(freelistLock()); |
0 | 892 NOT_PRODUCT(verify_objects_initialized()); |
893 Space::object_iterate_mem(mr, cl); | |
894 } | |
895 | |
896 // Callers of this iterator beware: The closure application should | |
897 // be robust in the face of uninitialized objects and should (always) | |
898 // return a correct size so that the next addr + size below gives us a | |
899 // valid block boundary. [See for instance, | |
900 // ScanMarkedObjectsAgainCarefullyClosure::do_object_careful() | |
901 // in ConcurrentMarkSweepGeneration.cpp.] | |
902 HeapWord* | |
903 CompactibleFreeListSpace::object_iterate_careful(ObjectClosureCareful* cl) { | |
904 assert_lock_strong(freelistLock()); | |
905 HeapWord *addr, *last; | |
906 size_t size; | |
907 for (addr = bottom(), last = end(); | |
908 addr < last; addr += size) { | |
909 FreeChunk* fc = (FreeChunk*)addr; | |
910 if (fc->isFree()) { | |
911 // Since we hold the free list lock, which protects direct | |
912 // allocation in this generation by mutators, a free object | |
913 // will remain free throughout this iteration code. | |
914 size = fc->size(); | |
915 } else { | |
916 // Note that the object need not necessarily be initialized, | |
917 // because (for instance) the free list lock does NOT protect | |
918 // object initialization. The closure application below must | |
919 // therefore be correct in the face of uninitialized objects. | |
920 size = cl->do_object_careful(oop(addr)); | |
921 if (size == 0) { | |
922 // An unparsable object found. Signal early termination. | |
923 return addr; | |
924 } | |
925 } | |
926 } | |
927 return NULL; | |
928 } | |
929 | |
930 // Callers of this iterator beware: The closure application should | |
931 // be robust in the face of uninitialized objects and should (always) | |
932 // return a correct size so that the next addr + size below gives us a | |
933 // valid block boundary. [See for instance, | |
934 // ScanMarkedObjectsAgainCarefullyClosure::do_object_careful() | |
935 // in ConcurrentMarkSweepGeneration.cpp.] | |
936 HeapWord* | |
937 CompactibleFreeListSpace::object_iterate_careful_m(MemRegion mr, | |
938 ObjectClosureCareful* cl) { | |
939 assert_lock_strong(freelistLock()); | |
940 // Can't use used_region() below because it may not necessarily | |
941 // be the same as [bottom(),end()); although we could | |
942 // use [used_region().start(),round_to(used_region().end(),CardSize)), | |
943 // that appears too cumbersome, so we just do the simpler check | |
944 // in the assertion below. | |
945 assert(!mr.is_empty() && MemRegion(bottom(),end()).contains(mr), | |
946 "mr should be non-empty and within used space"); | |
947 HeapWord *addr, *end; | |
948 size_t size; | |
949 for (addr = block_start_careful(mr.start()), end = mr.end(); | |
950 addr < end; addr += size) { | |
951 FreeChunk* fc = (FreeChunk*)addr; | |
952 if (fc->isFree()) { | |
953 // Since we hold the free list lock, which protects direct | |
954 // allocation in this generation by mutators, a free object | |
955 // will remain free throughout this iteration code. | |
956 size = fc->size(); | |
957 } else { | |
958 // Note that the object need not necessarily be initialized, | |
959 // because (for instance) the free list lock does NOT protect | |
960 // object initialization. The closure application below must | |
961 // therefore be correct in the face of uninitialized objects. | |
962 size = cl->do_object_careful_m(oop(addr), mr); | |
963 if (size == 0) { | |
964 // An unparsable object found. Signal early termination. | |
965 return addr; | |
966 } | |
967 } | |
968 } | |
969 return NULL; | |
970 } | |
971 | |
972 | |
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973 HeapWord* CompactibleFreeListSpace::block_start_const(const void* p) const { |
0 | 974 NOT_PRODUCT(verify_objects_initialized()); |
975 return _bt.block_start(p); | |
976 } | |
977 | |
978 HeapWord* CompactibleFreeListSpace::block_start_careful(const void* p) const { | |
979 return _bt.block_start_careful(p); | |
980 } | |
981 | |
982 size_t CompactibleFreeListSpace::block_size(const HeapWord* p) const { | |
983 NOT_PRODUCT(verify_objects_initialized()); | |
984 // This must be volatile, or else there is a danger that the compiler | |
985 // will compile the code below into a sometimes-infinite loop, by keeping | |
986 // the value read the first time in a register. | |
987 while (true) { | |
988 // We must do this until we get a consistent view of the object. | |
187 | 989 if (FreeChunk::indicatesFreeChunk(p)) { |
990 volatile FreeChunk* fc = (volatile FreeChunk*)p; | |
991 size_t res = fc->size(); | |
992 // If the object is still a free chunk, return the size, else it | |
993 // has been allocated so try again. | |
994 if (FreeChunk::indicatesFreeChunk(p)) { | |
0 | 995 assert(res != 0, "Block size should not be 0"); |
996 return res; | |
997 } | |
187 | 998 } else { |
999 // must read from what 'p' points to in each loop. | |
1000 klassOop k = ((volatile oopDesc*)p)->klass_or_null(); | |
1001 if (k != NULL) { | |
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1002 assert(k->is_oop(true /* ignore mark word */), "Should be klass oop"); |
187 | 1003 oop o = (oop)p; |
1004 assert(o->is_parsable(), "Should be parsable"); | |
1005 assert(o->is_oop(true /* ignore mark word */), "Should be an oop."); | |
1006 size_t res = o->size_given_klass(k->klass_part()); | |
1007 res = adjustObjectSize(res); | |
1008 assert(res != 0, "Block size should not be 0"); | |
1009 return res; | |
1010 } | |
0 | 1011 } |
1012 } | |
1013 } | |
1014 | |
1015 // A variant of the above that uses the Printezis bits for | |
1016 // unparsable but allocated objects. This avoids any possible | |
1017 // stalls waiting for mutators to initialize objects, and is | |
1018 // thus potentially faster than the variant above. However, | |
1019 // this variant may return a zero size for a block that is | |
1020 // under mutation and for which a consistent size cannot be | |
1021 // inferred without stalling; see CMSCollector::block_size_if_printezis_bits(). | |
1022 size_t CompactibleFreeListSpace::block_size_no_stall(HeapWord* p, | |
1023 const CMSCollector* c) | |
1024 const { | |
1025 assert(MemRegion(bottom(), end()).contains(p), "p not in space"); | |
1026 // This must be volatile, or else there is a danger that the compiler | |
1027 // will compile the code below into a sometimes-infinite loop, by keeping | |
1028 // the value read the first time in a register. | |
1029 DEBUG_ONLY(uint loops = 0;) | |
1030 while (true) { | |
1031 // We must do this until we get a consistent view of the object. | |
187 | 1032 if (FreeChunk::indicatesFreeChunk(p)) { |
1033 volatile FreeChunk* fc = (volatile FreeChunk*)p; | |
1034 size_t res = fc->size(); | |
1035 if (FreeChunk::indicatesFreeChunk(p)) { | |
0 | 1036 assert(res != 0, "Block size should not be 0"); |
1037 assert(loops == 0, "Should be 0"); | |
1038 return res; | |
1039 } | |
1040 } else { | |
187 | 1041 // must read from what 'p' points to in each loop. |
1042 klassOop k = ((volatile oopDesc*)p)->klass_or_null(); | |
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1043 // We trust the size of any object that has a non-NULL |
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1044 // klass and (for those in the perm gen) is parsable |
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1045 // -- irrespective of its conc_safe-ty. |
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1046 if (k != NULL && ((oopDesc*)p)->is_parsable()) { |
187 | 1047 assert(k->is_oop(), "Should really be klass oop."); |
1048 oop o = (oop)p; | |
1049 assert(o->is_oop(), "Should be an oop"); | |
1050 size_t res = o->size_given_klass(k->klass_part()); | |
1051 res = adjustObjectSize(res); | |
1052 assert(res != 0, "Block size should not be 0"); | |
1053 return res; | |
1054 } else { | |
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1055 // May return 0 if P-bits not present. |
187 | 1056 return c->block_size_if_printezis_bits(p); |
1057 } | |
0 | 1058 } |
1059 assert(loops == 0, "Can loop at most once"); | |
1060 DEBUG_ONLY(loops++;) | |
1061 } | |
1062 } | |
1063 | |
1064 size_t CompactibleFreeListSpace::block_size_nopar(const HeapWord* p) const { | |
1065 NOT_PRODUCT(verify_objects_initialized()); | |
1066 assert(MemRegion(bottom(), end()).contains(p), "p not in space"); | |
1067 FreeChunk* fc = (FreeChunk*)p; | |
1068 if (fc->isFree()) { | |
1069 return fc->size(); | |
1070 } else { | |
1071 // Ignore mark word because this may be a recently promoted | |
1072 // object whose mark word is used to chain together grey | |
1073 // objects (the last one would have a null value). | |
1074 assert(oop(p)->is_oop(true), "Should be an oop"); | |
1075 return adjustObjectSize(oop(p)->size()); | |
1076 } | |
1077 } | |
1078 | |
1079 // This implementation assumes that the property of "being an object" is | |
1080 // stable. But being a free chunk may not be (because of parallel | |
1081 // promotion.) | |
1082 bool CompactibleFreeListSpace::block_is_obj(const HeapWord* p) const { | |
1083 FreeChunk* fc = (FreeChunk*)p; | |
1084 assert(is_in_reserved(p), "Should be in space"); | |
1085 // When doing a mark-sweep-compact of the CMS generation, this | |
1086 // assertion may fail because prepare_for_compaction() uses | |
1087 // space that is garbage to maintain information on ranges of | |
1088 // live objects so that these live ranges can be moved as a whole. | |
1089 // Comment out this assertion until that problem can be solved | |
1090 // (i.e., that the block start calculation may look at objects | |
1091 // at address below "p" in finding the object that contains "p" | |
1092 // and those objects (if garbage) may have been modified to hold | |
1093 // live range information. | |
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1094 // assert(CollectedHeap::use_parallel_gc_threads() || _bt.block_start(p) == p, |
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1095 // "Should be a block boundary"); |
187 | 1096 if (FreeChunk::indicatesFreeChunk(p)) return false; |
1097 klassOop k = oop(p)->klass_or_null(); | |
0 | 1098 if (k != NULL) { |
1099 // Ignore mark word because it may have been used to | |
1100 // chain together promoted objects (the last one | |
1101 // would have a null value). | |
1102 assert(oop(p)->is_oop(true), "Should be an oop"); | |
1103 return true; | |
1104 } else { | |
1105 return false; // Was not an object at the start of collection. | |
1106 } | |
1107 } | |
1108 | |
1109 // Check if the object is alive. This fact is checked either by consulting | |
1110 // the main marking bitmap in the sweeping phase or, if it's a permanent | |
1111 // generation and we're not in the sweeping phase, by checking the | |
1112 // perm_gen_verify_bit_map where we store the "deadness" information if | |
1113 // we did not sweep the perm gen in the most recent previous GC cycle. | |
1114 bool CompactibleFreeListSpace::obj_is_alive(const HeapWord* p) const { | |
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1115 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(), |
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1116 "Else races are possible"); |
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1117 assert(block_is_obj(p), "The address should point to an object"); |
0 | 1118 |
1119 // If we're sweeping, we use object liveness information from the main bit map | |
1120 // for both perm gen and old gen. | |
1121 // We don't need to lock the bitmap (live_map or dead_map below), because | |
1122 // EITHER we are in the middle of the sweeping phase, and the | |
1123 // main marking bit map (live_map below) is locked, | |
1124 // OR we're in other phases and perm_gen_verify_bit_map (dead_map below) | |
1125 // is stable, because it's mutated only in the sweeping phase. | |
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1126 // NOTE: This method is also used by jmap where, if class unloading is |
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1127 // off, the results can return "false" for legitimate perm objects, |
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1128 // when we are not in the midst of a sweeping phase, which can result |
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1129 // in jmap not reporting certain perm gen objects. This will be moot |
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1130 // if/when the perm gen goes away in the future. |
0 | 1131 if (_collector->abstract_state() == CMSCollector::Sweeping) { |
1132 CMSBitMap* live_map = _collector->markBitMap(); | |
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1133 return live_map->par_isMarked((HeapWord*) p); |
0 | 1134 } else { |
1135 // If we're not currently sweeping and we haven't swept the perm gen in | |
1136 // the previous concurrent cycle then we may have dead but unswept objects | |
1137 // in the perm gen. In this case, we use the "deadness" information | |
1138 // that we had saved in perm_gen_verify_bit_map at the last sweep. | |
1139 if (!CMSClassUnloadingEnabled && _collector->_permGen->reserved().contains(p)) { | |
1140 if (_collector->verifying()) { | |
1141 CMSBitMap* dead_map = _collector->perm_gen_verify_bit_map(); | |
1142 // Object is marked in the dead_map bitmap at the previous sweep | |
1143 // when we know that it's dead; if the bitmap is not allocated then | |
1144 // the object is alive. | |
1145 return (dead_map->sizeInBits() == 0) // bit_map has been allocated | |
1146 || !dead_map->par_isMarked((HeapWord*) p); | |
1147 } else { | |
1148 return false; // We can't say for sure if it's live, so we say that it's dead. | |
1149 } | |
1150 } | |
1151 } | |
1152 return true; | |
1153 } | |
1154 | |
1155 bool CompactibleFreeListSpace::block_is_obj_nopar(const HeapWord* p) const { | |
1156 FreeChunk* fc = (FreeChunk*)p; | |
1157 assert(is_in_reserved(p), "Should be in space"); | |
1158 assert(_bt.block_start(p) == p, "Should be a block boundary"); | |
1159 if (!fc->isFree()) { | |
1160 // Ignore mark word because it may have been used to | |
1161 // chain together promoted objects (the last one | |
1162 // would have a null value). | |
1163 assert(oop(p)->is_oop(true), "Should be an oop"); | |
1164 return true; | |
1165 } | |
1166 return false; | |
1167 } | |
1168 | |
1169 // "MT-safe but not guaranteed MT-precise" (TM); you may get an | |
1170 // approximate answer if you don't hold the freelistlock when you call this. | |
1171 size_t CompactibleFreeListSpace::totalSizeInIndexedFreeLists() const { | |
1172 size_t size = 0; | |
1173 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
1174 debug_only( | |
1175 // We may be calling here without the lock in which case we | |
1176 // won't do this modest sanity check. | |
1177 if (freelistLock()->owned_by_self()) { | |
1178 size_t total_list_size = 0; | |
1179 for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; | |
1180 fc = fc->next()) { | |
1181 total_list_size += i; | |
1182 } | |
1183 assert(total_list_size == i * _indexedFreeList[i].count(), | |
1184 "Count in list is incorrect"); | |
1185 } | |
1186 ) | |
1187 size += i * _indexedFreeList[i].count(); | |
1188 } | |
1189 return size; | |
1190 } | |
1191 | |
1192 HeapWord* CompactibleFreeListSpace::par_allocate(size_t size) { | |
1193 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
1194 return allocate(size); | |
1195 } | |
1196 | |
1197 HeapWord* | |
1198 CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlockRemainder(size_t size) { | |
1199 return getChunkFromLinearAllocBlockRemainder(&_smallLinearAllocBlock, size); | |
1200 } | |
1201 | |
1202 HeapWord* CompactibleFreeListSpace::allocate(size_t size) { | |
1203 assert_lock_strong(freelistLock()); | |
1204 HeapWord* res = NULL; | |
1205 assert(size == adjustObjectSize(size), | |
1206 "use adjustObjectSize() before calling into allocate()"); | |
1207 | |
1208 if (_adaptive_freelists) { | |
1209 res = allocate_adaptive_freelists(size); | |
1210 } else { // non-adaptive free lists | |
1211 res = allocate_non_adaptive_freelists(size); | |
1212 } | |
1213 | |
1214 if (res != NULL) { | |
1215 // check that res does lie in this space! | |
1216 assert(is_in_reserved(res), "Not in this space!"); | |
1217 assert(is_aligned((void*)res), "alignment check"); | |
1218 | |
1219 FreeChunk* fc = (FreeChunk*)res; | |
1220 fc->markNotFree(); | |
1221 assert(!fc->isFree(), "shouldn't be marked free"); | |
187 | 1222 assert(oop(fc)->klass_or_null() == NULL, "should look uninitialized"); |
0 | 1223 // Verify that the block offset table shows this to |
1224 // be a single block, but not one which is unallocated. | |
1225 _bt.verify_single_block(res, size); | |
1226 _bt.verify_not_unallocated(res, size); | |
1227 // mangle a just allocated object with a distinct pattern. | |
1228 debug_only(fc->mangleAllocated(size)); | |
1229 } | |
1230 | |
1231 return res; | |
1232 } | |
1233 | |
1234 HeapWord* CompactibleFreeListSpace::allocate_non_adaptive_freelists(size_t size) { | |
1235 HeapWord* res = NULL; | |
1236 // try and use linear allocation for smaller blocks | |
1237 if (size < _smallLinearAllocBlock._allocation_size_limit) { | |
1238 // if successful, the following also adjusts block offset table | |
1239 res = getChunkFromSmallLinearAllocBlock(size); | |
1240 } | |
1241 // Else triage to indexed lists for smaller sizes | |
1242 if (res == NULL) { | |
1243 if (size < SmallForDictionary) { | |
1244 res = (HeapWord*) getChunkFromIndexedFreeList(size); | |
1245 } else { | |
1246 // else get it from the big dictionary; if even this doesn't | |
1247 // work we are out of luck. | |
1248 res = (HeapWord*)getChunkFromDictionaryExact(size); | |
1249 } | |
1250 } | |
1251 | |
1252 return res; | |
1253 } | |
1254 | |
1255 HeapWord* CompactibleFreeListSpace::allocate_adaptive_freelists(size_t size) { | |
1256 assert_lock_strong(freelistLock()); | |
1257 HeapWord* res = NULL; | |
1258 assert(size == adjustObjectSize(size), | |
1259 "use adjustObjectSize() before calling into allocate()"); | |
1260 | |
1261 // Strategy | |
1262 // if small | |
1263 // exact size from small object indexed list if small | |
1264 // small or large linear allocation block (linAB) as appropriate | |
1265 // take from lists of greater sized chunks | |
1266 // else | |
1267 // dictionary | |
1268 // small or large linear allocation block if it has the space | |
1269 // Try allocating exact size from indexTable first | |
1270 if (size < IndexSetSize) { | |
1271 res = (HeapWord*) getChunkFromIndexedFreeList(size); | |
1272 if(res != NULL) { | |
1273 assert(res != (HeapWord*)_indexedFreeList[size].head(), | |
1274 "Not removed from free list"); | |
1275 // no block offset table adjustment is necessary on blocks in | |
1276 // the indexed lists. | |
1277 | |
1278 // Try allocating from the small LinAB | |
1279 } else if (size < _smallLinearAllocBlock._allocation_size_limit && | |
1280 (res = getChunkFromSmallLinearAllocBlock(size)) != NULL) { | |
1281 // if successful, the above also adjusts block offset table | |
1282 // Note that this call will refill the LinAB to | |
1283 // satisfy the request. This is different that | |
1284 // evm. | |
1285 // Don't record chunk off a LinAB? smallSplitBirth(size); | |
1286 } else { | |
1287 // Raid the exact free lists larger than size, even if they are not | |
1288 // overpopulated. | |
1289 res = (HeapWord*) getChunkFromGreater(size); | |
1290 } | |
1291 } else { | |
1292 // Big objects get allocated directly from the dictionary. | |
1293 res = (HeapWord*) getChunkFromDictionaryExact(size); | |
1294 if (res == NULL) { | |
1295 // Try hard not to fail since an allocation failure will likely | |
1296 // trigger a synchronous GC. Try to get the space from the | |
1297 // allocation blocks. | |
1298 res = getChunkFromSmallLinearAllocBlockRemainder(size); | |
1299 } | |
1300 } | |
1301 | |
1302 return res; | |
1303 } | |
1304 | |
1305 // A worst-case estimate of the space required (in HeapWords) to expand the heap | |
1306 // when promoting obj. | |
1307 size_t CompactibleFreeListSpace::expansionSpaceRequired(size_t obj_size) const { | |
1308 // Depending on the object size, expansion may require refilling either a | |
1309 // bigLAB or a smallLAB plus refilling a PromotionInfo object. MinChunkSize | |
1310 // is added because the dictionary may over-allocate to avoid fragmentation. | |
1311 size_t space = obj_size; | |
1312 if (!_adaptive_freelists) { | |
1313 space = MAX2(space, _smallLinearAllocBlock._refillSize); | |
1314 } | |
1315 space += _promoInfo.refillSize() + 2 * MinChunkSize; | |
1316 return space; | |
1317 } | |
1318 | |
1319 FreeChunk* CompactibleFreeListSpace::getChunkFromGreater(size_t numWords) { | |
1320 FreeChunk* ret; | |
1321 | |
1322 assert(numWords >= MinChunkSize, "Size is less than minimum"); | |
1323 assert(linearAllocationWouldFail() || bestFitFirst(), | |
1324 "Should not be here"); | |
1325 | |
1326 size_t i; | |
1327 size_t currSize = numWords + MinChunkSize; | |
1328 assert(currSize % MinObjAlignment == 0, "currSize should be aligned"); | |
1329 for (i = currSize; i < IndexSetSize; i += IndexSetStride) { | |
1330 FreeList* fl = &_indexedFreeList[i]; | |
1331 if (fl->head()) { | |
1332 ret = getFromListGreater(fl, numWords); | |
1333 assert(ret == NULL || ret->isFree(), "Should be returning a free chunk"); | |
1334 return ret; | |
1335 } | |
1336 } | |
1337 | |
1338 currSize = MAX2((size_t)SmallForDictionary, | |
1339 (size_t)(numWords + MinChunkSize)); | |
1340 | |
1341 /* Try to get a chunk that satisfies request, while avoiding | |
1342 fragmentation that can't be handled. */ | |
1343 { | |
1344 ret = dictionary()->getChunk(currSize); | |
1345 if (ret != NULL) { | |
1346 assert(ret->size() - numWords >= MinChunkSize, | |
1347 "Chunk is too small"); | |
1348 _bt.allocated((HeapWord*)ret, ret->size()); | |
1349 /* Carve returned chunk. */ | |
1350 (void) splitChunkAndReturnRemainder(ret, numWords); | |
1351 /* Label this as no longer a free chunk. */ | |
1352 assert(ret->isFree(), "This chunk should be free"); | |
1353 ret->linkPrev(NULL); | |
1354 } | |
1355 assert(ret == NULL || ret->isFree(), "Should be returning a free chunk"); | |
1356 return ret; | |
1357 } | |
1358 ShouldNotReachHere(); | |
1359 } | |
1360 | |
1361 bool CompactibleFreeListSpace::verifyChunkInIndexedFreeLists(FreeChunk* fc) | |
1362 const { | |
1363 assert(fc->size() < IndexSetSize, "Size of chunk is too large"); | |
1364 return _indexedFreeList[fc->size()].verifyChunkInFreeLists(fc); | |
1365 } | |
1366 | |
1367 bool CompactibleFreeListSpace::verifyChunkInFreeLists(FreeChunk* fc) const { | |
1368 if (fc->size() >= IndexSetSize) { | |
1369 return dictionary()->verifyChunkInFreeLists(fc); | |
1370 } else { | |
1371 return verifyChunkInIndexedFreeLists(fc); | |
1372 } | |
1373 } | |
1374 | |
1375 #ifndef PRODUCT | |
1376 void CompactibleFreeListSpace::assert_locked() const { | |
1377 CMSLockVerifier::assert_locked(freelistLock(), parDictionaryAllocLock()); | |
1378 } | |
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1379 |
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1380 void CompactibleFreeListSpace::assert_locked(const Mutex* lock) const { |
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1381 CMSLockVerifier::assert_locked(lock); |
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1382 } |
0 | 1383 #endif |
1384 | |
1385 FreeChunk* CompactibleFreeListSpace::allocateScratch(size_t size) { | |
1386 // In the parallel case, the main thread holds the free list lock | |
1387 // on behalf the parallel threads. | |
1388 FreeChunk* fc; | |
1389 { | |
1390 // If GC is parallel, this might be called by several threads. | |
1391 // This should be rare enough that the locking overhead won't affect | |
1392 // the sequential code. | |
1393 MutexLockerEx x(parDictionaryAllocLock(), | |
1394 Mutex::_no_safepoint_check_flag); | |
1395 fc = getChunkFromDictionary(size); | |
1396 } | |
1397 if (fc != NULL) { | |
1398 fc->dontCoalesce(); | |
1399 assert(fc->isFree(), "Should be free, but not coalescable"); | |
1400 // Verify that the block offset table shows this to | |
1401 // be a single block, but not one which is unallocated. | |
1402 _bt.verify_single_block((HeapWord*)fc, fc->size()); | |
1403 _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); | |
1404 } | |
1405 return fc; | |
1406 } | |
1407 | |
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1408 oop CompactibleFreeListSpace::promote(oop obj, size_t obj_size) { |
0 | 1409 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
1410 assert_locked(); | |
1411 | |
1412 // if we are tracking promotions, then first ensure space for | |
1413 // promotion (including spooling space for saving header if necessary). | |
1414 // then allocate and copy, then track promoted info if needed. | |
1415 // When tracking (see PromotionInfo::track()), the mark word may | |
1416 // be displaced and in this case restoration of the mark word | |
1417 // occurs in the (oop_since_save_marks_)iterate phase. | |
1418 if (_promoInfo.tracking() && !_promoInfo.ensure_spooling_space()) { | |
1419 return NULL; | |
1420 } | |
1421 // Call the allocate(size_t, bool) form directly to avoid the | |
1422 // additional call through the allocate(size_t) form. Having | |
1423 // the compile inline the call is problematic because allocate(size_t) | |
1424 // is a virtual method. | |
1425 HeapWord* res = allocate(adjustObjectSize(obj_size)); | |
1426 if (res != NULL) { | |
1427 Copy::aligned_disjoint_words((HeapWord*)obj, res, obj_size); | |
1428 // if we should be tracking promotions, do so. | |
1429 if (_promoInfo.tracking()) { | |
1430 _promoInfo.track((PromotedObject*)res); | |
1431 } | |
1432 } | |
1433 return oop(res); | |
1434 } | |
1435 | |
1436 HeapWord* | |
1437 CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlock(size_t size) { | |
1438 assert_locked(); | |
1439 assert(size >= MinChunkSize, "minimum chunk size"); | |
1440 assert(size < _smallLinearAllocBlock._allocation_size_limit, | |
1441 "maximum from smallLinearAllocBlock"); | |
1442 return getChunkFromLinearAllocBlock(&_smallLinearAllocBlock, size); | |
1443 } | |
1444 | |
1445 HeapWord* | |
1446 CompactibleFreeListSpace::getChunkFromLinearAllocBlock(LinearAllocBlock *blk, | |
1447 size_t size) { | |
1448 assert_locked(); | |
1449 assert(size >= MinChunkSize, "too small"); | |
1450 HeapWord* res = NULL; | |
1451 // Try to do linear allocation from blk, making sure that | |
1452 if (blk->_word_size == 0) { | |
1453 // We have probably been unable to fill this either in the prologue or | |
1454 // when it was exhausted at the last linear allocation. Bail out until | |
1455 // next time. | |
1456 assert(blk->_ptr == NULL, "consistency check"); | |
1457 return NULL; | |
1458 } | |
1459 assert(blk->_word_size != 0 && blk->_ptr != NULL, "consistency check"); | |
1460 res = getChunkFromLinearAllocBlockRemainder(blk, size); | |
1461 if (res != NULL) return res; | |
1462 | |
1463 // about to exhaust this linear allocation block | |
1464 if (blk->_word_size == size) { // exactly satisfied | |
1465 res = blk->_ptr; | |
1466 _bt.allocated(res, blk->_word_size); | |
1467 } else if (size + MinChunkSize <= blk->_refillSize) { | |
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1468 size_t sz = blk->_word_size; |
0 | 1469 // Update _unallocated_block if the size is such that chunk would be |
1470 // returned to the indexed free list. All other chunks in the indexed | |
1471 // free lists are allocated from the dictionary so that _unallocated_block | |
1472 // has already been adjusted for them. Do it here so that the cost | |
1473 // for all chunks added back to the indexed free lists. | |
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1474 if (sz < SmallForDictionary) { |
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1475 _bt.allocated(blk->_ptr, sz); |
0 | 1476 } |
1477 // Return the chunk that isn't big enough, and then refill below. | |
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1478 addChunkToFreeLists(blk->_ptr, sz); |
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1479 splitBirth(sz); |
0 | 1480 // Don't keep statistics on adding back chunk from a LinAB. |
1481 } else { | |
1482 // A refilled block would not satisfy the request. | |
1483 return NULL; | |
1484 } | |
1485 | |
1486 blk->_ptr = NULL; blk->_word_size = 0; | |
1487 refillLinearAllocBlock(blk); | |
1488 assert(blk->_ptr == NULL || blk->_word_size >= size + MinChunkSize, | |
1489 "block was replenished"); | |
1490 if (res != NULL) { | |
1491 splitBirth(size); | |
1492 repairLinearAllocBlock(blk); | |
1493 } else if (blk->_ptr != NULL) { | |
1494 res = blk->_ptr; | |
1495 size_t blk_size = blk->_word_size; | |
1496 blk->_word_size -= size; | |
1497 blk->_ptr += size; | |
1498 splitBirth(size); | |
1499 repairLinearAllocBlock(blk); | |
1500 // Update BOT last so that other (parallel) GC threads see a consistent | |
1501 // view of the BOT and free blocks. | |
1502 // Above must occur before BOT is updated below. | |
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1503 OrderAccess::storestore(); |
0 | 1504 _bt.split_block(res, blk_size, size); // adjust block offset table |
1505 } | |
1506 return res; | |
1507 } | |
1508 | |
1509 HeapWord* CompactibleFreeListSpace::getChunkFromLinearAllocBlockRemainder( | |
1510 LinearAllocBlock* blk, | |
1511 size_t size) { | |
1512 assert_locked(); | |
1513 assert(size >= MinChunkSize, "too small"); | |
1514 | |
1515 HeapWord* res = NULL; | |
1516 // This is the common case. Keep it simple. | |
1517 if (blk->_word_size >= size + MinChunkSize) { | |
1518 assert(blk->_ptr != NULL, "consistency check"); | |
1519 res = blk->_ptr; | |
1520 // Note that the BOT is up-to-date for the linAB before allocation. It | |
1521 // indicates the start of the linAB. The split_block() updates the | |
1522 // BOT for the linAB after the allocation (indicates the start of the | |
1523 // next chunk to be allocated). | |
1524 size_t blk_size = blk->_word_size; | |
1525 blk->_word_size -= size; | |
1526 blk->_ptr += size; | |
1527 splitBirth(size); | |
1528 repairLinearAllocBlock(blk); | |
1529 // Update BOT last so that other (parallel) GC threads see a consistent | |
1530 // view of the BOT and free blocks. | |
1531 // Above must occur before BOT is updated below. | |
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1532 OrderAccess::storestore(); |
0 | 1533 _bt.split_block(res, blk_size, size); // adjust block offset table |
1534 _bt.allocated(res, size); | |
1535 } | |
1536 return res; | |
1537 } | |
1538 | |
1539 FreeChunk* | |
1540 CompactibleFreeListSpace::getChunkFromIndexedFreeList(size_t size) { | |
1541 assert_locked(); | |
1542 assert(size < SmallForDictionary, "just checking"); | |
1543 FreeChunk* res; | |
1544 res = _indexedFreeList[size].getChunkAtHead(); | |
1545 if (res == NULL) { | |
1546 res = getChunkFromIndexedFreeListHelper(size); | |
1547 } | |
1548 _bt.verify_not_unallocated((HeapWord*) res, size); | |
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1549 assert(res == NULL || res->size() == size, "Incorrect block size"); |
0 | 1550 return res; |
1551 } | |
1552 | |
1553 FreeChunk* | |
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1554 CompactibleFreeListSpace::getChunkFromIndexedFreeListHelper(size_t size, |
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1555 bool replenish) { |
0 | 1556 assert_locked(); |
1557 FreeChunk* fc = NULL; | |
1558 if (size < SmallForDictionary) { | |
1559 assert(_indexedFreeList[size].head() == NULL || | |
1560 _indexedFreeList[size].surplus() <= 0, | |
1561 "List for this size should be empty or under populated"); | |
1562 // Try best fit in exact lists before replenishing the list | |
1563 if (!bestFitFirst() || (fc = bestFitSmall(size)) == NULL) { | |
1564 // Replenish list. | |
1565 // | |
1566 // Things tried that failed. | |
1567 // Tried allocating out of the two LinAB's first before | |
1568 // replenishing lists. | |
1569 // Tried small linAB of size 256 (size in indexed list) | |
1570 // and replenishing indexed lists from the small linAB. | |
1571 // | |
1572 FreeChunk* newFc = NULL; | |
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1573 const size_t replenish_size = CMSIndexedFreeListReplenish * size; |
0 | 1574 if (replenish_size < SmallForDictionary) { |
1575 // Do not replenish from an underpopulated size. | |
1576 if (_indexedFreeList[replenish_size].surplus() > 0 && | |
1577 _indexedFreeList[replenish_size].head() != NULL) { | |
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1578 newFc = _indexedFreeList[replenish_size].getChunkAtHead(); |
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1579 } else if (bestFitFirst()) { |
0 | 1580 newFc = bestFitSmall(replenish_size); |
1581 } | |
1582 } | |
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1583 if (newFc == NULL && replenish_size > size) { |
0 | 1584 assert(CMSIndexedFreeListReplenish > 1, "ctl pt invariant"); |
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1585 newFc = getChunkFromIndexedFreeListHelper(replenish_size, false); |
0 | 1586 } |
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1587 // Note: The stats update re split-death of block obtained above |
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1588 // will be recorded below precisely when we know we are going to |
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1589 // be actually splitting it into more than one pieces below. |
0 | 1590 if (newFc != NULL) { |
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1591 if (replenish || CMSReplenishIntermediate) { |
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1592 // Replenish this list and return one block to caller. |
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1593 size_t i; |
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1594 FreeChunk *curFc, *nextFc; |
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1595 size_t num_blk = newFc->size() / size; |
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1596 assert(num_blk >= 1, "Smaller than requested?"); |
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1597 assert(newFc->size() % size == 0, "Should be integral multiple of request"); |
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1598 if (num_blk > 1) { |
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1599 // we are sure we will be splitting the block just obtained |
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1600 // into multiple pieces; record the split-death of the original |
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1601 splitDeath(replenish_size); |
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1602 } |
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1603 // carve up and link blocks 0, ..., num_blk - 2 |
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1604 // The last chunk is not added to the lists but is returned as the |
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1605 // free chunk. |
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1606 for (curFc = newFc, nextFc = (FreeChunk*)((HeapWord*)curFc + size), |
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1607 i = 0; |
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1608 i < (num_blk - 1); |
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1609 curFc = nextFc, nextFc = (FreeChunk*)((HeapWord*)nextFc + size), |
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1610 i++) { |
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1611 curFc->setSize(size); |
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1612 // Don't record this as a return in order to try and |
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1613 // determine the "returns" from a GC. |
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1614 _bt.verify_not_unallocated((HeapWord*) fc, size); |
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1615 _indexedFreeList[size].returnChunkAtTail(curFc, false); |
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1616 _bt.mark_block((HeapWord*)curFc, size); |
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1617 splitBirth(size); |
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1618 // Don't record the initial population of the indexed list |
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1619 // as a split birth. |
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1620 } |
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1621 |
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1622 // check that the arithmetic was OK above |
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1623 assert((HeapWord*)nextFc == (HeapWord*)newFc + num_blk*size, |
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1624 "inconsistency in carving newFc"); |
0 | 1625 curFc->setSize(size); |
1626 _bt.mark_block((HeapWord*)curFc, size); | |
1627 splitBirth(size); | |
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1628 fc = curFc; |
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1629 } else { |
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1630 // Return entire block to caller |
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1631 fc = newFc; |
0 | 1632 } |
1633 } | |
1634 } | |
1635 } else { | |
1636 // Get a free chunk from the free chunk dictionary to be returned to | |
1637 // replenish the indexed free list. | |
1638 fc = getChunkFromDictionaryExact(size); | |
1639 } | |
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1640 // assert(fc == NULL || fc->isFree(), "Should be returning a free chunk"); |
0 | 1641 return fc; |
1642 } | |
1643 | |
1644 FreeChunk* | |
1645 CompactibleFreeListSpace::getChunkFromDictionary(size_t size) { | |
1646 assert_locked(); | |
1647 FreeChunk* fc = _dictionary->getChunk(size); | |
1648 if (fc == NULL) { | |
1649 return NULL; | |
1650 } | |
1651 _bt.allocated((HeapWord*)fc, fc->size()); | |
1652 if (fc->size() >= size + MinChunkSize) { | |
1653 fc = splitChunkAndReturnRemainder(fc, size); | |
1654 } | |
1655 assert(fc->size() >= size, "chunk too small"); | |
1656 assert(fc->size() < size + MinChunkSize, "chunk too big"); | |
1657 _bt.verify_single_block((HeapWord*)fc, fc->size()); | |
1658 return fc; | |
1659 } | |
1660 | |
1661 FreeChunk* | |
1662 CompactibleFreeListSpace::getChunkFromDictionaryExact(size_t size) { | |
1663 assert_locked(); | |
1664 FreeChunk* fc = _dictionary->getChunk(size); | |
1665 if (fc == NULL) { | |
1666 return fc; | |
1667 } | |
1668 _bt.allocated((HeapWord*)fc, fc->size()); | |
1669 if (fc->size() == size) { | |
1670 _bt.verify_single_block((HeapWord*)fc, size); | |
1671 return fc; | |
1672 } | |
1673 assert(fc->size() > size, "getChunk() guarantee"); | |
1674 if (fc->size() < size + MinChunkSize) { | |
1675 // Return the chunk to the dictionary and go get a bigger one. | |
1676 returnChunkToDictionary(fc); | |
1677 fc = _dictionary->getChunk(size + MinChunkSize); | |
1678 if (fc == NULL) { | |
1679 return NULL; | |
1680 } | |
1681 _bt.allocated((HeapWord*)fc, fc->size()); | |
1682 } | |
1683 assert(fc->size() >= size + MinChunkSize, "tautology"); | |
1684 fc = splitChunkAndReturnRemainder(fc, size); | |
1685 assert(fc->size() == size, "chunk is wrong size"); | |
1686 _bt.verify_single_block((HeapWord*)fc, size); | |
1687 return fc; | |
1688 } | |
1689 | |
1690 void | |
1691 CompactibleFreeListSpace::returnChunkToDictionary(FreeChunk* chunk) { | |
1692 assert_locked(); | |
1693 | |
1694 size_t size = chunk->size(); | |
1695 _bt.verify_single_block((HeapWord*)chunk, size); | |
1696 // adjust _unallocated_block downward, as necessary | |
1697 _bt.freed((HeapWord*)chunk, size); | |
1698 _dictionary->returnChunk(chunk); | |
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1699 #ifndef PRODUCT |
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1700 if (CMSCollector::abstract_state() != CMSCollector::Sweeping) { |
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1701 TreeChunk::as_TreeChunk(chunk)->list()->verify_stats(); |
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1702 } |
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1703 #endif // PRODUCT |
0 | 1704 } |
1705 | |
1706 void | |
1707 CompactibleFreeListSpace::returnChunkToFreeList(FreeChunk* fc) { | |
1708 assert_locked(); | |
1709 size_t size = fc->size(); | |
1710 _bt.verify_single_block((HeapWord*) fc, size); | |
1711 _bt.verify_not_unallocated((HeapWord*) fc, size); | |
1712 if (_adaptive_freelists) { | |
1713 _indexedFreeList[size].returnChunkAtTail(fc); | |
1714 } else { | |
1715 _indexedFreeList[size].returnChunkAtHead(fc); | |
1716 } | |
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1717 #ifndef PRODUCT |
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1718 if (CMSCollector::abstract_state() != CMSCollector::Sweeping) { |
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1719 _indexedFreeList[size].verify_stats(); |
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1720 } |
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1721 #endif // PRODUCT |
0 | 1722 } |
1723 | |
1724 // Add chunk to end of last block -- if it's the largest | |
1725 // block -- and update BOT and census data. We would | |
1726 // of course have preferred to coalesce it with the | |
1727 // last block, but it's currently less expensive to find the | |
1728 // largest block than it is to find the last. | |
1729 void | |
1730 CompactibleFreeListSpace::addChunkToFreeListsAtEndRecordingStats( | |
1731 HeapWord* chunk, size_t size) { | |
1732 // check that the chunk does lie in this space! | |
1733 assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!"); | |
1734 // One of the parallel gc task threads may be here | |
1735 // whilst others are allocating. | |
1736 Mutex* lock = NULL; | |
1737 if (ParallelGCThreads != 0) { | |
1738 lock = &_parDictionaryAllocLock; | |
1739 } | |
1740 FreeChunk* ec; | |
1741 { | |
1742 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); | |
1743 ec = dictionary()->findLargestDict(); // get largest block | |
1744 if (ec != NULL && ec->end() == chunk) { | |
1745 // It's a coterminal block - we can coalesce. | |
1746 size_t old_size = ec->size(); | |
1747 coalDeath(old_size); | |
1748 removeChunkFromDictionary(ec); | |
1749 size += old_size; | |
1750 } else { | |
1751 ec = (FreeChunk*)chunk; | |
1752 } | |
1753 } | |
1754 ec->setSize(size); | |
1755 debug_only(ec->mangleFreed(size)); | |
1756 if (size < SmallForDictionary) { | |
1757 lock = _indexedFreeListParLocks[size]; | |
1758 } | |
1759 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); | |
1760 addChunkAndRepairOffsetTable((HeapWord*)ec, size, true); | |
1761 // record the birth under the lock since the recording involves | |
1762 // manipulation of the list on which the chunk lives and | |
1763 // if the chunk is allocated and is the last on the list, | |
1764 // the list can go away. | |
1765 coalBirth(size); | |
1766 } | |
1767 | |
1768 void | |
1769 CompactibleFreeListSpace::addChunkToFreeLists(HeapWord* chunk, | |
1770 size_t size) { | |
1771 // check that the chunk does lie in this space! | |
1772 assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!"); | |
1773 assert_locked(); | |
1774 _bt.verify_single_block(chunk, size); | |
1775 | |
1776 FreeChunk* fc = (FreeChunk*) chunk; | |
1777 fc->setSize(size); | |
1778 debug_only(fc->mangleFreed(size)); | |
1779 if (size < SmallForDictionary) { | |
1780 returnChunkToFreeList(fc); | |
1781 } else { | |
1782 returnChunkToDictionary(fc); | |
1783 } | |
1784 } | |
1785 | |
1786 void | |
1787 CompactibleFreeListSpace::addChunkAndRepairOffsetTable(HeapWord* chunk, | |
1788 size_t size, bool coalesced) { | |
1789 assert_locked(); | |
1790 assert(chunk != NULL, "null chunk"); | |
1791 if (coalesced) { | |
1792 // repair BOT | |
1793 _bt.single_block(chunk, size); | |
1794 } | |
1795 addChunkToFreeLists(chunk, size); | |
1796 } | |
1797 | |
1798 // We _must_ find the purported chunk on our free lists; | |
1799 // we assert if we don't. | |
1800 void | |
1801 CompactibleFreeListSpace::removeFreeChunkFromFreeLists(FreeChunk* fc) { | |
1802 size_t size = fc->size(); | |
1803 assert_locked(); | |
1804 debug_only(verifyFreeLists()); | |
1805 if (size < SmallForDictionary) { | |
1806 removeChunkFromIndexedFreeList(fc); | |
1807 } else { | |
1808 removeChunkFromDictionary(fc); | |
1809 } | |
1810 _bt.verify_single_block((HeapWord*)fc, size); | |
1811 debug_only(verifyFreeLists()); | |
1812 } | |
1813 | |
1814 void | |
1815 CompactibleFreeListSpace::removeChunkFromDictionary(FreeChunk* fc) { | |
1816 size_t size = fc->size(); | |
1817 assert_locked(); | |
1818 assert(fc != NULL, "null chunk"); | |
1819 _bt.verify_single_block((HeapWord*)fc, size); | |
1820 _dictionary->removeChunk(fc); | |
1821 // adjust _unallocated_block upward, as necessary | |
1822 _bt.allocated((HeapWord*)fc, size); | |
1823 } | |
1824 | |
1825 void | |
1826 CompactibleFreeListSpace::removeChunkFromIndexedFreeList(FreeChunk* fc) { | |
1827 assert_locked(); | |
1828 size_t size = fc->size(); | |
1829 _bt.verify_single_block((HeapWord*)fc, size); | |
1830 NOT_PRODUCT( | |
1831 if (FLSVerifyIndexTable) { | |
1832 verifyIndexedFreeList(size); | |
1833 } | |
1834 ) | |
1835 _indexedFreeList[size].removeChunk(fc); | |
1836 NOT_PRODUCT( | |
1837 if (FLSVerifyIndexTable) { | |
1838 verifyIndexedFreeList(size); | |
1839 } | |
1840 ) | |
1841 } | |
1842 | |
1843 FreeChunk* CompactibleFreeListSpace::bestFitSmall(size_t numWords) { | |
1844 /* A hint is the next larger size that has a surplus. | |
1845 Start search at a size large enough to guarantee that | |
1846 the excess is >= MIN_CHUNK. */ | |
1847 size_t start = align_object_size(numWords + MinChunkSize); | |
1848 if (start < IndexSetSize) { | |
1849 FreeList* it = _indexedFreeList; | |
1850 size_t hint = _indexedFreeList[start].hint(); | |
1851 while (hint < IndexSetSize) { | |
1852 assert(hint % MinObjAlignment == 0, "hint should be aligned"); | |
1853 FreeList *fl = &_indexedFreeList[hint]; | |
1854 if (fl->surplus() > 0 && fl->head() != NULL) { | |
1855 // Found a list with surplus, reset original hint | |
1856 // and split out a free chunk which is returned. | |
1857 _indexedFreeList[start].set_hint(hint); | |
1858 FreeChunk* res = getFromListGreater(fl, numWords); | |
1859 assert(res == NULL || res->isFree(), | |
1860 "Should be returning a free chunk"); | |
1861 return res; | |
1862 } | |
1863 hint = fl->hint(); /* keep looking */ | |
1864 } | |
1865 /* None found. */ | |
1866 it[start].set_hint(IndexSetSize); | |
1867 } | |
1868 return NULL; | |
1869 } | |
1870 | |
1871 /* Requires fl->size >= numWords + MinChunkSize */ | |
1872 FreeChunk* CompactibleFreeListSpace::getFromListGreater(FreeList* fl, | |
1873 size_t numWords) { | |
1874 FreeChunk *curr = fl->head(); | |
1875 size_t oldNumWords = curr->size(); | |
1876 assert(numWords >= MinChunkSize, "Word size is too small"); | |
1877 assert(curr != NULL, "List is empty"); | |
1878 assert(oldNumWords >= numWords + MinChunkSize, | |
1879 "Size of chunks in the list is too small"); | |
1880 | |
1881 fl->removeChunk(curr); | |
1882 // recorded indirectly by splitChunkAndReturnRemainder - | |
1883 // smallSplit(oldNumWords, numWords); | |
1884 FreeChunk* new_chunk = splitChunkAndReturnRemainder(curr, numWords); | |
1885 // Does anything have to be done for the remainder in terms of | |
1886 // fixing the card table? | |
1887 assert(new_chunk == NULL || new_chunk->isFree(), | |
1888 "Should be returning a free chunk"); | |
1889 return new_chunk; | |
1890 } | |
1891 | |
1892 FreeChunk* | |
1893 CompactibleFreeListSpace::splitChunkAndReturnRemainder(FreeChunk* chunk, | |
1894 size_t new_size) { | |
1895 assert_locked(); | |
1896 size_t size = chunk->size(); | |
1897 assert(size > new_size, "Split from a smaller block?"); | |
1898 assert(is_aligned(chunk), "alignment problem"); | |
1899 assert(size == adjustObjectSize(size), "alignment problem"); | |
1900 size_t rem_size = size - new_size; | |
1901 assert(rem_size == adjustObjectSize(rem_size), "alignment problem"); | |
1902 assert(rem_size >= MinChunkSize, "Free chunk smaller than minimum"); | |
1903 FreeChunk* ffc = (FreeChunk*)((HeapWord*)chunk + new_size); | |
1904 assert(is_aligned(ffc), "alignment problem"); | |
1905 ffc->setSize(rem_size); | |
1906 ffc->linkNext(NULL); | |
1907 ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. | |
1908 // Above must occur before BOT is updated below. | |
1909 // adjust block offset table | |
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1910 OrderAccess::storestore(); |
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1911 assert(chunk->isFree() && ffc->isFree(), "Error"); |
0 | 1912 _bt.split_block((HeapWord*)chunk, chunk->size(), new_size); |
1913 if (rem_size < SmallForDictionary) { | |
1914 bool is_par = (SharedHeap::heap()->n_par_threads() > 0); | |
1915 if (is_par) _indexedFreeListParLocks[rem_size]->lock(); | |
1916 returnChunkToFreeList(ffc); | |
1917 split(size, rem_size); | |
1918 if (is_par) _indexedFreeListParLocks[rem_size]->unlock(); | |
1919 } else { | |
1920 returnChunkToDictionary(ffc); | |
1921 split(size ,rem_size); | |
1922 } | |
1923 chunk->setSize(new_size); | |
1924 return chunk; | |
1925 } | |
1926 | |
1927 void | |
1928 CompactibleFreeListSpace::sweep_completed() { | |
1929 // Now that space is probably plentiful, refill linear | |
1930 // allocation blocks as needed. | |
1931 refillLinearAllocBlocksIfNeeded(); | |
1932 } | |
1933 | |
1934 void | |
1935 CompactibleFreeListSpace::gc_prologue() { | |
1936 assert_locked(); | |
1937 if (PrintFLSStatistics != 0) { | |
1938 gclog_or_tty->print("Before GC:\n"); | |
1939 reportFreeListStatistics(); | |
1940 } | |
1941 refillLinearAllocBlocksIfNeeded(); | |
1942 } | |
1943 | |
1944 void | |
1945 CompactibleFreeListSpace::gc_epilogue() { | |
1946 assert_locked(); | |
1947 if (PrintGCDetails && Verbose && !_adaptive_freelists) { | |
1948 if (_smallLinearAllocBlock._word_size == 0) | |
1949 warning("CompactibleFreeListSpace(epilogue):: Linear allocation failure"); | |
1950 } | |
1951 assert(_promoInfo.noPromotions(), "_promoInfo inconsistency"); | |
1952 _promoInfo.stopTrackingPromotions(); | |
1953 repairLinearAllocationBlocks(); | |
1954 // Print Space's stats | |
1955 if (PrintFLSStatistics != 0) { | |
1956 gclog_or_tty->print("After GC:\n"); | |
1957 reportFreeListStatistics(); | |
1958 } | |
1959 } | |
1960 | |
1961 // Iteration support, mostly delegated from a CMS generation | |
1962 | |
1963 void CompactibleFreeListSpace::save_marks() { | |
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1964 assert(Thread::current()->is_VM_thread(), |
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1965 "Global variable should only be set when single-threaded"); |
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1966 // Mark the "end" of the used space at the time of this call; |
0 | 1967 // note, however, that promoted objects from this point |
1968 // on are tracked in the _promoInfo below. | |
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1969 set_saved_mark_word(unallocated_block()); |
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1970 #ifdef ASSERT |
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1971 // Check the sanity of save_marks() etc. |
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1972 MemRegion ur = used_region(); |
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1973 MemRegion urasm = used_region_at_save_marks(); |
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1974 assert(ur.contains(urasm), |
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1975 err_msg(" Error at save_marks(): [" PTR_FORMAT "," PTR_FORMAT ")" |
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1976 " should contain [" PTR_FORMAT "," PTR_FORMAT ")", |
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1977 ur.start(), ur.end(), urasm.start(), urasm.end())); |
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1978 #endif |
0 | 1979 // inform allocator that promotions should be tracked. |
1980 assert(_promoInfo.noPromotions(), "_promoInfo inconsistency"); | |
1981 _promoInfo.startTrackingPromotions(); | |
1982 } | |
1983 | |
1984 bool CompactibleFreeListSpace::no_allocs_since_save_marks() { | |
1985 assert(_promoInfo.tracking(), "No preceding save_marks?"); | |
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1986 assert(SharedHeap::heap()->n_par_threads() == 0, |
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1987 "Shouldn't be called if using parallel gc."); |
0 | 1988 return _promoInfo.noPromotions(); |
1989 } | |
1990 | |
1991 #define CFLS_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
1992 \ | |
1993 void CompactibleFreeListSpace:: \ | |
1994 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ | |
1995 assert(SharedHeap::heap()->n_par_threads() == 0, \ | |
1996 "Shouldn't be called (yet) during parallel part of gc."); \ | |
1997 _promoInfo.promoted_oops_iterate##nv_suffix(blk); \ | |
1998 /* \ | |
1999 * This also restores any displaced headers and removes the elements from \ | |
2000 * the iteration set as they are processed, so that we have a clean slate \ | |
2001 * at the end of the iteration. Note, thus, that if new objects are \ | |
2002 * promoted as a result of the iteration they are iterated over as well. \ | |
2003 */ \ | |
2004 assert(_promoInfo.noPromotions(), "_promoInfo inconsistency"); \ | |
2005 } | |
2006 | |
2007 ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DEFN) | |
2008 | |
2009 | |
2010 void CompactibleFreeListSpace::object_iterate_since_last_GC(ObjectClosure* cl) { | |
2011 // ugghh... how would one do this efficiently for a non-contiguous space? | |
2012 guarantee(false, "NYI"); | |
2013 } | |
2014 | |
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2015 bool CompactibleFreeListSpace::linearAllocationWouldFail() const { |
0 | 2016 return _smallLinearAllocBlock._word_size == 0; |
2017 } | |
2018 | |
2019 void CompactibleFreeListSpace::repairLinearAllocationBlocks() { | |
2020 // Fix up linear allocation blocks to look like free blocks | |
2021 repairLinearAllocBlock(&_smallLinearAllocBlock); | |
2022 } | |
2023 | |
2024 void CompactibleFreeListSpace::repairLinearAllocBlock(LinearAllocBlock* blk) { | |
2025 assert_locked(); | |
2026 if (blk->_ptr != NULL) { | |
2027 assert(blk->_word_size != 0 && blk->_word_size >= MinChunkSize, | |
2028 "Minimum block size requirement"); | |
2029 FreeChunk* fc = (FreeChunk*)(blk->_ptr); | |
2030 fc->setSize(blk->_word_size); | |
2031 fc->linkPrev(NULL); // mark as free | |
2032 fc->dontCoalesce(); | |
2033 assert(fc->isFree(), "just marked it free"); | |
2034 assert(fc->cantCoalesce(), "just marked it uncoalescable"); | |
2035 } | |
2036 } | |
2037 | |
2038 void CompactibleFreeListSpace::refillLinearAllocBlocksIfNeeded() { | |
2039 assert_locked(); | |
2040 if (_smallLinearAllocBlock._ptr == NULL) { | |
2041 assert(_smallLinearAllocBlock._word_size == 0, | |
2042 "Size of linAB should be zero if the ptr is NULL"); | |
2043 // Reset the linAB refill and allocation size limit. | |
2044 _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc, SmallForLinearAlloc); | |
2045 } | |
2046 refillLinearAllocBlockIfNeeded(&_smallLinearAllocBlock); | |
2047 } | |
2048 | |
2049 void | |
2050 CompactibleFreeListSpace::refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk) { | |
2051 assert_locked(); | |
2052 assert((blk->_ptr == NULL && blk->_word_size == 0) || | |
2053 (blk->_ptr != NULL && blk->_word_size >= MinChunkSize), | |
2054 "blk invariant"); | |
2055 if (blk->_ptr == NULL) { | |
2056 refillLinearAllocBlock(blk); | |
2057 } | |
2058 if (PrintMiscellaneous && Verbose) { | |
2059 if (blk->_word_size == 0) { | |
2060 warning("CompactibleFreeListSpace(prologue):: Linear allocation failure"); | |
2061 } | |
2062 } | |
2063 } | |
2064 | |
2065 void | |
2066 CompactibleFreeListSpace::refillLinearAllocBlock(LinearAllocBlock* blk) { | |
2067 assert_locked(); | |
2068 assert(blk->_word_size == 0 && blk->_ptr == NULL, | |
2069 "linear allocation block should be empty"); | |
2070 FreeChunk* fc; | |
2071 if (blk->_refillSize < SmallForDictionary && | |
2072 (fc = getChunkFromIndexedFreeList(blk->_refillSize)) != NULL) { | |
2073 // A linAB's strategy might be to use small sizes to reduce | |
2074 // fragmentation but still get the benefits of allocation from a | |
2075 // linAB. | |
2076 } else { | |
2077 fc = getChunkFromDictionary(blk->_refillSize); | |
2078 } | |
2079 if (fc != NULL) { | |
2080 blk->_ptr = (HeapWord*)fc; | |
2081 blk->_word_size = fc->size(); | |
2082 fc->dontCoalesce(); // to prevent sweeper from sweeping us up | |
2083 } | |
2084 } | |
2085 | |
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2086 // Support for concurrent collection policy decisions. |
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2087 bool CompactibleFreeListSpace::should_concurrent_collect() const { |
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2088 // In the future we might want to add in frgamentation stats -- |
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2089 // including erosion of the "mountain" into this decision as well. |
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2090 return !adaptive_freelists() && linearAllocationWouldFail(); |
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2091 } |
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2092 |
0 | 2093 // Support for compaction |
2094 | |
2095 void CompactibleFreeListSpace::prepare_for_compaction(CompactPoint* cp) { | |
2096 SCAN_AND_FORWARD(cp,end,block_is_obj,block_size); | |
2097 // prepare_for_compaction() uses the space between live objects | |
2098 // so that later phase can skip dead space quickly. So verification | |
2099 // of the free lists doesn't work after. | |
2100 } | |
2101 | |
2102 #define obj_size(q) adjustObjectSize(oop(q)->size()) | |
2103 #define adjust_obj_size(s) adjustObjectSize(s) | |
2104 | |
2105 void CompactibleFreeListSpace::adjust_pointers() { | |
2106 // In other versions of adjust_pointers(), a bail out | |
2107 // based on the amount of live data in the generation | |
2108 // (i.e., if 0, bail out) may be used. | |
2109 // Cannot test used() == 0 here because the free lists have already | |
2110 // been mangled by the compaction. | |
2111 | |
2112 SCAN_AND_ADJUST_POINTERS(adjust_obj_size); | |
2113 // See note about verification in prepare_for_compaction(). | |
2114 } | |
2115 | |
2116 void CompactibleFreeListSpace::compact() { | |
2117 SCAN_AND_COMPACT(obj_size); | |
2118 } | |
2119 | |
2120 // fragmentation_metric = 1 - [sum of (fbs**2) / (sum of fbs)**2] | |
2121 // where fbs is free block sizes | |
2122 double CompactibleFreeListSpace::flsFrag() const { | |
2123 size_t itabFree = totalSizeInIndexedFreeLists(); | |
2124 double frag = 0.0; | |
2125 size_t i; | |
2126 | |
2127 for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
2128 double sz = i; | |
2129 frag += _indexedFreeList[i].count() * (sz * sz); | |
2130 } | |
2131 | |
2132 double totFree = itabFree + | |
2133 _dictionary->totalChunkSize(DEBUG_ONLY(freelistLock())); | |
2134 if (totFree > 0) { | |
2135 frag = ((frag + _dictionary->sum_of_squared_block_sizes()) / | |
2136 (totFree * totFree)); | |
2137 frag = (double)1.0 - frag; | |
2138 } else { | |
2139 assert(frag == 0.0, "Follows from totFree == 0"); | |
2140 } | |
2141 return frag; | |
2142 } | |
2143 | |
2144 void CompactibleFreeListSpace::beginSweepFLCensus( | |
2145 float inter_sweep_current, | |
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2146 float inter_sweep_estimate, |
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2147 float intra_sweep_estimate) { |
0 | 2148 assert_locked(); |
2149 size_t i; | |
2150 for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
2151 FreeList* fl = &_indexedFreeList[i]; | |
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2152 if (PrintFLSStatistics > 1) { |
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2153 gclog_or_tty->print("size[%d] : ", i); |
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2154 } |
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2155 fl->compute_desired(inter_sweep_current, inter_sweep_estimate, intra_sweep_estimate); |
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2156 fl->set_coalDesired((ssize_t)((double)fl->desired() * CMSSmallCoalSurplusPercent)); |
0 | 2157 fl->set_beforeSweep(fl->count()); |
2158 fl->set_bfrSurp(fl->surplus()); | |
2159 } | |
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2160 _dictionary->beginSweepDictCensus(CMSLargeCoalSurplusPercent, |
0 | 2161 inter_sweep_current, |
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2162 inter_sweep_estimate, |
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2163 intra_sweep_estimate); |
0 | 2164 } |
2165 | |
2166 void CompactibleFreeListSpace::setFLSurplus() { | |
2167 assert_locked(); | |
2168 size_t i; | |
2169 for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
2170 FreeList *fl = &_indexedFreeList[i]; | |
2171 fl->set_surplus(fl->count() - | |
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2172 (ssize_t)((double)fl->desired() * CMSSmallSplitSurplusPercent)); |
0 | 2173 } |
2174 } | |
2175 | |
2176 void CompactibleFreeListSpace::setFLHints() { | |
2177 assert_locked(); | |
2178 size_t i; | |
2179 size_t h = IndexSetSize; | |
2180 for (i = IndexSetSize - 1; i != 0; i -= IndexSetStride) { | |
2181 FreeList *fl = &_indexedFreeList[i]; | |
2182 fl->set_hint(h); | |
2183 if (fl->surplus() > 0) { | |
2184 h = i; | |
2185 } | |
2186 } | |
2187 } | |
2188 | |
2189 void CompactibleFreeListSpace::clearFLCensus() { | |
2190 assert_locked(); | |
2191 int i; | |
2192 for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
2193 FreeList *fl = &_indexedFreeList[i]; | |
2194 fl->set_prevSweep(fl->count()); | |
2195 fl->set_coalBirths(0); | |
2196 fl->set_coalDeaths(0); | |
2197 fl->set_splitBirths(0); | |
2198 fl->set_splitDeaths(0); | |
2199 } | |
2200 } | |
2201 | |
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2202 void CompactibleFreeListSpace::endSweepFLCensus(size_t sweep_count) { |
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2203 if (PrintFLSStatistics > 0) { |
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2204 HeapWord* largestAddr = (HeapWord*) dictionary()->findLargestDict(); |
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2205 gclog_or_tty->print_cr("CMS: Large block " PTR_FORMAT, |
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2206 largestAddr); |
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2207 } |
0 | 2208 setFLSurplus(); |
2209 setFLHints(); | |
2210 if (PrintGC && PrintFLSCensus > 0) { | |
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2211 printFLCensus(sweep_count); |
0 | 2212 } |
2213 clearFLCensus(); | |
2214 assert_locked(); | |
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2215 _dictionary->endSweepDictCensus(CMSLargeSplitSurplusPercent); |
0 | 2216 } |
2217 | |
2218 bool CompactibleFreeListSpace::coalOverPopulated(size_t size) { | |
2219 if (size < SmallForDictionary) { | |
2220 FreeList *fl = &_indexedFreeList[size]; | |
2221 return (fl->coalDesired() < 0) || | |
2222 ((int)fl->count() > fl->coalDesired()); | |
2223 } else { | |
2224 return dictionary()->coalDictOverPopulated(size); | |
2225 } | |
2226 } | |
2227 | |
2228 void CompactibleFreeListSpace::smallCoalBirth(size_t size) { | |
2229 assert(size < SmallForDictionary, "Size too large for indexed list"); | |
2230 FreeList *fl = &_indexedFreeList[size]; | |
2231 fl->increment_coalBirths(); | |
2232 fl->increment_surplus(); | |
2233 } | |
2234 | |
2235 void CompactibleFreeListSpace::smallCoalDeath(size_t size) { | |
2236 assert(size < SmallForDictionary, "Size too large for indexed list"); | |
2237 FreeList *fl = &_indexedFreeList[size]; | |
2238 fl->increment_coalDeaths(); | |
2239 fl->decrement_surplus(); | |
2240 } | |
2241 | |
2242 void CompactibleFreeListSpace::coalBirth(size_t size) { | |
2243 if (size < SmallForDictionary) { | |
2244 smallCoalBirth(size); | |
2245 } else { | |
2246 dictionary()->dictCensusUpdate(size, | |
2247 false /* split */, | |
2248 true /* birth */); | |
2249 } | |
2250 } | |
2251 | |
2252 void CompactibleFreeListSpace::coalDeath(size_t size) { | |
2253 if(size < SmallForDictionary) { | |
2254 smallCoalDeath(size); | |
2255 } else { | |
2256 dictionary()->dictCensusUpdate(size, | |
2257 false /* split */, | |
2258 false /* birth */); | |
2259 } | |
2260 } | |
2261 | |
2262 void CompactibleFreeListSpace::smallSplitBirth(size_t size) { | |
2263 assert(size < SmallForDictionary, "Size too large for indexed list"); | |
2264 FreeList *fl = &_indexedFreeList[size]; | |
2265 fl->increment_splitBirths(); | |
2266 fl->increment_surplus(); | |
2267 } | |
2268 | |
2269 void CompactibleFreeListSpace::smallSplitDeath(size_t size) { | |
2270 assert(size < SmallForDictionary, "Size too large for indexed list"); | |
2271 FreeList *fl = &_indexedFreeList[size]; | |
2272 fl->increment_splitDeaths(); | |
2273 fl->decrement_surplus(); | |
2274 } | |
2275 | |
2276 void CompactibleFreeListSpace::splitBirth(size_t size) { | |
2277 if (size < SmallForDictionary) { | |
2278 smallSplitBirth(size); | |
2279 } else { | |
2280 dictionary()->dictCensusUpdate(size, | |
2281 true /* split */, | |
2282 true /* birth */); | |
2283 } | |
2284 } | |
2285 | |
2286 void CompactibleFreeListSpace::splitDeath(size_t size) { | |
2287 if (size < SmallForDictionary) { | |
2288 smallSplitDeath(size); | |
2289 } else { | |
2290 dictionary()->dictCensusUpdate(size, | |
2291 true /* split */, | |
2292 false /* birth */); | |
2293 } | |
2294 } | |
2295 | |
2296 void CompactibleFreeListSpace::split(size_t from, size_t to1) { | |
2297 size_t to2 = from - to1; | |
2298 splitDeath(from); | |
2299 splitBirth(to1); | |
2300 splitBirth(to2); | |
2301 } | |
2302 | |
2303 void CompactibleFreeListSpace::print() const { | |
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2304 print_on(tty); |
0 | 2305 } |
2306 | |
2307 void CompactibleFreeListSpace::prepare_for_verify() { | |
2308 assert_locked(); | |
2309 repairLinearAllocationBlocks(); | |
2310 // Verify that the SpoolBlocks look like free blocks of | |
2311 // appropriate sizes... To be done ... | |
2312 } | |
2313 | |
2314 class VerifyAllBlksClosure: public BlkClosure { | |
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2315 private: |
0 | 2316 const CompactibleFreeListSpace* _sp; |
2317 const MemRegion _span; | |
1716
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2318 HeapWord* _last_addr; |
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2319 size_t _last_size; |
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2320 bool _last_was_obj; |
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2321 bool _last_was_live; |
0 | 2322 |
2323 public: | |
2324 VerifyAllBlksClosure(const CompactibleFreeListSpace* sp, | |
1716
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2325 MemRegion span) : _sp(sp), _span(span), |
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2326 _last_addr(NULL), _last_size(0), |
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2327 _last_was_obj(false), _last_was_live(false) { } |
0 | 2328 |
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2329 virtual size_t do_blk(HeapWord* addr) { |
0 | 2330 size_t res; |
1716
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2331 bool was_obj = false; |
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2332 bool was_live = false; |
0 | 2333 if (_sp->block_is_obj(addr)) { |
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2334 was_obj = true; |
0 | 2335 oop p = oop(addr); |
2336 guarantee(p->is_oop(), "Should be an oop"); | |
2337 res = _sp->adjustObjectSize(p->size()); | |
2338 if (_sp->obj_is_alive(addr)) { | |
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2339 was_live = true; |
0 | 2340 p->verify(); |
2341 } | |
2342 } else { | |
2343 FreeChunk* fc = (FreeChunk*)addr; | |
2344 res = fc->size(); | |
2345 if (FLSVerifyLists && !fc->cantCoalesce()) { | |
2346 guarantee(_sp->verifyChunkInFreeLists(fc), | |
2347 "Chunk should be on a free list"); | |
2348 } | |
2349 } | |
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2350 if (res == 0) { |
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2351 gclog_or_tty->print_cr("Livelock: no rank reduction!"); |
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2352 gclog_or_tty->print_cr( |
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2353 " Current: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n" |
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2354 " Previous: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n", |
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2355 addr, res, was_obj ?"true":"false", was_live ?"true":"false", |
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2356 _last_addr, _last_size, _last_was_obj?"true":"false", _last_was_live?"true":"false"); |
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2357 _sp->print_on(gclog_or_tty); |
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2358 guarantee(false, "Seppuku!"); |
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2359 } |
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2360 _last_addr = addr; |
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2361 _last_size = res; |
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2362 _last_was_obj = was_obj; |
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2363 _last_was_live = was_live; |
0 | 2364 return res; |
2365 } | |
2366 }; | |
2367 | |
2368 class VerifyAllOopsClosure: public OopClosure { | |
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2369 private: |
0 | 2370 const CMSCollector* _collector; |
2371 const CompactibleFreeListSpace* _sp; | |
2372 const MemRegion _span; | |
2373 const bool _past_remark; | |
2374 const CMSBitMap* _bit_map; | |
2375 | |
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2376 protected: |
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2377 void do_oop(void* p, oop obj) { |
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2378 if (_span.contains(obj)) { // the interior oop points into CMS heap |
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2379 if (!_span.contains(p)) { // reference from outside CMS heap |
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2380 // Should be a valid object; the first disjunct below allows |
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2381 // us to sidestep an assertion in block_is_obj() that insists |
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2382 // that p be in _sp. Note that several generations (and spaces) |
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2383 // are spanned by _span (CMS heap) above. |
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2384 guarantee(!_sp->is_in_reserved(obj) || |
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2385 _sp->block_is_obj((HeapWord*)obj), |
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2386 "Should be an object"); |
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2387 guarantee(obj->is_oop(), "Should be an oop"); |
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2388 obj->verify(); |
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2389 if (_past_remark) { |
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2390 // Remark has been completed, the object should be marked |
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2391 _bit_map->isMarked((HeapWord*)obj); |
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2392 } |
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2393 } else { // reference within CMS heap |
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2394 if (_past_remark) { |
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2395 // Remark has been completed -- so the referent should have |
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2396 // been marked, if referring object is. |
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2397 if (_bit_map->isMarked(_collector->block_start(p))) { |
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2398 guarantee(_bit_map->isMarked((HeapWord*)obj), "Marking error?"); |
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2399 } |
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2400 } |
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2401 } |
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2402 } else if (_sp->is_in_reserved(p)) { |
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2403 // the reference is from FLS, and points out of FLS |
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2404 guarantee(obj->is_oop(), "Should be an oop"); |
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2405 obj->verify(); |
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2406 } |
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2407 } |
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2408 |
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2409 template <class T> void do_oop_work(T* p) { |
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2410 T heap_oop = oopDesc::load_heap_oop(p); |
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2411 if (!oopDesc::is_null(heap_oop)) { |
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2412 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
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2413 do_oop(p, obj); |
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2414 } |
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2415 } |
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2416 |
0 | 2417 public: |
2418 VerifyAllOopsClosure(const CMSCollector* collector, | |
2419 const CompactibleFreeListSpace* sp, MemRegion span, | |
2420 bool past_remark, CMSBitMap* bit_map) : | |
2421 OopClosure(), _collector(collector), _sp(sp), _span(span), | |
2422 _past_remark(past_remark), _bit_map(bit_map) { } | |
2423 | |
113
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2424 virtual void do_oop(oop* p) { VerifyAllOopsClosure::do_oop_work(p); } |
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2425 virtual void do_oop(narrowOop* p) { VerifyAllOopsClosure::do_oop_work(p); } |
0 | 2426 }; |
2427 | |
2428 void CompactibleFreeListSpace::verify(bool ignored) const { | |
2429 assert_lock_strong(&_freelistLock); | |
2430 verify_objects_initialized(); | |
2431 MemRegion span = _collector->_span; | |
2432 bool past_remark = (_collector->abstract_state() == | |
2433 CMSCollector::Sweeping); | |
2434 | |
2435 ResourceMark rm; | |
2436 HandleMark hm; | |
2437 | |
2438 // Check integrity of CFL data structures | |
2439 _promoInfo.verify(); | |
2440 _dictionary->verify(); | |
2441 if (FLSVerifyIndexTable) { | |
2442 verifyIndexedFreeLists(); | |
2443 } | |
2444 // Check integrity of all objects and free blocks in space | |
2445 { | |
2446 VerifyAllBlksClosure cl(this, span); | |
2447 ((CompactibleFreeListSpace*)this)->blk_iterate(&cl); // cast off const | |
2448 } | |
2449 // Check that all references in the heap to FLS | |
2450 // are to valid objects in FLS or that references in | |
2451 // FLS are to valid objects elsewhere in the heap | |
2452 if (FLSVerifyAllHeapReferences) | |
2453 { | |
2454 VerifyAllOopsClosure cl(_collector, this, span, past_remark, | |
2455 _collector->markBitMap()); | |
2456 CollectedHeap* ch = Universe::heap(); | |
2457 ch->oop_iterate(&cl); // all oops in generations | |
2458 ch->permanent_oop_iterate(&cl); // all oops in perm gen | |
2459 } | |
2460 | |
2461 if (VerifyObjectStartArray) { | |
2462 // Verify the block offset table | |
2463 _bt.verify(); | |
2464 } | |
2465 } | |
2466 | |
2467 #ifndef PRODUCT | |
2468 void CompactibleFreeListSpace::verifyFreeLists() const { | |
2469 if (FLSVerifyLists) { | |
2470 _dictionary->verify(); | |
2471 verifyIndexedFreeLists(); | |
2472 } else { | |
2473 if (FLSVerifyDictionary) { | |
2474 _dictionary->verify(); | |
2475 } | |
2476 if (FLSVerifyIndexTable) { | |
2477 verifyIndexedFreeLists(); | |
2478 } | |
2479 } | |
2480 } | |
2481 #endif | |
2482 | |
2483 void CompactibleFreeListSpace::verifyIndexedFreeLists() const { | |
2484 size_t i = 0; | |
2485 for (; i < MinChunkSize; i++) { | |
2486 guarantee(_indexedFreeList[i].head() == NULL, "should be NULL"); | |
2487 } | |
2488 for (; i < IndexSetSize; i++) { | |
2489 verifyIndexedFreeList(i); | |
2490 } | |
2491 } | |
2492 | |
2493 void CompactibleFreeListSpace::verifyIndexedFreeList(size_t size) const { | |
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2494 FreeChunk* fc = _indexedFreeList[size].head(); |
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2495 FreeChunk* tail = _indexedFreeList[size].tail(); |
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2496 size_t num = _indexedFreeList[size].count(); |
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2497 size_t n = 0; |
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2498 guarantee((size % 2 == 0) || fc == NULL, "Odd slots should be empty"); |
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2499 for (; fc != NULL; fc = fc->next(), n++) { |
0 | 2500 guarantee(fc->size() == size, "Size inconsistency"); |
2501 guarantee(fc->isFree(), "!free?"); | |
2502 guarantee(fc->next() == NULL || fc->next()->prev() == fc, "Broken list"); | |
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2503 guarantee((fc->next() == NULL) == (fc == tail), "Incorrect tail"); |
0 | 2504 } |
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2505 guarantee(n == num, "Incorrect count"); |
0 | 2506 } |
2507 | |
2508 #ifndef PRODUCT | |
2509 void CompactibleFreeListSpace::checkFreeListConsistency() const { | |
2510 assert(_dictionary->minSize() <= IndexSetSize, | |
2511 "Some sizes can't be allocated without recourse to" | |
2512 " linear allocation buffers"); | |
2513 assert(MIN_TREE_CHUNK_SIZE*HeapWordSize == sizeof(TreeChunk), | |
2514 "else MIN_TREE_CHUNK_SIZE is wrong"); | |
2515 assert((IndexSetStride == 2 && IndexSetStart == 2) || | |
2516 (IndexSetStride == 1 && IndexSetStart == 1), "just checking"); | |
2517 assert((IndexSetStride != 2) || (MinChunkSize % 2 == 0), | |
2518 "Some for-loops may be incorrectly initialized"); | |
2519 assert((IndexSetStride != 2) || (IndexSetSize % 2 == 1), | |
2520 "For-loops that iterate over IndexSet with stride 2 may be wrong"); | |
2521 } | |
2522 #endif | |
2523 | |
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2524 void CompactibleFreeListSpace::printFLCensus(size_t sweep_count) const { |
0 | 2525 assert_lock_strong(&_freelistLock); |
12
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2526 FreeList total; |
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2527 gclog_or_tty->print("end sweep# " SIZE_FORMAT "\n", sweep_count); |
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2528 FreeList::print_labels_on(gclog_or_tty, "size"); |
0 | 2529 size_t totalFree = 0; |
2530 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
2531 const FreeList *fl = &_indexedFreeList[i]; | |
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2532 totalFree += fl->count() * fl->size(); |
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2533 if (i % (40*IndexSetStride) == 0) { |
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2534 FreeList::print_labels_on(gclog_or_tty, "size"); |
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2535 } |
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2536 fl->print_on(gclog_or_tty); |
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2537 total.set_bfrSurp( total.bfrSurp() + fl->bfrSurp() ); |
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2538 total.set_surplus( total.surplus() + fl->surplus() ); |
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2539 total.set_desired( total.desired() + fl->desired() ); |
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2540 total.set_prevSweep( total.prevSweep() + fl->prevSweep() ); |
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2541 total.set_beforeSweep(total.beforeSweep() + fl->beforeSweep()); |
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2542 total.set_count( total.count() + fl->count() ); |
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2543 total.set_coalBirths( total.coalBirths() + fl->coalBirths() ); |
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2544 total.set_coalDeaths( total.coalDeaths() + fl->coalDeaths() ); |
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2545 total.set_splitBirths(total.splitBirths() + fl->splitBirths()); |
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2546 total.set_splitDeaths(total.splitDeaths() + fl->splitDeaths()); |
0 | 2547 } |
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2548 total.print_on(gclog_or_tty, "TOTAL"); |
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2549 gclog_or_tty->print_cr("Total free in indexed lists " |
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2550 SIZE_FORMAT " words", totalFree); |
0 | 2551 gclog_or_tty->print("growth: %8.5f deficit: %8.5f\n", |
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2552 (double)(total.splitBirths()+total.coalBirths()-total.splitDeaths()-total.coalDeaths())/ |
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2553 (total.prevSweep() != 0 ? (double)total.prevSweep() : 1.0), |
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2554 (double)(total.desired() - total.count())/(total.desired() != 0 ? (double)total.desired() : 1.0)); |
0 | 2555 _dictionary->printDictCensus(); |
2556 } | |
2557 | |
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2558 /////////////////////////////////////////////////////////////////////////// |
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2559 // CFLS_LAB |
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2560 /////////////////////////////////////////////////////////////////////////// |
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2561 |
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2562 #define VECTOR_257(x) \ |
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2563 /* 1 2 3 4 5 6 7 8 9 1x 11 12 13 14 15 16 17 18 19 2x 21 22 23 24 25 26 27 28 29 3x 31 32 */ \ |
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2564 { x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
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2565 x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
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2566 x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
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2567 x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
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2568 x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
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2569 x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
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2570 x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
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2571 x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
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2572 x } |
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2573 |
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2574 // Initialize with default setting of CMSParPromoteBlocksToClaim, _not_ |
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2575 // OldPLABSize, whose static default is different; if overridden at the |
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2576 // command-line, this will get reinitialized via a call to |
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2577 // modify_initialization() below. |
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2578 AdaptiveWeightedAverage CFLS_LAB::_blocks_to_claim[] = |
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2579 VECTOR_257(AdaptiveWeightedAverage(OldPLABWeight, (float)CMSParPromoteBlocksToClaim)); |
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2580 size_t CFLS_LAB::_global_num_blocks[] = VECTOR_257(0); |
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2581 int CFLS_LAB::_global_num_workers[] = VECTOR_257(0); |
0 | 2582 |
2583 CFLS_LAB::CFLS_LAB(CompactibleFreeListSpace* cfls) : | |
2584 _cfls(cfls) | |
2585 { | |
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2586 assert(CompactibleFreeListSpace::IndexSetSize == 257, "Modify VECTOR_257() macro above"); |
0 | 2587 for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
2588 i < CompactibleFreeListSpace::IndexSetSize; | |
2589 i += CompactibleFreeListSpace::IndexSetStride) { | |
2590 _indexedFreeList[i].set_size(i); | |
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2591 _num_blocks[i] = 0; |
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2592 } |
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2593 } |
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2594 |
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2595 static bool _CFLS_LAB_modified = false; |
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2596 |
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2597 void CFLS_LAB::modify_initialization(size_t n, unsigned wt) { |
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2598 assert(!_CFLS_LAB_modified, "Call only once"); |
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2599 _CFLS_LAB_modified = true; |
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2600 for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
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2601 i < CompactibleFreeListSpace::IndexSetSize; |
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2602 i += CompactibleFreeListSpace::IndexSetStride) { |
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2603 _blocks_to_claim[i].modify(n, wt, true /* force */); |
0 | 2604 } |
2605 } | |
2606 | |
2607 HeapWord* CFLS_LAB::alloc(size_t word_sz) { | |
2608 FreeChunk* res; | |
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2609 assert(word_sz == _cfls->adjustObjectSize(word_sz), "Error"); |
0 | 2610 if (word_sz >= CompactibleFreeListSpace::IndexSetSize) { |
2611 // This locking manages sync with other large object allocations. | |
2612 MutexLockerEx x(_cfls->parDictionaryAllocLock(), | |
2613 Mutex::_no_safepoint_check_flag); | |
2614 res = _cfls->getChunkFromDictionaryExact(word_sz); | |
2615 if (res == NULL) return NULL; | |
2616 } else { | |
2617 FreeList* fl = &_indexedFreeList[word_sz]; | |
2618 if (fl->count() == 0) { | |
2619 // Attempt to refill this local free list. | |
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2620 get_from_global_pool(word_sz, fl); |
0 | 2621 // If it didn't work, give up. |
2622 if (fl->count() == 0) return NULL; | |
2623 } | |
2624 res = fl->getChunkAtHead(); | |
2625 assert(res != NULL, "Why was count non-zero?"); | |
2626 } | |
2627 res->markNotFree(); | |
2628 assert(!res->isFree(), "shouldn't be marked free"); | |
187 | 2629 assert(oop(res)->klass_or_null() == NULL, "should look uninitialized"); |
0 | 2630 // mangle a just allocated object with a distinct pattern. |
2631 debug_only(res->mangleAllocated(word_sz)); | |
2632 return (HeapWord*)res; | |
2633 } | |
2634 | |
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2635 // Get a chunk of blocks of the right size and update related |
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2636 // book-keeping stats |
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2637 void CFLS_LAB::get_from_global_pool(size_t word_sz, FreeList* fl) { |
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2638 // Get the #blocks we want to claim |
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2639 size_t n_blks = (size_t)_blocks_to_claim[word_sz].average(); |
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2640 assert(n_blks > 0, "Error"); |
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2641 assert(ResizePLAB || n_blks == OldPLABSize, "Error"); |
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2642 // In some cases, when the application has a phase change, |
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2643 // there may be a sudden and sharp shift in the object survival |
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2644 // profile, and updating the counts at the end of a scavenge |
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2645 // may not be quick enough, giving rise to large scavenge pauses |
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2646 // during these phase changes. It is beneficial to detect such |
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2647 // changes on-the-fly during a scavenge and avoid such a phase-change |
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2648 // pothole. The following code is a heuristic attempt to do that. |
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2649 // It is protected by a product flag until we have gained |
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2650 // enough experience with this heuristic and fine-tuned its behaviour. |
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2651 // WARNING: This might increase fragmentation if we overreact to |
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2652 // small spikes, so some kind of historical smoothing based on |
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2653 // previous experience with the greater reactivity might be useful. |
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2654 // Lacking sufficient experience, CMSOldPLABResizeQuicker is disabled by |
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2655 // default. |
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2656 if (ResizeOldPLAB && CMSOldPLABResizeQuicker) { |
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2657 size_t multiple = _num_blocks[word_sz]/(CMSOldPLABToleranceFactor*CMSOldPLABNumRefills*n_blks); |
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2658 n_blks += CMSOldPLABReactivityFactor*multiple*n_blks; |
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2659 n_blks = MIN2(n_blks, CMSOldPLABMax); |
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2660 } |
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2661 assert(n_blks > 0, "Error"); |
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2662 _cfls->par_get_chunk_of_blocks(word_sz, n_blks, fl); |
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2663 // Update stats table entry for this block size |
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2664 _num_blocks[word_sz] += fl->count(); |
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2665 } |
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2666 |
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2667 void CFLS_LAB::compute_desired_plab_size() { |
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2668 for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
0 | 2669 i < CompactibleFreeListSpace::IndexSetSize; |
2670 i += CompactibleFreeListSpace::IndexSetStride) { | |
1145
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2671 assert((_global_num_workers[i] == 0) == (_global_num_blocks[i] == 0), |
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2672 "Counter inconsistency"); |
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2673 if (_global_num_workers[i] > 0) { |
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2674 // Need to smooth wrt historical average |
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2675 if (ResizeOldPLAB) { |
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2676 _blocks_to_claim[i].sample( |
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2677 MAX2((size_t)CMSOldPLABMin, |
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2678 MIN2((size_t)CMSOldPLABMax, |
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2679 _global_num_blocks[i]/(_global_num_workers[i]*CMSOldPLABNumRefills)))); |
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2680 } |
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2681 // Reset counters for next round |
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2682 _global_num_workers[i] = 0; |
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2683 _global_num_blocks[i] = 0; |
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2684 if (PrintOldPLAB) { |
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2685 gclog_or_tty->print_cr("[%d]: %d", i, (size_t)_blocks_to_claim[i].average()); |
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2686 } |
0 | 2687 } |
2688 } | |
2689 } | |
2690 | |
1145
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2691 void CFLS_LAB::retire(int tid) { |
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2692 // We run this single threaded with the world stopped; |
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2693 // so no need for locks and such. |
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2694 #define CFLS_LAB_PARALLEL_ACCESS 0 |
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2695 NOT_PRODUCT(Thread* t = Thread::current();) |
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2696 assert(Thread::current()->is_VM_thread(), "Error"); |
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2697 assert(CompactibleFreeListSpace::IndexSetStart == CompactibleFreeListSpace::IndexSetStride, |
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2698 "Will access to uninitialized slot below"); |
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2699 #if CFLS_LAB_PARALLEL_ACCESS |
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2700 for (size_t i = CompactibleFreeListSpace::IndexSetSize - 1; |
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2701 i > 0; |
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2702 i -= CompactibleFreeListSpace::IndexSetStride) { |
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2703 #else // CFLS_LAB_PARALLEL_ACCESS |
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2704 for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
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2705 i < CompactibleFreeListSpace::IndexSetSize; |
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2706 i += CompactibleFreeListSpace::IndexSetStride) { |
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2707 #endif // !CFLS_LAB_PARALLEL_ACCESS |
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2708 assert(_num_blocks[i] >= (size_t)_indexedFreeList[i].count(), |
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2709 "Can't retire more than what we obtained"); |
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2710 if (_num_blocks[i] > 0) { |
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2711 size_t num_retire = _indexedFreeList[i].count(); |
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2712 assert(_num_blocks[i] > num_retire, "Should have used at least one"); |
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2713 { |
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2714 #if CFLS_LAB_PARALLEL_ACCESS |
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2715 MutexLockerEx x(_cfls->_indexedFreeListParLocks[i], |
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2716 Mutex::_no_safepoint_check_flag); |
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2717 #endif // CFLS_LAB_PARALLEL_ACCESS |
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2718 // Update globals stats for num_blocks used |
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2719 _global_num_blocks[i] += (_num_blocks[i] - num_retire); |
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2720 _global_num_workers[i]++; |
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2721 assert(_global_num_workers[i] <= (ssize_t)ParallelGCThreads, "Too big"); |
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2722 if (num_retire > 0) { |
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2723 _cfls->_indexedFreeList[i].prepend(&_indexedFreeList[i]); |
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2724 // Reset this list. |
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2725 _indexedFreeList[i] = FreeList(); |
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2726 _indexedFreeList[i].set_size(i); |
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2727 } |
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2728 } |
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2729 if (PrintOldPLAB) { |
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2730 gclog_or_tty->print_cr("%d[%d]: %d/%d/%d", |
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2731 tid, i, num_retire, _num_blocks[i], (size_t)_blocks_to_claim[i].average()); |
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2732 } |
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2733 // Reset stats for next round |
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2734 _num_blocks[i] = 0; |
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2735 } |
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2736 } |
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|
2737 } |
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|
2738 |
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2739 void CompactibleFreeListSpace:: par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl) { |
0 | 2740 assert(fl->count() == 0, "Precondition."); |
2741 assert(word_sz < CompactibleFreeListSpace::IndexSetSize, | |
2742 "Precondition"); | |
2743 | |
1145
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2744 // We'll try all multiples of word_sz in the indexed set, starting with |
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2745 // word_sz itself and, if CMSSplitIndexedFreeListBlocks, try larger multiples, |
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2746 // then try getting a big chunk and splitting it. |
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|
2747 { |
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|
2748 bool found; |
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|
2749 int k; |
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2750 size_t cur_sz; |
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2751 for (k = 1, cur_sz = k * word_sz, found = false; |
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2752 (cur_sz < CompactibleFreeListSpace::IndexSetSize) && |
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2753 (CMSSplitIndexedFreeListBlocks || k <= 1); |
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2754 k++, cur_sz = k * word_sz) { |
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2755 FreeList fl_for_cur_sz; // Empty. |
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2756 fl_for_cur_sz.set_size(cur_sz); |
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2757 { |
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2758 MutexLockerEx x(_indexedFreeListParLocks[cur_sz], |
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2759 Mutex::_no_safepoint_check_flag); |
1716
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2760 FreeList* gfl = &_indexedFreeList[cur_sz]; |
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2761 if (gfl->count() != 0) { |
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2762 // nn is the number of chunks of size cur_sz that |
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2763 // we'd need to split k-ways each, in order to create |
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2764 // "n" chunks of size word_sz each. |
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2765 const size_t nn = MAX2(n/k, (size_t)1); |
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2766 gfl->getFirstNChunksFromList(nn, &fl_for_cur_sz); |
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2767 found = true; |
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2768 if (k > 1) { |
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2769 // Update split death stats for the cur_sz-size blocks list: |
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2770 // we increment the split death count by the number of blocks |
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2771 // we just took from the cur_sz-size blocks list and which |
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2772 // we will be splitting below. |
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2773 ssize_t deaths = gfl->splitDeaths() + |
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2774 fl_for_cur_sz.count(); |
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2775 gfl->set_splitDeaths(deaths); |
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2776 } |
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2777 } |
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2778 } |
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2779 // Now transfer fl_for_cur_sz to fl. Common case, we hope, is k = 1. |
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2780 if (found) { |
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2781 if (k == 1) { |
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2782 fl->prepend(&fl_for_cur_sz); |
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|
2783 } else { |
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2784 // Divide each block on fl_for_cur_sz up k ways. |
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2785 FreeChunk* fc; |
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2786 while ((fc = fl_for_cur_sz.getChunkAtHead()) != NULL) { |
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2787 // Must do this in reverse order, so that anybody attempting to |
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2788 // access the main chunk sees it as a single free block until we |
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2789 // change it. |
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2790 size_t fc_size = fc->size(); |
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2791 assert(fc->isFree(), "Error"); |
1145
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2792 for (int i = k-1; i >= 0; i--) { |
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2793 FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz); |
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2794 assert((i != 0) || |
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2795 ((fc == ffc) && ffc->isFree() && |
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2796 (ffc->size() == k*word_sz) && (fc_size == word_sz)), |
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|
2797 "Counting error"); |
1145
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2798 ffc->setSize(word_sz); |
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2799 ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. |
1145
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2800 ffc->linkNext(NULL); |
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2801 // Above must occur before BOT is updated below. |
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|
2802 OrderAccess::storestore(); |
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2803 // splitting from the right, fc_size == i * word_sz |
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2804 _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */); |
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2805 fc_size -= word_sz; |
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2806 assert(fc_size == i*word_sz, "Error"); |
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2807 _bt.verify_not_unallocated((HeapWord*)ffc, word_sz); |
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2808 _bt.verify_single_block((HeapWord*)fc, fc_size); |
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2809 _bt.verify_single_block((HeapWord*)ffc, word_sz); |
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|
2810 // Push this on "fl". |
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|
2811 fl->returnChunkAtHead(ffc); |
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|
2812 } |
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|
2813 // TRAP |
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|
2814 assert(fl->tail()->next() == NULL, "List invariant."); |
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|
2815 } |
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|
2816 } |
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|
2817 // Update birth stats for this block size. |
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2818 size_t num = fl->count(); |
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|
2819 MutexLockerEx x(_indexedFreeListParLocks[word_sz], |
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|
2820 Mutex::_no_safepoint_check_flag); |
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2821 ssize_t births = _indexedFreeList[word_sz].splitBirths() + num; |
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2822 _indexedFreeList[word_sz].set_splitBirths(births); |
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|
2823 return; |
0 | 2824 } |
2825 } | |
2826 } | |
2827 // Otherwise, we'll split a block from the dictionary. | |
2828 FreeChunk* fc = NULL; | |
2829 FreeChunk* rem_fc = NULL; | |
2830 size_t rem; | |
2831 { | |
2832 MutexLockerEx x(parDictionaryAllocLock(), | |
2833 Mutex::_no_safepoint_check_flag); | |
2834 while (n > 0) { | |
2835 fc = dictionary()->getChunk(MAX2(n * word_sz, | |
2836 _dictionary->minSize()), | |
2837 FreeBlockDictionary::atLeast); | |
2838 if (fc != NULL) { | |
1716
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|
2839 _bt.allocated((HeapWord*)fc, fc->size(), true /* reducing */); // update _unallocated_blk |
0 | 2840 dictionary()->dictCensusUpdate(fc->size(), |
2841 true /*split*/, | |
2842 false /*birth*/); | |
2843 break; | |
2844 } else { | |
2845 n--; | |
2846 } | |
2847 } | |
2848 if (fc == NULL) return; | |
1716
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|
2849 // Otherwise, split up that block. |
1145
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|
2850 assert((ssize_t)n >= 1, "Control point invariant"); |
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2851 assert(fc->isFree(), "Error: should be a free block"); |
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|
2852 _bt.verify_single_block((HeapWord*)fc, fc->size()); |
1145
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|
2853 const size_t nn = fc->size() / word_sz; |
0 | 2854 n = MIN2(nn, n); |
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|
2855 assert((ssize_t)n >= 1, "Control point invariant"); |
0 | 2856 rem = fc->size() - n * word_sz; |
2857 // If there is a remainder, and it's too small, allocate one fewer. | |
2858 if (rem > 0 && rem < MinChunkSize) { | |
2859 n--; rem += word_sz; | |
2860 } | |
1148
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|
2861 // Note that at this point we may have n == 0. |
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|
2862 assert((ssize_t)n >= 0, "Control point invariant"); |
05b775309e59
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jmasa
parents:
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|
2863 |
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|
2864 // If n is 0, the chunk fc that was found is not large |
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|
2865 // enough to leave a viable remainder. We are unable to |
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diff
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|
2866 // allocate even one block. Return fc to the |
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2867 // dictionary and return, leaving "fl" empty. |
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2868 if (n == 0) { |
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|
2869 returnChunkToDictionary(fc); |
1716
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2870 assert(fl->count() == 0, "We never allocated any blocks"); |
1148
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jmasa
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|
2871 return; |
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diff
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|
2872 } |
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|
2873 |
0 | 2874 // First return the remainder, if any. |
2875 // Note that we hold the lock until we decide if we're going to give | |
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|
2876 // back the remainder to the dictionary, since a concurrent allocation |
0 | 2877 // may otherwise see the heap as empty. (We're willing to take that |
2878 // hit if the block is a small block.) | |
2879 if (rem > 0) { | |
2880 size_t prefix_size = n * word_sz; | |
2881 rem_fc = (FreeChunk*)((HeapWord*)fc + prefix_size); | |
2882 rem_fc->setSize(rem); | |
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|
2883 rem_fc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. |
0 | 2884 rem_fc->linkNext(NULL); |
2885 // Above must occur before BOT is updated below. | |
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2886 assert((ssize_t)n > 0 && prefix_size > 0 && rem_fc > fc, "Error"); |
1716
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|
2887 OrderAccess::storestore(); |
0 | 2888 _bt.split_block((HeapWord*)fc, fc->size(), prefix_size); |
1716
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2889 assert(fc->isFree(), "Error"); |
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|
2890 fc->setSize(prefix_size); |
0 | 2891 if (rem >= IndexSetSize) { |
2892 returnChunkToDictionary(rem_fc); | |
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|
2893 dictionary()->dictCensusUpdate(rem, true /*split*/, true /*birth*/); |
0 | 2894 rem_fc = NULL; |
2895 } | |
2896 // Otherwise, return it to the small list below. | |
2897 } | |
2898 } | |
2899 if (rem_fc != NULL) { | |
2900 MutexLockerEx x(_indexedFreeListParLocks[rem], | |
2901 Mutex::_no_safepoint_check_flag); | |
2902 _bt.verify_not_unallocated((HeapWord*)rem_fc, rem_fc->size()); | |
2903 _indexedFreeList[rem].returnChunkAtHead(rem_fc); | |
2904 smallSplitBirth(rem); | |
2905 } | |
1145
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|
2906 assert((ssize_t)n > 0 && fc != NULL, "Consistency"); |
0 | 2907 // Now do the splitting up. |
2908 // Must do this in reverse order, so that anybody attempting to | |
2909 // access the main chunk sees it as a single free block until we | |
2910 // change it. | |
2911 size_t fc_size = n * word_sz; | |
2912 // All but first chunk in this loop | |
2913 for (ssize_t i = n-1; i > 0; i--) { | |
2914 FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz); | |
2915 ffc->setSize(word_sz); | |
1716
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2916 ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. |
0 | 2917 ffc->linkNext(NULL); |
2918 // Above must occur before BOT is updated below. | |
1716
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|
2919 OrderAccess::storestore(); |
0 | 2920 // splitting from the right, fc_size == (n - i + 1) * wordsize |
1716
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|
2921 _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */); |
0 | 2922 fc_size -= word_sz; |
2923 _bt.verify_not_unallocated((HeapWord*)ffc, ffc->size()); | |
2924 _bt.verify_single_block((HeapWord*)ffc, ffc->size()); | |
2925 _bt.verify_single_block((HeapWord*)fc, fc_size); | |
2926 // Push this on "fl". | |
2927 fl->returnChunkAtHead(ffc); | |
2928 } | |
2929 // First chunk | |
1716
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|
2930 assert(fc->isFree() && fc->size() == n*word_sz, "Error: should still be a free block"); |
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|
2931 // The blocks above should show their new sizes before the first block below |
0 | 2932 fc->setSize(word_sz); |
1716
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|
2933 fc->linkPrev(NULL); // idempotent wrt free-ness, see assert above |
0 | 2934 fc->linkNext(NULL); |
2935 _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); | |
2936 _bt.verify_single_block((HeapWord*)fc, fc->size()); | |
2937 fl->returnChunkAtHead(fc); | |
2938 | |
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2939 assert((ssize_t)n > 0 && (ssize_t)n == fl->count(), "Incorrect number of blocks"); |
0 | 2940 { |
1145
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2941 // Update the stats for this block size. |
0 | 2942 MutexLockerEx x(_indexedFreeListParLocks[word_sz], |
2943 Mutex::_no_safepoint_check_flag); | |
1145
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2944 const ssize_t births = _indexedFreeList[word_sz].splitBirths() + n; |
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2945 _indexedFreeList[word_sz].set_splitBirths(births); |
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2946 // ssize_t new_surplus = _indexedFreeList[word_sz].surplus() + n; |
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2947 // _indexedFreeList[word_sz].set_surplus(new_surplus); |
0 | 2948 } |
2949 | |
2950 // TRAP | |
2951 assert(fl->tail()->next() == NULL, "List invariant."); | |
2952 } | |
2953 | |
2954 // Set up the space's par_seq_tasks structure for work claiming | |
2955 // for parallel rescan. See CMSParRemarkTask where this is currently used. | |
2956 // XXX Need to suitably abstract and generalize this and the next | |
2957 // method into one. | |
2958 void | |
2959 CompactibleFreeListSpace:: | |
2960 initialize_sequential_subtasks_for_rescan(int n_threads) { | |
2961 // The "size" of each task is fixed according to rescan_task_size. | |
2962 assert(n_threads > 0, "Unexpected n_threads argument"); | |
2963 const size_t task_size = rescan_task_size(); | |
2964 size_t n_tasks = (used_region().word_size() + task_size - 1)/task_size; | |
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2965 assert((n_tasks == 0) == used_region().is_empty(), "n_tasks incorrect"); |
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2966 assert(n_tasks == 0 || |
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2967 ((used_region().start() + (n_tasks - 1)*task_size < used_region().end()) && |
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2968 (used_region().start() + n_tasks*task_size >= used_region().end())), |
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2969 "n_tasks calculation incorrect"); |
0 | 2970 SequentialSubTasksDone* pst = conc_par_seq_tasks(); |
2971 assert(!pst->valid(), "Clobbering existing data?"); | |
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2972 // Sets the condition for completion of the subtask (how many threads |
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2973 // need to finish in order to be done). |
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2974 pst->set_n_threads(n_threads); |
0 | 2975 pst->set_n_tasks((int)n_tasks); |
2976 } | |
2977 | |
2978 // Set up the space's par_seq_tasks structure for work claiming | |
2979 // for parallel concurrent marking. See CMSConcMarkTask where this is currently used. | |
2980 void | |
2981 CompactibleFreeListSpace:: | |
2982 initialize_sequential_subtasks_for_marking(int n_threads, | |
2983 HeapWord* low) { | |
2984 // The "size" of each task is fixed according to rescan_task_size. | |
2985 assert(n_threads > 0, "Unexpected n_threads argument"); | |
2986 const size_t task_size = marking_task_size(); | |
2987 assert(task_size > CardTableModRefBS::card_size_in_words && | |
2988 (task_size % CardTableModRefBS::card_size_in_words == 0), | |
2989 "Otherwise arithmetic below would be incorrect"); | |
2990 MemRegion span = _gen->reserved(); | |
2991 if (low != NULL) { | |
2992 if (span.contains(low)) { | |
2993 // Align low down to a card boundary so that | |
2994 // we can use block_offset_careful() on span boundaries. | |
2995 HeapWord* aligned_low = (HeapWord*)align_size_down((uintptr_t)low, | |
2996 CardTableModRefBS::card_size); | |
2997 // Clip span prefix at aligned_low | |
2998 span = span.intersection(MemRegion(aligned_low, span.end())); | |
2999 } else if (low > span.end()) { | |
3000 span = MemRegion(low, low); // Null region | |
3001 } // else use entire span | |
3002 } | |
3003 assert(span.is_empty() || | |
3004 ((uintptr_t)span.start() % CardTableModRefBS::card_size == 0), | |
3005 "span should start at a card boundary"); | |
3006 size_t n_tasks = (span.word_size() + task_size - 1)/task_size; | |
3007 assert((n_tasks == 0) == span.is_empty(), "Inconsistency"); | |
3008 assert(n_tasks == 0 || | |
3009 ((span.start() + (n_tasks - 1)*task_size < span.end()) && | |
3010 (span.start() + n_tasks*task_size >= span.end())), | |
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3011 "n_tasks calculation incorrect"); |
0 | 3012 SequentialSubTasksDone* pst = conc_par_seq_tasks(); |
3013 assert(!pst->valid(), "Clobbering existing data?"); | |
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3014 // Sets the condition for completion of the subtask (how many threads |
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3015 // need to finish in order to be done). |
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3016 pst->set_n_threads(n_threads); |
0 | 3017 pst->set_n_tasks((int)n_tasks); |
3018 } |