Mercurial > hg > graal-jvmci-8
annotate src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp @ 1951:899bbbdcb6ea
6997298: fatal error: must own lock CMS_markBitMap_lock during heap dump
Summary: Since we are at a stop-world pause, the existing CMS-phase checks are sufficient for safety, and the locking check can be safely elided. Elaborated documentation comment to the case where class unloading and verification are disabled, and the query happens when we aren't in the sweeping phase, where the answer "false" would be (almost everywhere) too pessimistic.
Reviewed-by: jmasa, johnc, tonyp
| author | ysr |
|---|---|
| date | Fri, 05 Nov 2010 13:20:37 -0700 |
| parents | 8b10f48633dc |
| children | 4df7f8cba524 |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2001, 2010, 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 | |
| 25 # include "incls/_precompiled.incl" | |
| 26 # include "incls/_compactibleFreeListSpace.cpp.incl" | |
| 27 | |
| 28 ///////////////////////////////////////////////////////////////////////// | |
| 29 //// CompactibleFreeListSpace | |
| 30 ///////////////////////////////////////////////////////////////////////// | |
| 31 | |
| 32 // highest ranked free list lock rank | |
| 33 int CompactibleFreeListSpace::_lockRank = Mutex::leaf + 3; | |
| 34 | |
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35 // Defaults are 0 so things will break badly if incorrectly initialized. |
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36 int CompactibleFreeListSpace::IndexSetStart = 0; |
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37 int CompactibleFreeListSpace::IndexSetStride = 0; |
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38 |
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39 size_t MinChunkSize = 0; |
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40 |
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41 void CompactibleFreeListSpace::set_cms_values() { |
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42 // Set CMS global values |
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43 assert(MinChunkSize == 0, "already set"); |
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44 #define numQuanta(x,y) ((x+y-1)/y) |
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45 MinChunkSize = numQuanta(sizeof(FreeChunk), MinObjAlignmentInBytes) * MinObjAlignment; |
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46 |
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47 assert(IndexSetStart == 0 && IndexSetStride == 0, "already set"); |
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48 IndexSetStart = MinObjAlignment; |
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49 IndexSetStride = MinObjAlignment; |
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50 } |
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51 |
| 0 | 52 // Constructor |
| 53 CompactibleFreeListSpace::CompactibleFreeListSpace(BlockOffsetSharedArray* bs, | |
| 54 MemRegion mr, bool use_adaptive_freelists, | |
| 55 FreeBlockDictionary::DictionaryChoice dictionaryChoice) : | |
| 56 _dictionaryChoice(dictionaryChoice), | |
| 57 _adaptive_freelists(use_adaptive_freelists), | |
| 58 _bt(bs, mr), | |
| 59 // free list locks are in the range of values taken by _lockRank | |
| 60 // This range currently is [_leaf+2, _leaf+3] | |
| 61 // Note: this requires that CFLspace c'tors | |
| 62 // are called serially in the order in which the locks are | |
| 63 // are acquired in the program text. This is true today. | |
| 64 _freelistLock(_lockRank--, "CompactibleFreeListSpace._lock", true), | |
| 65 _parDictionaryAllocLock(Mutex::leaf - 1, // == rank(ExpandHeap_lock) - 1 | |
| 66 "CompactibleFreeListSpace._dict_par_lock", true), | |
| 67 _rescan_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord * | |
| 68 CMSRescanMultiple), | |
| 69 _marking_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord * | |
| 70 CMSConcMarkMultiple), | |
| 71 _collector(NULL) | |
| 72 { | |
| 73 _bt.set_space(this); | |
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74 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle); |
| 0 | 75 // We have all of "mr", all of which we place in the dictionary |
| 76 // as one big chunk. We'll need to decide here which of several | |
| 77 // possible alternative dictionary implementations to use. For | |
| 78 // now the choice is easy, since we have only one working | |
| 79 // implementation, namely, the simple binary tree (splaying | |
| 80 // temporarily disabled). | |
| 81 switch (dictionaryChoice) { | |
| 82 case FreeBlockDictionary::dictionarySplayTree: | |
| 83 case FreeBlockDictionary::dictionarySkipList: | |
| 84 default: | |
| 85 warning("dictionaryChoice: selected option not understood; using" | |
| 86 " default BinaryTreeDictionary implementation instead."); | |
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87 case FreeBlockDictionary::dictionaryBinaryTree: |
| 0 | 88 _dictionary = new BinaryTreeDictionary(mr); |
| 89 break; | |
| 90 } | |
| 91 assert(_dictionary != NULL, "CMS dictionary initialization"); | |
| 92 // The indexed free lists are initially all empty and are lazily | |
| 93 // filled in on demand. Initialize the array elements to NULL. | |
| 94 initializeIndexedFreeListArray(); | |
| 95 | |
| 96 // Not using adaptive free lists assumes that allocation is first | |
| 97 // from the linAB's. Also a cms perm gen which can be compacted | |
| 98 // has to have the klass's klassKlass allocated at a lower | |
| 99 // address in the heap than the klass so that the klassKlass is | |
| 100 // moved to its new location before the klass is moved. | |
| 101 // Set the _refillSize for the linear allocation blocks | |
| 102 if (!use_adaptive_freelists) { | |
| 103 FreeChunk* fc = _dictionary->getChunk(mr.word_size()); | |
| 104 // The small linAB initially has all the space and will allocate | |
| 105 // a chunk of any size. | |
| 106 HeapWord* addr = (HeapWord*) fc; | |
| 107 _smallLinearAllocBlock.set(addr, fc->size() , | |
| 108 1024*SmallForLinearAlloc, fc->size()); | |
| 109 // Note that _unallocated_block is not updated here. | |
| 110 // Allocations from the linear allocation block should | |
| 111 // update it. | |
| 112 } else { | |
| 113 _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc, | |
| 114 SmallForLinearAlloc); | |
| 115 } | |
| 116 // CMSIndexedFreeListReplenish should be at least 1 | |
| 117 CMSIndexedFreeListReplenish = MAX2((uintx)1, CMSIndexedFreeListReplenish); | |
| 118 _promoInfo.setSpace(this); | |
| 119 if (UseCMSBestFit) { | |
| 120 _fitStrategy = FreeBlockBestFitFirst; | |
| 121 } else { | |
| 122 _fitStrategy = FreeBlockStrategyNone; | |
| 123 } | |
| 124 checkFreeListConsistency(); | |
| 125 | |
| 126 // Initialize locks for parallel case. | |
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127 |
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128 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 129 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
| 130 _indexedFreeListParLocks[i] = new Mutex(Mutex::leaf - 1, // == ExpandHeap_lock - 1 | |
| 131 "a freelist par lock", | |
| 132 true); | |
| 133 if (_indexedFreeListParLocks[i] == NULL) | |
| 134 vm_exit_during_initialization("Could not allocate a par lock"); | |
| 135 DEBUG_ONLY( | |
| 136 _indexedFreeList[i].set_protecting_lock(_indexedFreeListParLocks[i]); | |
| 137 ) | |
| 138 } | |
| 139 _dictionary->set_par_lock(&_parDictionaryAllocLock); | |
| 140 } | |
| 141 } | |
| 142 | |
| 143 // Like CompactibleSpace forward() but always calls cross_threshold() to | |
| 144 // update the block offset table. Removed initialize_threshold call because | |
| 145 // CFLS does not use a block offset array for contiguous spaces. | |
| 146 HeapWord* CompactibleFreeListSpace::forward(oop q, size_t size, | |
| 147 CompactPoint* cp, HeapWord* compact_top) { | |
| 148 // q is alive | |
| 149 // First check if we should switch compaction space | |
| 150 assert(this == cp->space, "'this' should be current compaction space."); | |
| 151 size_t compaction_max_size = pointer_delta(end(), compact_top); | |
| 152 assert(adjustObjectSize(size) == cp->space->adjust_object_size_v(size), | |
| 153 "virtual adjustObjectSize_v() method is not correct"); | |
| 154 size_t adjusted_size = adjustObjectSize(size); | |
| 155 assert(compaction_max_size >= MinChunkSize || compaction_max_size == 0, | |
| 156 "no small fragments allowed"); | |
| 157 assert(minimum_free_block_size() == MinChunkSize, | |
| 158 "for de-virtualized reference below"); | |
| 159 // Can't leave a nonzero size, residual fragment smaller than MinChunkSize | |
| 160 if (adjusted_size + MinChunkSize > compaction_max_size && | |
| 161 adjusted_size != compaction_max_size) { | |
| 162 do { | |
| 163 // switch to next compaction space | |
| 164 cp->space->set_compaction_top(compact_top); | |
| 165 cp->space = cp->space->next_compaction_space(); | |
| 166 if (cp->space == NULL) { | |
| 167 cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen); | |
| 168 assert(cp->gen != NULL, "compaction must succeed"); | |
| 169 cp->space = cp->gen->first_compaction_space(); | |
| 170 assert(cp->space != NULL, "generation must have a first compaction space"); | |
| 171 } | |
| 172 compact_top = cp->space->bottom(); | |
| 173 cp->space->set_compaction_top(compact_top); | |
| 174 // The correct adjusted_size may not be the same as that for this method | |
| 175 // (i.e., cp->space may no longer be "this" so adjust the size again. | |
| 176 // Use the virtual method which is not used above to save the virtual | |
| 177 // dispatch. | |
| 178 adjusted_size = cp->space->adjust_object_size_v(size); | |
| 179 compaction_max_size = pointer_delta(cp->space->end(), compact_top); | |
| 180 assert(cp->space->minimum_free_block_size() == 0, "just checking"); | |
| 181 } while (adjusted_size > compaction_max_size); | |
| 182 } | |
| 183 | |
| 184 // store the forwarding pointer into the mark word | |
| 185 if ((HeapWord*)q != compact_top) { | |
| 186 q->forward_to(oop(compact_top)); | |
| 187 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark"); | |
| 188 } else { | |
| 189 // if the object isn't moving we can just set the mark to the default | |
| 190 // mark and handle it specially later on. | |
| 191 q->init_mark(); | |
| 192 assert(q->forwardee() == NULL, "should be forwarded to NULL"); | |
| 193 } | |
| 194 | |
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195 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(q, adjusted_size)); |
| 0 | 196 compact_top += adjusted_size; |
| 197 | |
| 198 // we need to update the offset table so that the beginnings of objects can be | |
| 199 // found during scavenge. Note that we are updating the offset table based on | |
| 200 // where the object will be once the compaction phase finishes. | |
| 201 | |
| 202 // Always call cross_threshold(). A contiguous space can only call it when | |
| 203 // the compaction_top exceeds the current threshold but not for an | |
| 204 // non-contiguous space. | |
| 205 cp->threshold = | |
| 206 cp->space->cross_threshold(compact_top - adjusted_size, compact_top); | |
| 207 return compact_top; | |
| 208 } | |
| 209 | |
| 210 // A modified copy of OffsetTableContigSpace::cross_threshold() with _offsets -> _bt | |
| 211 // and use of single_block instead of alloc_block. The name here is not really | |
| 212 // appropriate - maybe a more general name could be invented for both the | |
| 213 // contiguous and noncontiguous spaces. | |
| 214 | |
| 215 HeapWord* CompactibleFreeListSpace::cross_threshold(HeapWord* start, HeapWord* the_end) { | |
| 216 _bt.single_block(start, the_end); | |
| 217 return end(); | |
| 218 } | |
| 219 | |
| 220 // Initialize them to NULL. | |
| 221 void CompactibleFreeListSpace::initializeIndexedFreeListArray() { | |
| 222 for (size_t i = 0; i < IndexSetSize; i++) { | |
| 223 // Note that on platforms where objects are double word aligned, | |
| 224 // the odd array elements are not used. It is convenient, however, | |
| 225 // to map directly from the object size to the array element. | |
| 226 _indexedFreeList[i].reset(IndexSetSize); | |
| 227 _indexedFreeList[i].set_size(i); | |
| 228 assert(_indexedFreeList[i].count() == 0, "reset check failed"); | |
| 229 assert(_indexedFreeList[i].head() == NULL, "reset check failed"); | |
| 230 assert(_indexedFreeList[i].tail() == NULL, "reset check failed"); | |
| 231 assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed"); | |
| 232 } | |
| 233 } | |
| 234 | |
| 235 void CompactibleFreeListSpace::resetIndexedFreeListArray() { | |
| 236 for (int i = 1; i < IndexSetSize; i++) { | |
| 237 assert(_indexedFreeList[i].size() == (size_t) i, | |
| 238 "Indexed free list sizes are incorrect"); | |
| 239 _indexedFreeList[i].reset(IndexSetSize); | |
| 240 assert(_indexedFreeList[i].count() == 0, "reset check failed"); | |
| 241 assert(_indexedFreeList[i].head() == NULL, "reset check failed"); | |
| 242 assert(_indexedFreeList[i].tail() == NULL, "reset check failed"); | |
| 243 assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed"); | |
| 244 } | |
| 245 } | |
| 246 | |
| 247 void CompactibleFreeListSpace::reset(MemRegion mr) { | |
| 248 resetIndexedFreeListArray(); | |
| 249 dictionary()->reset(); | |
| 250 if (BlockOffsetArrayUseUnallocatedBlock) { | |
| 251 assert(end() == mr.end(), "We are compacting to the bottom of CMS gen"); | |
| 252 // Everything's allocated until proven otherwise. | |
| 253 _bt.set_unallocated_block(end()); | |
| 254 } | |
| 255 if (!mr.is_empty()) { | |
| 256 assert(mr.word_size() >= MinChunkSize, "Chunk size is too small"); | |
| 257 _bt.single_block(mr.start(), mr.word_size()); | |
| 258 FreeChunk* fc = (FreeChunk*) mr.start(); | |
| 259 fc->setSize(mr.word_size()); | |
| 260 if (mr.word_size() >= IndexSetSize ) { | |
| 261 returnChunkToDictionary(fc); | |
| 262 } else { | |
| 263 _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); | |
| 264 _indexedFreeList[mr.word_size()].returnChunkAtHead(fc); | |
| 265 } | |
| 266 } | |
| 267 _promoInfo.reset(); | |
| 268 _smallLinearAllocBlock._ptr = NULL; | |
| 269 _smallLinearAllocBlock._word_size = 0; | |
| 270 } | |
| 271 | |
| 272 void CompactibleFreeListSpace::reset_after_compaction() { | |
| 273 // Reset the space to the new reality - one free chunk. | |
| 274 MemRegion mr(compaction_top(), end()); | |
| 275 reset(mr); | |
| 276 // Now refill the linear allocation block(s) if possible. | |
| 277 if (_adaptive_freelists) { | |
| 278 refillLinearAllocBlocksIfNeeded(); | |
| 279 } else { | |
| 280 // Place as much of mr in the linAB as we can get, | |
| 281 // provided it was big enough to go into the dictionary. | |
| 282 FreeChunk* fc = dictionary()->findLargestDict(); | |
| 283 if (fc != NULL) { | |
| 284 assert(fc->size() == mr.word_size(), | |
| 285 "Why was the chunk broken up?"); | |
| 286 removeChunkFromDictionary(fc); | |
| 287 HeapWord* addr = (HeapWord*) fc; | |
| 288 _smallLinearAllocBlock.set(addr, fc->size() , | |
| 289 1024*SmallForLinearAlloc, fc->size()); | |
| 290 // Note that _unallocated_block is not updated here. | |
| 291 } | |
| 292 } | |
| 293 } | |
| 294 | |
| 295 // Walks the entire dictionary, returning a coterminal | |
| 296 // chunk, if it exists. Use with caution since it involves | |
| 297 // a potentially complete walk of a potentially large tree. | |
| 298 FreeChunk* CompactibleFreeListSpace::find_chunk_at_end() { | |
| 299 | |
| 300 assert_lock_strong(&_freelistLock); | |
| 301 | |
| 302 return dictionary()->find_chunk_ends_at(end()); | |
| 303 } | |
| 304 | |
| 305 | |
| 306 #ifndef PRODUCT | |
| 307 void CompactibleFreeListSpace::initializeIndexedFreeListArrayReturnedBytes() { | |
| 308 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
| 309 _indexedFreeList[i].allocation_stats()->set_returnedBytes(0); | |
| 310 } | |
| 311 } | |
| 312 | |
| 313 size_t CompactibleFreeListSpace::sumIndexedFreeListArrayReturnedBytes() { | |
| 314 size_t sum = 0; | |
| 315 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
| 316 sum += _indexedFreeList[i].allocation_stats()->returnedBytes(); | |
| 317 } | |
| 318 return sum; | |
| 319 } | |
| 320 | |
| 321 size_t CompactibleFreeListSpace::totalCountInIndexedFreeLists() const { | |
| 322 size_t count = 0; | |
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323 for (int i = (int)MinChunkSize; i < IndexSetSize; i++) { |
| 0 | 324 debug_only( |
| 325 ssize_t total_list_count = 0; | |
| 326 for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; | |
| 327 fc = fc->next()) { | |
| 328 total_list_count++; | |
| 329 } | |
| 330 assert(total_list_count == _indexedFreeList[i].count(), | |
| 331 "Count in list is incorrect"); | |
| 332 ) | |
| 333 count += _indexedFreeList[i].count(); | |
| 334 } | |
| 335 return count; | |
| 336 } | |
| 337 | |
| 338 size_t CompactibleFreeListSpace::totalCount() { | |
| 339 size_t num = totalCountInIndexedFreeLists(); | |
| 340 num += dictionary()->totalCount(); | |
| 341 if (_smallLinearAllocBlock._word_size != 0) { | |
| 342 num++; | |
| 343 } | |
| 344 return num; | |
| 345 } | |
| 346 #endif | |
| 347 | |
| 348 bool CompactibleFreeListSpace::is_free_block(const HeapWord* p) const { | |
| 349 FreeChunk* fc = (FreeChunk*) p; | |
| 350 return fc->isFree(); | |
| 351 } | |
| 352 | |
| 353 size_t CompactibleFreeListSpace::used() const { | |
| 354 return capacity() - free(); | |
| 355 } | |
| 356 | |
| 357 size_t CompactibleFreeListSpace::free() const { | |
| 358 // "MT-safe, but not MT-precise"(TM), if you will: i.e. | |
| 359 // if you do this while the structures are in flux you | |
| 360 // may get an approximate answer only; for instance | |
| 361 // because there is concurrent allocation either | |
| 362 // directly by mutators or for promotion during a GC. | |
| 363 // It's "MT-safe", however, in the sense that you are guaranteed | |
| 364 // not to crash and burn, for instance, because of walking | |
| 365 // pointers that could disappear as you were walking them. | |
| 366 // The approximation is because the various components | |
| 367 // that are read below are not read atomically (and | |
| 368 // further the computation of totalSizeInIndexedFreeLists() | |
| 369 // is itself a non-atomic computation. The normal use of | |
| 370 // this is during a resize operation at the end of GC | |
| 371 // and at that time you are guaranteed to get the | |
| 372 // correct actual value. However, for instance, this is | |
| 373 // also read completely asynchronously by the "perf-sampler" | |
| 374 // that supports jvmstat, and you are apt to see the values | |
| 375 // flicker in such cases. | |
| 376 assert(_dictionary != NULL, "No _dictionary?"); | |
| 377 return (_dictionary->totalChunkSize(DEBUG_ONLY(freelistLock())) + | |
| 378 totalSizeInIndexedFreeLists() + | |
| 379 _smallLinearAllocBlock._word_size) * HeapWordSize; | |
| 380 } | |
| 381 | |
| 382 size_t CompactibleFreeListSpace::max_alloc_in_words() const { | |
| 383 assert(_dictionary != NULL, "No _dictionary?"); | |
| 384 assert_locked(); | |
| 385 size_t res = _dictionary->maxChunkSize(); | |
| 386 res = MAX2(res, MIN2(_smallLinearAllocBlock._word_size, | |
| 387 (size_t) SmallForLinearAlloc - 1)); | |
| 388 // XXX the following could potentially be pretty slow; | |
| 389 // should one, pesimally for the rare cases when res | |
| 390 // caclulated above is less than IndexSetSize, | |
| 391 // just return res calculated above? My reasoning was that | |
| 392 // those cases will be so rare that the extra time spent doesn't | |
| 393 // really matter.... | |
| 394 // Note: do not change the loop test i >= res + IndexSetStride | |
| 395 // to i > res below, because i is unsigned and res may be zero. | |
| 396 for (size_t i = IndexSetSize - 1; i >= res + IndexSetStride; | |
| 397 i -= IndexSetStride) { | |
| 398 if (_indexedFreeList[i].head() != NULL) { | |
| 399 assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList"); | |
| 400 return i; | |
| 401 } | |
| 402 } | |
| 403 return res; | |
| 404 } | |
| 405 | |
|
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406 void LinearAllocBlock::print_on(outputStream* st) const { |
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407 st->print_cr(" LinearAllocBlock: ptr = " PTR_FORMAT ", word_size = " SIZE_FORMAT |
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408 ", refillsize = " SIZE_FORMAT ", allocation_size_limit = " SIZE_FORMAT, |
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409 _ptr, _word_size, _refillSize, _allocation_size_limit); |
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410 } |
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411 |
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412 void CompactibleFreeListSpace::print_on(outputStream* st) const { |
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413 st->print_cr("COMPACTIBLE FREELIST SPACE"); |
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414 st->print_cr(" Space:"); |
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415 Space::print_on(st); |
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416 |
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417 st->print_cr("promoInfo:"); |
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418 _promoInfo.print_on(st); |
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419 |
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420 st->print_cr("_smallLinearAllocBlock"); |
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421 _smallLinearAllocBlock.print_on(st); |
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422 |
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423 // dump_memory_block(_smallLinearAllocBlock->_ptr, 128); |
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424 |
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425 st->print_cr(" _fitStrategy = %s, _adaptive_freelists = %s", |
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426 _fitStrategy?"true":"false", _adaptive_freelists?"true":"false"); |
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427 } |
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428 |
|
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429 void CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st) |
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430 const { |
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431 reportIndexedFreeListStatistics(); |
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432 gclog_or_tty->print_cr("Layout of Indexed Freelists"); |
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433 gclog_or_tty->print_cr("---------------------------"); |
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434 FreeList::print_labels_on(st, "size"); |
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435 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
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436 _indexedFreeList[i].print_on(gclog_or_tty); |
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437 for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; |
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438 fc = fc->next()) { |
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439 gclog_or_tty->print_cr("\t[" PTR_FORMAT "," PTR_FORMAT ") %s", |
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440 fc, (HeapWord*)fc + i, |
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441 fc->cantCoalesce() ? "\t CC" : ""); |
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442 } |
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443 } |
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444 } |
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445 |
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446 void CompactibleFreeListSpace::print_promo_info_blocks(outputStream* st) |
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447 const { |
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448 _promoInfo.print_on(st); |
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449 } |
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450 |
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451 void CompactibleFreeListSpace::print_dictionary_free_lists(outputStream* st) |
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452 const { |
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453 _dictionary->reportStatistics(); |
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454 st->print_cr("Layout of Freelists in Tree"); |
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455 st->print_cr("---------------------------"); |
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456 _dictionary->print_free_lists(st); |
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457 } |
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458 |
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459 class BlkPrintingClosure: public BlkClosure { |
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460 const CMSCollector* _collector; |
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461 const CompactibleFreeListSpace* _sp; |
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462 const CMSBitMap* _live_bit_map; |
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463 const bool _post_remark; |
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464 outputStream* _st; |
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465 public: |
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466 BlkPrintingClosure(const CMSCollector* collector, |
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467 const CompactibleFreeListSpace* sp, |
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468 const CMSBitMap* live_bit_map, |
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469 outputStream* st): |
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470 _collector(collector), |
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471 _sp(sp), |
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472 _live_bit_map(live_bit_map), |
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473 _post_remark(collector->abstract_state() > CMSCollector::FinalMarking), |
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474 _st(st) { } |
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475 size_t do_blk(HeapWord* addr); |
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476 }; |
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477 |
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478 size_t BlkPrintingClosure::do_blk(HeapWord* addr) { |
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479 size_t sz = _sp->block_size_no_stall(addr, _collector); |
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480 assert(sz != 0, "Should always be able to compute a size"); |
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481 if (_sp->block_is_obj(addr)) { |
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482 const bool dead = _post_remark && !_live_bit_map->isMarked(addr); |
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483 _st->print_cr(PTR_FORMAT ": %s object of size " SIZE_FORMAT "%s", |
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484 addr, |
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485 dead ? "dead" : "live", |
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486 sz, |
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487 (!dead && CMSPrintObjectsInDump) ? ":" : "."); |
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488 if (CMSPrintObjectsInDump && !dead) { |
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489 oop(addr)->print_on(_st); |
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490 _st->print_cr("--------------------------------------"); |
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491 } |
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492 } else { // free block |
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493 _st->print_cr(PTR_FORMAT ": free block of size " SIZE_FORMAT "%s", |
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494 addr, sz, CMSPrintChunksInDump ? ":" : "."); |
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495 if (CMSPrintChunksInDump) { |
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496 ((FreeChunk*)addr)->print_on(_st); |
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497 _st->print_cr("--------------------------------------"); |
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498 } |
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499 } |
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500 return sz; |
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501 } |
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502 |
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503 void CompactibleFreeListSpace::dump_at_safepoint_with_locks(CMSCollector* c, |
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504 outputStream* st) { |
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505 st->print_cr("\n========================="); |
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506 st->print_cr("Block layout in CMS Heap:"); |
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507 st->print_cr("========================="); |
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508 BlkPrintingClosure bpcl(c, this, c->markBitMap(), st); |
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509 blk_iterate(&bpcl); |
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510 |
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511 st->print_cr("\n======================================="); |
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512 st->print_cr("Order & Layout of Promotion Info Blocks"); |
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513 st->print_cr("======================================="); |
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514 print_promo_info_blocks(st); |
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515 |
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516 st->print_cr("\n==========================="); |
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517 st->print_cr("Order of Indexed Free Lists"); |
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518 st->print_cr("========================="); |
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519 print_indexed_free_lists(st); |
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520 |
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521 st->print_cr("\n================================="); |
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522 st->print_cr("Order of Free Lists in Dictionary"); |
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523 st->print_cr("================================="); |
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524 print_dictionary_free_lists(st); |
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525 } |
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526 |
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527 |
| 0 | 528 void CompactibleFreeListSpace::reportFreeListStatistics() const { |
| 529 assert_lock_strong(&_freelistLock); | |
| 530 assert(PrintFLSStatistics != 0, "Reporting error"); | |
| 531 _dictionary->reportStatistics(); | |
| 532 if (PrintFLSStatistics > 1) { | |
| 533 reportIndexedFreeListStatistics(); | |
| 534 size_t totalSize = totalSizeInIndexedFreeLists() + | |
| 535 _dictionary->totalChunkSize(DEBUG_ONLY(freelistLock())); | |
| 536 gclog_or_tty->print(" free=%ld frag=%1.4f\n", totalSize, flsFrag()); | |
| 537 } | |
| 538 } | |
| 539 | |
| 540 void CompactibleFreeListSpace::reportIndexedFreeListStatistics() const { | |
| 541 assert_lock_strong(&_freelistLock); | |
| 542 gclog_or_tty->print("Statistics for IndexedFreeLists:\n" | |
| 543 "--------------------------------\n"); | |
| 544 size_t totalSize = totalSizeInIndexedFreeLists(); | |
| 545 size_t freeBlocks = numFreeBlocksInIndexedFreeLists(); | |
| 546 gclog_or_tty->print("Total Free Space: %d\n", totalSize); | |
| 547 gclog_or_tty->print("Max Chunk Size: %d\n", maxChunkSizeInIndexedFreeLists()); | |
| 548 gclog_or_tty->print("Number of Blocks: %d\n", freeBlocks); | |
| 549 if (freeBlocks != 0) { | |
| 550 gclog_or_tty->print("Av. Block Size: %d\n", totalSize/freeBlocks); | |
| 551 } | |
| 552 } | |
| 553 | |
| 554 size_t CompactibleFreeListSpace::numFreeBlocksInIndexedFreeLists() const { | |
| 555 size_t res = 0; | |
| 556 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
| 557 debug_only( | |
| 558 ssize_t recount = 0; | |
| 559 for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; | |
| 560 fc = fc->next()) { | |
| 561 recount += 1; | |
| 562 } | |
| 563 assert(recount == _indexedFreeList[i].count(), | |
| 564 "Incorrect count in list"); | |
| 565 ) | |
| 566 res += _indexedFreeList[i].count(); | |
| 567 } | |
| 568 return res; | |
| 569 } | |
| 570 | |
| 571 size_t CompactibleFreeListSpace::maxChunkSizeInIndexedFreeLists() const { | |
| 572 for (size_t i = IndexSetSize - 1; i != 0; i -= IndexSetStride) { | |
| 573 if (_indexedFreeList[i].head() != NULL) { | |
| 574 assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList"); | |
| 575 return (size_t)i; | |
| 576 } | |
| 577 } | |
| 578 return 0; | |
| 579 } | |
| 580 | |
| 581 void CompactibleFreeListSpace::set_end(HeapWord* value) { | |
| 582 HeapWord* prevEnd = end(); | |
| 583 assert(prevEnd != value, "unnecessary set_end call"); | |
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584 assert(prevEnd == NULL || !BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(), |
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585 "New end is below unallocated block"); |
| 0 | 586 _end = value; |
| 587 if (prevEnd != NULL) { | |
| 588 // Resize the underlying block offset table. | |
| 589 _bt.resize(pointer_delta(value, bottom())); | |
|
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590 if (value <= prevEnd) { |
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591 assert(!BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(), |
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592 "New end is below unallocated block"); |
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593 } else { |
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594 // Now, take this new chunk and add it to the free blocks. |
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595 // Note that the BOT has not yet been updated for this block. |
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596 size_t newFcSize = pointer_delta(value, prevEnd); |
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597 // XXX This is REALLY UGLY and should be fixed up. XXX |
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598 if (!_adaptive_freelists && _smallLinearAllocBlock._ptr == NULL) { |
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599 // Mark the boundary of the new block in BOT |
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600 _bt.mark_block(prevEnd, value); |
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601 // put it all in the linAB |
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602 if (ParallelGCThreads == 0) { |
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603 _smallLinearAllocBlock._ptr = prevEnd; |
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604 _smallLinearAllocBlock._word_size = newFcSize; |
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605 repairLinearAllocBlock(&_smallLinearAllocBlock); |
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606 } else { // ParallelGCThreads > 0 |
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607 MutexLockerEx x(parDictionaryAllocLock(), |
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608 Mutex::_no_safepoint_check_flag); |
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609 _smallLinearAllocBlock._ptr = prevEnd; |
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610 _smallLinearAllocBlock._word_size = newFcSize; |
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611 repairLinearAllocBlock(&_smallLinearAllocBlock); |
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612 } |
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613 // Births of chunks put into a LinAB are not recorded. Births |
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614 // of chunks as they are allocated out of a LinAB are. |
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615 } else { |
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616 // Add the block to the free lists, if possible coalescing it |
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617 // with the last free block, and update the BOT and census data. |
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618 addChunkToFreeListsAtEndRecordingStats(prevEnd, newFcSize); |
| 0 | 619 } |
| 620 } | |
| 621 } | |
| 622 } | |
| 623 | |
| 624 class FreeListSpace_DCTOC : public Filtering_DCTOC { | |
| 625 CompactibleFreeListSpace* _cfls; | |
| 626 CMSCollector* _collector; | |
| 627 protected: | |
| 628 // Override. | |
| 629 #define walk_mem_region_with_cl_DECL(ClosureType) \ | |
| 630 virtual void walk_mem_region_with_cl(MemRegion mr, \ | |
| 631 HeapWord* bottom, HeapWord* top, \ | |
| 632 ClosureType* cl); \ | |
| 633 void walk_mem_region_with_cl_par(MemRegion mr, \ | |
| 634 HeapWord* bottom, HeapWord* top, \ | |
| 635 ClosureType* cl); \ | |
| 636 void walk_mem_region_with_cl_nopar(MemRegion mr, \ | |
| 637 HeapWord* bottom, HeapWord* top, \ | |
| 638 ClosureType* cl) | |
| 639 walk_mem_region_with_cl_DECL(OopClosure); | |
| 640 walk_mem_region_with_cl_DECL(FilteringClosure); | |
| 641 | |
| 642 public: | |
| 643 FreeListSpace_DCTOC(CompactibleFreeListSpace* sp, | |
| 644 CMSCollector* collector, | |
| 645 OopClosure* cl, | |
| 646 CardTableModRefBS::PrecisionStyle precision, | |
| 647 HeapWord* boundary) : | |
| 648 Filtering_DCTOC(sp, cl, precision, boundary), | |
| 649 _cfls(sp), _collector(collector) {} | |
| 650 }; | |
| 651 | |
| 652 // We de-virtualize the block-related calls below, since we know that our | |
| 653 // space is a CompactibleFreeListSpace. | |
| 654 #define FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \ | |
| 655 void FreeListSpace_DCTOC::walk_mem_region_with_cl(MemRegion mr, \ | |
| 656 HeapWord* bottom, \ | |
| 657 HeapWord* top, \ | |
| 658 ClosureType* cl) { \ | |
| 659 if (SharedHeap::heap()->n_par_threads() > 0) { \ | |
| 660 walk_mem_region_with_cl_par(mr, bottom, top, cl); \ | |
| 661 } else { \ | |
| 662 walk_mem_region_with_cl_nopar(mr, bottom, top, cl); \ | |
| 663 } \ | |
| 664 } \ | |
| 665 void FreeListSpace_DCTOC::walk_mem_region_with_cl_par(MemRegion mr, \ | |
| 666 HeapWord* bottom, \ | |
| 667 HeapWord* top, \ | |
| 668 ClosureType* cl) { \ | |
| 669 /* Skip parts that are before "mr", in case "block_start" sent us \ | |
| 670 back too far. */ \ | |
| 671 HeapWord* mr_start = mr.start(); \ | |
| 672 size_t bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom); \ | |
| 673 HeapWord* next = bottom + bot_size; \ | |
| 674 while (next < mr_start) { \ | |
| 675 bottom = next; \ | |
| 676 bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom); \ | |
| 677 next = bottom + bot_size; \ | |
| 678 } \ | |
| 679 \ | |
| 680 while (bottom < top) { \ | |
| 681 if (_cfls->CompactibleFreeListSpace::block_is_obj(bottom) && \ | |
| 682 !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks( \ | |
| 683 oop(bottom)) && \ | |
| 684 !_collector->CMSCollector::is_dead_obj(oop(bottom))) { \ | |
| 685 size_t word_sz = oop(bottom)->oop_iterate(cl, mr); \ | |
| 686 bottom += _cfls->adjustObjectSize(word_sz); \ | |
| 687 } else { \ | |
| 688 bottom += _cfls->CompactibleFreeListSpace::block_size(bottom); \ | |
| 689 } \ | |
| 690 } \ | |
| 691 } \ | |
| 692 void FreeListSpace_DCTOC::walk_mem_region_with_cl_nopar(MemRegion mr, \ | |
| 693 HeapWord* bottom, \ | |
| 694 HeapWord* top, \ | |
| 695 ClosureType* cl) { \ | |
| 696 /* Skip parts that are before "mr", in case "block_start" sent us \ | |
| 697 back too far. */ \ | |
| 698 HeapWord* mr_start = mr.start(); \ | |
| 699 size_t bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom); \ | |
| 700 HeapWord* next = bottom + bot_size; \ | |
| 701 while (next < mr_start) { \ | |
| 702 bottom = next; \ | |
| 703 bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom); \ | |
| 704 next = bottom + bot_size; \ | |
| 705 } \ | |
| 706 \ | |
| 707 while (bottom < top) { \ | |
| 708 if (_cfls->CompactibleFreeListSpace::block_is_obj_nopar(bottom) && \ | |
| 709 !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks( \ | |
| 710 oop(bottom)) && \ | |
| 711 !_collector->CMSCollector::is_dead_obj(oop(bottom))) { \ | |
| 712 size_t word_sz = oop(bottom)->oop_iterate(cl, mr); \ | |
| 713 bottom += _cfls->adjustObjectSize(word_sz); \ | |
| 714 } else { \ | |
| 715 bottom += _cfls->CompactibleFreeListSpace::block_size_nopar(bottom); \ | |
| 716 } \ | |
| 717 } \ | |
| 718 } | |
| 719 | |
| 720 // (There are only two of these, rather than N, because the split is due | |
| 721 // only to the introduction of the FilteringClosure, a local part of the | |
| 722 // impl of this abstraction.) | |
| 723 FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(OopClosure) | |
| 724 FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure) | |
| 725 | |
| 726 DirtyCardToOopClosure* | |
| 727 CompactibleFreeListSpace::new_dcto_cl(OopClosure* cl, | |
| 728 CardTableModRefBS::PrecisionStyle precision, | |
| 729 HeapWord* boundary) { | |
| 730 return new FreeListSpace_DCTOC(this, _collector, cl, precision, boundary); | |
| 731 } | |
| 732 | |
| 733 | |
| 734 // Note on locking for the space iteration functions: | |
| 735 // since the collector's iteration activities are concurrent with | |
| 736 // allocation activities by mutators, absent a suitable mutual exclusion | |
| 737 // mechanism the iterators may go awry. For instace a block being iterated | |
| 738 // may suddenly be allocated or divided up and part of it allocated and | |
| 739 // so on. | |
| 740 | |
| 741 // Apply the given closure to each block in the space. | |
| 742 void CompactibleFreeListSpace::blk_iterate_careful(BlkClosureCareful* cl) { | |
| 743 assert_lock_strong(freelistLock()); | |
| 744 HeapWord *cur, *limit; | |
| 745 for (cur = bottom(), limit = end(); cur < limit; | |
| 746 cur += cl->do_blk_careful(cur)); | |
| 747 } | |
| 748 | |
| 749 // Apply the given closure to each block in the space. | |
| 750 void CompactibleFreeListSpace::blk_iterate(BlkClosure* cl) { | |
| 751 assert_lock_strong(freelistLock()); | |
| 752 HeapWord *cur, *limit; | |
| 753 for (cur = bottom(), limit = end(); cur < limit; | |
| 754 cur += cl->do_blk(cur)); | |
| 755 } | |
| 756 | |
| 757 // Apply the given closure to each oop in the space. | |
| 758 void CompactibleFreeListSpace::oop_iterate(OopClosure* cl) { | |
| 759 assert_lock_strong(freelistLock()); | |
| 760 HeapWord *cur, *limit; | |
| 761 size_t curSize; | |
| 762 for (cur = bottom(), limit = end(); cur < limit; | |
| 763 cur += curSize) { | |
| 764 curSize = block_size(cur); | |
| 765 if (block_is_obj(cur)) { | |
| 766 oop(cur)->oop_iterate(cl); | |
| 767 } | |
| 768 } | |
| 769 } | |
| 770 | |
| 771 // Apply the given closure to each oop in the space \intersect memory region. | |
| 772 void CompactibleFreeListSpace::oop_iterate(MemRegion mr, OopClosure* cl) { | |
| 773 assert_lock_strong(freelistLock()); | |
| 774 if (is_empty()) { | |
| 775 return; | |
| 776 } | |
| 777 MemRegion cur = MemRegion(bottom(), end()); | |
| 778 mr = mr.intersection(cur); | |
| 779 if (mr.is_empty()) { | |
| 780 return; | |
| 781 } | |
| 782 if (mr.equals(cur)) { | |
| 783 oop_iterate(cl); | |
| 784 return; | |
| 785 } | |
| 786 assert(mr.end() <= end(), "just took an intersection above"); | |
| 787 HeapWord* obj_addr = block_start(mr.start()); | |
| 788 HeapWord* t = mr.end(); | |
| 789 | |
| 790 SpaceMemRegionOopsIterClosure smr_blk(cl, mr); | |
| 791 if (block_is_obj(obj_addr)) { | |
| 792 // Handle first object specially. | |
| 793 oop obj = oop(obj_addr); | |
| 794 obj_addr += adjustObjectSize(obj->oop_iterate(&smr_blk)); | |
| 795 } else { | |
| 796 FreeChunk* fc = (FreeChunk*)obj_addr; | |
| 797 obj_addr += fc->size(); | |
| 798 } | |
| 799 while (obj_addr < t) { | |
| 800 HeapWord* obj = obj_addr; | |
| 801 obj_addr += block_size(obj_addr); | |
| 802 // If "obj_addr" is not greater than top, then the | |
| 803 // entire object "obj" is within the region. | |
| 804 if (obj_addr <= t) { | |
| 805 if (block_is_obj(obj)) { | |
| 806 oop(obj)->oop_iterate(cl); | |
| 807 } | |
| 808 } else { | |
| 809 // "obj" extends beyond end of region | |
| 810 if (block_is_obj(obj)) { | |
| 811 oop(obj)->oop_iterate(&smr_blk); | |
| 812 } | |
| 813 break; | |
| 814 } | |
| 815 } | |
| 816 } | |
| 817 | |
| 818 // NOTE: In the following methods, in order to safely be able to | |
| 819 // apply the closure to an object, we need to be sure that the | |
| 820 // object has been initialized. We are guaranteed that an object | |
| 821 // is initialized if we are holding the Heap_lock with the | |
| 822 // world stopped. | |
| 823 void CompactibleFreeListSpace::verify_objects_initialized() const { | |
| 824 if (is_init_completed()) { | |
| 825 assert_locked_or_safepoint(Heap_lock); | |
| 826 if (Universe::is_fully_initialized()) { | |
| 827 guarantee(SafepointSynchronize::is_at_safepoint(), | |
| 828 "Required for objects to be initialized"); | |
| 829 } | |
| 830 } // else make a concession at vm start-up | |
| 831 } | |
| 832 | |
| 833 // Apply the given closure to each object in the space | |
| 834 void CompactibleFreeListSpace::object_iterate(ObjectClosure* blk) { | |
| 835 assert_lock_strong(freelistLock()); | |
| 836 NOT_PRODUCT(verify_objects_initialized()); | |
| 837 HeapWord *cur, *limit; | |
| 838 size_t curSize; | |
| 839 for (cur = bottom(), limit = end(); cur < limit; | |
| 840 cur += curSize) { | |
| 841 curSize = block_size(cur); | |
| 842 if (block_is_obj(cur)) { | |
| 843 blk->do_object(oop(cur)); | |
| 844 } | |
| 845 } | |
| 846 } | |
| 847 | |
|
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848 // Apply the given closure to each live object in the space |
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849 // The usage of CompactibleFreeListSpace |
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850 // by the ConcurrentMarkSweepGeneration for concurrent GC's allows |
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851 // objects in the space with references to objects that are no longer |
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852 // valid. For example, an object may reference another object |
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853 // that has already been sweep up (collected). This method uses |
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854 // obj_is_alive() to determine whether it is safe to apply the closure to |
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855 // an object. See obj_is_alive() for details on how liveness of an |
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856 // object is decided. |
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857 |
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858 void CompactibleFreeListSpace::safe_object_iterate(ObjectClosure* blk) { |
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859 assert_lock_strong(freelistLock()); |
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860 NOT_PRODUCT(verify_objects_initialized()); |
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861 HeapWord *cur, *limit; |
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862 size_t curSize; |
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863 for (cur = bottom(), limit = end(); cur < limit; |
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864 cur += curSize) { |
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865 curSize = block_size(cur); |
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866 if (block_is_obj(cur) && obj_is_alive(cur)) { |
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867 blk->do_object(oop(cur)); |
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868 } |
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869 } |
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870 } |
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871 |
| 0 | 872 void CompactibleFreeListSpace::object_iterate_mem(MemRegion mr, |
| 873 UpwardsObjectClosure* cl) { | |
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874 assert_locked(freelistLock()); |
| 0 | 875 NOT_PRODUCT(verify_objects_initialized()); |
| 876 Space::object_iterate_mem(mr, cl); | |
| 877 } | |
| 878 | |
| 879 // Callers of this iterator beware: The closure application should | |
| 880 // be robust in the face of uninitialized objects and should (always) | |
| 881 // return a correct size so that the next addr + size below gives us a | |
| 882 // valid block boundary. [See for instance, | |
| 883 // ScanMarkedObjectsAgainCarefullyClosure::do_object_careful() | |
| 884 // in ConcurrentMarkSweepGeneration.cpp.] | |
| 885 HeapWord* | |
| 886 CompactibleFreeListSpace::object_iterate_careful(ObjectClosureCareful* cl) { | |
| 887 assert_lock_strong(freelistLock()); | |
| 888 HeapWord *addr, *last; | |
| 889 size_t size; | |
| 890 for (addr = bottom(), last = end(); | |
| 891 addr < last; addr += size) { | |
| 892 FreeChunk* fc = (FreeChunk*)addr; | |
| 893 if (fc->isFree()) { | |
| 894 // Since we hold the free list lock, which protects direct | |
| 895 // allocation in this generation by mutators, a free object | |
| 896 // will remain free throughout this iteration code. | |
| 897 size = fc->size(); | |
| 898 } else { | |
| 899 // Note that the object need not necessarily be initialized, | |
| 900 // because (for instance) the free list lock does NOT protect | |
| 901 // object initialization. The closure application below must | |
| 902 // therefore be correct in the face of uninitialized objects. | |
| 903 size = cl->do_object_careful(oop(addr)); | |
| 904 if (size == 0) { | |
| 905 // An unparsable object found. Signal early termination. | |
| 906 return addr; | |
| 907 } | |
| 908 } | |
| 909 } | |
| 910 return NULL; | |
| 911 } | |
| 912 | |
| 913 // Callers of this iterator beware: The closure application should | |
| 914 // be robust in the face of uninitialized objects and should (always) | |
| 915 // return a correct size so that the next addr + size below gives us a | |
| 916 // valid block boundary. [See for instance, | |
| 917 // ScanMarkedObjectsAgainCarefullyClosure::do_object_careful() | |
| 918 // in ConcurrentMarkSweepGeneration.cpp.] | |
| 919 HeapWord* | |
| 920 CompactibleFreeListSpace::object_iterate_careful_m(MemRegion mr, | |
| 921 ObjectClosureCareful* cl) { | |
| 922 assert_lock_strong(freelistLock()); | |
| 923 // Can't use used_region() below because it may not necessarily | |
| 924 // be the same as [bottom(),end()); although we could | |
| 925 // use [used_region().start(),round_to(used_region().end(),CardSize)), | |
| 926 // that appears too cumbersome, so we just do the simpler check | |
| 927 // in the assertion below. | |
| 928 assert(!mr.is_empty() && MemRegion(bottom(),end()).contains(mr), | |
| 929 "mr should be non-empty and within used space"); | |
| 930 HeapWord *addr, *end; | |
| 931 size_t size; | |
| 932 for (addr = block_start_careful(mr.start()), end = mr.end(); | |
| 933 addr < end; addr += size) { | |
| 934 FreeChunk* fc = (FreeChunk*)addr; | |
| 935 if (fc->isFree()) { | |
| 936 // Since we hold the free list lock, which protects direct | |
| 937 // allocation in this generation by mutators, a free object | |
| 938 // will remain free throughout this iteration code. | |
| 939 size = fc->size(); | |
| 940 } else { | |
| 941 // Note that the object need not necessarily be initialized, | |
| 942 // because (for instance) the free list lock does NOT protect | |
| 943 // object initialization. The closure application below must | |
| 944 // therefore be correct in the face of uninitialized objects. | |
| 945 size = cl->do_object_careful_m(oop(addr), mr); | |
| 946 if (size == 0) { | |
| 947 // An unparsable object found. Signal early termination. | |
| 948 return addr; | |
| 949 } | |
| 950 } | |
| 951 } | |
| 952 return NULL; | |
| 953 } | |
| 954 | |
| 955 | |
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956 HeapWord* CompactibleFreeListSpace::block_start_const(const void* p) const { |
| 0 | 957 NOT_PRODUCT(verify_objects_initialized()); |
| 958 return _bt.block_start(p); | |
| 959 } | |
| 960 | |
| 961 HeapWord* CompactibleFreeListSpace::block_start_careful(const void* p) const { | |
| 962 return _bt.block_start_careful(p); | |
| 963 } | |
| 964 | |
| 965 size_t CompactibleFreeListSpace::block_size(const HeapWord* p) const { | |
| 966 NOT_PRODUCT(verify_objects_initialized()); | |
| 967 // This must be volatile, or else there is a danger that the compiler | |
| 968 // will compile the code below into a sometimes-infinite loop, by keeping | |
| 969 // the value read the first time in a register. | |
| 970 while (true) { | |
| 971 // We must do this until we get a consistent view of the object. | |
| 187 | 972 if (FreeChunk::indicatesFreeChunk(p)) { |
| 973 volatile FreeChunk* fc = (volatile FreeChunk*)p; | |
| 974 size_t res = fc->size(); | |
| 975 // If the object is still a free chunk, return the size, else it | |
| 976 // has been allocated so try again. | |
| 977 if (FreeChunk::indicatesFreeChunk(p)) { | |
| 0 | 978 assert(res != 0, "Block size should not be 0"); |
| 979 return res; | |
| 980 } | |
| 187 | 981 } else { |
| 982 // must read from what 'p' points to in each loop. | |
| 983 klassOop k = ((volatile oopDesc*)p)->klass_or_null(); | |
| 984 if (k != NULL) { | |
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985 assert(k->is_oop(true /* ignore mark word */), "Should be klass oop"); |
| 187 | 986 oop o = (oop)p; |
| 987 assert(o->is_parsable(), "Should be parsable"); | |
| 988 assert(o->is_oop(true /* ignore mark word */), "Should be an oop."); | |
| 989 size_t res = o->size_given_klass(k->klass_part()); | |
| 990 res = adjustObjectSize(res); | |
| 991 assert(res != 0, "Block size should not be 0"); | |
| 992 return res; | |
| 993 } | |
| 0 | 994 } |
| 995 } | |
| 996 } | |
| 997 | |
| 998 // A variant of the above that uses the Printezis bits for | |
| 999 // unparsable but allocated objects. This avoids any possible | |
| 1000 // stalls waiting for mutators to initialize objects, and is | |
| 1001 // thus potentially faster than the variant above. However, | |
| 1002 // this variant may return a zero size for a block that is | |
| 1003 // under mutation and for which a consistent size cannot be | |
| 1004 // inferred without stalling; see CMSCollector::block_size_if_printezis_bits(). | |
| 1005 size_t CompactibleFreeListSpace::block_size_no_stall(HeapWord* p, | |
| 1006 const CMSCollector* c) | |
| 1007 const { | |
| 1008 assert(MemRegion(bottom(), end()).contains(p), "p not in space"); | |
| 1009 // This must be volatile, or else there is a danger that the compiler | |
| 1010 // will compile the code below into a sometimes-infinite loop, by keeping | |
| 1011 // the value read the first time in a register. | |
| 1012 DEBUG_ONLY(uint loops = 0;) | |
| 1013 while (true) { | |
| 1014 // We must do this until we get a consistent view of the object. | |
| 187 | 1015 if (FreeChunk::indicatesFreeChunk(p)) { |
| 1016 volatile FreeChunk* fc = (volatile FreeChunk*)p; | |
| 1017 size_t res = fc->size(); | |
| 1018 if (FreeChunk::indicatesFreeChunk(p)) { | |
| 0 | 1019 assert(res != 0, "Block size should not be 0"); |
| 1020 assert(loops == 0, "Should be 0"); | |
| 1021 return res; | |
| 1022 } | |
| 1023 } else { | |
| 187 | 1024 // must read from what 'p' points to in each loop. |
| 1025 klassOop k = ((volatile oopDesc*)p)->klass_or_null(); | |
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1026 if (k != NULL && |
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1027 ((oopDesc*)p)->is_parsable() && |
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1028 ((oopDesc*)p)->is_conc_safe()) { |
| 187 | 1029 assert(k->is_oop(), "Should really be klass oop."); |
| 1030 oop o = (oop)p; | |
| 1031 assert(o->is_oop(), "Should be an oop"); | |
| 1032 size_t res = o->size_given_klass(k->klass_part()); | |
| 1033 res = adjustObjectSize(res); | |
| 1034 assert(res != 0, "Block size should not be 0"); | |
| 1035 return res; | |
| 1036 } else { | |
| 1037 return c->block_size_if_printezis_bits(p); | |
| 1038 } | |
| 0 | 1039 } |
| 1040 assert(loops == 0, "Can loop at most once"); | |
| 1041 DEBUG_ONLY(loops++;) | |
| 1042 } | |
| 1043 } | |
| 1044 | |
| 1045 size_t CompactibleFreeListSpace::block_size_nopar(const HeapWord* p) const { | |
| 1046 NOT_PRODUCT(verify_objects_initialized()); | |
| 1047 assert(MemRegion(bottom(), end()).contains(p), "p not in space"); | |
| 1048 FreeChunk* fc = (FreeChunk*)p; | |
| 1049 if (fc->isFree()) { | |
| 1050 return fc->size(); | |
| 1051 } else { | |
| 1052 // Ignore mark word because this may be a recently promoted | |
| 1053 // object whose mark word is used to chain together grey | |
| 1054 // objects (the last one would have a null value). | |
| 1055 assert(oop(p)->is_oop(true), "Should be an oop"); | |
| 1056 return adjustObjectSize(oop(p)->size()); | |
| 1057 } | |
| 1058 } | |
| 1059 | |
| 1060 // This implementation assumes that the property of "being an object" is | |
| 1061 // stable. But being a free chunk may not be (because of parallel | |
| 1062 // promotion.) | |
| 1063 bool CompactibleFreeListSpace::block_is_obj(const HeapWord* p) const { | |
| 1064 FreeChunk* fc = (FreeChunk*)p; | |
| 1065 assert(is_in_reserved(p), "Should be in space"); | |
| 1066 // When doing a mark-sweep-compact of the CMS generation, this | |
| 1067 // assertion may fail because prepare_for_compaction() uses | |
| 1068 // space that is garbage to maintain information on ranges of | |
| 1069 // live objects so that these live ranges can be moved as a whole. | |
| 1070 // Comment out this assertion until that problem can be solved | |
| 1071 // (i.e., that the block start calculation may look at objects | |
| 1072 // at address below "p" in finding the object that contains "p" | |
| 1073 // and those objects (if garbage) may have been modified to hold | |
| 1074 // live range information. | |
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1075 // assert(CollectedHeap::use_parallel_gc_threads() || _bt.block_start(p) == p, |
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1076 // "Should be a block boundary"); |
| 187 | 1077 if (FreeChunk::indicatesFreeChunk(p)) return false; |
| 1078 klassOop k = oop(p)->klass_or_null(); | |
| 0 | 1079 if (k != NULL) { |
| 1080 // Ignore mark word because it may have been used to | |
| 1081 // chain together promoted objects (the last one | |
| 1082 // would have a null value). | |
| 1083 assert(oop(p)->is_oop(true), "Should be an oop"); | |
| 1084 return true; | |
| 1085 } else { | |
| 1086 return false; // Was not an object at the start of collection. | |
| 1087 } | |
| 1088 } | |
| 1089 | |
| 1090 // Check if the object is alive. This fact is checked either by consulting | |
| 1091 // the main marking bitmap in the sweeping phase or, if it's a permanent | |
| 1092 // generation and we're not in the sweeping phase, by checking the | |
| 1093 // perm_gen_verify_bit_map where we store the "deadness" information if | |
| 1094 // we did not sweep the perm gen in the most recent previous GC cycle. | |
| 1095 bool CompactibleFreeListSpace::obj_is_alive(const HeapWord* p) const { | |
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1096 assert(block_is_obj(p), "The address should point to an object"); |
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1097 assert(SafepointSynchronize::is_at_safepoint(), "Else races are possible"); |
| 0 | 1098 |
| 1099 // If we're sweeping, we use object liveness information from the main bit map | |
| 1100 // for both perm gen and old gen. | |
| 1101 // We don't need to lock the bitmap (live_map or dead_map below), because | |
| 1102 // EITHER we are in the middle of the sweeping phase, and the | |
| 1103 // main marking bit map (live_map below) is locked, | |
| 1104 // OR we're in other phases and perm_gen_verify_bit_map (dead_map below) | |
| 1105 // is stable, because it's mutated only in the sweeping phase. | |
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1106 // NOTE: This method is also used by jmap where, if class unloading is |
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1107 // off, the results can return "false" for legitimate perm objects, |
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1108 // when we are not in the midst of a sweeping phase, which can result |
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1109 // in jmap not reporting certain perm gen objects. This will be moot |
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1110 // if/when the perm gen goes away in the future. |
| 0 | 1111 if (_collector->abstract_state() == CMSCollector::Sweeping) { |
| 1112 CMSBitMap* live_map = _collector->markBitMap(); | |
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1113 return live_map->par_isMarked((HeapWord*) p); |
| 0 | 1114 } else { |
| 1115 // If we're not currently sweeping and we haven't swept the perm gen in | |
| 1116 // the previous concurrent cycle then we may have dead but unswept objects | |
| 1117 // in the perm gen. In this case, we use the "deadness" information | |
| 1118 // that we had saved in perm_gen_verify_bit_map at the last sweep. | |
| 1119 if (!CMSClassUnloadingEnabled && _collector->_permGen->reserved().contains(p)) { | |
| 1120 if (_collector->verifying()) { | |
| 1121 CMSBitMap* dead_map = _collector->perm_gen_verify_bit_map(); | |
| 1122 // Object is marked in the dead_map bitmap at the previous sweep | |
| 1123 // when we know that it's dead; if the bitmap is not allocated then | |
| 1124 // the object is alive. | |
| 1125 return (dead_map->sizeInBits() == 0) // bit_map has been allocated | |
| 1126 || !dead_map->par_isMarked((HeapWord*) p); | |
| 1127 } else { | |
| 1128 return false; // We can't say for sure if it's live, so we say that it's dead. | |
| 1129 } | |
| 1130 } | |
| 1131 } | |
| 1132 return true; | |
| 1133 } | |
| 1134 | |
| 1135 bool CompactibleFreeListSpace::block_is_obj_nopar(const HeapWord* p) const { | |
| 1136 FreeChunk* fc = (FreeChunk*)p; | |
| 1137 assert(is_in_reserved(p), "Should be in space"); | |
| 1138 assert(_bt.block_start(p) == p, "Should be a block boundary"); | |
| 1139 if (!fc->isFree()) { | |
| 1140 // Ignore mark word because it may have been used to | |
| 1141 // chain together promoted objects (the last one | |
| 1142 // would have a null value). | |
| 1143 assert(oop(p)->is_oop(true), "Should be an oop"); | |
| 1144 return true; | |
| 1145 } | |
| 1146 return false; | |
| 1147 } | |
| 1148 | |
| 1149 // "MT-safe but not guaranteed MT-precise" (TM); you may get an | |
| 1150 // approximate answer if you don't hold the freelistlock when you call this. | |
| 1151 size_t CompactibleFreeListSpace::totalSizeInIndexedFreeLists() const { | |
| 1152 size_t size = 0; | |
| 1153 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
| 1154 debug_only( | |
| 1155 // We may be calling here without the lock in which case we | |
| 1156 // won't do this modest sanity check. | |
| 1157 if (freelistLock()->owned_by_self()) { | |
| 1158 size_t total_list_size = 0; | |
| 1159 for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; | |
| 1160 fc = fc->next()) { | |
| 1161 total_list_size += i; | |
| 1162 } | |
| 1163 assert(total_list_size == i * _indexedFreeList[i].count(), | |
| 1164 "Count in list is incorrect"); | |
| 1165 } | |
| 1166 ) | |
| 1167 size += i * _indexedFreeList[i].count(); | |
| 1168 } | |
| 1169 return size; | |
| 1170 } | |
| 1171 | |
| 1172 HeapWord* CompactibleFreeListSpace::par_allocate(size_t size) { | |
| 1173 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 1174 return allocate(size); | |
| 1175 } | |
| 1176 | |
| 1177 HeapWord* | |
| 1178 CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlockRemainder(size_t size) { | |
| 1179 return getChunkFromLinearAllocBlockRemainder(&_smallLinearAllocBlock, size); | |
| 1180 } | |
| 1181 | |
| 1182 HeapWord* CompactibleFreeListSpace::allocate(size_t size) { | |
| 1183 assert_lock_strong(freelistLock()); | |
| 1184 HeapWord* res = NULL; | |
| 1185 assert(size == adjustObjectSize(size), | |
| 1186 "use adjustObjectSize() before calling into allocate()"); | |
| 1187 | |
| 1188 if (_adaptive_freelists) { | |
| 1189 res = allocate_adaptive_freelists(size); | |
| 1190 } else { // non-adaptive free lists | |
| 1191 res = allocate_non_adaptive_freelists(size); | |
| 1192 } | |
| 1193 | |
| 1194 if (res != NULL) { | |
| 1195 // check that res does lie in this space! | |
| 1196 assert(is_in_reserved(res), "Not in this space!"); | |
| 1197 assert(is_aligned((void*)res), "alignment check"); | |
| 1198 | |
| 1199 FreeChunk* fc = (FreeChunk*)res; | |
| 1200 fc->markNotFree(); | |
| 1201 assert(!fc->isFree(), "shouldn't be marked free"); | |
| 187 | 1202 assert(oop(fc)->klass_or_null() == NULL, "should look uninitialized"); |
| 0 | 1203 // Verify that the block offset table shows this to |
| 1204 // be a single block, but not one which is unallocated. | |
| 1205 _bt.verify_single_block(res, size); | |
| 1206 _bt.verify_not_unallocated(res, size); | |
| 1207 // mangle a just allocated object with a distinct pattern. | |
| 1208 debug_only(fc->mangleAllocated(size)); | |
| 1209 } | |
| 1210 | |
| 1211 return res; | |
| 1212 } | |
| 1213 | |
| 1214 HeapWord* CompactibleFreeListSpace::allocate_non_adaptive_freelists(size_t size) { | |
| 1215 HeapWord* res = NULL; | |
| 1216 // try and use linear allocation for smaller blocks | |
| 1217 if (size < _smallLinearAllocBlock._allocation_size_limit) { | |
| 1218 // if successful, the following also adjusts block offset table | |
| 1219 res = getChunkFromSmallLinearAllocBlock(size); | |
| 1220 } | |
| 1221 // Else triage to indexed lists for smaller sizes | |
| 1222 if (res == NULL) { | |
| 1223 if (size < SmallForDictionary) { | |
| 1224 res = (HeapWord*) getChunkFromIndexedFreeList(size); | |
| 1225 } else { | |
| 1226 // else get it from the big dictionary; if even this doesn't | |
| 1227 // work we are out of luck. | |
| 1228 res = (HeapWord*)getChunkFromDictionaryExact(size); | |
| 1229 } | |
| 1230 } | |
| 1231 | |
| 1232 return res; | |
| 1233 } | |
| 1234 | |
| 1235 HeapWord* CompactibleFreeListSpace::allocate_adaptive_freelists(size_t size) { | |
| 1236 assert_lock_strong(freelistLock()); | |
| 1237 HeapWord* res = NULL; | |
| 1238 assert(size == adjustObjectSize(size), | |
| 1239 "use adjustObjectSize() before calling into allocate()"); | |
| 1240 | |
| 1241 // Strategy | |
| 1242 // if small | |
| 1243 // exact size from small object indexed list if small | |
| 1244 // small or large linear allocation block (linAB) as appropriate | |
| 1245 // take from lists of greater sized chunks | |
| 1246 // else | |
| 1247 // dictionary | |
| 1248 // small or large linear allocation block if it has the space | |
| 1249 // Try allocating exact size from indexTable first | |
| 1250 if (size < IndexSetSize) { | |
| 1251 res = (HeapWord*) getChunkFromIndexedFreeList(size); | |
| 1252 if(res != NULL) { | |
| 1253 assert(res != (HeapWord*)_indexedFreeList[size].head(), | |
| 1254 "Not removed from free list"); | |
| 1255 // no block offset table adjustment is necessary on blocks in | |
| 1256 // the indexed lists. | |
| 1257 | |
| 1258 // Try allocating from the small LinAB | |
| 1259 } else if (size < _smallLinearAllocBlock._allocation_size_limit && | |
| 1260 (res = getChunkFromSmallLinearAllocBlock(size)) != NULL) { | |
| 1261 // if successful, the above also adjusts block offset table | |
| 1262 // Note that this call will refill the LinAB to | |
| 1263 // satisfy the request. This is different that | |
| 1264 // evm. | |
| 1265 // Don't record chunk off a LinAB? smallSplitBirth(size); | |
| 1266 } else { | |
| 1267 // Raid the exact free lists larger than size, even if they are not | |
| 1268 // overpopulated. | |
| 1269 res = (HeapWord*) getChunkFromGreater(size); | |
| 1270 } | |
| 1271 } else { | |
| 1272 // Big objects get allocated directly from the dictionary. | |
| 1273 res = (HeapWord*) getChunkFromDictionaryExact(size); | |
| 1274 if (res == NULL) { | |
| 1275 // Try hard not to fail since an allocation failure will likely | |
| 1276 // trigger a synchronous GC. Try to get the space from the | |
| 1277 // allocation blocks. | |
| 1278 res = getChunkFromSmallLinearAllocBlockRemainder(size); | |
| 1279 } | |
| 1280 } | |
| 1281 | |
| 1282 return res; | |
| 1283 } | |
| 1284 | |
| 1285 // A worst-case estimate of the space required (in HeapWords) to expand the heap | |
| 1286 // when promoting obj. | |
| 1287 size_t CompactibleFreeListSpace::expansionSpaceRequired(size_t obj_size) const { | |
| 1288 // Depending on the object size, expansion may require refilling either a | |
| 1289 // bigLAB or a smallLAB plus refilling a PromotionInfo object. MinChunkSize | |
| 1290 // is added because the dictionary may over-allocate to avoid fragmentation. | |
| 1291 size_t space = obj_size; | |
| 1292 if (!_adaptive_freelists) { | |
| 1293 space = MAX2(space, _smallLinearAllocBlock._refillSize); | |
| 1294 } | |
| 1295 space += _promoInfo.refillSize() + 2 * MinChunkSize; | |
| 1296 return space; | |
| 1297 } | |
| 1298 | |
| 1299 FreeChunk* CompactibleFreeListSpace::getChunkFromGreater(size_t numWords) { | |
| 1300 FreeChunk* ret; | |
| 1301 | |
| 1302 assert(numWords >= MinChunkSize, "Size is less than minimum"); | |
| 1303 assert(linearAllocationWouldFail() || bestFitFirst(), | |
| 1304 "Should not be here"); | |
| 1305 | |
| 1306 size_t i; | |
| 1307 size_t currSize = numWords + MinChunkSize; | |
| 1308 assert(currSize % MinObjAlignment == 0, "currSize should be aligned"); | |
| 1309 for (i = currSize; i < IndexSetSize; i += IndexSetStride) { | |
| 1310 FreeList* fl = &_indexedFreeList[i]; | |
| 1311 if (fl->head()) { | |
| 1312 ret = getFromListGreater(fl, numWords); | |
| 1313 assert(ret == NULL || ret->isFree(), "Should be returning a free chunk"); | |
| 1314 return ret; | |
| 1315 } | |
| 1316 } | |
| 1317 | |
| 1318 currSize = MAX2((size_t)SmallForDictionary, | |
| 1319 (size_t)(numWords + MinChunkSize)); | |
| 1320 | |
| 1321 /* Try to get a chunk that satisfies request, while avoiding | |
| 1322 fragmentation that can't be handled. */ | |
| 1323 { | |
| 1324 ret = dictionary()->getChunk(currSize); | |
| 1325 if (ret != NULL) { | |
| 1326 assert(ret->size() - numWords >= MinChunkSize, | |
| 1327 "Chunk is too small"); | |
| 1328 _bt.allocated((HeapWord*)ret, ret->size()); | |
| 1329 /* Carve returned chunk. */ | |
| 1330 (void) splitChunkAndReturnRemainder(ret, numWords); | |
| 1331 /* Label this as no longer a free chunk. */ | |
| 1332 assert(ret->isFree(), "This chunk should be free"); | |
| 1333 ret->linkPrev(NULL); | |
| 1334 } | |
| 1335 assert(ret == NULL || ret->isFree(), "Should be returning a free chunk"); | |
| 1336 return ret; | |
| 1337 } | |
| 1338 ShouldNotReachHere(); | |
| 1339 } | |
| 1340 | |
| 1341 bool CompactibleFreeListSpace::verifyChunkInIndexedFreeLists(FreeChunk* fc) | |
| 1342 const { | |
| 1343 assert(fc->size() < IndexSetSize, "Size of chunk is too large"); | |
| 1344 return _indexedFreeList[fc->size()].verifyChunkInFreeLists(fc); | |
| 1345 } | |
| 1346 | |
| 1347 bool CompactibleFreeListSpace::verifyChunkInFreeLists(FreeChunk* fc) const { | |
| 1348 if (fc->size() >= IndexSetSize) { | |
| 1349 return dictionary()->verifyChunkInFreeLists(fc); | |
| 1350 } else { | |
| 1351 return verifyChunkInIndexedFreeLists(fc); | |
| 1352 } | |
| 1353 } | |
| 1354 | |
| 1355 #ifndef PRODUCT | |
| 1356 void CompactibleFreeListSpace::assert_locked() const { | |
| 1357 CMSLockVerifier::assert_locked(freelistLock(), parDictionaryAllocLock()); | |
| 1358 } | |
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1359 |
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1360 void CompactibleFreeListSpace::assert_locked(const Mutex* lock) const { |
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1361 CMSLockVerifier::assert_locked(lock); |
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1362 } |
| 0 | 1363 #endif |
| 1364 | |
| 1365 FreeChunk* CompactibleFreeListSpace::allocateScratch(size_t size) { | |
| 1366 // In the parallel case, the main thread holds the free list lock | |
| 1367 // on behalf the parallel threads. | |
| 1368 FreeChunk* fc; | |
| 1369 { | |
| 1370 // If GC is parallel, this might be called by several threads. | |
| 1371 // This should be rare enough that the locking overhead won't affect | |
| 1372 // the sequential code. | |
| 1373 MutexLockerEx x(parDictionaryAllocLock(), | |
| 1374 Mutex::_no_safepoint_check_flag); | |
| 1375 fc = getChunkFromDictionary(size); | |
| 1376 } | |
| 1377 if (fc != NULL) { | |
| 1378 fc->dontCoalesce(); | |
| 1379 assert(fc->isFree(), "Should be free, but not coalescable"); | |
| 1380 // Verify that the block offset table shows this to | |
| 1381 // be a single block, but not one which is unallocated. | |
| 1382 _bt.verify_single_block((HeapWord*)fc, fc->size()); | |
| 1383 _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); | |
| 1384 } | |
| 1385 return fc; | |
| 1386 } | |
| 1387 | |
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1388 oop CompactibleFreeListSpace::promote(oop obj, size_t obj_size) { |
| 0 | 1389 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
| 1390 assert_locked(); | |
| 1391 | |
| 1392 // if we are tracking promotions, then first ensure space for | |
| 1393 // promotion (including spooling space for saving header if necessary). | |
| 1394 // then allocate and copy, then track promoted info if needed. | |
| 1395 // When tracking (see PromotionInfo::track()), the mark word may | |
| 1396 // be displaced and in this case restoration of the mark word | |
| 1397 // occurs in the (oop_since_save_marks_)iterate phase. | |
| 1398 if (_promoInfo.tracking() && !_promoInfo.ensure_spooling_space()) { | |
| 1399 return NULL; | |
| 1400 } | |
| 1401 // Call the allocate(size_t, bool) form directly to avoid the | |
| 1402 // additional call through the allocate(size_t) form. Having | |
| 1403 // the compile inline the call is problematic because allocate(size_t) | |
| 1404 // is a virtual method. | |
| 1405 HeapWord* res = allocate(adjustObjectSize(obj_size)); | |
| 1406 if (res != NULL) { | |
| 1407 Copy::aligned_disjoint_words((HeapWord*)obj, res, obj_size); | |
| 1408 // if we should be tracking promotions, do so. | |
| 1409 if (_promoInfo.tracking()) { | |
| 1410 _promoInfo.track((PromotedObject*)res); | |
| 1411 } | |
| 1412 } | |
| 1413 return oop(res); | |
| 1414 } | |
| 1415 | |
| 1416 HeapWord* | |
| 1417 CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlock(size_t size) { | |
| 1418 assert_locked(); | |
| 1419 assert(size >= MinChunkSize, "minimum chunk size"); | |
| 1420 assert(size < _smallLinearAllocBlock._allocation_size_limit, | |
| 1421 "maximum from smallLinearAllocBlock"); | |
| 1422 return getChunkFromLinearAllocBlock(&_smallLinearAllocBlock, size); | |
| 1423 } | |
| 1424 | |
| 1425 HeapWord* | |
| 1426 CompactibleFreeListSpace::getChunkFromLinearAllocBlock(LinearAllocBlock *blk, | |
| 1427 size_t size) { | |
| 1428 assert_locked(); | |
| 1429 assert(size >= MinChunkSize, "too small"); | |
| 1430 HeapWord* res = NULL; | |
| 1431 // Try to do linear allocation from blk, making sure that | |
| 1432 if (blk->_word_size == 0) { | |
| 1433 // We have probably been unable to fill this either in the prologue or | |
| 1434 // when it was exhausted at the last linear allocation. Bail out until | |
| 1435 // next time. | |
| 1436 assert(blk->_ptr == NULL, "consistency check"); | |
| 1437 return NULL; | |
| 1438 } | |
| 1439 assert(blk->_word_size != 0 && blk->_ptr != NULL, "consistency check"); | |
| 1440 res = getChunkFromLinearAllocBlockRemainder(blk, size); | |
| 1441 if (res != NULL) return res; | |
| 1442 | |
| 1443 // about to exhaust this linear allocation block | |
| 1444 if (blk->_word_size == size) { // exactly satisfied | |
| 1445 res = blk->_ptr; | |
| 1446 _bt.allocated(res, blk->_word_size); | |
| 1447 } else if (size + MinChunkSize <= blk->_refillSize) { | |
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1448 size_t sz = blk->_word_size; |
| 0 | 1449 // Update _unallocated_block if the size is such that chunk would be |
| 1450 // returned to the indexed free list. All other chunks in the indexed | |
| 1451 // free lists are allocated from the dictionary so that _unallocated_block | |
| 1452 // has already been adjusted for them. Do it here so that the cost | |
| 1453 // for all chunks added back to the indexed free lists. | |
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1454 if (sz < SmallForDictionary) { |
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1455 _bt.allocated(blk->_ptr, sz); |
| 0 | 1456 } |
| 1457 // Return the chunk that isn't big enough, and then refill below. | |
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1458 addChunkToFreeLists(blk->_ptr, sz); |
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1459 splitBirth(sz); |
| 0 | 1460 // Don't keep statistics on adding back chunk from a LinAB. |
| 1461 } else { | |
| 1462 // A refilled block would not satisfy the request. | |
| 1463 return NULL; | |
| 1464 } | |
| 1465 | |
| 1466 blk->_ptr = NULL; blk->_word_size = 0; | |
| 1467 refillLinearAllocBlock(blk); | |
| 1468 assert(blk->_ptr == NULL || blk->_word_size >= size + MinChunkSize, | |
| 1469 "block was replenished"); | |
| 1470 if (res != NULL) { | |
| 1471 splitBirth(size); | |
| 1472 repairLinearAllocBlock(blk); | |
| 1473 } else if (blk->_ptr != NULL) { | |
| 1474 res = blk->_ptr; | |
| 1475 size_t blk_size = blk->_word_size; | |
| 1476 blk->_word_size -= size; | |
| 1477 blk->_ptr += size; | |
| 1478 splitBirth(size); | |
| 1479 repairLinearAllocBlock(blk); | |
| 1480 // Update BOT last so that other (parallel) GC threads see a consistent | |
| 1481 // view of the BOT and free blocks. | |
| 1482 // Above must occur before BOT is updated below. | |
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1483 OrderAccess::storestore(); |
| 0 | 1484 _bt.split_block(res, blk_size, size); // adjust block offset table |
| 1485 } | |
| 1486 return res; | |
| 1487 } | |
| 1488 | |
| 1489 HeapWord* CompactibleFreeListSpace::getChunkFromLinearAllocBlockRemainder( | |
| 1490 LinearAllocBlock* blk, | |
| 1491 size_t size) { | |
| 1492 assert_locked(); | |
| 1493 assert(size >= MinChunkSize, "too small"); | |
| 1494 | |
| 1495 HeapWord* res = NULL; | |
| 1496 // This is the common case. Keep it simple. | |
| 1497 if (blk->_word_size >= size + MinChunkSize) { | |
| 1498 assert(blk->_ptr != NULL, "consistency check"); | |
| 1499 res = blk->_ptr; | |
| 1500 // Note that the BOT is up-to-date for the linAB before allocation. It | |
| 1501 // indicates the start of the linAB. The split_block() updates the | |
| 1502 // BOT for the linAB after the allocation (indicates the start of the | |
| 1503 // next chunk to be allocated). | |
| 1504 size_t blk_size = blk->_word_size; | |
| 1505 blk->_word_size -= size; | |
| 1506 blk->_ptr += size; | |
| 1507 splitBirth(size); | |
| 1508 repairLinearAllocBlock(blk); | |
| 1509 // Update BOT last so that other (parallel) GC threads see a consistent | |
| 1510 // view of the BOT and free blocks. | |
| 1511 // Above must occur before BOT is updated below. | |
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1512 OrderAccess::storestore(); |
| 0 | 1513 _bt.split_block(res, blk_size, size); // adjust block offset table |
| 1514 _bt.allocated(res, size); | |
| 1515 } | |
| 1516 return res; | |
| 1517 } | |
| 1518 | |
| 1519 FreeChunk* | |
| 1520 CompactibleFreeListSpace::getChunkFromIndexedFreeList(size_t size) { | |
| 1521 assert_locked(); | |
| 1522 assert(size < SmallForDictionary, "just checking"); | |
| 1523 FreeChunk* res; | |
| 1524 res = _indexedFreeList[size].getChunkAtHead(); | |
| 1525 if (res == NULL) { | |
| 1526 res = getChunkFromIndexedFreeListHelper(size); | |
| 1527 } | |
| 1528 _bt.verify_not_unallocated((HeapWord*) res, size); | |
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1529 assert(res == NULL || res->size() == size, "Incorrect block size"); |
| 0 | 1530 return res; |
| 1531 } | |
| 1532 | |
| 1533 FreeChunk* | |
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1534 CompactibleFreeListSpace::getChunkFromIndexedFreeListHelper(size_t size, |
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1535 bool replenish) { |
| 0 | 1536 assert_locked(); |
| 1537 FreeChunk* fc = NULL; | |
| 1538 if (size < SmallForDictionary) { | |
| 1539 assert(_indexedFreeList[size].head() == NULL || | |
| 1540 _indexedFreeList[size].surplus() <= 0, | |
| 1541 "List for this size should be empty or under populated"); | |
| 1542 // Try best fit in exact lists before replenishing the list | |
| 1543 if (!bestFitFirst() || (fc = bestFitSmall(size)) == NULL) { | |
| 1544 // Replenish list. | |
| 1545 // | |
| 1546 // Things tried that failed. | |
| 1547 // Tried allocating out of the two LinAB's first before | |
| 1548 // replenishing lists. | |
| 1549 // Tried small linAB of size 256 (size in indexed list) | |
| 1550 // and replenishing indexed lists from the small linAB. | |
| 1551 // | |
| 1552 FreeChunk* newFc = NULL; | |
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1553 const size_t replenish_size = CMSIndexedFreeListReplenish * size; |
| 0 | 1554 if (replenish_size < SmallForDictionary) { |
| 1555 // Do not replenish from an underpopulated size. | |
| 1556 if (_indexedFreeList[replenish_size].surplus() > 0 && | |
| 1557 _indexedFreeList[replenish_size].head() != NULL) { | |
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1558 newFc = _indexedFreeList[replenish_size].getChunkAtHead(); |
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1559 } else if (bestFitFirst()) { |
| 0 | 1560 newFc = bestFitSmall(replenish_size); |
| 1561 } | |
| 1562 } | |
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1563 if (newFc == NULL && replenish_size > size) { |
| 0 | 1564 assert(CMSIndexedFreeListReplenish > 1, "ctl pt invariant"); |
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1565 newFc = getChunkFromIndexedFreeListHelper(replenish_size, false); |
| 0 | 1566 } |
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1567 // Note: The stats update re split-death of block obtained above |
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1568 // will be recorded below precisely when we know we are going to |
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1569 // be actually splitting it into more than one pieces below. |
| 0 | 1570 if (newFc != NULL) { |
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1571 if (replenish || CMSReplenishIntermediate) { |
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1572 // Replenish this list and return one block to caller. |
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1573 size_t i; |
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1574 FreeChunk *curFc, *nextFc; |
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1575 size_t num_blk = newFc->size() / size; |
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1576 assert(num_blk >= 1, "Smaller than requested?"); |
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1577 assert(newFc->size() % size == 0, "Should be integral multiple of request"); |
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1578 if (num_blk > 1) { |
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1579 // we are sure we will be splitting the block just obtained |
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1580 // into multiple pieces; record the split-death of the original |
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1581 splitDeath(replenish_size); |
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1582 } |
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1583 // carve up and link blocks 0, ..., num_blk - 2 |
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1584 // The last chunk is not added to the lists but is returned as the |
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1585 // free chunk. |
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1586 for (curFc = newFc, nextFc = (FreeChunk*)((HeapWord*)curFc + size), |
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1587 i = 0; |
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1588 i < (num_blk - 1); |
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1589 curFc = nextFc, nextFc = (FreeChunk*)((HeapWord*)nextFc + size), |
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1590 i++) { |
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1591 curFc->setSize(size); |
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1592 // Don't record this as a return in order to try and |
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1593 // determine the "returns" from a GC. |
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1594 _bt.verify_not_unallocated((HeapWord*) fc, size); |
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1595 _indexedFreeList[size].returnChunkAtTail(curFc, false); |
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1596 _bt.mark_block((HeapWord*)curFc, size); |
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1597 splitBirth(size); |
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1598 // Don't record the initial population of the indexed list |
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1599 // as a split birth. |
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1600 } |
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1601 |
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1602 // check that the arithmetic was OK above |
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1603 assert((HeapWord*)nextFc == (HeapWord*)newFc + num_blk*size, |
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1604 "inconsistency in carving newFc"); |
| 0 | 1605 curFc->setSize(size); |
| 1606 _bt.mark_block((HeapWord*)curFc, size); | |
| 1607 splitBirth(size); | |
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1608 fc = curFc; |
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1609 } else { |
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1610 // Return entire block to caller |
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1611 fc = newFc; |
| 0 | 1612 } |
| 1613 } | |
| 1614 } | |
| 1615 } else { | |
| 1616 // Get a free chunk from the free chunk dictionary to be returned to | |
| 1617 // replenish the indexed free list. | |
| 1618 fc = getChunkFromDictionaryExact(size); | |
| 1619 } | |
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1620 // assert(fc == NULL || fc->isFree(), "Should be returning a free chunk"); |
| 0 | 1621 return fc; |
| 1622 } | |
| 1623 | |
| 1624 FreeChunk* | |
| 1625 CompactibleFreeListSpace::getChunkFromDictionary(size_t size) { | |
| 1626 assert_locked(); | |
| 1627 FreeChunk* fc = _dictionary->getChunk(size); | |
| 1628 if (fc == NULL) { | |
| 1629 return NULL; | |
| 1630 } | |
| 1631 _bt.allocated((HeapWord*)fc, fc->size()); | |
| 1632 if (fc->size() >= size + MinChunkSize) { | |
| 1633 fc = splitChunkAndReturnRemainder(fc, size); | |
| 1634 } | |
| 1635 assert(fc->size() >= size, "chunk too small"); | |
| 1636 assert(fc->size() < size + MinChunkSize, "chunk too big"); | |
| 1637 _bt.verify_single_block((HeapWord*)fc, fc->size()); | |
| 1638 return fc; | |
| 1639 } | |
| 1640 | |
| 1641 FreeChunk* | |
| 1642 CompactibleFreeListSpace::getChunkFromDictionaryExact(size_t size) { | |
| 1643 assert_locked(); | |
| 1644 FreeChunk* fc = _dictionary->getChunk(size); | |
| 1645 if (fc == NULL) { | |
| 1646 return fc; | |
| 1647 } | |
| 1648 _bt.allocated((HeapWord*)fc, fc->size()); | |
| 1649 if (fc->size() == size) { | |
| 1650 _bt.verify_single_block((HeapWord*)fc, size); | |
| 1651 return fc; | |
| 1652 } | |
| 1653 assert(fc->size() > size, "getChunk() guarantee"); | |
| 1654 if (fc->size() < size + MinChunkSize) { | |
| 1655 // Return the chunk to the dictionary and go get a bigger one. | |
| 1656 returnChunkToDictionary(fc); | |
| 1657 fc = _dictionary->getChunk(size + MinChunkSize); | |
| 1658 if (fc == NULL) { | |
| 1659 return NULL; | |
| 1660 } | |
| 1661 _bt.allocated((HeapWord*)fc, fc->size()); | |
| 1662 } | |
| 1663 assert(fc->size() >= size + MinChunkSize, "tautology"); | |
| 1664 fc = splitChunkAndReturnRemainder(fc, size); | |
| 1665 assert(fc->size() == size, "chunk is wrong size"); | |
| 1666 _bt.verify_single_block((HeapWord*)fc, size); | |
| 1667 return fc; | |
| 1668 } | |
| 1669 | |
| 1670 void | |
| 1671 CompactibleFreeListSpace::returnChunkToDictionary(FreeChunk* chunk) { | |
| 1672 assert_locked(); | |
| 1673 | |
| 1674 size_t size = chunk->size(); | |
| 1675 _bt.verify_single_block((HeapWord*)chunk, size); | |
| 1676 // adjust _unallocated_block downward, as necessary | |
| 1677 _bt.freed((HeapWord*)chunk, size); | |
| 1678 _dictionary->returnChunk(chunk); | |
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1679 #ifndef PRODUCT |
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1680 if (CMSCollector::abstract_state() != CMSCollector::Sweeping) { |
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1681 TreeChunk::as_TreeChunk(chunk)->list()->verify_stats(); |
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1682 } |
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1683 #endif // PRODUCT |
| 0 | 1684 } |
| 1685 | |
| 1686 void | |
| 1687 CompactibleFreeListSpace::returnChunkToFreeList(FreeChunk* fc) { | |
| 1688 assert_locked(); | |
| 1689 size_t size = fc->size(); | |
| 1690 _bt.verify_single_block((HeapWord*) fc, size); | |
| 1691 _bt.verify_not_unallocated((HeapWord*) fc, size); | |
| 1692 if (_adaptive_freelists) { | |
| 1693 _indexedFreeList[size].returnChunkAtTail(fc); | |
| 1694 } else { | |
| 1695 _indexedFreeList[size].returnChunkAtHead(fc); | |
| 1696 } | |
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1697 #ifndef PRODUCT |
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1698 if (CMSCollector::abstract_state() != CMSCollector::Sweeping) { |
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1699 _indexedFreeList[size].verify_stats(); |
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1700 } |
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1701 #endif // PRODUCT |
| 0 | 1702 } |
| 1703 | |
| 1704 // Add chunk to end of last block -- if it's the largest | |
| 1705 // block -- and update BOT and census data. We would | |
| 1706 // of course have preferred to coalesce it with the | |
| 1707 // last block, but it's currently less expensive to find the | |
| 1708 // largest block than it is to find the last. | |
| 1709 void | |
| 1710 CompactibleFreeListSpace::addChunkToFreeListsAtEndRecordingStats( | |
| 1711 HeapWord* chunk, size_t size) { | |
| 1712 // check that the chunk does lie in this space! | |
| 1713 assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!"); | |
| 1714 // One of the parallel gc task threads may be here | |
| 1715 // whilst others are allocating. | |
| 1716 Mutex* lock = NULL; | |
| 1717 if (ParallelGCThreads != 0) { | |
| 1718 lock = &_parDictionaryAllocLock; | |
| 1719 } | |
| 1720 FreeChunk* ec; | |
| 1721 { | |
| 1722 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); | |
| 1723 ec = dictionary()->findLargestDict(); // get largest block | |
| 1724 if (ec != NULL && ec->end() == chunk) { | |
| 1725 // It's a coterminal block - we can coalesce. | |
| 1726 size_t old_size = ec->size(); | |
| 1727 coalDeath(old_size); | |
| 1728 removeChunkFromDictionary(ec); | |
| 1729 size += old_size; | |
| 1730 } else { | |
| 1731 ec = (FreeChunk*)chunk; | |
| 1732 } | |
| 1733 } | |
| 1734 ec->setSize(size); | |
| 1735 debug_only(ec->mangleFreed(size)); | |
| 1736 if (size < SmallForDictionary) { | |
| 1737 lock = _indexedFreeListParLocks[size]; | |
| 1738 } | |
| 1739 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); | |
| 1740 addChunkAndRepairOffsetTable((HeapWord*)ec, size, true); | |
| 1741 // record the birth under the lock since the recording involves | |
| 1742 // manipulation of the list on which the chunk lives and | |
| 1743 // if the chunk is allocated and is the last on the list, | |
| 1744 // the list can go away. | |
| 1745 coalBirth(size); | |
| 1746 } | |
| 1747 | |
| 1748 void | |
| 1749 CompactibleFreeListSpace::addChunkToFreeLists(HeapWord* chunk, | |
| 1750 size_t size) { | |
| 1751 // check that the chunk does lie in this space! | |
| 1752 assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!"); | |
| 1753 assert_locked(); | |
| 1754 _bt.verify_single_block(chunk, size); | |
| 1755 | |
| 1756 FreeChunk* fc = (FreeChunk*) chunk; | |
| 1757 fc->setSize(size); | |
| 1758 debug_only(fc->mangleFreed(size)); | |
| 1759 if (size < SmallForDictionary) { | |
| 1760 returnChunkToFreeList(fc); | |
| 1761 } else { | |
| 1762 returnChunkToDictionary(fc); | |
| 1763 } | |
| 1764 } | |
| 1765 | |
| 1766 void | |
| 1767 CompactibleFreeListSpace::addChunkAndRepairOffsetTable(HeapWord* chunk, | |
| 1768 size_t size, bool coalesced) { | |
| 1769 assert_locked(); | |
| 1770 assert(chunk != NULL, "null chunk"); | |
| 1771 if (coalesced) { | |
| 1772 // repair BOT | |
| 1773 _bt.single_block(chunk, size); | |
| 1774 } | |
| 1775 addChunkToFreeLists(chunk, size); | |
| 1776 } | |
| 1777 | |
| 1778 // We _must_ find the purported chunk on our free lists; | |
| 1779 // we assert if we don't. | |
| 1780 void | |
| 1781 CompactibleFreeListSpace::removeFreeChunkFromFreeLists(FreeChunk* fc) { | |
| 1782 size_t size = fc->size(); | |
| 1783 assert_locked(); | |
| 1784 debug_only(verifyFreeLists()); | |
| 1785 if (size < SmallForDictionary) { | |
| 1786 removeChunkFromIndexedFreeList(fc); | |
| 1787 } else { | |
| 1788 removeChunkFromDictionary(fc); | |
| 1789 } | |
| 1790 _bt.verify_single_block((HeapWord*)fc, size); | |
| 1791 debug_only(verifyFreeLists()); | |
| 1792 } | |
| 1793 | |
| 1794 void | |
| 1795 CompactibleFreeListSpace::removeChunkFromDictionary(FreeChunk* fc) { | |
| 1796 size_t size = fc->size(); | |
| 1797 assert_locked(); | |
| 1798 assert(fc != NULL, "null chunk"); | |
| 1799 _bt.verify_single_block((HeapWord*)fc, size); | |
| 1800 _dictionary->removeChunk(fc); | |
| 1801 // adjust _unallocated_block upward, as necessary | |
| 1802 _bt.allocated((HeapWord*)fc, size); | |
| 1803 } | |
| 1804 | |
| 1805 void | |
| 1806 CompactibleFreeListSpace::removeChunkFromIndexedFreeList(FreeChunk* fc) { | |
| 1807 assert_locked(); | |
| 1808 size_t size = fc->size(); | |
| 1809 _bt.verify_single_block((HeapWord*)fc, size); | |
| 1810 NOT_PRODUCT( | |
| 1811 if (FLSVerifyIndexTable) { | |
| 1812 verifyIndexedFreeList(size); | |
| 1813 } | |
| 1814 ) | |
| 1815 _indexedFreeList[size].removeChunk(fc); | |
| 1816 debug_only(fc->clearNext()); | |
| 1817 debug_only(fc->clearPrev()); | |
| 1818 NOT_PRODUCT( | |
| 1819 if (FLSVerifyIndexTable) { | |
| 1820 verifyIndexedFreeList(size); | |
| 1821 } | |
| 1822 ) | |
| 1823 } | |
| 1824 | |
| 1825 FreeChunk* CompactibleFreeListSpace::bestFitSmall(size_t numWords) { | |
| 1826 /* A hint is the next larger size that has a surplus. | |
| 1827 Start search at a size large enough to guarantee that | |
| 1828 the excess is >= MIN_CHUNK. */ | |
| 1829 size_t start = align_object_size(numWords + MinChunkSize); | |
| 1830 if (start < IndexSetSize) { | |
| 1831 FreeList* it = _indexedFreeList; | |
| 1832 size_t hint = _indexedFreeList[start].hint(); | |
| 1833 while (hint < IndexSetSize) { | |
| 1834 assert(hint % MinObjAlignment == 0, "hint should be aligned"); | |
| 1835 FreeList *fl = &_indexedFreeList[hint]; | |
| 1836 if (fl->surplus() > 0 && fl->head() != NULL) { | |
| 1837 // Found a list with surplus, reset original hint | |
| 1838 // and split out a free chunk which is returned. | |
| 1839 _indexedFreeList[start].set_hint(hint); | |
| 1840 FreeChunk* res = getFromListGreater(fl, numWords); | |
| 1841 assert(res == NULL || res->isFree(), | |
| 1842 "Should be returning a free chunk"); | |
| 1843 return res; | |
| 1844 } | |
| 1845 hint = fl->hint(); /* keep looking */ | |
| 1846 } | |
| 1847 /* None found. */ | |
| 1848 it[start].set_hint(IndexSetSize); | |
| 1849 } | |
| 1850 return NULL; | |
| 1851 } | |
| 1852 | |
| 1853 /* Requires fl->size >= numWords + MinChunkSize */ | |
| 1854 FreeChunk* CompactibleFreeListSpace::getFromListGreater(FreeList* fl, | |
| 1855 size_t numWords) { | |
| 1856 FreeChunk *curr = fl->head(); | |
| 1857 size_t oldNumWords = curr->size(); | |
| 1858 assert(numWords >= MinChunkSize, "Word size is too small"); | |
| 1859 assert(curr != NULL, "List is empty"); | |
| 1860 assert(oldNumWords >= numWords + MinChunkSize, | |
| 1861 "Size of chunks in the list is too small"); | |
| 1862 | |
| 1863 fl->removeChunk(curr); | |
| 1864 // recorded indirectly by splitChunkAndReturnRemainder - | |
| 1865 // smallSplit(oldNumWords, numWords); | |
| 1866 FreeChunk* new_chunk = splitChunkAndReturnRemainder(curr, numWords); | |
| 1867 // Does anything have to be done for the remainder in terms of | |
| 1868 // fixing the card table? | |
| 1869 assert(new_chunk == NULL || new_chunk->isFree(), | |
| 1870 "Should be returning a free chunk"); | |
| 1871 return new_chunk; | |
| 1872 } | |
| 1873 | |
| 1874 FreeChunk* | |
| 1875 CompactibleFreeListSpace::splitChunkAndReturnRemainder(FreeChunk* chunk, | |
| 1876 size_t new_size) { | |
| 1877 assert_locked(); | |
| 1878 size_t size = chunk->size(); | |
| 1879 assert(size > new_size, "Split from a smaller block?"); | |
| 1880 assert(is_aligned(chunk), "alignment problem"); | |
| 1881 assert(size == adjustObjectSize(size), "alignment problem"); | |
| 1882 size_t rem_size = size - new_size; | |
| 1883 assert(rem_size == adjustObjectSize(rem_size), "alignment problem"); | |
| 1884 assert(rem_size >= MinChunkSize, "Free chunk smaller than minimum"); | |
| 1885 FreeChunk* ffc = (FreeChunk*)((HeapWord*)chunk + new_size); | |
| 1886 assert(is_aligned(ffc), "alignment problem"); | |
| 1887 ffc->setSize(rem_size); | |
| 1888 ffc->linkNext(NULL); | |
| 1889 ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. | |
| 1890 // Above must occur before BOT is updated below. | |
| 1891 // adjust block offset table | |
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1892 OrderAccess::storestore(); |
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1893 assert(chunk->isFree() && ffc->isFree(), "Error"); |
| 0 | 1894 _bt.split_block((HeapWord*)chunk, chunk->size(), new_size); |
| 1895 if (rem_size < SmallForDictionary) { | |
| 1896 bool is_par = (SharedHeap::heap()->n_par_threads() > 0); | |
| 1897 if (is_par) _indexedFreeListParLocks[rem_size]->lock(); | |
| 1898 returnChunkToFreeList(ffc); | |
| 1899 split(size, rem_size); | |
| 1900 if (is_par) _indexedFreeListParLocks[rem_size]->unlock(); | |
| 1901 } else { | |
| 1902 returnChunkToDictionary(ffc); | |
| 1903 split(size ,rem_size); | |
| 1904 } | |
| 1905 chunk->setSize(new_size); | |
| 1906 return chunk; | |
| 1907 } | |
| 1908 | |
| 1909 void | |
| 1910 CompactibleFreeListSpace::sweep_completed() { | |
| 1911 // Now that space is probably plentiful, refill linear | |
| 1912 // allocation blocks as needed. | |
| 1913 refillLinearAllocBlocksIfNeeded(); | |
| 1914 } | |
| 1915 | |
| 1916 void | |
| 1917 CompactibleFreeListSpace::gc_prologue() { | |
| 1918 assert_locked(); | |
| 1919 if (PrintFLSStatistics != 0) { | |
| 1920 gclog_or_tty->print("Before GC:\n"); | |
| 1921 reportFreeListStatistics(); | |
| 1922 } | |
| 1923 refillLinearAllocBlocksIfNeeded(); | |
| 1924 } | |
| 1925 | |
| 1926 void | |
| 1927 CompactibleFreeListSpace::gc_epilogue() { | |
| 1928 assert_locked(); | |
| 1929 if (PrintGCDetails && Verbose && !_adaptive_freelists) { | |
| 1930 if (_smallLinearAllocBlock._word_size == 0) | |
| 1931 warning("CompactibleFreeListSpace(epilogue):: Linear allocation failure"); | |
| 1932 } | |
| 1933 assert(_promoInfo.noPromotions(), "_promoInfo inconsistency"); | |
| 1934 _promoInfo.stopTrackingPromotions(); | |
| 1935 repairLinearAllocationBlocks(); | |
| 1936 // Print Space's stats | |
| 1937 if (PrintFLSStatistics != 0) { | |
| 1938 gclog_or_tty->print("After GC:\n"); | |
| 1939 reportFreeListStatistics(); | |
| 1940 } | |
| 1941 } | |
| 1942 | |
| 1943 // Iteration support, mostly delegated from a CMS generation | |
| 1944 | |
| 1945 void CompactibleFreeListSpace::save_marks() { | |
| 1946 // mark the "end" of the used space at the time of this call; | |
| 1947 // note, however, that promoted objects from this point | |
| 1948 // on are tracked in the _promoInfo below. | |
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1949 set_saved_mark_word(unallocated_block()); |
| 0 | 1950 // inform allocator that promotions should be tracked. |
| 1951 assert(_promoInfo.noPromotions(), "_promoInfo inconsistency"); | |
| 1952 _promoInfo.startTrackingPromotions(); | |
| 1953 } | |
| 1954 | |
| 1955 bool CompactibleFreeListSpace::no_allocs_since_save_marks() { | |
| 1956 assert(_promoInfo.tracking(), "No preceding save_marks?"); | |
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1957 assert(SharedHeap::heap()->n_par_threads() == 0, |
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1958 "Shouldn't be called if using parallel gc."); |
| 0 | 1959 return _promoInfo.noPromotions(); |
| 1960 } | |
| 1961 | |
| 1962 #define CFLS_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
| 1963 \ | |
| 1964 void CompactibleFreeListSpace:: \ | |
| 1965 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ | |
| 1966 assert(SharedHeap::heap()->n_par_threads() == 0, \ | |
| 1967 "Shouldn't be called (yet) during parallel part of gc."); \ | |
| 1968 _promoInfo.promoted_oops_iterate##nv_suffix(blk); \ | |
| 1969 /* \ | |
| 1970 * This also restores any displaced headers and removes the elements from \ | |
| 1971 * the iteration set as they are processed, so that we have a clean slate \ | |
| 1972 * at the end of the iteration. Note, thus, that if new objects are \ | |
| 1973 * promoted as a result of the iteration they are iterated over as well. \ | |
| 1974 */ \ | |
| 1975 assert(_promoInfo.noPromotions(), "_promoInfo inconsistency"); \ | |
| 1976 } | |
| 1977 | |
| 1978 ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DEFN) | |
| 1979 | |
| 1980 | |
| 1981 void CompactibleFreeListSpace::object_iterate_since_last_GC(ObjectClosure* cl) { | |
| 1982 // ugghh... how would one do this efficiently for a non-contiguous space? | |
| 1983 guarantee(false, "NYI"); | |
| 1984 } | |
| 1985 | |
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1986 bool CompactibleFreeListSpace::linearAllocationWouldFail() const { |
| 0 | 1987 return _smallLinearAllocBlock._word_size == 0; |
| 1988 } | |
| 1989 | |
| 1990 void CompactibleFreeListSpace::repairLinearAllocationBlocks() { | |
| 1991 // Fix up linear allocation blocks to look like free blocks | |
| 1992 repairLinearAllocBlock(&_smallLinearAllocBlock); | |
| 1993 } | |
| 1994 | |
| 1995 void CompactibleFreeListSpace::repairLinearAllocBlock(LinearAllocBlock* blk) { | |
| 1996 assert_locked(); | |
| 1997 if (blk->_ptr != NULL) { | |
| 1998 assert(blk->_word_size != 0 && blk->_word_size >= MinChunkSize, | |
| 1999 "Minimum block size requirement"); | |
| 2000 FreeChunk* fc = (FreeChunk*)(blk->_ptr); | |
| 2001 fc->setSize(blk->_word_size); | |
| 2002 fc->linkPrev(NULL); // mark as free | |
| 2003 fc->dontCoalesce(); | |
| 2004 assert(fc->isFree(), "just marked it free"); | |
| 2005 assert(fc->cantCoalesce(), "just marked it uncoalescable"); | |
| 2006 } | |
| 2007 } | |
| 2008 | |
| 2009 void CompactibleFreeListSpace::refillLinearAllocBlocksIfNeeded() { | |
| 2010 assert_locked(); | |
| 2011 if (_smallLinearAllocBlock._ptr == NULL) { | |
| 2012 assert(_smallLinearAllocBlock._word_size == 0, | |
| 2013 "Size of linAB should be zero if the ptr is NULL"); | |
| 2014 // Reset the linAB refill and allocation size limit. | |
| 2015 _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc, SmallForLinearAlloc); | |
| 2016 } | |
| 2017 refillLinearAllocBlockIfNeeded(&_smallLinearAllocBlock); | |
| 2018 } | |
| 2019 | |
| 2020 void | |
| 2021 CompactibleFreeListSpace::refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk) { | |
| 2022 assert_locked(); | |
| 2023 assert((blk->_ptr == NULL && blk->_word_size == 0) || | |
| 2024 (blk->_ptr != NULL && blk->_word_size >= MinChunkSize), | |
| 2025 "blk invariant"); | |
| 2026 if (blk->_ptr == NULL) { | |
| 2027 refillLinearAllocBlock(blk); | |
| 2028 } | |
| 2029 if (PrintMiscellaneous && Verbose) { | |
| 2030 if (blk->_word_size == 0) { | |
| 2031 warning("CompactibleFreeListSpace(prologue):: Linear allocation failure"); | |
| 2032 } | |
| 2033 } | |
| 2034 } | |
| 2035 | |
| 2036 void | |
| 2037 CompactibleFreeListSpace::refillLinearAllocBlock(LinearAllocBlock* blk) { | |
| 2038 assert_locked(); | |
| 2039 assert(blk->_word_size == 0 && blk->_ptr == NULL, | |
| 2040 "linear allocation block should be empty"); | |
| 2041 FreeChunk* fc; | |
| 2042 if (blk->_refillSize < SmallForDictionary && | |
| 2043 (fc = getChunkFromIndexedFreeList(blk->_refillSize)) != NULL) { | |
| 2044 // A linAB's strategy might be to use small sizes to reduce | |
| 2045 // fragmentation but still get the benefits of allocation from a | |
| 2046 // linAB. | |
| 2047 } else { | |
| 2048 fc = getChunkFromDictionary(blk->_refillSize); | |
| 2049 } | |
| 2050 if (fc != NULL) { | |
| 2051 blk->_ptr = (HeapWord*)fc; | |
| 2052 blk->_word_size = fc->size(); | |
| 2053 fc->dontCoalesce(); // to prevent sweeper from sweeping us up | |
| 2054 } | |
| 2055 } | |
| 2056 | |
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2057 // Support for concurrent collection policy decisions. |
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2058 bool CompactibleFreeListSpace::should_concurrent_collect() const { |
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2059 // In the future we might want to add in frgamentation stats -- |
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2060 // including erosion of the "mountain" into this decision as well. |
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2061 return !adaptive_freelists() && linearAllocationWouldFail(); |
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2062 } |
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2063 |
| 0 | 2064 // Support for compaction |
| 2065 | |
| 2066 void CompactibleFreeListSpace::prepare_for_compaction(CompactPoint* cp) { | |
| 2067 SCAN_AND_FORWARD(cp,end,block_is_obj,block_size); | |
| 2068 // prepare_for_compaction() uses the space between live objects | |
| 2069 // so that later phase can skip dead space quickly. So verification | |
| 2070 // of the free lists doesn't work after. | |
| 2071 } | |
| 2072 | |
| 2073 #define obj_size(q) adjustObjectSize(oop(q)->size()) | |
| 2074 #define adjust_obj_size(s) adjustObjectSize(s) | |
| 2075 | |
| 2076 void CompactibleFreeListSpace::adjust_pointers() { | |
| 2077 // In other versions of adjust_pointers(), a bail out | |
| 2078 // based on the amount of live data in the generation | |
| 2079 // (i.e., if 0, bail out) may be used. | |
| 2080 // Cannot test used() == 0 here because the free lists have already | |
| 2081 // been mangled by the compaction. | |
| 2082 | |
| 2083 SCAN_AND_ADJUST_POINTERS(adjust_obj_size); | |
| 2084 // See note about verification in prepare_for_compaction(). | |
| 2085 } | |
| 2086 | |
| 2087 void CompactibleFreeListSpace::compact() { | |
| 2088 SCAN_AND_COMPACT(obj_size); | |
| 2089 } | |
| 2090 | |
| 2091 // fragmentation_metric = 1 - [sum of (fbs**2) / (sum of fbs)**2] | |
| 2092 // where fbs is free block sizes | |
| 2093 double CompactibleFreeListSpace::flsFrag() const { | |
| 2094 size_t itabFree = totalSizeInIndexedFreeLists(); | |
| 2095 double frag = 0.0; | |
| 2096 size_t i; | |
| 2097 | |
| 2098 for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
| 2099 double sz = i; | |
| 2100 frag += _indexedFreeList[i].count() * (sz * sz); | |
| 2101 } | |
| 2102 | |
| 2103 double totFree = itabFree + | |
| 2104 _dictionary->totalChunkSize(DEBUG_ONLY(freelistLock())); | |
| 2105 if (totFree > 0) { | |
| 2106 frag = ((frag + _dictionary->sum_of_squared_block_sizes()) / | |
| 2107 (totFree * totFree)); | |
| 2108 frag = (double)1.0 - frag; | |
| 2109 } else { | |
| 2110 assert(frag == 0.0, "Follows from totFree == 0"); | |
| 2111 } | |
| 2112 return frag; | |
| 2113 } | |
| 2114 | |
| 2115 void CompactibleFreeListSpace::beginSweepFLCensus( | |
| 2116 float inter_sweep_current, | |
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2117 float inter_sweep_estimate, |
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2118 float intra_sweep_estimate) { |
| 0 | 2119 assert_locked(); |
| 2120 size_t i; | |
| 2121 for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
| 2122 FreeList* fl = &_indexedFreeList[i]; | |
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2123 if (PrintFLSStatistics > 1) { |
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2124 gclog_or_tty->print("size[%d] : ", i); |
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2125 } |
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2126 fl->compute_desired(inter_sweep_current, inter_sweep_estimate, intra_sweep_estimate); |
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2127 fl->set_coalDesired((ssize_t)((double)fl->desired() * CMSSmallCoalSurplusPercent)); |
| 0 | 2128 fl->set_beforeSweep(fl->count()); |
| 2129 fl->set_bfrSurp(fl->surplus()); | |
| 2130 } | |
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2131 _dictionary->beginSweepDictCensus(CMSLargeCoalSurplusPercent, |
| 0 | 2132 inter_sweep_current, |
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2133 inter_sweep_estimate, |
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2134 intra_sweep_estimate); |
| 0 | 2135 } |
| 2136 | |
| 2137 void CompactibleFreeListSpace::setFLSurplus() { | |
| 2138 assert_locked(); | |
| 2139 size_t i; | |
| 2140 for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
| 2141 FreeList *fl = &_indexedFreeList[i]; | |
| 2142 fl->set_surplus(fl->count() - | |
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2143 (ssize_t)((double)fl->desired() * CMSSmallSplitSurplusPercent)); |
| 0 | 2144 } |
| 2145 } | |
| 2146 | |
| 2147 void CompactibleFreeListSpace::setFLHints() { | |
| 2148 assert_locked(); | |
| 2149 size_t i; | |
| 2150 size_t h = IndexSetSize; | |
| 2151 for (i = IndexSetSize - 1; i != 0; i -= IndexSetStride) { | |
| 2152 FreeList *fl = &_indexedFreeList[i]; | |
| 2153 fl->set_hint(h); | |
| 2154 if (fl->surplus() > 0) { | |
| 2155 h = i; | |
| 2156 } | |
| 2157 } | |
| 2158 } | |
| 2159 | |
| 2160 void CompactibleFreeListSpace::clearFLCensus() { | |
| 2161 assert_locked(); | |
| 2162 int i; | |
| 2163 for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
| 2164 FreeList *fl = &_indexedFreeList[i]; | |
| 2165 fl->set_prevSweep(fl->count()); | |
| 2166 fl->set_coalBirths(0); | |
| 2167 fl->set_coalDeaths(0); | |
| 2168 fl->set_splitBirths(0); | |
| 2169 fl->set_splitDeaths(0); | |
| 2170 } | |
| 2171 } | |
| 2172 | |
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2173 void CompactibleFreeListSpace::endSweepFLCensus(size_t sweep_count) { |
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2174 if (PrintFLSStatistics > 0) { |
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2175 HeapWord* largestAddr = (HeapWord*) dictionary()->findLargestDict(); |
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2176 gclog_or_tty->print_cr("CMS: Large block " PTR_FORMAT, |
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2177 largestAddr); |
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2178 } |
| 0 | 2179 setFLSurplus(); |
| 2180 setFLHints(); | |
| 2181 if (PrintGC && PrintFLSCensus > 0) { | |
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2182 printFLCensus(sweep_count); |
| 0 | 2183 } |
| 2184 clearFLCensus(); | |
| 2185 assert_locked(); | |
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2186 _dictionary->endSweepDictCensus(CMSLargeSplitSurplusPercent); |
| 0 | 2187 } |
| 2188 | |
| 2189 bool CompactibleFreeListSpace::coalOverPopulated(size_t size) { | |
| 2190 if (size < SmallForDictionary) { | |
| 2191 FreeList *fl = &_indexedFreeList[size]; | |
| 2192 return (fl->coalDesired() < 0) || | |
| 2193 ((int)fl->count() > fl->coalDesired()); | |
| 2194 } else { | |
| 2195 return dictionary()->coalDictOverPopulated(size); | |
| 2196 } | |
| 2197 } | |
| 2198 | |
| 2199 void CompactibleFreeListSpace::smallCoalBirth(size_t size) { | |
| 2200 assert(size < SmallForDictionary, "Size too large for indexed list"); | |
| 2201 FreeList *fl = &_indexedFreeList[size]; | |
| 2202 fl->increment_coalBirths(); | |
| 2203 fl->increment_surplus(); | |
| 2204 } | |
| 2205 | |
| 2206 void CompactibleFreeListSpace::smallCoalDeath(size_t size) { | |
| 2207 assert(size < SmallForDictionary, "Size too large for indexed list"); | |
| 2208 FreeList *fl = &_indexedFreeList[size]; | |
| 2209 fl->increment_coalDeaths(); | |
| 2210 fl->decrement_surplus(); | |
| 2211 } | |
| 2212 | |
| 2213 void CompactibleFreeListSpace::coalBirth(size_t size) { | |
| 2214 if (size < SmallForDictionary) { | |
| 2215 smallCoalBirth(size); | |
| 2216 } else { | |
| 2217 dictionary()->dictCensusUpdate(size, | |
| 2218 false /* split */, | |
| 2219 true /* birth */); | |
| 2220 } | |
| 2221 } | |
| 2222 | |
| 2223 void CompactibleFreeListSpace::coalDeath(size_t size) { | |
| 2224 if(size < SmallForDictionary) { | |
| 2225 smallCoalDeath(size); | |
| 2226 } else { | |
| 2227 dictionary()->dictCensusUpdate(size, | |
| 2228 false /* split */, | |
| 2229 false /* birth */); | |
| 2230 } | |
| 2231 } | |
| 2232 | |
| 2233 void CompactibleFreeListSpace::smallSplitBirth(size_t size) { | |
| 2234 assert(size < SmallForDictionary, "Size too large for indexed list"); | |
| 2235 FreeList *fl = &_indexedFreeList[size]; | |
| 2236 fl->increment_splitBirths(); | |
| 2237 fl->increment_surplus(); | |
| 2238 } | |
| 2239 | |
| 2240 void CompactibleFreeListSpace::smallSplitDeath(size_t size) { | |
| 2241 assert(size < SmallForDictionary, "Size too large for indexed list"); | |
| 2242 FreeList *fl = &_indexedFreeList[size]; | |
| 2243 fl->increment_splitDeaths(); | |
| 2244 fl->decrement_surplus(); | |
| 2245 } | |
| 2246 | |
| 2247 void CompactibleFreeListSpace::splitBirth(size_t size) { | |
| 2248 if (size < SmallForDictionary) { | |
| 2249 smallSplitBirth(size); | |
| 2250 } else { | |
| 2251 dictionary()->dictCensusUpdate(size, | |
| 2252 true /* split */, | |
| 2253 true /* birth */); | |
| 2254 } | |
| 2255 } | |
| 2256 | |
| 2257 void CompactibleFreeListSpace::splitDeath(size_t size) { | |
| 2258 if (size < SmallForDictionary) { | |
| 2259 smallSplitDeath(size); | |
| 2260 } else { | |
| 2261 dictionary()->dictCensusUpdate(size, | |
| 2262 true /* split */, | |
| 2263 false /* birth */); | |
| 2264 } | |
| 2265 } | |
| 2266 | |
| 2267 void CompactibleFreeListSpace::split(size_t from, size_t to1) { | |
| 2268 size_t to2 = from - to1; | |
| 2269 splitDeath(from); | |
| 2270 splitBirth(to1); | |
| 2271 splitBirth(to2); | |
| 2272 } | |
| 2273 | |
| 2274 void CompactibleFreeListSpace::print() const { | |
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2275 Space::print_on(tty); |
| 0 | 2276 } |
| 2277 | |
| 2278 void CompactibleFreeListSpace::prepare_for_verify() { | |
| 2279 assert_locked(); | |
| 2280 repairLinearAllocationBlocks(); | |
| 2281 // Verify that the SpoolBlocks look like free blocks of | |
| 2282 // appropriate sizes... To be done ... | |
| 2283 } | |
| 2284 | |
| 2285 class VerifyAllBlksClosure: public BlkClosure { | |
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2286 private: |
| 0 | 2287 const CompactibleFreeListSpace* _sp; |
| 2288 const MemRegion _span; | |
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2289 HeapWord* _last_addr; |
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2290 size_t _last_size; |
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2291 bool _last_was_obj; |
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2292 bool _last_was_live; |
| 0 | 2293 |
| 2294 public: | |
| 2295 VerifyAllBlksClosure(const CompactibleFreeListSpace* sp, | |
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2296 MemRegion span) : _sp(sp), _span(span), |
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2297 _last_addr(NULL), _last_size(0), |
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2298 _last_was_obj(false), _last_was_live(false) { } |
| 0 | 2299 |
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2300 virtual size_t do_blk(HeapWord* addr) { |
| 0 | 2301 size_t res; |
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2302 bool was_obj = false; |
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2303 bool was_live = false; |
| 0 | 2304 if (_sp->block_is_obj(addr)) { |
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2305 was_obj = true; |
| 0 | 2306 oop p = oop(addr); |
| 2307 guarantee(p->is_oop(), "Should be an oop"); | |
| 2308 res = _sp->adjustObjectSize(p->size()); | |
| 2309 if (_sp->obj_is_alive(addr)) { | |
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2310 was_live = true; |
| 0 | 2311 p->verify(); |
| 2312 } | |
| 2313 } else { | |
| 2314 FreeChunk* fc = (FreeChunk*)addr; | |
| 2315 res = fc->size(); | |
| 2316 if (FLSVerifyLists && !fc->cantCoalesce()) { | |
| 2317 guarantee(_sp->verifyChunkInFreeLists(fc), | |
| 2318 "Chunk should be on a free list"); | |
| 2319 } | |
| 2320 } | |
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2321 if (res == 0) { |
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2322 gclog_or_tty->print_cr("Livelock: no rank reduction!"); |
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2323 gclog_or_tty->print_cr( |
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2324 " Current: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n" |
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2325 " Previous: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n", |
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2326 addr, res, was_obj ?"true":"false", was_live ?"true":"false", |
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2327 _last_addr, _last_size, _last_was_obj?"true":"false", _last_was_live?"true":"false"); |
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2328 _sp->print_on(gclog_or_tty); |
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2329 guarantee(false, "Seppuku!"); |
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2330 } |
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2331 _last_addr = addr; |
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2332 _last_size = res; |
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2333 _last_was_obj = was_obj; |
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2334 _last_was_live = was_live; |
| 0 | 2335 return res; |
| 2336 } | |
| 2337 }; | |
| 2338 | |
| 2339 class VerifyAllOopsClosure: public OopClosure { | |
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2340 private: |
| 0 | 2341 const CMSCollector* _collector; |
| 2342 const CompactibleFreeListSpace* _sp; | |
| 2343 const MemRegion _span; | |
| 2344 const bool _past_remark; | |
| 2345 const CMSBitMap* _bit_map; | |
| 2346 | |
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2347 protected: |
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2348 void do_oop(void* p, oop obj) { |
|
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2349 if (_span.contains(obj)) { // the interior oop points into CMS heap |
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2350 if (!_span.contains(p)) { // reference from outside CMS heap |
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2351 // Should be a valid object; the first disjunct below allows |
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2352 // us to sidestep an assertion in block_is_obj() that insists |
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2353 // that p be in _sp. Note that several generations (and spaces) |
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2354 // are spanned by _span (CMS heap) above. |
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2355 guarantee(!_sp->is_in_reserved(obj) || |
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2356 _sp->block_is_obj((HeapWord*)obj), |
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2357 "Should be an object"); |
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2358 guarantee(obj->is_oop(), "Should be an oop"); |
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2359 obj->verify(); |
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2360 if (_past_remark) { |
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2361 // Remark has been completed, the object should be marked |
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2362 _bit_map->isMarked((HeapWord*)obj); |
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2363 } |
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2364 } else { // reference within CMS heap |
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2365 if (_past_remark) { |
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2366 // Remark has been completed -- so the referent should have |
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2367 // been marked, if referring object is. |
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2368 if (_bit_map->isMarked(_collector->block_start(p))) { |
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2369 guarantee(_bit_map->isMarked((HeapWord*)obj), "Marking error?"); |
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2370 } |
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2371 } |
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2372 } |
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2373 } else if (_sp->is_in_reserved(p)) { |
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2374 // the reference is from FLS, and points out of FLS |
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2375 guarantee(obj->is_oop(), "Should be an oop"); |
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2376 obj->verify(); |
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2377 } |
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2378 } |
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2379 |
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2380 template <class T> void do_oop_work(T* p) { |
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2381 T heap_oop = oopDesc::load_heap_oop(p); |
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2382 if (!oopDesc::is_null(heap_oop)) { |
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2383 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
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2384 do_oop(p, obj); |
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2385 } |
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2386 } |
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2387 |
| 0 | 2388 public: |
| 2389 VerifyAllOopsClosure(const CMSCollector* collector, | |
| 2390 const CompactibleFreeListSpace* sp, MemRegion span, | |
| 2391 bool past_remark, CMSBitMap* bit_map) : | |
| 2392 OopClosure(), _collector(collector), _sp(sp), _span(span), | |
| 2393 _past_remark(past_remark), _bit_map(bit_map) { } | |
| 2394 | |
|
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2395 virtual void do_oop(oop* p) { VerifyAllOopsClosure::do_oop_work(p); } |
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2396 virtual void do_oop(narrowOop* p) { VerifyAllOopsClosure::do_oop_work(p); } |
| 0 | 2397 }; |
| 2398 | |
| 2399 void CompactibleFreeListSpace::verify(bool ignored) const { | |
| 2400 assert_lock_strong(&_freelistLock); | |
| 2401 verify_objects_initialized(); | |
| 2402 MemRegion span = _collector->_span; | |
| 2403 bool past_remark = (_collector->abstract_state() == | |
| 2404 CMSCollector::Sweeping); | |
| 2405 | |
| 2406 ResourceMark rm; | |
| 2407 HandleMark hm; | |
| 2408 | |
| 2409 // Check integrity of CFL data structures | |
| 2410 _promoInfo.verify(); | |
| 2411 _dictionary->verify(); | |
| 2412 if (FLSVerifyIndexTable) { | |
| 2413 verifyIndexedFreeLists(); | |
| 2414 } | |
| 2415 // Check integrity of all objects and free blocks in space | |
| 2416 { | |
| 2417 VerifyAllBlksClosure cl(this, span); | |
| 2418 ((CompactibleFreeListSpace*)this)->blk_iterate(&cl); // cast off const | |
| 2419 } | |
| 2420 // Check that all references in the heap to FLS | |
| 2421 // are to valid objects in FLS or that references in | |
| 2422 // FLS are to valid objects elsewhere in the heap | |
| 2423 if (FLSVerifyAllHeapReferences) | |
| 2424 { | |
| 2425 VerifyAllOopsClosure cl(_collector, this, span, past_remark, | |
| 2426 _collector->markBitMap()); | |
| 2427 CollectedHeap* ch = Universe::heap(); | |
| 2428 ch->oop_iterate(&cl); // all oops in generations | |
| 2429 ch->permanent_oop_iterate(&cl); // all oops in perm gen | |
| 2430 } | |
| 2431 | |
| 2432 if (VerifyObjectStartArray) { | |
| 2433 // Verify the block offset table | |
| 2434 _bt.verify(); | |
| 2435 } | |
| 2436 } | |
| 2437 | |
| 2438 #ifndef PRODUCT | |
| 2439 void CompactibleFreeListSpace::verifyFreeLists() const { | |
| 2440 if (FLSVerifyLists) { | |
| 2441 _dictionary->verify(); | |
| 2442 verifyIndexedFreeLists(); | |
| 2443 } else { | |
| 2444 if (FLSVerifyDictionary) { | |
| 2445 _dictionary->verify(); | |
| 2446 } | |
| 2447 if (FLSVerifyIndexTable) { | |
| 2448 verifyIndexedFreeLists(); | |
| 2449 } | |
| 2450 } | |
| 2451 } | |
| 2452 #endif | |
| 2453 | |
| 2454 void CompactibleFreeListSpace::verifyIndexedFreeLists() const { | |
| 2455 size_t i = 0; | |
| 2456 for (; i < MinChunkSize; i++) { | |
| 2457 guarantee(_indexedFreeList[i].head() == NULL, "should be NULL"); | |
| 2458 } | |
| 2459 for (; i < IndexSetSize; i++) { | |
| 2460 verifyIndexedFreeList(i); | |
| 2461 } | |
| 2462 } | |
| 2463 | |
| 2464 void CompactibleFreeListSpace::verifyIndexedFreeList(size_t size) const { | |
|
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2465 FreeChunk* fc = _indexedFreeList[size].head(); |
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2466 FreeChunk* tail = _indexedFreeList[size].tail(); |
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2467 size_t num = _indexedFreeList[size].count(); |
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2468 size_t n = 0; |
|
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2469 guarantee((size % 2 == 0) || fc == NULL, "Odd slots should be empty"); |
|
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2470 for (; fc != NULL; fc = fc->next(), n++) { |
| 0 | 2471 guarantee(fc->size() == size, "Size inconsistency"); |
| 2472 guarantee(fc->isFree(), "!free?"); | |
| 2473 guarantee(fc->next() == NULL || fc->next()->prev() == fc, "Broken list"); | |
|
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2474 guarantee((fc->next() == NULL) == (fc == tail), "Incorrect tail"); |
| 0 | 2475 } |
|
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2476 guarantee(n == num, "Incorrect count"); |
| 0 | 2477 } |
| 2478 | |
| 2479 #ifndef PRODUCT | |
| 2480 void CompactibleFreeListSpace::checkFreeListConsistency() const { | |
| 2481 assert(_dictionary->minSize() <= IndexSetSize, | |
| 2482 "Some sizes can't be allocated without recourse to" | |
| 2483 " linear allocation buffers"); | |
| 2484 assert(MIN_TREE_CHUNK_SIZE*HeapWordSize == sizeof(TreeChunk), | |
| 2485 "else MIN_TREE_CHUNK_SIZE is wrong"); | |
| 2486 assert((IndexSetStride == 2 && IndexSetStart == 2) || | |
| 2487 (IndexSetStride == 1 && IndexSetStart == 1), "just checking"); | |
| 2488 assert((IndexSetStride != 2) || (MinChunkSize % 2 == 0), | |
| 2489 "Some for-loops may be incorrectly initialized"); | |
| 2490 assert((IndexSetStride != 2) || (IndexSetSize % 2 == 1), | |
| 2491 "For-loops that iterate over IndexSet with stride 2 may be wrong"); | |
| 2492 } | |
| 2493 #endif | |
| 2494 | |
|
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2495 void CompactibleFreeListSpace::printFLCensus(size_t sweep_count) const { |
| 0 | 2496 assert_lock_strong(&_freelistLock); |
|
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|
2497 FreeList total; |
|
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2498 gclog_or_tty->print("end sweep# " SIZE_FORMAT "\n", sweep_count); |
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|
2499 FreeList::print_labels_on(gclog_or_tty, "size"); |
| 0 | 2500 size_t totalFree = 0; |
| 2501 for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { | |
| 2502 const FreeList *fl = &_indexedFreeList[i]; | |
|
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2503 totalFree += fl->count() * fl->size(); |
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2504 if (i % (40*IndexSetStride) == 0) { |
|
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|
2505 FreeList::print_labels_on(gclog_or_tty, "size"); |
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|
2506 } |
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|
2507 fl->print_on(gclog_or_tty); |
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|
2508 total.set_bfrSurp( total.bfrSurp() + fl->bfrSurp() ); |
|
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2509 total.set_surplus( total.surplus() + fl->surplus() ); |
|
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2510 total.set_desired( total.desired() + fl->desired() ); |
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2511 total.set_prevSweep( total.prevSweep() + fl->prevSweep() ); |
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2512 total.set_beforeSweep(total.beforeSweep() + fl->beforeSweep()); |
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2513 total.set_count( total.count() + fl->count() ); |
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2514 total.set_coalBirths( total.coalBirths() + fl->coalBirths() ); |
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2515 total.set_coalDeaths( total.coalDeaths() + fl->coalDeaths() ); |
|
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2516 total.set_splitBirths(total.splitBirths() + fl->splitBirths()); |
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2517 total.set_splitDeaths(total.splitDeaths() + fl->splitDeaths()); |
| 0 | 2518 } |
|
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2519 total.print_on(gclog_or_tty, "TOTAL"); |
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2520 gclog_or_tty->print_cr("Total free in indexed lists " |
|
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|
2521 SIZE_FORMAT " words", totalFree); |
| 0 | 2522 gclog_or_tty->print("growth: %8.5f deficit: %8.5f\n", |
|
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2523 (double)(total.splitBirths()+total.coalBirths()-total.splitDeaths()-total.coalDeaths())/ |
|
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2524 (total.prevSweep() != 0 ? (double)total.prevSweep() : 1.0), |
|
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2525 (double)(total.desired() - total.count())/(total.desired() != 0 ? (double)total.desired() : 1.0)); |
| 0 | 2526 _dictionary->printDictCensus(); |
| 2527 } | |
| 2528 | |
|
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2529 /////////////////////////////////////////////////////////////////////////// |
|
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2530 // CFLS_LAB |
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2531 /////////////////////////////////////////////////////////////////////////// |
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2532 |
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2533 #define VECTOR_257(x) \ |
|
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2534 /* 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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2535 { 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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2536 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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2537 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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2538 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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2539 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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2540 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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2541 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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2542 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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2543 x } |
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2544 |
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2545 // Initialize with default setting of CMSParPromoteBlocksToClaim, _not_ |
|
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2546 // OldPLABSize, whose static default is different; if overridden at the |
|
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2547 // command-line, this will get reinitialized via a call to |
|
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2548 // modify_initialization() below. |
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2549 AdaptiveWeightedAverage CFLS_LAB::_blocks_to_claim[] = |
|
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2550 VECTOR_257(AdaptiveWeightedAverage(OldPLABWeight, (float)CMSParPromoteBlocksToClaim)); |
|
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2551 size_t CFLS_LAB::_global_num_blocks[] = VECTOR_257(0); |
|
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2552 int CFLS_LAB::_global_num_workers[] = VECTOR_257(0); |
| 0 | 2553 |
| 2554 CFLS_LAB::CFLS_LAB(CompactibleFreeListSpace* cfls) : | |
| 2555 _cfls(cfls) | |
| 2556 { | |
|
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2557 assert(CompactibleFreeListSpace::IndexSetSize == 257, "Modify VECTOR_257() macro above"); |
| 0 | 2558 for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
| 2559 i < CompactibleFreeListSpace::IndexSetSize; | |
| 2560 i += CompactibleFreeListSpace::IndexSetStride) { | |
| 2561 _indexedFreeList[i].set_size(i); | |
|
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2562 _num_blocks[i] = 0; |
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2563 } |
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2564 } |
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2565 |
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2566 static bool _CFLS_LAB_modified = false; |
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2567 |
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2568 void CFLS_LAB::modify_initialization(size_t n, unsigned wt) { |
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2569 assert(!_CFLS_LAB_modified, "Call only once"); |
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2570 _CFLS_LAB_modified = true; |
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2571 for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
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2572 i < CompactibleFreeListSpace::IndexSetSize; |
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2573 i += CompactibleFreeListSpace::IndexSetStride) { |
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2574 _blocks_to_claim[i].modify(n, wt, true /* force */); |
| 0 | 2575 } |
| 2576 } | |
| 2577 | |
| 2578 HeapWord* CFLS_LAB::alloc(size_t word_sz) { | |
| 2579 FreeChunk* res; | |
|
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2580 assert(word_sz == _cfls->adjustObjectSize(word_sz), "Error"); |
| 0 | 2581 if (word_sz >= CompactibleFreeListSpace::IndexSetSize) { |
| 2582 // This locking manages sync with other large object allocations. | |
| 2583 MutexLockerEx x(_cfls->parDictionaryAllocLock(), | |
| 2584 Mutex::_no_safepoint_check_flag); | |
| 2585 res = _cfls->getChunkFromDictionaryExact(word_sz); | |
| 2586 if (res == NULL) return NULL; | |
| 2587 } else { | |
| 2588 FreeList* fl = &_indexedFreeList[word_sz]; | |
| 2589 if (fl->count() == 0) { | |
| 2590 // Attempt to refill this local free list. | |
|
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2591 get_from_global_pool(word_sz, fl); |
| 0 | 2592 // If it didn't work, give up. |
| 2593 if (fl->count() == 0) return NULL; | |
| 2594 } | |
| 2595 res = fl->getChunkAtHead(); | |
| 2596 assert(res != NULL, "Why was count non-zero?"); | |
| 2597 } | |
| 2598 res->markNotFree(); | |
| 2599 assert(!res->isFree(), "shouldn't be marked free"); | |
| 187 | 2600 assert(oop(res)->klass_or_null() == NULL, "should look uninitialized"); |
| 0 | 2601 // mangle a just allocated object with a distinct pattern. |
| 2602 debug_only(res->mangleAllocated(word_sz)); | |
| 2603 return (HeapWord*)res; | |
| 2604 } | |
| 2605 | |
|
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2606 // Get a chunk of blocks of the right size and update related |
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2607 // book-keeping stats |
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2608 void CFLS_LAB::get_from_global_pool(size_t word_sz, FreeList* fl) { |
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2609 // Get the #blocks we want to claim |
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2610 size_t n_blks = (size_t)_blocks_to_claim[word_sz].average(); |
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2611 assert(n_blks > 0, "Error"); |
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2612 assert(ResizePLAB || n_blks == OldPLABSize, "Error"); |
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2613 // In some cases, when the application has a phase change, |
|
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2614 // there may be a sudden and sharp shift in the object survival |
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2615 // profile, and updating the counts at the end of a scavenge |
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2616 // may not be quick enough, giving rise to large scavenge pauses |
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2617 // during these phase changes. It is beneficial to detect such |
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2618 // changes on-the-fly during a scavenge and avoid such a phase-change |
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2619 // pothole. The following code is a heuristic attempt to do that. |
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2620 // It is protected by a product flag until we have gained |
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2621 // enough experience with this heuristic and fine-tuned its behaviour. |
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2622 // WARNING: This might increase fragmentation if we overreact to |
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2623 // small spikes, so some kind of historical smoothing based on |
|
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2624 // previous experience with the greater reactivity might be useful. |
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2625 // Lacking sufficient experience, CMSOldPLABResizeQuicker is disabled by |
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2626 // default. |
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2627 if (ResizeOldPLAB && CMSOldPLABResizeQuicker) { |
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2628 size_t multiple = _num_blocks[word_sz]/(CMSOldPLABToleranceFactor*CMSOldPLABNumRefills*n_blks); |
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2629 n_blks += CMSOldPLABReactivityFactor*multiple*n_blks; |
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2630 n_blks = MIN2(n_blks, CMSOldPLABMax); |
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2631 } |
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2632 assert(n_blks > 0, "Error"); |
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2633 _cfls->par_get_chunk_of_blocks(word_sz, n_blks, fl); |
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2634 // Update stats table entry for this block size |
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2635 _num_blocks[word_sz] += fl->count(); |
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2636 } |
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2637 |
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2638 void CFLS_LAB::compute_desired_plab_size() { |
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2639 for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
| 0 | 2640 i < CompactibleFreeListSpace::IndexSetSize; |
| 2641 i += CompactibleFreeListSpace::IndexSetStride) { | |
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2642 assert((_global_num_workers[i] == 0) == (_global_num_blocks[i] == 0), |
|
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2643 "Counter inconsistency"); |
|
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2644 if (_global_num_workers[i] > 0) { |
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2645 // Need to smooth wrt historical average |
|
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2646 if (ResizeOldPLAB) { |
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2647 _blocks_to_claim[i].sample( |
|
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2648 MAX2((size_t)CMSOldPLABMin, |
|
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2649 MIN2((size_t)CMSOldPLABMax, |
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2650 _global_num_blocks[i]/(_global_num_workers[i]*CMSOldPLABNumRefills)))); |
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2651 } |
|
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2652 // Reset counters for next round |
|
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2653 _global_num_workers[i] = 0; |
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2654 _global_num_blocks[i] = 0; |
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2655 if (PrintOldPLAB) { |
|
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2656 gclog_or_tty->print_cr("[%d]: %d", i, (size_t)_blocks_to_claim[i].average()); |
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2657 } |
| 0 | 2658 } |
| 2659 } | |
| 2660 } | |
| 2661 | |
|
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2662 void CFLS_LAB::retire(int tid) { |
|
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2663 // We run this single threaded with the world stopped; |
|
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2664 // so no need for locks and such. |
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2665 #define CFLS_LAB_PARALLEL_ACCESS 0 |
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2666 NOT_PRODUCT(Thread* t = Thread::current();) |
|
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2667 assert(Thread::current()->is_VM_thread(), "Error"); |
|
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2668 assert(CompactibleFreeListSpace::IndexSetStart == CompactibleFreeListSpace::IndexSetStride, |
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2669 "Will access to uninitialized slot below"); |
|
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2670 #if CFLS_LAB_PARALLEL_ACCESS |
|
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2671 for (size_t i = CompactibleFreeListSpace::IndexSetSize - 1; |
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2672 i > 0; |
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2673 i -= CompactibleFreeListSpace::IndexSetStride) { |
|
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2674 #else // CFLS_LAB_PARALLEL_ACCESS |
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2675 for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
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2676 i < CompactibleFreeListSpace::IndexSetSize; |
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2677 i += CompactibleFreeListSpace::IndexSetStride) { |
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2678 #endif // !CFLS_LAB_PARALLEL_ACCESS |
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2679 assert(_num_blocks[i] >= (size_t)_indexedFreeList[i].count(), |
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2680 "Can't retire more than what we obtained"); |
|
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2681 if (_num_blocks[i] > 0) { |
|
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2682 size_t num_retire = _indexedFreeList[i].count(); |
|
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2683 assert(_num_blocks[i] > num_retire, "Should have used at least one"); |
|
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2684 { |
|
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2685 #if CFLS_LAB_PARALLEL_ACCESS |
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2686 MutexLockerEx x(_cfls->_indexedFreeListParLocks[i], |
|
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2687 Mutex::_no_safepoint_check_flag); |
|
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2688 #endif // CFLS_LAB_PARALLEL_ACCESS |
|
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2689 // Update globals stats for num_blocks used |
|
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2690 _global_num_blocks[i] += (_num_blocks[i] - num_retire); |
|
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2691 _global_num_workers[i]++; |
|
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2692 assert(_global_num_workers[i] <= (ssize_t)ParallelGCThreads, "Too big"); |
|
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2693 if (num_retire > 0) { |
|
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2694 _cfls->_indexedFreeList[i].prepend(&_indexedFreeList[i]); |
|
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2695 // Reset this list. |
|
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2696 _indexedFreeList[i] = FreeList(); |
|
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2697 _indexedFreeList[i].set_size(i); |
|
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2698 } |
|
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|
2699 } |
|
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|
2700 if (PrintOldPLAB) { |
|
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|
2701 gclog_or_tty->print_cr("%d[%d]: %d/%d/%d", |
|
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2702 tid, i, num_retire, _num_blocks[i], (size_t)_blocks_to_claim[i].average()); |
|
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|
2703 } |
|
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2704 // Reset stats for next round |
|
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|
2705 _num_blocks[i] = 0; |
|
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2706 } |
|
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|
2707 } |
|
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|
2708 } |
|
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|
2709 |
|
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2710 void CompactibleFreeListSpace:: par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl) { |
| 0 | 2711 assert(fl->count() == 0, "Precondition."); |
| 2712 assert(word_sz < CompactibleFreeListSpace::IndexSetSize, | |
| 2713 "Precondition"); | |
| 2714 | |
|
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2715 // We'll try all multiples of word_sz in the indexed set, starting with |
|
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2716 // word_sz itself and, if CMSSplitIndexedFreeListBlocks, try larger multiples, |
|
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2717 // then try getting a big chunk and splitting it. |
|
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|
2718 { |
|
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|
2719 bool found; |
|
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|
2720 int k; |
|
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2721 size_t cur_sz; |
|
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2722 for (k = 1, cur_sz = k * word_sz, found = false; |
|
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2723 (cur_sz < CompactibleFreeListSpace::IndexSetSize) && |
|
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2724 (CMSSplitIndexedFreeListBlocks || k <= 1); |
|
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2725 k++, cur_sz = k * word_sz) { |
|
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|
2726 FreeList fl_for_cur_sz; // Empty. |
|
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2727 fl_for_cur_sz.set_size(cur_sz); |
|
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2728 { |
|
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|
2729 MutexLockerEx x(_indexedFreeListParLocks[cur_sz], |
|
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|
2730 Mutex::_no_safepoint_check_flag); |
|
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2731 FreeList* gfl = &_indexedFreeList[cur_sz]; |
|
1145
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2732 if (gfl->count() != 0) { |
|
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|
2733 // nn is the number of chunks of size cur_sz that |
|
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|
2734 // we'd need to split k-ways each, in order to create |
|
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|
2735 // "n" chunks of size word_sz each. |
|
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2736 const size_t nn = MAX2(n/k, (size_t)1); |
|
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|
2737 gfl->getFirstNChunksFromList(nn, &fl_for_cur_sz); |
|
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|
2738 found = true; |
|
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2739 if (k > 1) { |
|
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|
2740 // Update split death stats for the cur_sz-size blocks list: |
|
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|
2741 // we increment the split death count by the number of blocks |
|
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2742 // we just took from the cur_sz-size blocks list and which |
|
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2743 // we will be splitting below. |
|
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2744 ssize_t deaths = gfl->splitDeaths() + |
|
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|
2745 fl_for_cur_sz.count(); |
|
1716
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|
2746 gfl->set_splitDeaths(deaths); |
|
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|
2747 } |
|
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|
2748 } |
|
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|
2749 } |
|
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|
2750 // Now transfer fl_for_cur_sz to fl. Common case, we hope, is k = 1. |
|
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|
2751 if (found) { |
|
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|
2752 if (k == 1) { |
|
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|
2753 fl->prepend(&fl_for_cur_sz); |
|
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|
2754 } else { |
|
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|
2755 // Divide each block on fl_for_cur_sz up k ways. |
|
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|
2756 FreeChunk* fc; |
|
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|
2757 while ((fc = fl_for_cur_sz.getChunkAtHead()) != NULL) { |
|
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|
2758 // Must do this in reverse order, so that anybody attempting to |
|
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|
2759 // access the main chunk sees it as a single free block until we |
|
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|
2760 // change it. |
|
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|
2761 size_t fc_size = fc->size(); |
|
1716
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|
2762 assert(fc->isFree(), "Error"); |
|
1145
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|
2763 for (int i = k-1; i >= 0; i--) { |
|
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|
2764 FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz); |
|
1716
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|
2765 assert((i != 0) || |
|
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|
2766 ((fc == ffc) && ffc->isFree() && |
|
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|
2767 (ffc->size() == k*word_sz) && (fc_size == word_sz)), |
|
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|
2768 "Counting error"); |
|
1145
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|
2769 ffc->setSize(word_sz); |
|
1716
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|
2770 ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. |
|
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|
2771 ffc->linkNext(NULL); |
|
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|
2772 // Above must occur before BOT is updated below. |
|
1716
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|
2773 OrderAccess::storestore(); |
|
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|
2774 // splitting from the right, fc_size == i * word_sz |
|
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|
2775 _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */); |
|
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|
2776 fc_size -= word_sz; |
|
1716
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|
2777 assert(fc_size == i*word_sz, "Error"); |
|
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|
2778 _bt.verify_not_unallocated((HeapWord*)ffc, word_sz); |
|
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|
2779 _bt.verify_single_block((HeapWord*)fc, fc_size); |
|
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|
2780 _bt.verify_single_block((HeapWord*)ffc, word_sz); |
|
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|
2781 // Push this on "fl". |
|
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|
2782 fl->returnChunkAtHead(ffc); |
|
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|
2783 } |
|
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|
2784 // TRAP |
|
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|
2785 assert(fl->tail()->next() == NULL, "List invariant."); |
|
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|
2786 } |
|
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|
2787 } |
|
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|
2788 // Update birth stats for this block size. |
|
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|
2789 size_t num = fl->count(); |
|
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|
2790 MutexLockerEx x(_indexedFreeListParLocks[word_sz], |
|
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|
2791 Mutex::_no_safepoint_check_flag); |
|
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|
2792 ssize_t births = _indexedFreeList[word_sz].splitBirths() + num; |
|
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|
2793 _indexedFreeList[word_sz].set_splitBirths(births); |
|
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|
2794 return; |
| 0 | 2795 } |
| 2796 } | |
| 2797 } | |
| 2798 // Otherwise, we'll split a block from the dictionary. | |
| 2799 FreeChunk* fc = NULL; | |
| 2800 FreeChunk* rem_fc = NULL; | |
| 2801 size_t rem; | |
| 2802 { | |
| 2803 MutexLockerEx x(parDictionaryAllocLock(), | |
| 2804 Mutex::_no_safepoint_check_flag); | |
| 2805 while (n > 0) { | |
| 2806 fc = dictionary()->getChunk(MAX2(n * word_sz, | |
| 2807 _dictionary->minSize()), | |
| 2808 FreeBlockDictionary::atLeast); | |
| 2809 if (fc != NULL) { | |
|
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|
2810 _bt.allocated((HeapWord*)fc, fc->size(), true /* reducing */); // update _unallocated_blk |
| 0 | 2811 dictionary()->dictCensusUpdate(fc->size(), |
| 2812 true /*split*/, | |
| 2813 false /*birth*/); | |
| 2814 break; | |
| 2815 } else { | |
| 2816 n--; | |
| 2817 } | |
| 2818 } | |
| 2819 if (fc == NULL) return; | |
|
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|
2820 // Otherwise, split up that block. |
|
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2821 assert((ssize_t)n >= 1, "Control point invariant"); |
|
1716
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|
2822 assert(fc->isFree(), "Error: should be a free block"); |
|
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|
2823 _bt.verify_single_block((HeapWord*)fc, fc->size()); |
|
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|
2824 const size_t nn = fc->size() / word_sz; |
| 0 | 2825 n = MIN2(nn, n); |
|
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|
2826 assert((ssize_t)n >= 1, "Control point invariant"); |
| 0 | 2827 rem = fc->size() - n * word_sz; |
| 2828 // If there is a remainder, and it's too small, allocate one fewer. | |
| 2829 if (rem > 0 && rem < MinChunkSize) { | |
| 2830 n--; rem += word_sz; | |
| 2831 } | |
|
1148
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|
2832 // Note that at this point we may have n == 0. |
|
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|
2833 assert((ssize_t)n >= 0, "Control point invariant"); |
|
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2834 |
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2835 // If n is 0, the chunk fc that was found is not large |
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2836 // enough to leave a viable remainder. We are unable to |
|
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2837 // allocate even one block. Return fc to the |
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2838 // dictionary and return, leaving "fl" empty. |
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2839 if (n == 0) { |
|
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2840 returnChunkToDictionary(fc); |
|
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2841 assert(fl->count() == 0, "We never allocated any blocks"); |
|
1148
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2842 return; |
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2843 } |
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2844 |
| 0 | 2845 // First return the remainder, if any. |
| 2846 // Note that we hold the lock until we decide if we're going to give | |
|
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2847 // back the remainder to the dictionary, since a concurrent allocation |
| 0 | 2848 // may otherwise see the heap as empty. (We're willing to take that |
| 2849 // hit if the block is a small block.) | |
| 2850 if (rem > 0) { | |
| 2851 size_t prefix_size = n * word_sz; | |
| 2852 rem_fc = (FreeChunk*)((HeapWord*)fc + prefix_size); | |
| 2853 rem_fc->setSize(rem); | |
|
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2854 rem_fc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. |
| 0 | 2855 rem_fc->linkNext(NULL); |
| 2856 // Above must occur before BOT is updated below. | |
|
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2857 assert((ssize_t)n > 0 && prefix_size > 0 && rem_fc > fc, "Error"); |
|
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2858 OrderAccess::storestore(); |
| 0 | 2859 _bt.split_block((HeapWord*)fc, fc->size(), prefix_size); |
|
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2860 assert(fc->isFree(), "Error"); |
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2861 fc->setSize(prefix_size); |
| 0 | 2862 if (rem >= IndexSetSize) { |
| 2863 returnChunkToDictionary(rem_fc); | |
|
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2864 dictionary()->dictCensusUpdate(rem, true /*split*/, true /*birth*/); |
| 0 | 2865 rem_fc = NULL; |
| 2866 } | |
| 2867 // Otherwise, return it to the small list below. | |
| 2868 } | |
| 2869 } | |
| 2870 if (rem_fc != NULL) { | |
| 2871 MutexLockerEx x(_indexedFreeListParLocks[rem], | |
| 2872 Mutex::_no_safepoint_check_flag); | |
| 2873 _bt.verify_not_unallocated((HeapWord*)rem_fc, rem_fc->size()); | |
| 2874 _indexedFreeList[rem].returnChunkAtHead(rem_fc); | |
| 2875 smallSplitBirth(rem); | |
| 2876 } | |
|
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2877 assert((ssize_t)n > 0 && fc != NULL, "Consistency"); |
| 0 | 2878 // Now do the splitting up. |
| 2879 // Must do this in reverse order, so that anybody attempting to | |
| 2880 // access the main chunk sees it as a single free block until we | |
| 2881 // change it. | |
| 2882 size_t fc_size = n * word_sz; | |
| 2883 // All but first chunk in this loop | |
| 2884 for (ssize_t i = n-1; i > 0; i--) { | |
| 2885 FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz); | |
| 2886 ffc->setSize(word_sz); | |
|
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2887 ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. |
| 0 | 2888 ffc->linkNext(NULL); |
| 2889 // Above must occur before BOT is updated below. | |
|
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2890 OrderAccess::storestore(); |
| 0 | 2891 // splitting from the right, fc_size == (n - i + 1) * wordsize |
|
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2892 _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */); |
| 0 | 2893 fc_size -= word_sz; |
| 2894 _bt.verify_not_unallocated((HeapWord*)ffc, ffc->size()); | |
| 2895 _bt.verify_single_block((HeapWord*)ffc, ffc->size()); | |
| 2896 _bt.verify_single_block((HeapWord*)fc, fc_size); | |
| 2897 // Push this on "fl". | |
| 2898 fl->returnChunkAtHead(ffc); | |
| 2899 } | |
| 2900 // First chunk | |
|
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2901 assert(fc->isFree() && fc->size() == n*word_sz, "Error: should still be a free block"); |
|
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2902 // The blocks above should show their new sizes before the first block below |
| 0 | 2903 fc->setSize(word_sz); |
|
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2904 fc->linkPrev(NULL); // idempotent wrt free-ness, see assert above |
| 0 | 2905 fc->linkNext(NULL); |
| 2906 _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); | |
| 2907 _bt.verify_single_block((HeapWord*)fc, fc->size()); | |
| 2908 fl->returnChunkAtHead(fc); | |
| 2909 | |
|
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2910 assert((ssize_t)n > 0 && (ssize_t)n == fl->count(), "Incorrect number of blocks"); |
| 0 | 2911 { |
|
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2912 // Update the stats for this block size. |
| 0 | 2913 MutexLockerEx x(_indexedFreeListParLocks[word_sz], |
| 2914 Mutex::_no_safepoint_check_flag); | |
|
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2915 const ssize_t births = _indexedFreeList[word_sz].splitBirths() + n; |
|
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2916 _indexedFreeList[word_sz].set_splitBirths(births); |
|
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2917 // ssize_t new_surplus = _indexedFreeList[word_sz].surplus() + n; |
|
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2918 // _indexedFreeList[word_sz].set_surplus(new_surplus); |
| 0 | 2919 } |
| 2920 | |
| 2921 // TRAP | |
| 2922 assert(fl->tail()->next() == NULL, "List invariant."); | |
| 2923 } | |
| 2924 | |
| 2925 // Set up the space's par_seq_tasks structure for work claiming | |
| 2926 // for parallel rescan. See CMSParRemarkTask where this is currently used. | |
| 2927 // XXX Need to suitably abstract and generalize this and the next | |
| 2928 // method into one. | |
| 2929 void | |
| 2930 CompactibleFreeListSpace:: | |
| 2931 initialize_sequential_subtasks_for_rescan(int n_threads) { | |
| 2932 // The "size" of each task is fixed according to rescan_task_size. | |
| 2933 assert(n_threads > 0, "Unexpected n_threads argument"); | |
| 2934 const size_t task_size = rescan_task_size(); | |
| 2935 size_t n_tasks = (used_region().word_size() + task_size - 1)/task_size; | |
|
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2936 assert((n_tasks == 0) == used_region().is_empty(), "n_tasks incorrect"); |
|
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2937 assert(n_tasks == 0 || |
|
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2938 ((used_region().start() + (n_tasks - 1)*task_size < used_region().end()) && |
|
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2939 (used_region().start() + n_tasks*task_size >= used_region().end())), |
|
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2940 "n_tasks calculation incorrect"); |
| 0 | 2941 SequentialSubTasksDone* pst = conc_par_seq_tasks(); |
| 2942 assert(!pst->valid(), "Clobbering existing data?"); | |
|
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2943 // Sets the condition for completion of the subtask (how many threads |
|
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|
2944 // need to finish in order to be done). |
|
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2945 pst->set_n_threads(n_threads); |
| 0 | 2946 pst->set_n_tasks((int)n_tasks); |
| 2947 } | |
| 2948 | |
| 2949 // Set up the space's par_seq_tasks structure for work claiming | |
| 2950 // for parallel concurrent marking. See CMSConcMarkTask where this is currently used. | |
| 2951 void | |
| 2952 CompactibleFreeListSpace:: | |
| 2953 initialize_sequential_subtasks_for_marking(int n_threads, | |
| 2954 HeapWord* low) { | |
| 2955 // The "size" of each task is fixed according to rescan_task_size. | |
| 2956 assert(n_threads > 0, "Unexpected n_threads argument"); | |
| 2957 const size_t task_size = marking_task_size(); | |
| 2958 assert(task_size > CardTableModRefBS::card_size_in_words && | |
| 2959 (task_size % CardTableModRefBS::card_size_in_words == 0), | |
| 2960 "Otherwise arithmetic below would be incorrect"); | |
| 2961 MemRegion span = _gen->reserved(); | |
| 2962 if (low != NULL) { | |
| 2963 if (span.contains(low)) { | |
| 2964 // Align low down to a card boundary so that | |
| 2965 // we can use block_offset_careful() on span boundaries. | |
| 2966 HeapWord* aligned_low = (HeapWord*)align_size_down((uintptr_t)low, | |
| 2967 CardTableModRefBS::card_size); | |
| 2968 // Clip span prefix at aligned_low | |
| 2969 span = span.intersection(MemRegion(aligned_low, span.end())); | |
| 2970 } else if (low > span.end()) { | |
| 2971 span = MemRegion(low, low); // Null region | |
| 2972 } // else use entire span | |
| 2973 } | |
| 2974 assert(span.is_empty() || | |
| 2975 ((uintptr_t)span.start() % CardTableModRefBS::card_size == 0), | |
| 2976 "span should start at a card boundary"); | |
| 2977 size_t n_tasks = (span.word_size() + task_size - 1)/task_size; | |
| 2978 assert((n_tasks == 0) == span.is_empty(), "Inconsistency"); | |
| 2979 assert(n_tasks == 0 || | |
| 2980 ((span.start() + (n_tasks - 1)*task_size < span.end()) && | |
| 2981 (span.start() + n_tasks*task_size >= span.end())), | |
|
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2982 "n_tasks calculation incorrect"); |
| 0 | 2983 SequentialSubTasksDone* pst = conc_par_seq_tasks(); |
| 2984 assert(!pst->valid(), "Clobbering existing data?"); | |
|
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2985 // Sets the condition for completion of the subtask (how many threads |
|
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|
2986 // need to finish in order to be done). |
|
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|
2987 pst->set_n_threads(n_threads); |
| 0 | 2988 pst->set_n_tasks((int)n_tasks); |
| 2989 } |