Mercurial > hg > graal-compiler
diff src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | 6432c3bb6240 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,2845 @@ +/* + * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +# include "incls/_precompiled.incl" +# include "incls/_compactibleFreeListSpace.cpp.incl" + +///////////////////////////////////////////////////////////////////////// +//// CompactibleFreeListSpace +///////////////////////////////////////////////////////////////////////// + +// highest ranked free list lock rank +int CompactibleFreeListSpace::_lockRank = Mutex::leaf + 3; + +// Constructor +CompactibleFreeListSpace::CompactibleFreeListSpace(BlockOffsetSharedArray* bs, + MemRegion mr, bool use_adaptive_freelists, + FreeBlockDictionary::DictionaryChoice dictionaryChoice) : + _dictionaryChoice(dictionaryChoice), + _adaptive_freelists(use_adaptive_freelists), + _bt(bs, mr), + // free list locks are in the range of values taken by _lockRank + // This range currently is [_leaf+2, _leaf+3] + // Note: this requires that CFLspace c'tors + // are called serially in the order in which the locks are + // are acquired in the program text. This is true today. + _freelistLock(_lockRank--, "CompactibleFreeListSpace._lock", true), + _parDictionaryAllocLock(Mutex::leaf - 1, // == rank(ExpandHeap_lock) - 1 + "CompactibleFreeListSpace._dict_par_lock", true), + _rescan_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord * + CMSRescanMultiple), + _marking_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord * + CMSConcMarkMultiple), + _collector(NULL) +{ + _bt.set_space(this); + initialize(mr, true); + // We have all of "mr", all of which we place in the dictionary + // as one big chunk. We'll need to decide here which of several + // possible alternative dictionary implementations to use. For + // now the choice is easy, since we have only one working + // implementation, namely, the simple binary tree (splaying + // temporarily disabled). + switch (dictionaryChoice) { + case FreeBlockDictionary::dictionaryBinaryTree: + _dictionary = new BinaryTreeDictionary(mr); + break; + case FreeBlockDictionary::dictionarySplayTree: + case FreeBlockDictionary::dictionarySkipList: + default: + warning("dictionaryChoice: selected option not understood; using" + " default BinaryTreeDictionary implementation instead."); + _dictionary = new BinaryTreeDictionary(mr); + break; + } + splitBirth(mr.word_size()); + assert(_dictionary != NULL, "CMS dictionary initialization"); + // The indexed free lists are initially all empty and are lazily + // filled in on demand. Initialize the array elements to NULL. + initializeIndexedFreeListArray(); + + // Not using adaptive free lists assumes that allocation is first + // from the linAB's. Also a cms perm gen which can be compacted + // has to have the klass's klassKlass allocated at a lower + // address in the heap than the klass so that the klassKlass is + // moved to its new location before the klass is moved. + // Set the _refillSize for the linear allocation blocks + if (!use_adaptive_freelists) { + FreeChunk* fc = _dictionary->getChunk(mr.word_size()); + // The small linAB initially has all the space and will allocate + // a chunk of any size. + HeapWord* addr = (HeapWord*) fc; + _smallLinearAllocBlock.set(addr, fc->size() , + 1024*SmallForLinearAlloc, fc->size()); + // Note that _unallocated_block is not updated here. + // Allocations from the linear allocation block should + // update it. + } else { + _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc, + SmallForLinearAlloc); + } + // CMSIndexedFreeListReplenish should be at least 1 + CMSIndexedFreeListReplenish = MAX2((uintx)1, CMSIndexedFreeListReplenish); + _promoInfo.setSpace(this); + if (UseCMSBestFit) { + _fitStrategy = FreeBlockBestFitFirst; + } else { + _fitStrategy = FreeBlockStrategyNone; + } + checkFreeListConsistency(); + + // Initialize locks for parallel case. + if (ParallelGCThreads > 0) { + for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + _indexedFreeListParLocks[i] = new Mutex(Mutex::leaf - 1, // == ExpandHeap_lock - 1 + "a freelist par lock", + true); + if (_indexedFreeListParLocks[i] == NULL) + vm_exit_during_initialization("Could not allocate a par lock"); + DEBUG_ONLY( + _indexedFreeList[i].set_protecting_lock(_indexedFreeListParLocks[i]); + ) + } + _dictionary->set_par_lock(&_parDictionaryAllocLock); + } +} + +// Like CompactibleSpace forward() but always calls cross_threshold() to +// update the block offset table. Removed initialize_threshold call because +// CFLS does not use a block offset array for contiguous spaces. +HeapWord* CompactibleFreeListSpace::forward(oop q, size_t size, + CompactPoint* cp, HeapWord* compact_top) { + // q is alive + // First check if we should switch compaction space + assert(this == cp->space, "'this' should be current compaction space."); + size_t compaction_max_size = pointer_delta(end(), compact_top); + assert(adjustObjectSize(size) == cp->space->adjust_object_size_v(size), + "virtual adjustObjectSize_v() method is not correct"); + size_t adjusted_size = adjustObjectSize(size); + assert(compaction_max_size >= MinChunkSize || compaction_max_size == 0, + "no small fragments allowed"); + assert(minimum_free_block_size() == MinChunkSize, + "for de-virtualized reference below"); + // Can't leave a nonzero size, residual fragment smaller than MinChunkSize + if (adjusted_size + MinChunkSize > compaction_max_size && + adjusted_size != compaction_max_size) { + do { + // switch to next compaction space + cp->space->set_compaction_top(compact_top); + cp->space = cp->space->next_compaction_space(); + if (cp->space == NULL) { + cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen); + assert(cp->gen != NULL, "compaction must succeed"); + cp->space = cp->gen->first_compaction_space(); + assert(cp->space != NULL, "generation must have a first compaction space"); + } + compact_top = cp->space->bottom(); + cp->space->set_compaction_top(compact_top); + // The correct adjusted_size may not be the same as that for this method + // (i.e., cp->space may no longer be "this" so adjust the size again. + // Use the virtual method which is not used above to save the virtual + // dispatch. + adjusted_size = cp->space->adjust_object_size_v(size); + compaction_max_size = pointer_delta(cp->space->end(), compact_top); + assert(cp->space->minimum_free_block_size() == 0, "just checking"); + } while (adjusted_size > compaction_max_size); + } + + // store the forwarding pointer into the mark word + if ((HeapWord*)q != compact_top) { + q->forward_to(oop(compact_top)); + assert(q->is_gc_marked(), "encoding the pointer should preserve the mark"); + } else { + // if the object isn't moving we can just set the mark to the default + // mark and handle it specially later on. + q->init_mark(); + assert(q->forwardee() == NULL, "should be forwarded to NULL"); + } + + debug_only(MarkSweep::register_live_oop(q, adjusted_size)); + compact_top += adjusted_size; + + // we need to update the offset table so that the beginnings of objects can be + // found during scavenge. Note that we are updating the offset table based on + // where the object will be once the compaction phase finishes. + + // Always call cross_threshold(). A contiguous space can only call it when + // the compaction_top exceeds the current threshold but not for an + // non-contiguous space. + cp->threshold = + cp->space->cross_threshold(compact_top - adjusted_size, compact_top); + return compact_top; +} + +// A modified copy of OffsetTableContigSpace::cross_threshold() with _offsets -> _bt +// and use of single_block instead of alloc_block. The name here is not really +// appropriate - maybe a more general name could be invented for both the +// contiguous and noncontiguous spaces. + +HeapWord* CompactibleFreeListSpace::cross_threshold(HeapWord* start, HeapWord* the_end) { + _bt.single_block(start, the_end); + return end(); +} + +// Initialize them to NULL. +void CompactibleFreeListSpace::initializeIndexedFreeListArray() { + for (size_t i = 0; i < IndexSetSize; i++) { + // Note that on platforms where objects are double word aligned, + // the odd array elements are not used. It is convenient, however, + // to map directly from the object size to the array element. + _indexedFreeList[i].reset(IndexSetSize); + _indexedFreeList[i].set_size(i); + assert(_indexedFreeList[i].count() == 0, "reset check failed"); + assert(_indexedFreeList[i].head() == NULL, "reset check failed"); + assert(_indexedFreeList[i].tail() == NULL, "reset check failed"); + assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed"); + } +} + +void CompactibleFreeListSpace::resetIndexedFreeListArray() { + for (int i = 1; i < IndexSetSize; i++) { + assert(_indexedFreeList[i].size() == (size_t) i, + "Indexed free list sizes are incorrect"); + _indexedFreeList[i].reset(IndexSetSize); + assert(_indexedFreeList[i].count() == 0, "reset check failed"); + assert(_indexedFreeList[i].head() == NULL, "reset check failed"); + assert(_indexedFreeList[i].tail() == NULL, "reset check failed"); + assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed"); + } +} + +void CompactibleFreeListSpace::reset(MemRegion mr) { + resetIndexedFreeListArray(); + dictionary()->reset(); + if (BlockOffsetArrayUseUnallocatedBlock) { + assert(end() == mr.end(), "We are compacting to the bottom of CMS gen"); + // Everything's allocated until proven otherwise. + _bt.set_unallocated_block(end()); + } + if (!mr.is_empty()) { + assert(mr.word_size() >= MinChunkSize, "Chunk size is too small"); + _bt.single_block(mr.start(), mr.word_size()); + FreeChunk* fc = (FreeChunk*) mr.start(); + fc->setSize(mr.word_size()); + if (mr.word_size() >= IndexSetSize ) { + returnChunkToDictionary(fc); + } else { + _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); + _indexedFreeList[mr.word_size()].returnChunkAtHead(fc); + } + } + _promoInfo.reset(); + _smallLinearAllocBlock._ptr = NULL; + _smallLinearAllocBlock._word_size = 0; +} + +void CompactibleFreeListSpace::reset_after_compaction() { + // Reset the space to the new reality - one free chunk. + MemRegion mr(compaction_top(), end()); + reset(mr); + // Now refill the linear allocation block(s) if possible. + if (_adaptive_freelists) { + refillLinearAllocBlocksIfNeeded(); + } else { + // Place as much of mr in the linAB as we can get, + // provided it was big enough to go into the dictionary. + FreeChunk* fc = dictionary()->findLargestDict(); + if (fc != NULL) { + assert(fc->size() == mr.word_size(), + "Why was the chunk broken up?"); + removeChunkFromDictionary(fc); + HeapWord* addr = (HeapWord*) fc; + _smallLinearAllocBlock.set(addr, fc->size() , + 1024*SmallForLinearAlloc, fc->size()); + // Note that _unallocated_block is not updated here. + } + } +} + +// Walks the entire dictionary, returning a coterminal +// chunk, if it exists. Use with caution since it involves +// a potentially complete walk of a potentially large tree. +FreeChunk* CompactibleFreeListSpace::find_chunk_at_end() { + + assert_lock_strong(&_freelistLock); + + return dictionary()->find_chunk_ends_at(end()); +} + + +#ifndef PRODUCT +void CompactibleFreeListSpace::initializeIndexedFreeListArrayReturnedBytes() { + for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + _indexedFreeList[i].allocation_stats()->set_returnedBytes(0); + } +} + +size_t CompactibleFreeListSpace::sumIndexedFreeListArrayReturnedBytes() { + size_t sum = 0; + for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + sum += _indexedFreeList[i].allocation_stats()->returnedBytes(); + } + return sum; +} + +size_t CompactibleFreeListSpace::totalCountInIndexedFreeLists() const { + size_t count = 0; + for (int i = MinChunkSize; i < IndexSetSize; i++) { + debug_only( + ssize_t total_list_count = 0; + for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; + fc = fc->next()) { + total_list_count++; + } + assert(total_list_count == _indexedFreeList[i].count(), + "Count in list is incorrect"); + ) + count += _indexedFreeList[i].count(); + } + return count; +} + +size_t CompactibleFreeListSpace::totalCount() { + size_t num = totalCountInIndexedFreeLists(); + num += dictionary()->totalCount(); + if (_smallLinearAllocBlock._word_size != 0) { + num++; + } + return num; +} +#endif + +bool CompactibleFreeListSpace::is_free_block(const HeapWord* p) const { + FreeChunk* fc = (FreeChunk*) p; + return fc->isFree(); +} + +size_t CompactibleFreeListSpace::used() const { + return capacity() - free(); +} + +size_t CompactibleFreeListSpace::free() const { + // "MT-safe, but not MT-precise"(TM), if you will: i.e. + // if you do this while the structures are in flux you + // may get an approximate answer only; for instance + // because there is concurrent allocation either + // directly by mutators or for promotion during a GC. + // It's "MT-safe", however, in the sense that you are guaranteed + // not to crash and burn, for instance, because of walking + // pointers that could disappear as you were walking them. + // The approximation is because the various components + // that are read below are not read atomically (and + // further the computation of totalSizeInIndexedFreeLists() + // is itself a non-atomic computation. The normal use of + // this is during a resize operation at the end of GC + // and at that time you are guaranteed to get the + // correct actual value. However, for instance, this is + // also read completely asynchronously by the "perf-sampler" + // that supports jvmstat, and you are apt to see the values + // flicker in such cases. + assert(_dictionary != NULL, "No _dictionary?"); + return (_dictionary->totalChunkSize(DEBUG_ONLY(freelistLock())) + + totalSizeInIndexedFreeLists() + + _smallLinearAllocBlock._word_size) * HeapWordSize; +} + +size_t CompactibleFreeListSpace::max_alloc_in_words() const { + assert(_dictionary != NULL, "No _dictionary?"); + assert_locked(); + size_t res = _dictionary->maxChunkSize(); + res = MAX2(res, MIN2(_smallLinearAllocBlock._word_size, + (size_t) SmallForLinearAlloc - 1)); + // XXX the following could potentially be pretty slow; + // should one, pesimally for the rare cases when res + // caclulated above is less than IndexSetSize, + // just return res calculated above? My reasoning was that + // those cases will be so rare that the extra time spent doesn't + // really matter.... + // Note: do not change the loop test i >= res + IndexSetStride + // to i > res below, because i is unsigned and res may be zero. + for (size_t i = IndexSetSize - 1; i >= res + IndexSetStride; + i -= IndexSetStride) { + if (_indexedFreeList[i].head() != NULL) { + assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList"); + return i; + } + } + return res; +} + +void CompactibleFreeListSpace::reportFreeListStatistics() const { + assert_lock_strong(&_freelistLock); + assert(PrintFLSStatistics != 0, "Reporting error"); + _dictionary->reportStatistics(); + if (PrintFLSStatistics > 1) { + reportIndexedFreeListStatistics(); + size_t totalSize = totalSizeInIndexedFreeLists() + + _dictionary->totalChunkSize(DEBUG_ONLY(freelistLock())); + gclog_or_tty->print(" free=%ld frag=%1.4f\n", totalSize, flsFrag()); + } +} + +void CompactibleFreeListSpace::reportIndexedFreeListStatistics() const { + assert_lock_strong(&_freelistLock); + gclog_or_tty->print("Statistics for IndexedFreeLists:\n" + "--------------------------------\n"); + size_t totalSize = totalSizeInIndexedFreeLists(); + size_t freeBlocks = numFreeBlocksInIndexedFreeLists(); + gclog_or_tty->print("Total Free Space: %d\n", totalSize); + gclog_or_tty->print("Max Chunk Size: %d\n", maxChunkSizeInIndexedFreeLists()); + gclog_or_tty->print("Number of Blocks: %d\n", freeBlocks); + if (freeBlocks != 0) { + gclog_or_tty->print("Av. Block Size: %d\n", totalSize/freeBlocks); + } +} + +size_t CompactibleFreeListSpace::numFreeBlocksInIndexedFreeLists() const { + size_t res = 0; + for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + debug_only( + ssize_t recount = 0; + for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; + fc = fc->next()) { + recount += 1; + } + assert(recount == _indexedFreeList[i].count(), + "Incorrect count in list"); + ) + res += _indexedFreeList[i].count(); + } + return res; +} + +size_t CompactibleFreeListSpace::maxChunkSizeInIndexedFreeLists() const { + for (size_t i = IndexSetSize - 1; i != 0; i -= IndexSetStride) { + if (_indexedFreeList[i].head() != NULL) { + assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList"); + return (size_t)i; + } + } + return 0; +} + +void CompactibleFreeListSpace::set_end(HeapWord* value) { + HeapWord* prevEnd = end(); + assert(prevEnd != value, "unnecessary set_end call"); + assert(prevEnd == NULL || value >= unallocated_block(), "New end is below unallocated block"); + _end = value; + if (prevEnd != NULL) { + // Resize the underlying block offset table. + _bt.resize(pointer_delta(value, bottom())); + if (value <= prevEnd) { + assert(value >= unallocated_block(), "New end is below unallocated block"); + } else { + // Now, take this new chunk and add it to the free blocks. + // Note that the BOT has not yet been updated for this block. + size_t newFcSize = pointer_delta(value, prevEnd); + // XXX This is REALLY UGLY and should be fixed up. XXX + if (!_adaptive_freelists && _smallLinearAllocBlock._ptr == NULL) { + // Mark the boundary of the new block in BOT + _bt.mark_block(prevEnd, value); + // put it all in the linAB + if (ParallelGCThreads == 0) { + _smallLinearAllocBlock._ptr = prevEnd; + _smallLinearAllocBlock._word_size = newFcSize; + repairLinearAllocBlock(&_smallLinearAllocBlock); + } else { // ParallelGCThreads > 0 + MutexLockerEx x(parDictionaryAllocLock(), + Mutex::_no_safepoint_check_flag); + _smallLinearAllocBlock._ptr = prevEnd; + _smallLinearAllocBlock._word_size = newFcSize; + repairLinearAllocBlock(&_smallLinearAllocBlock); + } + // Births of chunks put into a LinAB are not recorded. Births + // of chunks as they are allocated out of a LinAB are. + } else { + // Add the block to the free lists, if possible coalescing it + // with the last free block, and update the BOT and census data. + addChunkToFreeListsAtEndRecordingStats(prevEnd, newFcSize); + } + } + } +} + +class FreeListSpace_DCTOC : public Filtering_DCTOC { + CompactibleFreeListSpace* _cfls; + CMSCollector* _collector; +protected: + // Override. +#define walk_mem_region_with_cl_DECL(ClosureType) \ + virtual void walk_mem_region_with_cl(MemRegion mr, \ + HeapWord* bottom, HeapWord* top, \ + ClosureType* cl); \ + void walk_mem_region_with_cl_par(MemRegion mr, \ + HeapWord* bottom, HeapWord* top, \ + ClosureType* cl); \ + void walk_mem_region_with_cl_nopar(MemRegion mr, \ + HeapWord* bottom, HeapWord* top, \ + ClosureType* cl) + walk_mem_region_with_cl_DECL(OopClosure); + walk_mem_region_with_cl_DECL(FilteringClosure); + +public: + FreeListSpace_DCTOC(CompactibleFreeListSpace* sp, + CMSCollector* collector, + OopClosure* cl, + CardTableModRefBS::PrecisionStyle precision, + HeapWord* boundary) : + Filtering_DCTOC(sp, cl, precision, boundary), + _cfls(sp), _collector(collector) {} +}; + +// We de-virtualize the block-related calls below, since we know that our +// space is a CompactibleFreeListSpace. +#define FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \ +void FreeListSpace_DCTOC::walk_mem_region_with_cl(MemRegion mr, \ + HeapWord* bottom, \ + HeapWord* top, \ + ClosureType* cl) { \ + if (SharedHeap::heap()->n_par_threads() > 0) { \ + walk_mem_region_with_cl_par(mr, bottom, top, cl); \ + } else { \ + walk_mem_region_with_cl_nopar(mr, bottom, top, cl); \ + } \ +} \ +void FreeListSpace_DCTOC::walk_mem_region_with_cl_par(MemRegion mr, \ + HeapWord* bottom, \ + HeapWord* top, \ + ClosureType* cl) { \ + /* Skip parts that are before "mr", in case "block_start" sent us \ + back too far. */ \ + HeapWord* mr_start = mr.start(); \ + size_t bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom); \ + HeapWord* next = bottom + bot_size; \ + while (next < mr_start) { \ + bottom = next; \ + bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom); \ + next = bottom + bot_size; \ + } \ + \ + while (bottom < top) { \ + if (_cfls->CompactibleFreeListSpace::block_is_obj(bottom) && \ + !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks( \ + oop(bottom)) && \ + !_collector->CMSCollector::is_dead_obj(oop(bottom))) { \ + size_t word_sz = oop(bottom)->oop_iterate(cl, mr); \ + bottom += _cfls->adjustObjectSize(word_sz); \ + } else { \ + bottom += _cfls->CompactibleFreeListSpace::block_size(bottom); \ + } \ + } \ +} \ +void FreeListSpace_DCTOC::walk_mem_region_with_cl_nopar(MemRegion mr, \ + HeapWord* bottom, \ + HeapWord* top, \ + ClosureType* cl) { \ + /* Skip parts that are before "mr", in case "block_start" sent us \ + back too far. */ \ + HeapWord* mr_start = mr.start(); \ + size_t bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom); \ + HeapWord* next = bottom + bot_size; \ + while (next < mr_start) { \ + bottom = next; \ + bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom); \ + next = bottom + bot_size; \ + } \ + \ + while (bottom < top) { \ + if (_cfls->CompactibleFreeListSpace::block_is_obj_nopar(bottom) && \ + !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks( \ + oop(bottom)) && \ + !_collector->CMSCollector::is_dead_obj(oop(bottom))) { \ + size_t word_sz = oop(bottom)->oop_iterate(cl, mr); \ + bottom += _cfls->adjustObjectSize(word_sz); \ + } else { \ + bottom += _cfls->CompactibleFreeListSpace::block_size_nopar(bottom); \ + } \ + } \ +} + +// (There are only two of these, rather than N, because the split is due +// only to the introduction of the FilteringClosure, a local part of the +// impl of this abstraction.) +FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(OopClosure) +FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure) + +DirtyCardToOopClosure* +CompactibleFreeListSpace::new_dcto_cl(OopClosure* cl, + CardTableModRefBS::PrecisionStyle precision, + HeapWord* boundary) { + return new FreeListSpace_DCTOC(this, _collector, cl, precision, boundary); +} + + +// Note on locking for the space iteration functions: +// since the collector's iteration activities are concurrent with +// allocation activities by mutators, absent a suitable mutual exclusion +// mechanism the iterators may go awry. For instace a block being iterated +// may suddenly be allocated or divided up and part of it allocated and +// so on. + +// Apply the given closure to each block in the space. +void CompactibleFreeListSpace::blk_iterate_careful(BlkClosureCareful* cl) { + assert_lock_strong(freelistLock()); + HeapWord *cur, *limit; + for (cur = bottom(), limit = end(); cur < limit; + cur += cl->do_blk_careful(cur)); +} + +// Apply the given closure to each block in the space. +void CompactibleFreeListSpace::blk_iterate(BlkClosure* cl) { + assert_lock_strong(freelistLock()); + HeapWord *cur, *limit; + for (cur = bottom(), limit = end(); cur < limit; + cur += cl->do_blk(cur)); +} + +// Apply the given closure to each oop in the space. +void CompactibleFreeListSpace::oop_iterate(OopClosure* cl) { + assert_lock_strong(freelistLock()); + HeapWord *cur, *limit; + size_t curSize; + for (cur = bottom(), limit = end(); cur < limit; + cur += curSize) { + curSize = block_size(cur); + if (block_is_obj(cur)) { + oop(cur)->oop_iterate(cl); + } + } +} + +// Apply the given closure to each oop in the space \intersect memory region. +void CompactibleFreeListSpace::oop_iterate(MemRegion mr, OopClosure* cl) { + assert_lock_strong(freelistLock()); + if (is_empty()) { + return; + } + MemRegion cur = MemRegion(bottom(), end()); + mr = mr.intersection(cur); + if (mr.is_empty()) { + return; + } + if (mr.equals(cur)) { + oop_iterate(cl); + return; + } + assert(mr.end() <= end(), "just took an intersection above"); + HeapWord* obj_addr = block_start(mr.start()); + HeapWord* t = mr.end(); + + SpaceMemRegionOopsIterClosure smr_blk(cl, mr); + if (block_is_obj(obj_addr)) { + // Handle first object specially. + oop obj = oop(obj_addr); + obj_addr += adjustObjectSize(obj->oop_iterate(&smr_blk)); + } else { + FreeChunk* fc = (FreeChunk*)obj_addr; + obj_addr += fc->size(); + } + while (obj_addr < t) { + HeapWord* obj = obj_addr; + obj_addr += block_size(obj_addr); + // If "obj_addr" is not greater than top, then the + // entire object "obj" is within the region. + if (obj_addr <= t) { + if (block_is_obj(obj)) { + oop(obj)->oop_iterate(cl); + } + } else { + // "obj" extends beyond end of region + if (block_is_obj(obj)) { + oop(obj)->oop_iterate(&smr_blk); + } + break; + } + } +} + +// NOTE: In the following methods, in order to safely be able to +// apply the closure to an object, we need to be sure that the +// object has been initialized. We are guaranteed that an object +// is initialized if we are holding the Heap_lock with the +// world stopped. +void CompactibleFreeListSpace::verify_objects_initialized() const { + if (is_init_completed()) { + assert_locked_or_safepoint(Heap_lock); + if (Universe::is_fully_initialized()) { + guarantee(SafepointSynchronize::is_at_safepoint(), + "Required for objects to be initialized"); + } + } // else make a concession at vm start-up +} + +// Apply the given closure to each object in the space +void CompactibleFreeListSpace::object_iterate(ObjectClosure* blk) { + assert_lock_strong(freelistLock()); + NOT_PRODUCT(verify_objects_initialized()); + HeapWord *cur, *limit; + size_t curSize; + for (cur = bottom(), limit = end(); cur < limit; + cur += curSize) { + curSize = block_size(cur); + if (block_is_obj(cur)) { + blk->do_object(oop(cur)); + } + } +} + +void CompactibleFreeListSpace::object_iterate_mem(MemRegion mr, + UpwardsObjectClosure* cl) { + assert_locked(); + NOT_PRODUCT(verify_objects_initialized()); + Space::object_iterate_mem(mr, cl); +} + +// Callers of this iterator beware: The closure application should +// be robust in the face of uninitialized objects and should (always) +// return a correct size so that the next addr + size below gives us a +// valid block boundary. [See for instance, +// ScanMarkedObjectsAgainCarefullyClosure::do_object_careful() +// in ConcurrentMarkSweepGeneration.cpp.] +HeapWord* +CompactibleFreeListSpace::object_iterate_careful(ObjectClosureCareful* cl) { + assert_lock_strong(freelistLock()); + HeapWord *addr, *last; + size_t size; + for (addr = bottom(), last = end(); + addr < last; addr += size) { + FreeChunk* fc = (FreeChunk*)addr; + if (fc->isFree()) { + // Since we hold the free list lock, which protects direct + // allocation in this generation by mutators, a free object + // will remain free throughout this iteration code. + size = fc->size(); + } else { + // Note that the object need not necessarily be initialized, + // because (for instance) the free list lock does NOT protect + // object initialization. The closure application below must + // therefore be correct in the face of uninitialized objects. + size = cl->do_object_careful(oop(addr)); + if (size == 0) { + // An unparsable object found. Signal early termination. + return addr; + } + } + } + return NULL; +} + +// Callers of this iterator beware: The closure application should +// be robust in the face of uninitialized objects and should (always) +// return a correct size so that the next addr + size below gives us a +// valid block boundary. [See for instance, +// ScanMarkedObjectsAgainCarefullyClosure::do_object_careful() +// in ConcurrentMarkSweepGeneration.cpp.] +HeapWord* +CompactibleFreeListSpace::object_iterate_careful_m(MemRegion mr, + ObjectClosureCareful* cl) { + assert_lock_strong(freelistLock()); + // Can't use used_region() below because it may not necessarily + // be the same as [bottom(),end()); although we could + // use [used_region().start(),round_to(used_region().end(),CardSize)), + // that appears too cumbersome, so we just do the simpler check + // in the assertion below. + assert(!mr.is_empty() && MemRegion(bottom(),end()).contains(mr), + "mr should be non-empty and within used space"); + HeapWord *addr, *end; + size_t size; + for (addr = block_start_careful(mr.start()), end = mr.end(); + addr < end; addr += size) { + FreeChunk* fc = (FreeChunk*)addr; + if (fc->isFree()) { + // Since we hold the free list lock, which protects direct + // allocation in this generation by mutators, a free object + // will remain free throughout this iteration code. + size = fc->size(); + } else { + // Note that the object need not necessarily be initialized, + // because (for instance) the free list lock does NOT protect + // object initialization. The closure application below must + // therefore be correct in the face of uninitialized objects. + size = cl->do_object_careful_m(oop(addr), mr); + if (size == 0) { + // An unparsable object found. Signal early termination. + return addr; + } + } + } + return NULL; +} + + +HeapWord* CompactibleFreeListSpace::block_start(const void* p) const { + NOT_PRODUCT(verify_objects_initialized()); + return _bt.block_start(p); +} + +HeapWord* CompactibleFreeListSpace::block_start_careful(const void* p) const { + return _bt.block_start_careful(p); +} + +size_t CompactibleFreeListSpace::block_size(const HeapWord* p) const { + NOT_PRODUCT(verify_objects_initialized()); + assert(MemRegion(bottom(), end()).contains(p), "p not in space"); + // This must be volatile, or else there is a danger that the compiler + // will compile the code below into a sometimes-infinite loop, by keeping + // the value read the first time in a register. + oop o = (oop)p; + volatile oop* second_word_addr = o->klass_addr(); + while (true) { + klassOop k = (klassOop)(*second_word_addr); + // We must do this until we get a consistent view of the object. + if (FreeChunk::secondWordIndicatesFreeChunk((intptr_t)k)) { + FreeChunk* fc = (FreeChunk*)p; + volatile size_t* sz_addr = (volatile size_t*)(fc->size_addr()); + size_t res = (*sz_addr); + klassOop k2 = (klassOop)(*second_word_addr); // Read to confirm. + if (k == k2) { + assert(res != 0, "Block size should not be 0"); + return res; + } + } else if (k != NULL) { + assert(k->is_oop(true /* ignore mark word */), "Should really be klass oop."); + assert(o->is_parsable(), "Should be parsable"); + assert(o->is_oop(true /* ignore mark word */), "Should be an oop."); + size_t res = o->size_given_klass(k->klass_part()); + res = adjustObjectSize(res); + assert(res != 0, "Block size should not be 0"); + return res; + } + } +} + +// A variant of the above that uses the Printezis bits for +// unparsable but allocated objects. This avoids any possible +// stalls waiting for mutators to initialize objects, and is +// thus potentially faster than the variant above. However, +// this variant may return a zero size for a block that is +// under mutation and for which a consistent size cannot be +// inferred without stalling; see CMSCollector::block_size_if_printezis_bits(). +size_t CompactibleFreeListSpace::block_size_no_stall(HeapWord* p, + const CMSCollector* c) +const { + assert(MemRegion(bottom(), end()).contains(p), "p not in space"); + // This must be volatile, or else there is a danger that the compiler + // will compile the code below into a sometimes-infinite loop, by keeping + // the value read the first time in a register. + oop o = (oop)p; + volatile oop* second_word_addr = o->klass_addr(); + DEBUG_ONLY(uint loops = 0;) + while (true) { + klassOop k = (klassOop)(*second_word_addr); + // We must do this until we get a consistent view of the object. + if (FreeChunk::secondWordIndicatesFreeChunk((intptr_t)k)) { + FreeChunk* fc = (FreeChunk*)p; + volatile size_t* sz_addr = (volatile size_t*)(fc->size_addr()); + size_t res = (*sz_addr); + klassOop k2 = (klassOop)(*second_word_addr); // Read to confirm. + if (k == k2) { + assert(res != 0, "Block size should not be 0"); + assert(loops == 0, "Should be 0"); + return res; + } + } else if (k != NULL && o->is_parsable()) { + assert(k->is_oop(), "Should really be klass oop."); + assert(o->is_oop(), "Should be an oop"); + size_t res = o->size_given_klass(k->klass_part()); + res = adjustObjectSize(res); + assert(res != 0, "Block size should not be 0"); + return res; + } else { + return c->block_size_if_printezis_bits(p); + } + assert(loops == 0, "Can loop at most once"); + DEBUG_ONLY(loops++;) + } +} + +size_t CompactibleFreeListSpace::block_size_nopar(const HeapWord* p) const { + NOT_PRODUCT(verify_objects_initialized()); + assert(MemRegion(bottom(), end()).contains(p), "p not in space"); + FreeChunk* fc = (FreeChunk*)p; + if (fc->isFree()) { + return fc->size(); + } else { + // Ignore mark word because this may be a recently promoted + // object whose mark word is used to chain together grey + // objects (the last one would have a null value). + assert(oop(p)->is_oop(true), "Should be an oop"); + return adjustObjectSize(oop(p)->size()); + } +} + +// This implementation assumes that the property of "being an object" is +// stable. But being a free chunk may not be (because of parallel +// promotion.) +bool CompactibleFreeListSpace::block_is_obj(const HeapWord* p) const { + FreeChunk* fc = (FreeChunk*)p; + assert(is_in_reserved(p), "Should be in space"); + // When doing a mark-sweep-compact of the CMS generation, this + // assertion may fail because prepare_for_compaction() uses + // space that is garbage to maintain information on ranges of + // live objects so that these live ranges can be moved as a whole. + // Comment out this assertion until that problem can be solved + // (i.e., that the block start calculation may look at objects + // at address below "p" in finding the object that contains "p" + // and those objects (if garbage) may have been modified to hold + // live range information. + // assert(ParallelGCThreads > 0 || _bt.block_start(p) == p, "Should be a block boundary"); + klassOop k = oop(p)->klass(); + intptr_t ki = (intptr_t)k; + if (FreeChunk::secondWordIndicatesFreeChunk(ki)) return false; + if (k != NULL) { + // Ignore mark word because it may have been used to + // chain together promoted objects (the last one + // would have a null value). + assert(oop(p)->is_oop(true), "Should be an oop"); + return true; + } else { + return false; // Was not an object at the start of collection. + } +} + +// Check if the object is alive. This fact is checked either by consulting +// the main marking bitmap in the sweeping phase or, if it's a permanent +// generation and we're not in the sweeping phase, by checking the +// perm_gen_verify_bit_map where we store the "deadness" information if +// we did not sweep the perm gen in the most recent previous GC cycle. +bool CompactibleFreeListSpace::obj_is_alive(const HeapWord* p) const { + assert (block_is_obj(p), "The address should point to an object"); + + // If we're sweeping, we use object liveness information from the main bit map + // for both perm gen and old gen. + // We don't need to lock the bitmap (live_map or dead_map below), because + // EITHER we are in the middle of the sweeping phase, and the + // main marking bit map (live_map below) is locked, + // OR we're in other phases and perm_gen_verify_bit_map (dead_map below) + // is stable, because it's mutated only in the sweeping phase. + if (_collector->abstract_state() == CMSCollector::Sweeping) { + CMSBitMap* live_map = _collector->markBitMap(); + return live_map->isMarked((HeapWord*) p); + } else { + // If we're not currently sweeping and we haven't swept the perm gen in + // the previous concurrent cycle then we may have dead but unswept objects + // in the perm gen. In this case, we use the "deadness" information + // that we had saved in perm_gen_verify_bit_map at the last sweep. + if (!CMSClassUnloadingEnabled && _collector->_permGen->reserved().contains(p)) { + if (_collector->verifying()) { + CMSBitMap* dead_map = _collector->perm_gen_verify_bit_map(); + // Object is marked in the dead_map bitmap at the previous sweep + // when we know that it's dead; if the bitmap is not allocated then + // the object is alive. + return (dead_map->sizeInBits() == 0) // bit_map has been allocated + || !dead_map->par_isMarked((HeapWord*) p); + } else { + return false; // We can't say for sure if it's live, so we say that it's dead. + } + } + } + return true; +} + +bool CompactibleFreeListSpace::block_is_obj_nopar(const HeapWord* p) const { + FreeChunk* fc = (FreeChunk*)p; + assert(is_in_reserved(p), "Should be in space"); + assert(_bt.block_start(p) == p, "Should be a block boundary"); + if (!fc->isFree()) { + // Ignore mark word because it may have been used to + // chain together promoted objects (the last one + // would have a null value). + assert(oop(p)->is_oop(true), "Should be an oop"); + return true; + } + return false; +} + +// "MT-safe but not guaranteed MT-precise" (TM); you may get an +// approximate answer if you don't hold the freelistlock when you call this. +size_t CompactibleFreeListSpace::totalSizeInIndexedFreeLists() const { + size_t size = 0; + for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + debug_only( + // We may be calling here without the lock in which case we + // won't do this modest sanity check. + if (freelistLock()->owned_by_self()) { + size_t total_list_size = 0; + for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; + fc = fc->next()) { + total_list_size += i; + } + assert(total_list_size == i * _indexedFreeList[i].count(), + "Count in list is incorrect"); + } + ) + size += i * _indexedFreeList[i].count(); + } + return size; +} + +HeapWord* CompactibleFreeListSpace::par_allocate(size_t size) { + MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); + return allocate(size); +} + +HeapWord* +CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlockRemainder(size_t size) { + return getChunkFromLinearAllocBlockRemainder(&_smallLinearAllocBlock, size); +} + +HeapWord* CompactibleFreeListSpace::allocate(size_t size) { + assert_lock_strong(freelistLock()); + HeapWord* res = NULL; + assert(size == adjustObjectSize(size), + "use adjustObjectSize() before calling into allocate()"); + + if (_adaptive_freelists) { + res = allocate_adaptive_freelists(size); + } else { // non-adaptive free lists + res = allocate_non_adaptive_freelists(size); + } + + if (res != NULL) { + // check that res does lie in this space! + assert(is_in_reserved(res), "Not in this space!"); + assert(is_aligned((void*)res), "alignment check"); + + FreeChunk* fc = (FreeChunk*)res; + fc->markNotFree(); + assert(!fc->isFree(), "shouldn't be marked free"); + assert(oop(fc)->klass() == NULL, "should look uninitialized"); + // Verify that the block offset table shows this to + // be a single block, but not one which is unallocated. + _bt.verify_single_block(res, size); + _bt.verify_not_unallocated(res, size); + // mangle a just allocated object with a distinct pattern. + debug_only(fc->mangleAllocated(size)); + } + + return res; +} + +HeapWord* CompactibleFreeListSpace::allocate_non_adaptive_freelists(size_t size) { + HeapWord* res = NULL; + // try and use linear allocation for smaller blocks + if (size < _smallLinearAllocBlock._allocation_size_limit) { + // if successful, the following also adjusts block offset table + res = getChunkFromSmallLinearAllocBlock(size); + } + // Else triage to indexed lists for smaller sizes + if (res == NULL) { + if (size < SmallForDictionary) { + res = (HeapWord*) getChunkFromIndexedFreeList(size); + } else { + // else get it from the big dictionary; if even this doesn't + // work we are out of luck. + res = (HeapWord*)getChunkFromDictionaryExact(size); + } + } + + return res; +} + +HeapWord* CompactibleFreeListSpace::allocate_adaptive_freelists(size_t size) { + assert_lock_strong(freelistLock()); + HeapWord* res = NULL; + assert(size == adjustObjectSize(size), + "use adjustObjectSize() before calling into allocate()"); + + // Strategy + // if small + // exact size from small object indexed list if small + // small or large linear allocation block (linAB) as appropriate + // take from lists of greater sized chunks + // else + // dictionary + // small or large linear allocation block if it has the space + // Try allocating exact size from indexTable first + if (size < IndexSetSize) { + res = (HeapWord*) getChunkFromIndexedFreeList(size); + if(res != NULL) { + assert(res != (HeapWord*)_indexedFreeList[size].head(), + "Not removed from free list"); + // no block offset table adjustment is necessary on blocks in + // the indexed lists. + + // Try allocating from the small LinAB + } else if (size < _smallLinearAllocBlock._allocation_size_limit && + (res = getChunkFromSmallLinearAllocBlock(size)) != NULL) { + // if successful, the above also adjusts block offset table + // Note that this call will refill the LinAB to + // satisfy the request. This is different that + // evm. + // Don't record chunk off a LinAB? smallSplitBirth(size); + + } else { + // Raid the exact free lists larger than size, even if they are not + // overpopulated. + res = (HeapWord*) getChunkFromGreater(size); + } + } else { + // Big objects get allocated directly from the dictionary. + res = (HeapWord*) getChunkFromDictionaryExact(size); + if (res == NULL) { + // Try hard not to fail since an allocation failure will likely + // trigger a synchronous GC. Try to get the space from the + // allocation blocks. + res = getChunkFromSmallLinearAllocBlockRemainder(size); + } + } + + return res; +} + +// A worst-case estimate of the space required (in HeapWords) to expand the heap +// when promoting obj. +size_t CompactibleFreeListSpace::expansionSpaceRequired(size_t obj_size) const { + // Depending on the object size, expansion may require refilling either a + // bigLAB or a smallLAB plus refilling a PromotionInfo object. MinChunkSize + // is added because the dictionary may over-allocate to avoid fragmentation. + size_t space = obj_size; + if (!_adaptive_freelists) { + space = MAX2(space, _smallLinearAllocBlock._refillSize); + } + space += _promoInfo.refillSize() + 2 * MinChunkSize; + return space; +} + +FreeChunk* CompactibleFreeListSpace::getChunkFromGreater(size_t numWords) { + FreeChunk* ret; + + assert(numWords >= MinChunkSize, "Size is less than minimum"); + assert(linearAllocationWouldFail() || bestFitFirst(), + "Should not be here"); + + size_t i; + size_t currSize = numWords + MinChunkSize; + assert(currSize % MinObjAlignment == 0, "currSize should be aligned"); + for (i = currSize; i < IndexSetSize; i += IndexSetStride) { + FreeList* fl = &_indexedFreeList[i]; + if (fl->head()) { + ret = getFromListGreater(fl, numWords); + assert(ret == NULL || ret->isFree(), "Should be returning a free chunk"); + return ret; + } + } + + currSize = MAX2((size_t)SmallForDictionary, + (size_t)(numWords + MinChunkSize)); + + /* Try to get a chunk that satisfies request, while avoiding + fragmentation that can't be handled. */ + { + ret = dictionary()->getChunk(currSize); + if (ret != NULL) { + assert(ret->size() - numWords >= MinChunkSize, + "Chunk is too small"); + _bt.allocated((HeapWord*)ret, ret->size()); + /* Carve returned chunk. */ + (void) splitChunkAndReturnRemainder(ret, numWords); + /* Label this as no longer a free chunk. */ + assert(ret->isFree(), "This chunk should be free"); + ret->linkPrev(NULL); + } + assert(ret == NULL || ret->isFree(), "Should be returning a free chunk"); + return ret; + } + ShouldNotReachHere(); +} + +bool CompactibleFreeListSpace::verifyChunkInIndexedFreeLists(FreeChunk* fc) + const { + assert(fc->size() < IndexSetSize, "Size of chunk is too large"); + return _indexedFreeList[fc->size()].verifyChunkInFreeLists(fc); +} + +bool CompactibleFreeListSpace::verifyChunkInFreeLists(FreeChunk* fc) const { + if (fc->size() >= IndexSetSize) { + return dictionary()->verifyChunkInFreeLists(fc); + } else { + return verifyChunkInIndexedFreeLists(fc); + } +} + +#ifndef PRODUCT +void CompactibleFreeListSpace::assert_locked() const { + CMSLockVerifier::assert_locked(freelistLock(), parDictionaryAllocLock()); +} +#endif + +FreeChunk* CompactibleFreeListSpace::allocateScratch(size_t size) { + // In the parallel case, the main thread holds the free list lock + // on behalf the parallel threads. + assert_locked(); + FreeChunk* fc; + { + // If GC is parallel, this might be called by several threads. + // This should be rare enough that the locking overhead won't affect + // the sequential code. + MutexLockerEx x(parDictionaryAllocLock(), + Mutex::_no_safepoint_check_flag); + fc = getChunkFromDictionary(size); + } + if (fc != NULL) { + fc->dontCoalesce(); + assert(fc->isFree(), "Should be free, but not coalescable"); + // Verify that the block offset table shows this to + // be a single block, but not one which is unallocated. + _bt.verify_single_block((HeapWord*)fc, fc->size()); + _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); + } + return fc; +} + +oop CompactibleFreeListSpace::promote(oop obj, size_t obj_size, oop* ref) { + assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); + assert_locked(); + + // if we are tracking promotions, then first ensure space for + // promotion (including spooling space for saving header if necessary). + // then allocate and copy, then track promoted info if needed. + // When tracking (see PromotionInfo::track()), the mark word may + // be displaced and in this case restoration of the mark word + // occurs in the (oop_since_save_marks_)iterate phase. + if (_promoInfo.tracking() && !_promoInfo.ensure_spooling_space()) { + return NULL; + } + // Call the allocate(size_t, bool) form directly to avoid the + // additional call through the allocate(size_t) form. Having + // the compile inline the call is problematic because allocate(size_t) + // is a virtual method. + HeapWord* res = allocate(adjustObjectSize(obj_size)); + if (res != NULL) { + Copy::aligned_disjoint_words((HeapWord*)obj, res, obj_size); + // if we should be tracking promotions, do so. + if (_promoInfo.tracking()) { + _promoInfo.track((PromotedObject*)res); + } + } + return oop(res); +} + +HeapWord* +CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlock(size_t size) { + assert_locked(); + assert(size >= MinChunkSize, "minimum chunk size"); + assert(size < _smallLinearAllocBlock._allocation_size_limit, + "maximum from smallLinearAllocBlock"); + return getChunkFromLinearAllocBlock(&_smallLinearAllocBlock, size); +} + +HeapWord* +CompactibleFreeListSpace::getChunkFromLinearAllocBlock(LinearAllocBlock *blk, + size_t size) { + assert_locked(); + assert(size >= MinChunkSize, "too small"); + HeapWord* res = NULL; + // Try to do linear allocation from blk, making sure that + if (blk->_word_size == 0) { + // We have probably been unable to fill this either in the prologue or + // when it was exhausted at the last linear allocation. Bail out until + // next time. + assert(blk->_ptr == NULL, "consistency check"); + return NULL; + } + assert(blk->_word_size != 0 && blk->_ptr != NULL, "consistency check"); + res = getChunkFromLinearAllocBlockRemainder(blk, size); + if (res != NULL) return res; + + // about to exhaust this linear allocation block + if (blk->_word_size == size) { // exactly satisfied + res = blk->_ptr; + _bt.allocated(res, blk->_word_size); + } else if (size + MinChunkSize <= blk->_refillSize) { + // Update _unallocated_block if the size is such that chunk would be + // returned to the indexed free list. All other chunks in the indexed + // free lists are allocated from the dictionary so that _unallocated_block + // has already been adjusted for them. Do it here so that the cost + // for all chunks added back to the indexed free lists. + if (blk->_word_size < SmallForDictionary) { + _bt.allocated(blk->_ptr, blk->_word_size); + } + // Return the chunk that isn't big enough, and then refill below. + addChunkToFreeLists(blk->_ptr, blk->_word_size); + _bt.verify_single_block(blk->_ptr, (blk->_ptr + blk->_word_size)); + // Don't keep statistics on adding back chunk from a LinAB. + } else { + // A refilled block would not satisfy the request. + return NULL; + } + + blk->_ptr = NULL; blk->_word_size = 0; + refillLinearAllocBlock(blk); + assert(blk->_ptr == NULL || blk->_word_size >= size + MinChunkSize, + "block was replenished"); + if (res != NULL) { + splitBirth(size); + repairLinearAllocBlock(blk); + } else if (blk->_ptr != NULL) { + res = blk->_ptr; + size_t blk_size = blk->_word_size; + blk->_word_size -= size; + blk->_ptr += size; + splitBirth(size); + repairLinearAllocBlock(blk); + // Update BOT last so that other (parallel) GC threads see a consistent + // view of the BOT and free blocks. + // Above must occur before BOT is updated below. + _bt.split_block(res, blk_size, size); // adjust block offset table + } + return res; +} + +HeapWord* CompactibleFreeListSpace::getChunkFromLinearAllocBlockRemainder( + LinearAllocBlock* blk, + size_t size) { + assert_locked(); + assert(size >= MinChunkSize, "too small"); + + HeapWord* res = NULL; + // This is the common case. Keep it simple. + if (blk->_word_size >= size + MinChunkSize) { + assert(blk->_ptr != NULL, "consistency check"); + res = blk->_ptr; + // Note that the BOT is up-to-date for the linAB before allocation. It + // indicates the start of the linAB. The split_block() updates the + // BOT for the linAB after the allocation (indicates the start of the + // next chunk to be allocated). + size_t blk_size = blk->_word_size; + blk->_word_size -= size; + blk->_ptr += size; + splitBirth(size); + repairLinearAllocBlock(blk); + // Update BOT last so that other (parallel) GC threads see a consistent + // view of the BOT and free blocks. + // Above must occur before BOT is updated below. + _bt.split_block(res, blk_size, size); // adjust block offset table + _bt.allocated(res, size); + } + return res; +} + +FreeChunk* +CompactibleFreeListSpace::getChunkFromIndexedFreeList(size_t size) { + assert_locked(); + assert(size < SmallForDictionary, "just checking"); + FreeChunk* res; + res = _indexedFreeList[size].getChunkAtHead(); + if (res == NULL) { + res = getChunkFromIndexedFreeListHelper(size); + } + _bt.verify_not_unallocated((HeapWord*) res, size); + return res; +} + +FreeChunk* +CompactibleFreeListSpace::getChunkFromIndexedFreeListHelper(size_t size) { + assert_locked(); + FreeChunk* fc = NULL; + if (size < SmallForDictionary) { + assert(_indexedFreeList[size].head() == NULL || + _indexedFreeList[size].surplus() <= 0, + "List for this size should be empty or under populated"); + // Try best fit in exact lists before replenishing the list + if (!bestFitFirst() || (fc = bestFitSmall(size)) == NULL) { + // Replenish list. + // + // Things tried that failed. + // Tried allocating out of the two LinAB's first before + // replenishing lists. + // Tried small linAB of size 256 (size in indexed list) + // and replenishing indexed lists from the small linAB. + // + FreeChunk* newFc = NULL; + size_t replenish_size = CMSIndexedFreeListReplenish * size; + if (replenish_size < SmallForDictionary) { + // Do not replenish from an underpopulated size. + if (_indexedFreeList[replenish_size].surplus() > 0 && + _indexedFreeList[replenish_size].head() != NULL) { + newFc = + _indexedFreeList[replenish_size].getChunkAtHead(); + } else { + newFc = bestFitSmall(replenish_size); + } + } + if (newFc != NULL) { + splitDeath(replenish_size); + } else if (replenish_size > size) { + assert(CMSIndexedFreeListReplenish > 1, "ctl pt invariant"); + newFc = + getChunkFromIndexedFreeListHelper(replenish_size); + } + if (newFc != NULL) { + assert(newFc->size() == replenish_size, "Got wrong size"); + size_t i; + FreeChunk *curFc, *nextFc; + // carve up and link blocks 0, ..., CMSIndexedFreeListReplenish - 2 + // The last chunk is not added to the lists but is returned as the + // free chunk. + for (curFc = newFc, nextFc = (FreeChunk*)((HeapWord*)curFc + size), + i = 0; + i < (CMSIndexedFreeListReplenish - 1); + curFc = nextFc, nextFc = (FreeChunk*)((HeapWord*)nextFc + size), + i++) { + curFc->setSize(size); + // Don't record this as a return in order to try and + // determine the "returns" from a GC. + _bt.verify_not_unallocated((HeapWord*) fc, size); + _indexedFreeList[size].returnChunkAtTail(curFc, false); + _bt.mark_block((HeapWord*)curFc, size); + splitBirth(size); + // Don't record the initial population of the indexed list + // as a split birth. + } + + // check that the arithmetic was OK above + assert((HeapWord*)nextFc == (HeapWord*)newFc + replenish_size, + "inconsistency in carving newFc"); + curFc->setSize(size); + _bt.mark_block((HeapWord*)curFc, size); + splitBirth(size); + return curFc; + } + } + } else { + // Get a free chunk from the free chunk dictionary to be returned to + // replenish the indexed free list. + fc = getChunkFromDictionaryExact(size); + } + assert(fc == NULL || fc->isFree(), "Should be returning a free chunk"); + return fc; +} + +FreeChunk* +CompactibleFreeListSpace::getChunkFromDictionary(size_t size) { + assert_locked(); + FreeChunk* fc = _dictionary->getChunk(size); + if (fc == NULL) { + return NULL; + } + _bt.allocated((HeapWord*)fc, fc->size()); + if (fc->size() >= size + MinChunkSize) { + fc = splitChunkAndReturnRemainder(fc, size); + } + assert(fc->size() >= size, "chunk too small"); + assert(fc->size() < size + MinChunkSize, "chunk too big"); + _bt.verify_single_block((HeapWord*)fc, fc->size()); + return fc; +} + +FreeChunk* +CompactibleFreeListSpace::getChunkFromDictionaryExact(size_t size) { + assert_locked(); + FreeChunk* fc = _dictionary->getChunk(size); + if (fc == NULL) { + return fc; + } + _bt.allocated((HeapWord*)fc, fc->size()); + if (fc->size() == size) { + _bt.verify_single_block((HeapWord*)fc, size); + return fc; + } + assert(fc->size() > size, "getChunk() guarantee"); + if (fc->size() < size + MinChunkSize) { + // Return the chunk to the dictionary and go get a bigger one. + returnChunkToDictionary(fc); + fc = _dictionary->getChunk(size + MinChunkSize); + if (fc == NULL) { + return NULL; + } + _bt.allocated((HeapWord*)fc, fc->size()); + } + assert(fc->size() >= size + MinChunkSize, "tautology"); + fc = splitChunkAndReturnRemainder(fc, size); + assert(fc->size() == size, "chunk is wrong size"); + _bt.verify_single_block((HeapWord*)fc, size); + return fc; +} + +void +CompactibleFreeListSpace::returnChunkToDictionary(FreeChunk* chunk) { + assert_locked(); + + size_t size = chunk->size(); + _bt.verify_single_block((HeapWord*)chunk, size); + // adjust _unallocated_block downward, as necessary + _bt.freed((HeapWord*)chunk, size); + _dictionary->returnChunk(chunk); +} + +void +CompactibleFreeListSpace::returnChunkToFreeList(FreeChunk* fc) { + assert_locked(); + size_t size = fc->size(); + _bt.verify_single_block((HeapWord*) fc, size); + _bt.verify_not_unallocated((HeapWord*) fc, size); + if (_adaptive_freelists) { + _indexedFreeList[size].returnChunkAtTail(fc); + } else { + _indexedFreeList[size].returnChunkAtHead(fc); + } +} + +// Add chunk to end of last block -- if it's the largest +// block -- and update BOT and census data. We would +// of course have preferred to coalesce it with the +// last block, but it's currently less expensive to find the +// largest block than it is to find the last. +void +CompactibleFreeListSpace::addChunkToFreeListsAtEndRecordingStats( + HeapWord* chunk, size_t size) { + // check that the chunk does lie in this space! + assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!"); + assert_locked(); + // One of the parallel gc task threads may be here + // whilst others are allocating. + Mutex* lock = NULL; + if (ParallelGCThreads != 0) { + lock = &_parDictionaryAllocLock; + } + FreeChunk* ec; + { + MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); + ec = dictionary()->findLargestDict(); // get largest block + if (ec != NULL && ec->end() == chunk) { + // It's a coterminal block - we can coalesce. + size_t old_size = ec->size(); + coalDeath(old_size); + removeChunkFromDictionary(ec); + size += old_size; + } else { + ec = (FreeChunk*)chunk; + } + } + ec->setSize(size); + debug_only(ec->mangleFreed(size)); + if (size < SmallForDictionary) { + lock = _indexedFreeListParLocks[size]; + } + MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); + addChunkAndRepairOffsetTable((HeapWord*)ec, size, true); + // record the birth under the lock since the recording involves + // manipulation of the list on which the chunk lives and + // if the chunk is allocated and is the last on the list, + // the list can go away. + coalBirth(size); +} + +void +CompactibleFreeListSpace::addChunkToFreeLists(HeapWord* chunk, + size_t size) { + // check that the chunk does lie in this space! + assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!"); + assert_locked(); + _bt.verify_single_block(chunk, size); + + FreeChunk* fc = (FreeChunk*) chunk; + fc->setSize(size); + debug_only(fc->mangleFreed(size)); + if (size < SmallForDictionary) { + returnChunkToFreeList(fc); + } else { + returnChunkToDictionary(fc); + } +} + +void +CompactibleFreeListSpace::addChunkAndRepairOffsetTable(HeapWord* chunk, + size_t size, bool coalesced) { + assert_locked(); + assert(chunk != NULL, "null chunk"); + if (coalesced) { + // repair BOT + _bt.single_block(chunk, size); + } + addChunkToFreeLists(chunk, size); +} + +// We _must_ find the purported chunk on our free lists; +// we assert if we don't. +void +CompactibleFreeListSpace::removeFreeChunkFromFreeLists(FreeChunk* fc) { + size_t size = fc->size(); + assert_locked(); + debug_only(verifyFreeLists()); + if (size < SmallForDictionary) { + removeChunkFromIndexedFreeList(fc); + } else { + removeChunkFromDictionary(fc); + } + _bt.verify_single_block((HeapWord*)fc, size); + debug_only(verifyFreeLists()); +} + +void +CompactibleFreeListSpace::removeChunkFromDictionary(FreeChunk* fc) { + size_t size = fc->size(); + assert_locked(); + assert(fc != NULL, "null chunk"); + _bt.verify_single_block((HeapWord*)fc, size); + _dictionary->removeChunk(fc); + // adjust _unallocated_block upward, as necessary + _bt.allocated((HeapWord*)fc, size); +} + +void +CompactibleFreeListSpace::removeChunkFromIndexedFreeList(FreeChunk* fc) { + assert_locked(); + size_t size = fc->size(); + _bt.verify_single_block((HeapWord*)fc, size); + NOT_PRODUCT( + if (FLSVerifyIndexTable) { + verifyIndexedFreeList(size); + } + ) + _indexedFreeList[size].removeChunk(fc); + debug_only(fc->clearNext()); + debug_only(fc->clearPrev()); + NOT_PRODUCT( + if (FLSVerifyIndexTable) { + verifyIndexedFreeList(size); + } + ) +} + +FreeChunk* CompactibleFreeListSpace::bestFitSmall(size_t numWords) { + /* A hint is the next larger size that has a surplus. + Start search at a size large enough to guarantee that + the excess is >= MIN_CHUNK. */ + size_t start = align_object_size(numWords + MinChunkSize); + if (start < IndexSetSize) { + FreeList* it = _indexedFreeList; + size_t hint = _indexedFreeList[start].hint(); + while (hint < IndexSetSize) { + assert(hint % MinObjAlignment == 0, "hint should be aligned"); + FreeList *fl = &_indexedFreeList[hint]; + if (fl->surplus() > 0 && fl->head() != NULL) { + // Found a list with surplus, reset original hint + // and split out a free chunk which is returned. + _indexedFreeList[start].set_hint(hint); + FreeChunk* res = getFromListGreater(fl, numWords); + assert(res == NULL || res->isFree(), + "Should be returning a free chunk"); + return res; + } + hint = fl->hint(); /* keep looking */ + } + /* None found. */ + it[start].set_hint(IndexSetSize); + } + return NULL; +} + +/* Requires fl->size >= numWords + MinChunkSize */ +FreeChunk* CompactibleFreeListSpace::getFromListGreater(FreeList* fl, + size_t numWords) { + FreeChunk *curr = fl->head(); + size_t oldNumWords = curr->size(); + assert(numWords >= MinChunkSize, "Word size is too small"); + assert(curr != NULL, "List is empty"); + assert(oldNumWords >= numWords + MinChunkSize, + "Size of chunks in the list is too small"); + + fl->removeChunk(curr); + // recorded indirectly by splitChunkAndReturnRemainder - + // smallSplit(oldNumWords, numWords); + FreeChunk* new_chunk = splitChunkAndReturnRemainder(curr, numWords); + // Does anything have to be done for the remainder in terms of + // fixing the card table? + assert(new_chunk == NULL || new_chunk->isFree(), + "Should be returning a free chunk"); + return new_chunk; +} + +FreeChunk* +CompactibleFreeListSpace::splitChunkAndReturnRemainder(FreeChunk* chunk, + size_t new_size) { + assert_locked(); + size_t size = chunk->size(); + assert(size > new_size, "Split from a smaller block?"); + assert(is_aligned(chunk), "alignment problem"); + assert(size == adjustObjectSize(size), "alignment problem"); + size_t rem_size = size - new_size; + assert(rem_size == adjustObjectSize(rem_size), "alignment problem"); + assert(rem_size >= MinChunkSize, "Free chunk smaller than minimum"); + FreeChunk* ffc = (FreeChunk*)((HeapWord*)chunk + new_size); + assert(is_aligned(ffc), "alignment problem"); + ffc->setSize(rem_size); + ffc->linkNext(NULL); + ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. + // Above must occur before BOT is updated below. + // adjust block offset table + _bt.split_block((HeapWord*)chunk, chunk->size(), new_size); + if (rem_size < SmallForDictionary) { + bool is_par = (SharedHeap::heap()->n_par_threads() > 0); + if (is_par) _indexedFreeListParLocks[rem_size]->lock(); + returnChunkToFreeList(ffc); + split(size, rem_size); + if (is_par) _indexedFreeListParLocks[rem_size]->unlock(); + } else { + returnChunkToDictionary(ffc); + split(size ,rem_size); + } + chunk->setSize(new_size); + return chunk; +} + +void +CompactibleFreeListSpace::sweep_completed() { + // Now that space is probably plentiful, refill linear + // allocation blocks as needed. + refillLinearAllocBlocksIfNeeded(); +} + +void +CompactibleFreeListSpace::gc_prologue() { + assert_locked(); + if (PrintFLSStatistics != 0) { + gclog_or_tty->print("Before GC:\n"); + reportFreeListStatistics(); + } + refillLinearAllocBlocksIfNeeded(); +} + +void +CompactibleFreeListSpace::gc_epilogue() { + assert_locked(); + if (PrintGCDetails && Verbose && !_adaptive_freelists) { + if (_smallLinearAllocBlock._word_size == 0) + warning("CompactibleFreeListSpace(epilogue):: Linear allocation failure"); + } + assert(_promoInfo.noPromotions(), "_promoInfo inconsistency"); + _promoInfo.stopTrackingPromotions(); + repairLinearAllocationBlocks(); + // Print Space's stats + if (PrintFLSStatistics != 0) { + gclog_or_tty->print("After GC:\n"); + reportFreeListStatistics(); + } +} + +// Iteration support, mostly delegated from a CMS generation + +void CompactibleFreeListSpace::save_marks() { + // mark the "end" of the used space at the time of this call; + // note, however, that promoted objects from this point + // on are tracked in the _promoInfo below. + set_saved_mark_word(BlockOffsetArrayUseUnallocatedBlock ? + unallocated_block() : end()); + // inform allocator that promotions should be tracked. + assert(_promoInfo.noPromotions(), "_promoInfo inconsistency"); + _promoInfo.startTrackingPromotions(); +} + +bool CompactibleFreeListSpace::no_allocs_since_save_marks() { + assert(_promoInfo.tracking(), "No preceding save_marks?"); + guarantee(SharedHeap::heap()->n_par_threads() == 0, + "Shouldn't be called (yet) during parallel part of gc."); + return _promoInfo.noPromotions(); +} + +#define CFLS_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ + \ +void CompactibleFreeListSpace:: \ +oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ + assert(SharedHeap::heap()->n_par_threads() == 0, \ + "Shouldn't be called (yet) during parallel part of gc."); \ + _promoInfo.promoted_oops_iterate##nv_suffix(blk); \ + /* \ + * This also restores any displaced headers and removes the elements from \ + * the iteration set as they are processed, so that we have a clean slate \ + * at the end of the iteration. Note, thus, that if new objects are \ + * promoted as a result of the iteration they are iterated over as well. \ + */ \ + assert(_promoInfo.noPromotions(), "_promoInfo inconsistency"); \ +} + +ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DEFN) + +////////////////////////////////////////////////////////////////////////////// +// We go over the list of promoted objects, removing each from the list, +// and applying the closure (this may, in turn, add more elements to +// the tail of the promoted list, and these newly added objects will +// also be processed) until the list is empty. +// To aid verification and debugging, in the non-product builds +// we actually forward _promoHead each time we process a promoted oop. +// Note that this is not necessary in general (i.e. when we don't need to +// call PromotionInfo::verify()) because oop_iterate can only add to the +// end of _promoTail, and never needs to look at _promoHead. + +#define PROMOTED_OOPS_ITERATE_DEFN(OopClosureType, nv_suffix) \ + \ +void PromotionInfo::promoted_oops_iterate##nv_suffix(OopClosureType* cl) { \ + NOT_PRODUCT(verify()); \ + PromotedObject *curObj, *nextObj; \ + for (curObj = _promoHead; curObj != NULL; curObj = nextObj) { \ + if ((nextObj = curObj->next()) == NULL) { \ + /* protect ourselves against additions due to closure application \ + below by resetting the list. */ \ + assert(_promoTail == curObj, "Should have been the tail"); \ + _promoHead = _promoTail = NULL; \ + } \ + if (curObj->hasDisplacedMark()) { \ + /* restore displaced header */ \ + oop(curObj)->set_mark(nextDisplacedHeader()); \ + } else { \ + /* restore prototypical header */ \ + oop(curObj)->init_mark(); \ + } \ + /* The "promoted_mark" should now not be set */ \ + assert(!curObj->hasPromotedMark(), \ + "Should have been cleared by restoring displaced mark-word"); \ + NOT_PRODUCT(_promoHead = nextObj); \ + if (cl != NULL) oop(curObj)->oop_iterate(cl); \ + if (nextObj == NULL) { /* start at head of list reset above */ \ + nextObj = _promoHead; \ + } \ + } \ + assert(noPromotions(), "post-condition violation"); \ + assert(_promoHead == NULL && _promoTail == NULL, "emptied promoted list");\ + assert(_spoolHead == _spoolTail, "emptied spooling buffers"); \ + assert(_firstIndex == _nextIndex, "empty buffer"); \ +} + +// This should have been ALL_SINCE_...() just like the others, +// but, because the body of the method above is somehwat longer, +// the MSVC compiler cannot cope; as a workaround, we split the +// macro into its 3 constituent parts below (see original macro +// definition in specializedOopClosures.hpp). +SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG(PROMOTED_OOPS_ITERATE_DEFN) +PROMOTED_OOPS_ITERATE_DEFN(OopsInGenClosure,_v) + + +void CompactibleFreeListSpace::object_iterate_since_last_GC(ObjectClosure* cl) { + // ugghh... how would one do this efficiently for a non-contiguous space? + guarantee(false, "NYI"); +} + +bool CompactibleFreeListSpace::linearAllocationWouldFail() { + return _smallLinearAllocBlock._word_size == 0; +} + +void CompactibleFreeListSpace::repairLinearAllocationBlocks() { + // Fix up linear allocation blocks to look like free blocks + repairLinearAllocBlock(&_smallLinearAllocBlock); +} + +void CompactibleFreeListSpace::repairLinearAllocBlock(LinearAllocBlock* blk) { + assert_locked(); + if (blk->_ptr != NULL) { + assert(blk->_word_size != 0 && blk->_word_size >= MinChunkSize, + "Minimum block size requirement"); + FreeChunk* fc = (FreeChunk*)(blk->_ptr); + fc->setSize(blk->_word_size); + fc->linkPrev(NULL); // mark as free + fc->dontCoalesce(); + assert(fc->isFree(), "just marked it free"); + assert(fc->cantCoalesce(), "just marked it uncoalescable"); + } +} + +void CompactibleFreeListSpace::refillLinearAllocBlocksIfNeeded() { + assert_locked(); + if (_smallLinearAllocBlock._ptr == NULL) { + assert(_smallLinearAllocBlock._word_size == 0, + "Size of linAB should be zero if the ptr is NULL"); + // Reset the linAB refill and allocation size limit. + _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc, SmallForLinearAlloc); + } + refillLinearAllocBlockIfNeeded(&_smallLinearAllocBlock); +} + +void +CompactibleFreeListSpace::refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk) { + assert_locked(); + assert((blk->_ptr == NULL && blk->_word_size == 0) || + (blk->_ptr != NULL && blk->_word_size >= MinChunkSize), + "blk invariant"); + if (blk->_ptr == NULL) { + refillLinearAllocBlock(blk); + } + if (PrintMiscellaneous && Verbose) { + if (blk->_word_size == 0) { + warning("CompactibleFreeListSpace(prologue):: Linear allocation failure"); + } + } +} + +void +CompactibleFreeListSpace::refillLinearAllocBlock(LinearAllocBlock* blk) { + assert_locked(); + assert(blk->_word_size == 0 && blk->_ptr == NULL, + "linear allocation block should be empty"); + FreeChunk* fc; + if (blk->_refillSize < SmallForDictionary && + (fc = getChunkFromIndexedFreeList(blk->_refillSize)) != NULL) { + // A linAB's strategy might be to use small sizes to reduce + // fragmentation but still get the benefits of allocation from a + // linAB. + } else { + fc = getChunkFromDictionary(blk->_refillSize); + } + if (fc != NULL) { + blk->_ptr = (HeapWord*)fc; + blk->_word_size = fc->size(); + fc->dontCoalesce(); // to prevent sweeper from sweeping us up + } +} + +// Support for compaction + +void CompactibleFreeListSpace::prepare_for_compaction(CompactPoint* cp) { + SCAN_AND_FORWARD(cp,end,block_is_obj,block_size); + // prepare_for_compaction() uses the space between live objects + // so that later phase can skip dead space quickly. So verification + // of the free lists doesn't work after. +} + +#define obj_size(q) adjustObjectSize(oop(q)->size()) +#define adjust_obj_size(s) adjustObjectSize(s) + +void CompactibleFreeListSpace::adjust_pointers() { + // In other versions of adjust_pointers(), a bail out + // based on the amount of live data in the generation + // (i.e., if 0, bail out) may be used. + // Cannot test used() == 0 here because the free lists have already + // been mangled by the compaction. + + SCAN_AND_ADJUST_POINTERS(adjust_obj_size); + // See note about verification in prepare_for_compaction(). +} + +void CompactibleFreeListSpace::compact() { + SCAN_AND_COMPACT(obj_size); +} + +// fragmentation_metric = 1 - [sum of (fbs**2) / (sum of fbs)**2] +// where fbs is free block sizes +double CompactibleFreeListSpace::flsFrag() const { + size_t itabFree = totalSizeInIndexedFreeLists(); + double frag = 0.0; + size_t i; + + for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + double sz = i; + frag += _indexedFreeList[i].count() * (sz * sz); + } + + double totFree = itabFree + + _dictionary->totalChunkSize(DEBUG_ONLY(freelistLock())); + if (totFree > 0) { + frag = ((frag + _dictionary->sum_of_squared_block_sizes()) / + (totFree * totFree)); + frag = (double)1.0 - frag; + } else { + assert(frag == 0.0, "Follows from totFree == 0"); + } + return frag; +} + +#define CoalSurplusPercent 1.05 +#define SplitSurplusPercent 1.10 + +void CompactibleFreeListSpace::beginSweepFLCensus( + float inter_sweep_current, + float inter_sweep_estimate) { + assert_locked(); + size_t i; + for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + FreeList* fl = &_indexedFreeList[i]; + fl->compute_desired(inter_sweep_current, inter_sweep_estimate); + fl->set_coalDesired((ssize_t)((double)fl->desired() * CoalSurplusPercent)); + fl->set_beforeSweep(fl->count()); + fl->set_bfrSurp(fl->surplus()); + } + _dictionary->beginSweepDictCensus(CoalSurplusPercent, + inter_sweep_current, + inter_sweep_estimate); +} + +void CompactibleFreeListSpace::setFLSurplus() { + assert_locked(); + size_t i; + for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + FreeList *fl = &_indexedFreeList[i]; + fl->set_surplus(fl->count() - + (ssize_t)((double)fl->desired() * SplitSurplusPercent)); + } +} + +void CompactibleFreeListSpace::setFLHints() { + assert_locked(); + size_t i; + size_t h = IndexSetSize; + for (i = IndexSetSize - 1; i != 0; i -= IndexSetStride) { + FreeList *fl = &_indexedFreeList[i]; + fl->set_hint(h); + if (fl->surplus() > 0) { + h = i; + } + } +} + +void CompactibleFreeListSpace::clearFLCensus() { + assert_locked(); + int i; + for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + FreeList *fl = &_indexedFreeList[i]; + fl->set_prevSweep(fl->count()); + fl->set_coalBirths(0); + fl->set_coalDeaths(0); + fl->set_splitBirths(0); + fl->set_splitDeaths(0); + } +} + +void CompactibleFreeListSpace::endSweepFLCensus(int sweepCt) { + setFLSurplus(); + setFLHints(); + if (PrintGC && PrintFLSCensus > 0) { + printFLCensus(sweepCt); + } + clearFLCensus(); + assert_locked(); + _dictionary->endSweepDictCensus(SplitSurplusPercent); +} + +bool CompactibleFreeListSpace::coalOverPopulated(size_t size) { + if (size < SmallForDictionary) { + FreeList *fl = &_indexedFreeList[size]; + return (fl->coalDesired() < 0) || + ((int)fl->count() > fl->coalDesired()); + } else { + return dictionary()->coalDictOverPopulated(size); + } +} + +void CompactibleFreeListSpace::smallCoalBirth(size_t size) { + assert(size < SmallForDictionary, "Size too large for indexed list"); + FreeList *fl = &_indexedFreeList[size]; + fl->increment_coalBirths(); + fl->increment_surplus(); +} + +void CompactibleFreeListSpace::smallCoalDeath(size_t size) { + assert(size < SmallForDictionary, "Size too large for indexed list"); + FreeList *fl = &_indexedFreeList[size]; + fl->increment_coalDeaths(); + fl->decrement_surplus(); +} + +void CompactibleFreeListSpace::coalBirth(size_t size) { + if (size < SmallForDictionary) { + smallCoalBirth(size); + } else { + dictionary()->dictCensusUpdate(size, + false /* split */, + true /* birth */); + } +} + +void CompactibleFreeListSpace::coalDeath(size_t size) { + if(size < SmallForDictionary) { + smallCoalDeath(size); + } else { + dictionary()->dictCensusUpdate(size, + false /* split */, + false /* birth */); + } +} + +void CompactibleFreeListSpace::smallSplitBirth(size_t size) { + assert(size < SmallForDictionary, "Size too large for indexed list"); + FreeList *fl = &_indexedFreeList[size]; + fl->increment_splitBirths(); + fl->increment_surplus(); +} + +void CompactibleFreeListSpace::smallSplitDeath(size_t size) { + assert(size < SmallForDictionary, "Size too large for indexed list"); + FreeList *fl = &_indexedFreeList[size]; + fl->increment_splitDeaths(); + fl->decrement_surplus(); +} + +void CompactibleFreeListSpace::splitBirth(size_t size) { + if (size < SmallForDictionary) { + smallSplitBirth(size); + } else { + dictionary()->dictCensusUpdate(size, + true /* split */, + true /* birth */); + } +} + +void CompactibleFreeListSpace::splitDeath(size_t size) { + if (size < SmallForDictionary) { + smallSplitDeath(size); + } else { + dictionary()->dictCensusUpdate(size, + true /* split */, + false /* birth */); + } +} + +void CompactibleFreeListSpace::split(size_t from, size_t to1) { + size_t to2 = from - to1; + splitDeath(from); + splitBirth(to1); + splitBirth(to2); +} + + +void CompactibleFreeListSpace::print() const { + tty->print(" CompactibleFreeListSpace"); + Space::print(); +} + +void CompactibleFreeListSpace::prepare_for_verify() { + assert_locked(); + repairLinearAllocationBlocks(); + // Verify that the SpoolBlocks look like free blocks of + // appropriate sizes... To be done ... +} + +class VerifyAllBlksClosure: public BlkClosure { + const CompactibleFreeListSpace* _sp; + const MemRegion _span; + + public: + VerifyAllBlksClosure(const CompactibleFreeListSpace* sp, + MemRegion span) : _sp(sp), _span(span) { } + + size_t do_blk(HeapWord* addr) { + size_t res; + if (_sp->block_is_obj(addr)) { + oop p = oop(addr); + guarantee(p->is_oop(), "Should be an oop"); + res = _sp->adjustObjectSize(p->size()); + if (_sp->obj_is_alive(addr)) { + p->verify(); + } + } else { + FreeChunk* fc = (FreeChunk*)addr; + res = fc->size(); + if (FLSVerifyLists && !fc->cantCoalesce()) { + guarantee(_sp->verifyChunkInFreeLists(fc), + "Chunk should be on a free list"); + } + } + guarantee(res != 0, "Livelock: no rank reduction!"); + return res; + } +}; + +class VerifyAllOopsClosure: public OopClosure { + const CMSCollector* _collector; + const CompactibleFreeListSpace* _sp; + const MemRegion _span; + const bool _past_remark; + const CMSBitMap* _bit_map; + + public: + VerifyAllOopsClosure(const CMSCollector* collector, + const CompactibleFreeListSpace* sp, MemRegion span, + bool past_remark, CMSBitMap* bit_map) : + OopClosure(), _collector(collector), _sp(sp), _span(span), + _past_remark(past_remark), _bit_map(bit_map) { } + + void do_oop(oop* ptr) { + oop p = *ptr; + if (p != NULL) { + if (_span.contains(p)) { // the interior oop points into CMS heap + if (!_span.contains(ptr)) { // reference from outside CMS heap + // Should be a valid object; the first disjunct below allows + // us to sidestep an assertion in block_is_obj() that insists + // that p be in _sp. Note that several generations (and spaces) + // are spanned by _span (CMS heap) above. + guarantee(!_sp->is_in_reserved(p) || _sp->block_is_obj((HeapWord*)p), + "Should be an object"); + guarantee(p->is_oop(), "Should be an oop"); + p->verify(); + if (_past_remark) { + // Remark has been completed, the object should be marked + _bit_map->isMarked((HeapWord*)p); + } + } + else { // reference within CMS heap + if (_past_remark) { + // Remark has been completed -- so the referent should have + // been marked, if referring object is. + if (_bit_map->isMarked(_collector->block_start(ptr))) { + guarantee(_bit_map->isMarked((HeapWord*)p), "Marking error?"); + } + } + } + } else if (_sp->is_in_reserved(ptr)) { + // the reference is from FLS, and points out of FLS + guarantee(p->is_oop(), "Should be an oop"); + p->verify(); + } + } + } +}; + +void CompactibleFreeListSpace::verify(bool ignored) const { + assert_lock_strong(&_freelistLock); + verify_objects_initialized(); + MemRegion span = _collector->_span; + bool past_remark = (_collector->abstract_state() == + CMSCollector::Sweeping); + + ResourceMark rm; + HandleMark hm; + + // Check integrity of CFL data structures + _promoInfo.verify(); + _dictionary->verify(); + if (FLSVerifyIndexTable) { + verifyIndexedFreeLists(); + } + // Check integrity of all objects and free blocks in space + { + VerifyAllBlksClosure cl(this, span); + ((CompactibleFreeListSpace*)this)->blk_iterate(&cl); // cast off const + } + // Check that all references in the heap to FLS + // are to valid objects in FLS or that references in + // FLS are to valid objects elsewhere in the heap + if (FLSVerifyAllHeapReferences) + { + VerifyAllOopsClosure cl(_collector, this, span, past_remark, + _collector->markBitMap()); + CollectedHeap* ch = Universe::heap(); + ch->oop_iterate(&cl); // all oops in generations + ch->permanent_oop_iterate(&cl); // all oops in perm gen + } + + if (VerifyObjectStartArray) { + // Verify the block offset table + _bt.verify(); + } +} + +#ifndef PRODUCT +void CompactibleFreeListSpace::verifyFreeLists() const { + if (FLSVerifyLists) { + _dictionary->verify(); + verifyIndexedFreeLists(); + } else { + if (FLSVerifyDictionary) { + _dictionary->verify(); + } + if (FLSVerifyIndexTable) { + verifyIndexedFreeLists(); + } + } +} +#endif + +void CompactibleFreeListSpace::verifyIndexedFreeLists() const { + size_t i = 0; + for (; i < MinChunkSize; i++) { + guarantee(_indexedFreeList[i].head() == NULL, "should be NULL"); + } + for (; i < IndexSetSize; i++) { + verifyIndexedFreeList(i); + } +} + +void CompactibleFreeListSpace::verifyIndexedFreeList(size_t size) const { + guarantee(size % 2 == 0, "Odd slots should be empty"); + for (FreeChunk* fc = _indexedFreeList[size].head(); fc != NULL; + fc = fc->next()) { + guarantee(fc->size() == size, "Size inconsistency"); + guarantee(fc->isFree(), "!free?"); + guarantee(fc->next() == NULL || fc->next()->prev() == fc, "Broken list"); + } +} + +#ifndef PRODUCT +void CompactibleFreeListSpace::checkFreeListConsistency() const { + assert(_dictionary->minSize() <= IndexSetSize, + "Some sizes can't be allocated without recourse to" + " linear allocation buffers"); + assert(MIN_TREE_CHUNK_SIZE*HeapWordSize == sizeof(TreeChunk), + "else MIN_TREE_CHUNK_SIZE is wrong"); + assert((IndexSetStride == 2 && IndexSetStart == 2) || + (IndexSetStride == 1 && IndexSetStart == 1), "just checking"); + assert((IndexSetStride != 2) || (MinChunkSize % 2 == 0), + "Some for-loops may be incorrectly initialized"); + assert((IndexSetStride != 2) || (IndexSetSize % 2 == 1), + "For-loops that iterate over IndexSet with stride 2 may be wrong"); +} +#endif + +void CompactibleFreeListSpace::printFLCensus(int sweepCt) const { + assert_lock_strong(&_freelistLock); + ssize_t bfrSurp = 0; + ssize_t surplus = 0; + ssize_t desired = 0; + ssize_t prevSweep = 0; + ssize_t beforeSweep = 0; + ssize_t count = 0; + ssize_t coalBirths = 0; + ssize_t coalDeaths = 0; + ssize_t splitBirths = 0; + ssize_t splitDeaths = 0; + gclog_or_tty->print("end sweep# %d\n", sweepCt); + gclog_or_tty->print("%4s\t" "%7s\t" "%7s\t" "%7s\t" "%7s\t" + "%7s\t" "%7s\t" "%7s\t" "%7s\t" "%7s\t" + "%7s\t" "\n", + "size", "bfrsurp", "surplus", "desired", "prvSwep", + "bfrSwep", "count", "cBirths", "cDeaths", "sBirths", + "sDeaths"); + + size_t totalFree = 0; + for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + const FreeList *fl = &_indexedFreeList[i]; + totalFree += fl->count() * fl->size(); + + gclog_or_tty->print("%4d\t" "%7d\t" "%7d\t" "%7d\t" + "%7d\t" "%7d\t" "%7d\t" "%7d\t" + "%7d\t" "%7d\t" "%7d\t" "\n", + fl->size(), fl->bfrSurp(), fl->surplus(), fl->desired(), + fl->prevSweep(), fl->beforeSweep(), fl->count(), fl->coalBirths(), + fl->coalDeaths(), fl->splitBirths(), fl->splitDeaths()); + bfrSurp += fl->bfrSurp(); + surplus += fl->surplus(); + desired += fl->desired(); + prevSweep += fl->prevSweep(); + beforeSweep += fl->beforeSweep(); + count += fl->count(); + coalBirths += fl->coalBirths(); + coalDeaths += fl->coalDeaths(); + splitBirths += fl->splitBirths(); + splitDeaths += fl->splitDeaths(); + } + gclog_or_tty->print("%4s\t" + "%7d\t" "%7d\t" "%7d\t" "%7d\t" "%7d\t" + "%7d\t" "%7d\t" "%7d\t" "%7d\t" "%7d\t" "\n", + "totl", + bfrSurp, surplus, desired, prevSweep, beforeSweep, + count, coalBirths, coalDeaths, splitBirths, splitDeaths); + gclog_or_tty->print_cr("Total free in indexed lists %d words", totalFree); + gclog_or_tty->print("growth: %8.5f deficit: %8.5f\n", + (double)(splitBirths+coalBirths-splitDeaths-coalDeaths)/ + (prevSweep != 0 ? (double)prevSweep : 1.0), + (double)(desired - count)/(desired != 0 ? (double)desired : 1.0)); + _dictionary->printDictCensus(); +} + +// Return the next displaced header, incrementing the pointer and +// recycling spool area as necessary. +markOop PromotionInfo::nextDisplacedHeader() { + assert(_spoolHead != NULL, "promotionInfo inconsistency"); + assert(_spoolHead != _spoolTail || _firstIndex < _nextIndex, + "Empty spool space: no displaced header can be fetched"); + assert(_spoolHead->bufferSize > _firstIndex, "Off by one error at head?"); + markOop hdr = _spoolHead->displacedHdr[_firstIndex]; + // Spool forward + if (++_firstIndex == _spoolHead->bufferSize) { // last location in this block + // forward to next block, recycling this block into spare spool buffer + SpoolBlock* tmp = _spoolHead->nextSpoolBlock; + assert(_spoolHead != _spoolTail, "Spooling storage mix-up"); + _spoolHead->nextSpoolBlock = _spareSpool; + _spareSpool = _spoolHead; + _spoolHead = tmp; + _firstIndex = 1; + NOT_PRODUCT( + if (_spoolHead == NULL) { // all buffers fully consumed + assert(_spoolTail == NULL && _nextIndex == 1, + "spool buffers processing inconsistency"); + } + ) + } + return hdr; +} + +void PromotionInfo::track(PromotedObject* trackOop) { + track(trackOop, oop(trackOop)->klass()); +} + +void PromotionInfo::track(PromotedObject* trackOop, klassOop klassOfOop) { + // make a copy of header as it may need to be spooled + markOop mark = oop(trackOop)->mark(); + trackOop->clearNext(); + if (mark->must_be_preserved_for_cms_scavenge(klassOfOop)) { + // save non-prototypical header, and mark oop + saveDisplacedHeader(mark); + trackOop->setDisplacedMark(); + } else { + // we'd like to assert something like the following: + // assert(mark == markOopDesc::prototype(), "consistency check"); + // ... but the above won't work because the age bits have not (yet) been + // cleared. The remainder of the check would be identical to the + // condition checked in must_be_preserved() above, so we don't really + // have anything useful to check here! + } + if (_promoTail != NULL) { + assert(_promoHead != NULL, "List consistency"); + _promoTail->setNext(trackOop); + _promoTail = trackOop; + } else { + assert(_promoHead == NULL, "List consistency"); + _promoHead = _promoTail = trackOop; + } + // Mask as newly promoted, so we can skip over such objects + // when scanning dirty cards + assert(!trackOop->hasPromotedMark(), "Should not have been marked"); + trackOop->setPromotedMark(); +} + +// Save the given displaced header, incrementing the pointer and +// obtaining more spool area as necessary. +void PromotionInfo::saveDisplacedHeader(markOop hdr) { + assert(_spoolHead != NULL && _spoolTail != NULL, + "promotionInfo inconsistency"); + assert(_spoolTail->bufferSize > _nextIndex, "Off by one error at tail?"); + _spoolTail->displacedHdr[_nextIndex] = hdr; + // Spool forward + if (++_nextIndex == _spoolTail->bufferSize) { // last location in this block + // get a new spooling block + assert(_spoolTail->nextSpoolBlock == NULL, "tail should terminate spool list"); + _splice_point = _spoolTail; // save for splicing + _spoolTail->nextSpoolBlock = getSpoolBlock(); // might fail + _spoolTail = _spoolTail->nextSpoolBlock; // might become NULL ... + // ... but will attempt filling before next promotion attempt + _nextIndex = 1; + } +} + +// Ensure that spooling space exists. Return false if spooling space +// could not be obtained. +bool PromotionInfo::ensure_spooling_space_work() { + assert(!has_spooling_space(), "Only call when there is no spooling space"); + // Try and obtain more spooling space + SpoolBlock* newSpool = getSpoolBlock(); + assert(newSpool == NULL || + (newSpool->bufferSize != 0 && newSpool->nextSpoolBlock == NULL), + "getSpoolBlock() sanity check"); + if (newSpool == NULL) { + return false; + } + _nextIndex = 1; + if (_spoolTail == NULL) { + _spoolTail = newSpool; + if (_spoolHead == NULL) { + _spoolHead = newSpool; + _firstIndex = 1; + } else { + assert(_splice_point != NULL && _splice_point->nextSpoolBlock == NULL, + "Splice point invariant"); + // Extra check that _splice_point is connected to list + #ifdef ASSERT + { + SpoolBlock* blk = _spoolHead; + for (; blk->nextSpoolBlock != NULL; + blk = blk->nextSpoolBlock); + assert(blk != NULL && blk == _splice_point, + "Splice point incorrect"); + } + #endif // ASSERT + _splice_point->nextSpoolBlock = newSpool; + } + } else { + assert(_spoolHead != NULL, "spool list consistency"); + _spoolTail->nextSpoolBlock = newSpool; + _spoolTail = newSpool; + } + return true; +} + +// Get a free spool buffer from the free pool, getting a new block +// from the heap if necessary. +SpoolBlock* PromotionInfo::getSpoolBlock() { + SpoolBlock* res; + if ((res = _spareSpool) != NULL) { + _spareSpool = _spareSpool->nextSpoolBlock; + res->nextSpoolBlock = NULL; + } else { // spare spool exhausted, get some from heap + res = (SpoolBlock*)(space()->allocateScratch(refillSize())); + if (res != NULL) { + res->init(); + } + } + assert(res == NULL || res->nextSpoolBlock == NULL, "postcondition"); + return res; +} + +void PromotionInfo::startTrackingPromotions() { + assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex, + "spooling inconsistency?"); + _firstIndex = _nextIndex = 1; + _tracking = true; +} + +void PromotionInfo::stopTrackingPromotions() { + assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex, + "spooling inconsistency?"); + _firstIndex = _nextIndex = 1; + _tracking = false; +} + +// When _spoolTail is not NULL, then the slot <_spoolTail, _nextIndex> +// points to the next slot available for filling. +// The set of slots holding displaced headers are then all those in the +// right-open interval denoted by: +// +// [ <_spoolHead, _firstIndex>, <_spoolTail, _nextIndex> ) +// +// When _spoolTail is NULL, then the set of slots with displaced headers +// is all those starting at the slot <_spoolHead, _firstIndex> and +// going up to the last slot of last block in the linked list. +// In this lartter case, _splice_point points to the tail block of +// this linked list of blocks holding displaced headers. +void PromotionInfo::verify() const { + // Verify the following: + // 1. the number of displaced headers matches the number of promoted + // objects that have displaced headers + // 2. each promoted object lies in this space + debug_only( + PromotedObject* junk = NULL; + assert(junk->next_addr() == (void*)(oop(junk)->mark_addr()), + "Offset of PromotedObject::_next is expected to align with " + " the OopDesc::_mark within OopDesc"); + ) + // FIXME: guarantee???? + guarantee(_spoolHead == NULL || _spoolTail != NULL || + _splice_point != NULL, "list consistency"); + guarantee(_promoHead == NULL || _promoTail != NULL, "list consistency"); + // count the number of objects with displaced headers + size_t numObjsWithDisplacedHdrs = 0; + for (PromotedObject* curObj = _promoHead; curObj != NULL; curObj = curObj->next()) { + guarantee(space()->is_in_reserved((HeapWord*)curObj), "Containment"); + // the last promoted object may fail the mark() != NULL test of is_oop(). + guarantee(curObj->next() == NULL || oop(curObj)->is_oop(), "must be an oop"); + if (curObj->hasDisplacedMark()) { + numObjsWithDisplacedHdrs++; + } + } + // Count the number of displaced headers + size_t numDisplacedHdrs = 0; + for (SpoolBlock* curSpool = _spoolHead; + curSpool != _spoolTail && curSpool != NULL; + curSpool = curSpool->nextSpoolBlock) { + // the first entry is just a self-pointer; indices 1 through + // bufferSize - 1 are occupied (thus, bufferSize - 1 slots). + guarantee((void*)curSpool->displacedHdr == (void*)&curSpool->displacedHdr, + "first entry of displacedHdr should be self-referential"); + numDisplacedHdrs += curSpool->bufferSize - 1; + } + guarantee((_spoolHead == _spoolTail) == (numDisplacedHdrs == 0), + "internal consistency"); + guarantee(_spoolTail != NULL || _nextIndex == 1, + "Inconsistency between _spoolTail and _nextIndex"); + // We overcounted (_firstIndex-1) worth of slots in block + // _spoolHead and we undercounted (_nextIndex-1) worth of + // slots in block _spoolTail. We make an appropriate + // adjustment by subtracting the first and adding the + // second: - (_firstIndex - 1) + (_nextIndex - 1) + numDisplacedHdrs += (_nextIndex - _firstIndex); + guarantee(numDisplacedHdrs == numObjsWithDisplacedHdrs, "Displaced hdr count"); +} + + +CFLS_LAB::CFLS_LAB(CompactibleFreeListSpace* cfls) : + _cfls(cfls) +{ + _blocks_to_claim = CMSParPromoteBlocksToClaim; + for (size_t i = CompactibleFreeListSpace::IndexSetStart; + i < CompactibleFreeListSpace::IndexSetSize; + i += CompactibleFreeListSpace::IndexSetStride) { + _indexedFreeList[i].set_size(i); + } +} + +HeapWord* CFLS_LAB::alloc(size_t word_sz) { + FreeChunk* res; + word_sz = _cfls->adjustObjectSize(word_sz); + if (word_sz >= CompactibleFreeListSpace::IndexSetSize) { + // This locking manages sync with other large object allocations. + MutexLockerEx x(_cfls->parDictionaryAllocLock(), + Mutex::_no_safepoint_check_flag); + res = _cfls->getChunkFromDictionaryExact(word_sz); + if (res == NULL) return NULL; + } else { + FreeList* fl = &_indexedFreeList[word_sz]; + bool filled = false; //TRAP + if (fl->count() == 0) { + bool filled = true; //TRAP + // Attempt to refill this local free list. + _cfls->par_get_chunk_of_blocks(word_sz, _blocks_to_claim, fl); + // If it didn't work, give up. + if (fl->count() == 0) return NULL; + } + res = fl->getChunkAtHead(); + assert(res != NULL, "Why was count non-zero?"); + } + res->markNotFree(); + assert(!res->isFree(), "shouldn't be marked free"); + assert(oop(res)->klass() == NULL, "should look uninitialized"); + // mangle a just allocated object with a distinct pattern. + debug_only(res->mangleAllocated(word_sz)); + return (HeapWord*)res; +} + +void CFLS_LAB::retire() { + for (size_t i = CompactibleFreeListSpace::IndexSetStart; + i < CompactibleFreeListSpace::IndexSetSize; + i += CompactibleFreeListSpace::IndexSetStride) { + if (_indexedFreeList[i].count() > 0) { + MutexLockerEx x(_cfls->_indexedFreeListParLocks[i], + Mutex::_no_safepoint_check_flag); + _cfls->_indexedFreeList[i].prepend(&_indexedFreeList[i]); + // Reset this list. + _indexedFreeList[i] = FreeList(); + _indexedFreeList[i].set_size(i); + } + } +} + +void +CompactibleFreeListSpace:: +par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl) { + assert(fl->count() == 0, "Precondition."); + assert(word_sz < CompactibleFreeListSpace::IndexSetSize, + "Precondition"); + + // We'll try all multiples of word_sz in the indexed set (starting with + // word_sz itself), then try getting a big chunk and splitting it. + int k = 1; + size_t cur_sz = k * word_sz; + bool found = false; + while (cur_sz < CompactibleFreeListSpace::IndexSetSize && k == 1) { + FreeList* gfl = &_indexedFreeList[cur_sz]; + FreeList fl_for_cur_sz; // Empty. + fl_for_cur_sz.set_size(cur_sz); + { + MutexLockerEx x(_indexedFreeListParLocks[cur_sz], + Mutex::_no_safepoint_check_flag); + if (gfl->count() != 0) { + size_t nn = MAX2(n/k, (size_t)1); + gfl->getFirstNChunksFromList(nn, &fl_for_cur_sz); + found = true; + } + } + // Now transfer fl_for_cur_sz to fl. Common case, we hope, is k = 1. + if (found) { + if (k == 1) { + fl->prepend(&fl_for_cur_sz); + } else { + // Divide each block on fl_for_cur_sz up k ways. + FreeChunk* fc; + while ((fc = fl_for_cur_sz.getChunkAtHead()) != NULL) { + // Must do this in reverse order, so that anybody attempting to + // access the main chunk sees it as a single free block until we + // change it. + size_t fc_size = fc->size(); + for (int i = k-1; i >= 0; i--) { + FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz); + ffc->setSize(word_sz); + ffc->linkNext(NULL); + ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. + // Above must occur before BOT is updated below. + // splitting from the right, fc_size == (k - i + 1) * wordsize + _bt.mark_block((HeapWord*)ffc, word_sz); + fc_size -= word_sz; + _bt.verify_not_unallocated((HeapWord*)ffc, ffc->size()); + _bt.verify_single_block((HeapWord*)fc, fc_size); + _bt.verify_single_block((HeapWord*)ffc, ffc->size()); + // Push this on "fl". + fl->returnChunkAtHead(ffc); + } + // TRAP + assert(fl->tail()->next() == NULL, "List invariant."); + } + } + return; + } + k++; cur_sz = k * word_sz; + } + // Otherwise, we'll split a block from the dictionary. + FreeChunk* fc = NULL; + FreeChunk* rem_fc = NULL; + size_t rem; + { + MutexLockerEx x(parDictionaryAllocLock(), + Mutex::_no_safepoint_check_flag); + while (n > 0) { + fc = dictionary()->getChunk(MAX2(n * word_sz, + _dictionary->minSize()), + FreeBlockDictionary::atLeast); + if (fc != NULL) { + _bt.allocated((HeapWord*)fc, fc->size()); // update _unallocated_blk + dictionary()->dictCensusUpdate(fc->size(), + true /*split*/, + false /*birth*/); + break; + } else { + n--; + } + } + if (fc == NULL) return; + // Otherwise, split up that block. + size_t nn = fc->size() / word_sz; + n = MIN2(nn, n); + rem = fc->size() - n * word_sz; + // If there is a remainder, and it's too small, allocate one fewer. + if (rem > 0 && rem < MinChunkSize) { + n--; rem += word_sz; + } + // First return the remainder, if any. + // Note that we hold the lock until we decide if we're going to give + // back the remainder to the dictionary, since a contending allocator + // may otherwise see the heap as empty. (We're willing to take that + // hit if the block is a small block.) + if (rem > 0) { + size_t prefix_size = n * word_sz; + rem_fc = (FreeChunk*)((HeapWord*)fc + prefix_size); + rem_fc->setSize(rem); + rem_fc->linkNext(NULL); + rem_fc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. + // Above must occur before BOT is updated below. + _bt.split_block((HeapWord*)fc, fc->size(), prefix_size); + if (rem >= IndexSetSize) { + returnChunkToDictionary(rem_fc); + dictionary()->dictCensusUpdate(fc->size(), + true /*split*/, + true /*birth*/); + rem_fc = NULL; + } + // Otherwise, return it to the small list below. + } + } + // + if (rem_fc != NULL) { + MutexLockerEx x(_indexedFreeListParLocks[rem], + Mutex::_no_safepoint_check_flag); + _bt.verify_not_unallocated((HeapWord*)rem_fc, rem_fc->size()); + _indexedFreeList[rem].returnChunkAtHead(rem_fc); + smallSplitBirth(rem); + } + + // Now do the splitting up. + // Must do this in reverse order, so that anybody attempting to + // access the main chunk sees it as a single free block until we + // change it. + size_t fc_size = n * word_sz; + // All but first chunk in this loop + for (ssize_t i = n-1; i > 0; i--) { + FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz); + ffc->setSize(word_sz); + ffc->linkNext(NULL); + ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads. + // Above must occur before BOT is updated below. + // splitting from the right, fc_size == (n - i + 1) * wordsize + _bt.mark_block((HeapWord*)ffc, word_sz); + fc_size -= word_sz; + _bt.verify_not_unallocated((HeapWord*)ffc, ffc->size()); + _bt.verify_single_block((HeapWord*)ffc, ffc->size()); + _bt.verify_single_block((HeapWord*)fc, fc_size); + // Push this on "fl". + fl->returnChunkAtHead(ffc); + } + // First chunk + fc->setSize(word_sz); + fc->linkNext(NULL); + fc->linkPrev(NULL); + _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); + _bt.verify_single_block((HeapWord*)fc, fc->size()); + fl->returnChunkAtHead(fc); + + { + MutexLockerEx x(_indexedFreeListParLocks[word_sz], + Mutex::_no_safepoint_check_flag); + ssize_t new_births = _indexedFreeList[word_sz].splitBirths() + n; + _indexedFreeList[word_sz].set_splitBirths(new_births); + ssize_t new_surplus = _indexedFreeList[word_sz].surplus() + n; + _indexedFreeList[word_sz].set_surplus(new_surplus); + } + + // TRAP + assert(fl->tail()->next() == NULL, "List invariant."); +} + +// Set up the space's par_seq_tasks structure for work claiming +// for parallel rescan. See CMSParRemarkTask where this is currently used. +// XXX Need to suitably abstract and generalize this and the next +// method into one. +void +CompactibleFreeListSpace:: +initialize_sequential_subtasks_for_rescan(int n_threads) { + // The "size" of each task is fixed according to rescan_task_size. + assert(n_threads > 0, "Unexpected n_threads argument"); + const size_t task_size = rescan_task_size(); + size_t n_tasks = (used_region().word_size() + task_size - 1)/task_size; + assert((used_region().start() + (n_tasks - 1)*task_size < + used_region().end()) && + (used_region().start() + n_tasks*task_size >= + used_region().end()), "n_task calculation incorrect"); + SequentialSubTasksDone* pst = conc_par_seq_tasks(); + assert(!pst->valid(), "Clobbering existing data?"); + pst->set_par_threads(n_threads); + pst->set_n_tasks((int)n_tasks); +} + +// Set up the space's par_seq_tasks structure for work claiming +// for parallel concurrent marking. See CMSConcMarkTask where this is currently used. +void +CompactibleFreeListSpace:: +initialize_sequential_subtasks_for_marking(int n_threads, + HeapWord* low) { + // The "size" of each task is fixed according to rescan_task_size. + assert(n_threads > 0, "Unexpected n_threads argument"); + const size_t task_size = marking_task_size(); + assert(task_size > CardTableModRefBS::card_size_in_words && + (task_size % CardTableModRefBS::card_size_in_words == 0), + "Otherwise arithmetic below would be incorrect"); + MemRegion span = _gen->reserved(); + if (low != NULL) { + if (span.contains(low)) { + // Align low down to a card boundary so that + // we can use block_offset_careful() on span boundaries. + HeapWord* aligned_low = (HeapWord*)align_size_down((uintptr_t)low, + CardTableModRefBS::card_size); + // Clip span prefix at aligned_low + span = span.intersection(MemRegion(aligned_low, span.end())); + } else if (low > span.end()) { + span = MemRegion(low, low); // Null region + } // else use entire span + } + assert(span.is_empty() || + ((uintptr_t)span.start() % CardTableModRefBS::card_size == 0), + "span should start at a card boundary"); + size_t n_tasks = (span.word_size() + task_size - 1)/task_size; + assert((n_tasks == 0) == span.is_empty(), "Inconsistency"); + assert(n_tasks == 0 || + ((span.start() + (n_tasks - 1)*task_size < span.end()) && + (span.start() + n_tasks*task_size >= span.end())), + "n_task calculation incorrect"); + SequentialSubTasksDone* pst = conc_par_seq_tasks(); + assert(!pst->valid(), "Clobbering existing data?"); + pst->set_par_threads(n_threads); + pst->set_n_tasks((int)n_tasks); +}