| /* |
| * Copyright (c) 2001, 2015, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "gc_implementation/concurrentMarkSweep/cmsLockVerifier.hpp" |
| #include "gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp" |
| #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp" |
| #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" |
| #include "gc_implementation/shared/liveRange.hpp" |
| #include "gc_implementation/shared/spaceDecorator.hpp" |
| #include "gc_interface/collectedHeap.inline.hpp" |
| #include "memory/allocation.inline.hpp" |
| #include "memory/blockOffsetTable.inline.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "memory/space.inline.hpp" |
| #include "memory/universe.inline.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/globals.hpp" |
| #include "runtime/handles.inline.hpp" |
| #include "runtime/init.hpp" |
| #include "runtime/java.hpp" |
| #include "runtime/orderAccess.inline.hpp" |
| #include "runtime/vmThread.hpp" |
| #include "utilities/copy.hpp" |
| |
| ///////////////////////////////////////////////////////////////////////// |
| //// CompactibleFreeListSpace |
| ///////////////////////////////////////////////////////////////////////// |
| |
| // highest ranked free list lock rank |
| int CompactibleFreeListSpace::_lockRank = Mutex::leaf + 3; |
| |
| // Defaults are 0 so things will break badly if incorrectly initialized. |
| size_t CompactibleFreeListSpace::IndexSetStart = 0; |
| size_t CompactibleFreeListSpace::IndexSetStride = 0; |
| |
| size_t MinChunkSize = 0; |
| |
| void CompactibleFreeListSpace::set_cms_values() { |
| // Set CMS global values |
| assert(MinChunkSize == 0, "already set"); |
| |
| // MinChunkSize should be a multiple of MinObjAlignment and be large enough |
| // for chunks to contain a FreeChunk. |
| size_t min_chunk_size_in_bytes = align_size_up(sizeof(FreeChunk), MinObjAlignmentInBytes); |
| MinChunkSize = min_chunk_size_in_bytes / BytesPerWord; |
| |
| assert(IndexSetStart == 0 && IndexSetStride == 0, "already set"); |
| IndexSetStart = MinChunkSize; |
| IndexSetStride = MinObjAlignment; |
| } |
| |
| // Constructor |
| CompactibleFreeListSpace::CompactibleFreeListSpace(BlockOffsetSharedArray* bs, |
| MemRegion mr, bool use_adaptive_freelists, |
| FreeBlockDictionary<FreeChunk>::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, |
| Monitor::_safepoint_check_sometimes), |
| _parDictionaryAllocLock(Mutex::leaf - 1, // == rank(ExpandHeap_lock) - 1 |
| "CompactibleFreeListSpace._dict_par_lock", true, |
| Monitor::_safepoint_check_never), |
| _rescan_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord * |
| CMSRescanMultiple), |
| _marking_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord * |
| CMSConcMarkMultiple), |
| _collector(NULL), |
| _preconsumptionDirtyCardClosure(NULL) |
| { |
| assert(sizeof(FreeChunk) / BytesPerWord <= MinChunkSize, |
| "FreeChunk is larger than expected"); |
| _bt.set_space(this); |
| initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle); |
| // 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<FreeChunk>::dictionaryBinaryTree: |
| _dictionary = new AFLBinaryTreeDictionary(mr); |
| break; |
| case FreeBlockDictionary<FreeChunk>::dictionarySplayTree: |
| case FreeBlockDictionary<FreeChunk>::dictionarySkipList: |
| default: |
| warning("dictionaryChoice: selected option not understood; using" |
| " default BinaryTreeDictionary implementation instead."); |
| } |
| 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->get_chunk(mr.word_size(), |
| FreeBlockDictionary<FreeChunk>::atLeast); |
| // 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; |
| } |
| check_free_list_consistency(); |
| |
| // Initialize locks for parallel case. |
| for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
| _indexedFreeListParLocks[i] = new Mutex(Mutex::leaf - 1, // == ExpandHeap_lock - 1 |
| "a freelist par lock", true, Mutex::_safepoint_check_sometimes); |
| 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()->young_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"); |
| } |
| |
| 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 (size_t 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->set_size(mr.word_size()); |
| if (mr.word_size() >= IndexSetSize ) { |
| returnChunkToDictionary(fc); |
| } else { |
| _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); |
| _indexedFreeList[mr.word_size()].return_chunk_at_head(fc); |
| } |
| coalBirth(mr.word_size()); |
| } |
| _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()->find_largest_dict(); |
| 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_returned_bytes(0); |
| } |
| } |
| |
| size_t CompactibleFreeListSpace::sumIndexedFreeListArrayReturnedBytes() { |
| size_t sum = 0; |
| for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
| sum += _indexedFreeList[i].allocation_stats()->returned_bytes(); |
| } |
| return sum; |
| } |
| |
| size_t CompactibleFreeListSpace::totalCountInIndexedFreeLists() const { |
| size_t count = 0; |
| for (size_t i = IndexSetStart; 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()->total_count(); |
| if (_smallLinearAllocBlock._word_size != 0) { |
| num++; |
| } |
| return num; |
| } |
| #endif |
| |
| bool CompactibleFreeListSpace::is_free_block(const HeapWord* p) const { |
| FreeChunk* fc = (FreeChunk*) p; |
| return fc->is_free(); |
| } |
| |
| 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->total_chunk_size(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->max_chunk_size(); |
| res = MAX2(res, MIN2(_smallLinearAllocBlock._word_size, |
| (size_t) SmallForLinearAlloc - 1)); |
| // XXX the following could potentially be pretty slow; |
| // should one, pessimistically for the rare cases when res |
| // calculated 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 LinearAllocBlock::print_on(outputStream* st) const { |
| st->print_cr(" LinearAllocBlock: ptr = " PTR_FORMAT ", word_size = " SIZE_FORMAT |
| ", refillsize = " SIZE_FORMAT ", allocation_size_limit = " SIZE_FORMAT, |
| p2i(_ptr), _word_size, _refillSize, _allocation_size_limit); |
| } |
| |
| void CompactibleFreeListSpace::print_on(outputStream* st) const { |
| st->print_cr("COMPACTIBLE FREELIST SPACE"); |
| st->print_cr(" Space:"); |
| Space::print_on(st); |
| |
| st->print_cr("promoInfo:"); |
| _promoInfo.print_on(st); |
| |
| st->print_cr("_smallLinearAllocBlock"); |
| _smallLinearAllocBlock.print_on(st); |
| |
| // dump_memory_block(_smallLinearAllocBlock->_ptr, 128); |
| |
| st->print_cr(" _fitStrategy = %s, _adaptive_freelists = %s", |
| _fitStrategy?"true":"false", _adaptive_freelists?"true":"false"); |
| } |
| |
| void CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st) |
| const { |
| reportIndexedFreeListStatistics(); |
| gclog_or_tty->print_cr("Layout of Indexed Freelists"); |
| gclog_or_tty->print_cr("---------------------------"); |
| AdaptiveFreeList<FreeChunk>::print_labels_on(st, "size"); |
| for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
| _indexedFreeList[i].print_on(gclog_or_tty); |
| for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; |
| fc = fc->next()) { |
| gclog_or_tty->print_cr("\t[" PTR_FORMAT "," PTR_FORMAT ") %s", |
| p2i(fc), p2i((HeapWord*)fc + i), |
| fc->cantCoalesce() ? "\t CC" : ""); |
| } |
| } |
| } |
| |
| void CompactibleFreeListSpace::print_promo_info_blocks(outputStream* st) |
| const { |
| _promoInfo.print_on(st); |
| } |
| |
| void CompactibleFreeListSpace::print_dictionary_free_lists(outputStream* st) |
| const { |
| _dictionary->report_statistics(); |
| st->print_cr("Layout of Freelists in Tree"); |
| st->print_cr("---------------------------"); |
| _dictionary->print_free_lists(st); |
| } |
| |
| class BlkPrintingClosure: public BlkClosure { |
| const CMSCollector* _collector; |
| const CompactibleFreeListSpace* _sp; |
| const CMSBitMap* _live_bit_map; |
| const bool _post_remark; |
| outputStream* _st; |
| public: |
| BlkPrintingClosure(const CMSCollector* collector, |
| const CompactibleFreeListSpace* sp, |
| const CMSBitMap* live_bit_map, |
| outputStream* st): |
| _collector(collector), |
| _sp(sp), |
| _live_bit_map(live_bit_map), |
| _post_remark(collector->abstract_state() > CMSCollector::FinalMarking), |
| _st(st) { } |
| size_t do_blk(HeapWord* addr); |
| }; |
| |
| size_t BlkPrintingClosure::do_blk(HeapWord* addr) { |
| size_t sz = _sp->block_size_no_stall(addr, _collector); |
| assert(sz != 0, "Should always be able to compute a size"); |
| if (_sp->block_is_obj(addr)) { |
| const bool dead = _post_remark && !_live_bit_map->isMarked(addr); |
| _st->print_cr(PTR_FORMAT ": %s object of size " SIZE_FORMAT "%s", |
| p2i(addr), |
| dead ? "dead" : "live", |
| sz, |
| (!dead && CMSPrintObjectsInDump) ? ":" : "."); |
| if (CMSPrintObjectsInDump && !dead) { |
| oop(addr)->print_on(_st); |
| _st->print_cr("--------------------------------------"); |
| } |
| } else { // free block |
| _st->print_cr(PTR_FORMAT ": free block of size " SIZE_FORMAT "%s", |
| p2i(addr), sz, CMSPrintChunksInDump ? ":" : "."); |
| if (CMSPrintChunksInDump) { |
| ((FreeChunk*)addr)->print_on(_st); |
| _st->print_cr("--------------------------------------"); |
| } |
| } |
| return sz; |
| } |
| |
| void CompactibleFreeListSpace::dump_at_safepoint_with_locks(CMSCollector* c, |
| outputStream* st) { |
| st->print_cr("\n========================="); |
| st->print_cr("Block layout in CMS Heap:"); |
| st->print_cr("========================="); |
| BlkPrintingClosure bpcl(c, this, c->markBitMap(), st); |
| blk_iterate(&bpcl); |
| |
| st->print_cr("\n======================================="); |
| st->print_cr("Order & Layout of Promotion Info Blocks"); |
| st->print_cr("======================================="); |
| print_promo_info_blocks(st); |
| |
| st->print_cr("\n==========================="); |
| st->print_cr("Order of Indexed Free Lists"); |
| st->print_cr("========================="); |
| print_indexed_free_lists(st); |
| |
| st->print_cr("\n================================="); |
| st->print_cr("Order of Free Lists in Dictionary"); |
| st->print_cr("================================="); |
| print_dictionary_free_lists(st); |
| } |
| |
| |
| void CompactibleFreeListSpace::reportFreeListStatistics() const { |
| assert_lock_strong(&_freelistLock); |
| assert(PrintFLSStatistics != 0, "Reporting error"); |
| _dictionary->report_statistics(); |
| if (PrintFLSStatistics > 1) { |
| reportIndexedFreeListStatistics(); |
| size_t total_size = totalSizeInIndexedFreeLists() + |
| _dictionary->total_chunk_size(DEBUG_ONLY(freelistLock())); |
| gclog_or_tty->print(" free=" SIZE_FORMAT " frag=%1.4f\n", total_size, flsFrag()); |
| } |
| } |
| |
| void CompactibleFreeListSpace::reportIndexedFreeListStatistics() const { |
| assert_lock_strong(&_freelistLock); |
| gclog_or_tty->print("Statistics for IndexedFreeLists:\n" |
| "--------------------------------\n"); |
| size_t total_size = totalSizeInIndexedFreeLists(); |
| size_t free_blocks = numFreeBlocksInIndexedFreeLists(); |
| gclog_or_tty->print("Total Free Space: " SIZE_FORMAT "\n", total_size); |
| gclog_or_tty->print("Max Chunk Size: " SIZE_FORMAT "\n", maxChunkSizeInIndexedFreeLists()); |
| gclog_or_tty->print("Number of Blocks: " SIZE_FORMAT "\n", free_blocks); |
| if (free_blocks != 0) { |
| gclog_or_tty->print("Av. Block Size: " SIZE_FORMAT "\n", total_size/free_blocks); |
| } |
| } |
| |
| 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 || !BlockOffsetArrayUseUnallocatedBlock || 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(!BlockOffsetArrayUseUnallocatedBlock || 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 |
| 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(ExtendedOopClosure); |
| walk_mem_region_with_cl_DECL(FilteringClosure); |
| |
| public: |
| FreeListSpace_DCTOC(CompactibleFreeListSpace* sp, |
| CMSCollector* collector, |
| ExtendedOopClosure* 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) { \ |
| bool is_par = SharedHeap::heap()->n_par_threads() > 0; \ |
| if (is_par) { \ |
| assert(SharedHeap::heap()->n_par_threads() == \ |
| SharedHeap::heap()->workers()->active_workers(), "Mismatch"); \ |
| 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(ExtendedOopClosure) |
| FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure) |
| |
| DirtyCardToOopClosure* |
| CompactibleFreeListSpace::new_dcto_cl(ExtendedOopClosure* 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 instance 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(ExtendedOopClosure* 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); |
| } |
| } |
| } |
| |
| // 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)); |
| } |
| } |
| } |
| |
| // Apply the given closure to each live object in the space |
| // The usage of CompactibleFreeListSpace |
| // by the ConcurrentMarkSweepGeneration for concurrent GC's allows |
| // objects in the space with references to objects that are no longer |
| // valid. For example, an object may reference another object |
| // that has already been sweep up (collected). This method uses |
| // obj_is_alive() to determine whether it is safe to apply the closure to |
| // an object. See obj_is_alive() for details on how liveness of an |
| // object is decided. |
| |
| void CompactibleFreeListSpace::safe_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) && obj_is_alive(cur)) { |
| blk->do_object(oop(cur)); |
| } |
| } |
| } |
| |
| void CompactibleFreeListSpace::object_iterate_mem(MemRegion mr, |
| UpwardsObjectClosure* cl) { |
| assert_locked(freelistLock()); |
| NOT_PRODUCT(verify_objects_initialized()); |
| assert(!mr.is_empty(), "Should be non-empty"); |
| // We use MemRegion(bottom(), end()) rather than used_region() below |
| // because the two are not necessarily equal for some kinds of |
| // spaces, in particular, certain kinds of free list spaces. |
| // We could use the more complicated but more precise: |
| // MemRegion(used_region().start(), round_to(used_region().end(), CardSize)) |
| // but the slight imprecision seems acceptable in the assertion check. |
| assert(MemRegion(bottom(), end()).contains(mr), |
| "Should be within used space"); |
| HeapWord* prev = cl->previous(); // max address from last time |
| if (prev >= mr.end()) { // nothing to do |
| return; |
| } |
| // This assert will not work when we go from cms space to perm |
| // space, and use same closure. Easy fix deferred for later. XXX YSR |
| // assert(prev == NULL || contains(prev), "Should be within space"); |
| |
| bool last_was_obj_array = false; |
| HeapWord *blk_start_addr, *region_start_addr; |
| if (prev > mr.start()) { |
| region_start_addr = prev; |
| blk_start_addr = prev; |
| // The previous invocation may have pushed "prev" beyond the |
| // last allocated block yet there may be still be blocks |
| // in this region due to a particular coalescing policy. |
| // Relax the assertion so that the case where the unallocated |
| // block is maintained and "prev" is beyond the unallocated |
| // block does not cause the assertion to fire. |
| assert((BlockOffsetArrayUseUnallocatedBlock && |
| (!is_in(prev))) || |
| (blk_start_addr == block_start(region_start_addr)), "invariant"); |
| } else { |
| region_start_addr = mr.start(); |
| blk_start_addr = block_start(region_start_addr); |
| } |
| HeapWord* region_end_addr = mr.end(); |
| MemRegion derived_mr(region_start_addr, region_end_addr); |
| while (blk_start_addr < region_end_addr) { |
| const size_t size = block_size(blk_start_addr); |
| if (block_is_obj(blk_start_addr)) { |
| last_was_obj_array = cl->do_object_bm(oop(blk_start_addr), derived_mr); |
| } else { |
| last_was_obj_array = false; |
| } |
| blk_start_addr += size; |
| } |
| if (!last_was_obj_array) { |
| assert((bottom() <= blk_start_addr) && (blk_start_addr <= end()), |
| "Should be within (closed) used space"); |
| assert(blk_start_addr > prev, "Invariant"); |
| cl->set_previous(blk_start_addr); // min address for next time |
| } |
| } |
| |
| // 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->is_free()) { |
| // 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(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()); |
| // 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. |
| while (true) { |
| // We must do this until we get a consistent view of the object. |
| if (FreeChunk::indicatesFreeChunk(p)) { |
| volatile FreeChunk* fc = (volatile FreeChunk*)p; |
| size_t res = fc->size(); |
| |
| // Bugfix for systems with weak memory model (PPC64/IA64). The |
| // block's free bit was set and we have read the size of the |
| // block. Acquire and check the free bit again. If the block is |
| // still free, the read size is correct. |
| OrderAccess::acquire(); |
| |
| // If the object is still a free chunk, return the size, else it |
| // has been allocated so try again. |
| if (FreeChunk::indicatesFreeChunk(p)) { |
| assert(res != 0, "Block size should not be 0"); |
| return res; |
| } |
| } else { |
| // must read from what 'p' points to in each loop. |
| Klass* k = ((volatile oopDesc*)p)->klass_or_null(); |
| if (k != NULL) { |
| assert(k->is_klass(), "Should really be klass oop."); |
| oop o = (oop)p; |
| assert(o->is_oop(true /* ignore mark word */), "Should be an oop."); |
| |
| // Bugfix for systems with weak memory model (PPC64/IA64). |
| // The object o may be an array. Acquire to make sure that the array |
| // size (third word) is consistent. |
| OrderAccess::acquire(); |
| |
| size_t res = o->size_given_klass(k); |
| res = adjustObjectSize(res); |
| assert(res != 0, "Block size should not be 0"); |
| return res; |
| } |
| } |
| } |
| } |
| |
| // TODO: Now that is_parsable is gone, we should combine these two functions. |
| // 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. |
| DEBUG_ONLY(uint loops = 0;) |
| while (true) { |
| // We must do this until we get a consistent view of the object. |
| if (FreeChunk::indicatesFreeChunk(p)) { |
| volatile FreeChunk* fc = (volatile FreeChunk*)p; |
| size_t res = fc->size(); |
| |
| // Bugfix for systems with weak memory model (PPC64/IA64). The |
| // free bit of the block was set and we have read the size of |
| // the block. Acquire and check the free bit again. If the |
| // block is still free, the read size is correct. |
| OrderAccess::acquire(); |
| |
| if (FreeChunk::indicatesFreeChunk(p)) { |
| assert(res != 0, "Block size should not be 0"); |
| assert(loops == 0, "Should be 0"); |
| return res; |
| } |
| } else { |
| // must read from what 'p' points to in each loop. |
| Klass* k = ((volatile oopDesc*)p)->klass_or_null(); |
| // We trust the size of any object that has a non-NULL |
| // klass and (for those in the perm gen) is parsable |
| // -- irrespective of its conc_safe-ty. |
| if (k != NULL) { |
| assert(k->is_klass(), "Should really be klass oop."); |
| oop o = (oop)p; |
| assert(o->is_oop(), "Should be an oop"); |
| |
| // Bugfix for systems with weak memory model (PPC64/IA64). |
| // The object o may be an array. Acquire to make sure that the array |
| // size (third word) is consistent. |
| OrderAccess::acquire(); |
| |
| size_t res = o->size_given_klass(k); |
| res = adjustObjectSize(res); |
| assert(res != 0, "Block size should not be 0"); |
| return res; |
| } else { |
| // May return 0 if P-bits not present. |
| 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->is_free()) { |
| 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(CollectedHeap::use_parallel_gc_threads() || _bt.block_start(p) == p, |
| // "Should be a block boundary"); |
| if (FreeChunk::indicatesFreeChunk(p)) return false; |
| Klass* k = oop(p)->klass_or_null(); |
| 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(SafepointSynchronize::is_at_safepoint() || !is_init_completed(), |
| "Else races are possible"); |
| 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. |
| // NOTE: This method is also used by jmap where, if class unloading is |
| // off, the results can return "false" for legitimate perm objects, |
| // when we are not in the midst of a sweeping phase, which can result |
| // in jmap not reporting certain perm gen objects. This will be moot |
| // if/when the perm gen goes away in the future. |
| if (_collector->abstract_state() == CMSCollector::Sweeping) { |
| CMSBitMap* live_map = _collector->markBitMap(); |
| return live_map->par_isMarked((HeapWord*) p); |
| } |
| 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->is_free()) { |
| // 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->is_free(), "shouldn't be marked free"); |
| assert(oop(fc)->klass_or_null() == 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) { |
| AdaptiveFreeList<FreeChunk>* fl = &_indexedFreeList[i]; |
| if (fl->head()) { |
| ret = getFromListGreater(fl, numWords); |
| assert(ret == NULL || ret->is_free(), "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()->get_chunk(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->is_free(), "This chunk should be free"); |
| ret->link_prev(NULL); |
| } |
| assert(ret == NULL || ret->is_free(), "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()].verify_chunk_in_free_list(fc); |
| } |
| |
| bool CompactibleFreeListSpace::verify_chunk_is_linear_alloc_block(FreeChunk* fc) const { |
| assert((_smallLinearAllocBlock._ptr != (HeapWord*)fc) || |
| (_smallLinearAllocBlock._word_size == fc->size()), |
| "Linear allocation block shows incorrect size"); |
| return ((_smallLinearAllocBlock._ptr == (HeapWord*)fc) && |
| (_smallLinearAllocBlock._word_size == fc->size())); |
| } |
| |
| // Check if the purported free chunk is present either as a linear |
| // allocation block, the size-indexed table of (smaller) free blocks, |
| // or the larger free blocks kept in the binary tree dictionary. |
| bool CompactibleFreeListSpace::verify_chunk_in_free_list(FreeChunk* fc) const { |
| if (verify_chunk_is_linear_alloc_block(fc)) { |
| return true; |
| } else if (fc->size() < IndexSetSize) { |
| return verifyChunkInIndexedFreeLists(fc); |
| } else { |
| return dictionary()->verify_chunk_in_free_list(fc); |
| } |
| } |
| |
| #ifndef PRODUCT |
| void CompactibleFreeListSpace::assert_locked() const { |
| CMSLockVerifier::assert_locked(freelistLock(), parDictionaryAllocLock()); |
| } |
| |
| void CompactibleFreeListSpace::assert_locked(const Mutex* lock) const { |
| CMSLockVerifier::assert_locked(lock); |
| } |
| #endif |
| |
| FreeChunk* CompactibleFreeListSpace::allocateScratch(size_t size) { |
| // In the parallel case, the main thread holds the free list lock |
| // on behalf the parallel threads. |
| 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->is_free(), "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) { |
| 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) { |
| size_t sz = blk->_word_size; |
| // 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 (sz < SmallForDictionary) { |
| _bt.allocated(blk->_ptr, sz); |
| } |
| // Return the chunk that isn't big enough, and then refill below. |
| addChunkToFreeLists(blk->_ptr, sz); |
| split_birth(sz); |
| // 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) { |
| split_birth(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; |
| split_birth(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. |
| OrderAccess::storestore(); |
| _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; |
| split_birth(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. |
| OrderAccess::storestore(); |
| _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].get_chunk_at_head(); |
| if (res == NULL) { |
| res = getChunkFromIndexedFreeListHelper(size); |
| } |
| _bt.verify_not_unallocated((HeapWord*) res, size); |
| assert(res == NULL || res->size() == size, "Incorrect block size"); |
| return res; |
| } |
| |
| FreeChunk* |
| CompactibleFreeListSpace::getChunkFromIndexedFreeListHelper(size_t size, |
| bool replenish) { |
| 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; |
| const 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].get_chunk_at_head(); |
| } else if (bestFitFirst()) { |
| newFc = bestFitSmall(replenish_size); |
| } |
| } |
| if (newFc == NULL && replenish_size > size) { |
| assert(CMSIndexedFreeListReplenish > 1, "ctl pt invariant"); |
| newFc = getChunkFromIndexedFreeListHelper(replenish_size, false); |
| } |
| // Note: The stats update re split-death of block obtained above |
| // will be recorded below precisely when we know we are going to |
| // be actually splitting it into more than one pieces below. |
| if (newFc != NULL) { |
| if (replenish || CMSReplenishIntermediate) { |
| // Replenish this list and return one block to caller. |
| size_t i; |
| FreeChunk *curFc, *nextFc; |
| size_t num_blk = newFc->size() / size; |
| assert(num_blk >= 1, "Smaller than requested?"); |
| assert(newFc->size() % size == 0, "Should be integral multiple of request"); |
| if (num_blk > 1) { |
| // we are sure we will be splitting the block just obtained |
| // into multiple pieces; record the split-death of the original |
| splitDeath(replenish_size); |
| } |
| // carve up and link blocks 0, ..., num_blk - 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 < (num_blk - 1); |
| curFc = nextFc, nextFc = (FreeChunk*)((HeapWord*)nextFc + size), |
| i++) { |
| curFc->set_size(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].return_chunk_at_tail(curFc, false); |
| _bt.mark_block((HeapWord*)curFc, size); |
| split_birth(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 + num_blk*size, |
| "inconsistency in carving newFc"); |
| curFc->set_size(size); |
| _bt.mark_block((HeapWord*)curFc, size); |
| split_birth(size); |
| fc = curFc; |
| } else { |
| // Return entire block to caller |
| fc = newFc; |
| } |
| } |
| } |
| } 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->is_free(), "Should be returning a free chunk"); |
| return fc; |
| } |
| |
| FreeChunk* |
| CompactibleFreeListSpace::getChunkFromDictionary(size_t size) { |
| assert_locked(); |
| FreeChunk* fc = _dictionary->get_chunk(size, |
| FreeBlockDictionary<FreeChunk>::atLeast); |
| 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->get_chunk(size, |
| FreeBlockDictionary<FreeChunk>::atLeast); |
| 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, "get_chunk() guarantee"); |
| if (fc->size() < size + MinChunkSize) { |
| // Return the chunk to the dictionary and go get a bigger one. |
| returnChunkToDictionary(fc); |
| fc = _dictionary->get_chunk(size + MinChunkSize, |
| FreeBlockDictionary<FreeChunk>::atLeast); |
| 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->return_chunk(chunk); |
| #ifndef PRODUCT |
| if (CMSCollector::abstract_state() != CMSCollector::Sweeping) { |
| TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >* tc = TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >::as_TreeChunk(chunk); |
| TreeList<FreeChunk, AdaptiveFreeList<FreeChunk> >* tl = tc->list(); |
| tl->verify_stats(); |
| } |
| #endif // PRODUCT |
| } |
| |
| 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].return_chunk_at_tail(fc); |
| } else { |
| _indexedFreeList[size].return_chunk_at_head(fc); |
| } |
| #ifndef PRODUCT |
| if (CMSCollector::abstract_state() != CMSCollector::Sweeping) { |
| _indexedFreeList[size].verify_stats(); |
| } |
| #endif // PRODUCT |
| } |
| |
| // 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!"); |
| // One of the parallel gc task threads may be here |
| // whilst others are allocating. |
| Mutex* lock = &_parDictionaryAllocLock; |
| FreeChunk* ec; |
| { |
| MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); |
| ec = dictionary()->find_largest_dict(); // get largest block |
| if (ec != NULL && ec->end() == (uintptr_t*) 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->set_size(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->set_size(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->remove_chunk(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].remove_chunk(fc); |
| 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) { |
| AdaptiveFreeList<FreeChunk>* it = _indexedFreeList; |
| size_t hint = _indexedFreeList[start].hint(); |
| while (hint < IndexSetSize) { |
| assert(hint % MinObjAlignment == 0, "hint should be aligned"); |
| AdaptiveFreeList<FreeChunk> *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->is_free(), |
| "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(AdaptiveFreeList<FreeChunk>* 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->remove_chunk(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->is_free(), |
| "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_sz = size - new_size; |
| assert(rem_sz == adjustObjectSize(rem_sz), "alignment problem"); |
| assert(rem_sz >= MinChunkSize, "Free chunk smaller than minimum"); |
| FreeChunk* ffc = (FreeChunk*)((HeapWord*)chunk + new_size); |
| assert(is_aligned(ffc), "alignment problem"); |
| ffc->set_size(rem_sz); |
| ffc->link_next(NULL); |
| ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads. |
| // Above must occur before BOT is updated below. |
| // adjust block offset table |
| OrderAccess::storestore(); |
| assert(chunk->is_free() && ffc->is_free(), "Error"); |
| _bt.split_block((HeapWord*)chunk, chunk->size(), new_size); |
| if (rem_sz < SmallForDictionary) { |
| bool is_par = (SharedHeap::heap()->n_par_threads() > 0); |
| if (is_par) _indexedFreeListParLocks[rem_sz]->lock(); |
| assert(!is_par || |
| (SharedHeap::heap()->n_par_threads() == |
| SharedHeap::heap()->workers()->active_workers()), "Mismatch"); |
| returnChunkToFreeList(ffc); |
| split(size, rem_sz); |
| if (is_par) _indexedFreeListParLocks[rem_sz]->unlock(); |
| } else { |
| returnChunkToDictionary(ffc); |
| split(size, rem_sz); |
| } |
| chunk->set_size(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() { |
| assert(Thread::current()->is_VM_thread(), |
| "Global variable should only be set when single-threaded"); |
| // 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(unallocated_block()); |
| #ifdef ASSERT |
| // Check the sanity of save_marks() etc. |
| MemRegion ur = used_region(); |
| MemRegion urasm = used_region_at_save_marks(); |
| assert(ur.contains(urasm), |
| err_msg(" Error at save_marks(): [" PTR_FORMAT "," PTR_FORMAT ")" |
| " should contain [" PTR_FORMAT "," PTR_FORMAT ")", |
| p2i(ur.start()), p2i(ur.end()), p2i(urasm.start()), p2i(urasm.end()))); |
| #endif |
| // 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?"); |
| assert(SharedHeap::heap()->n_par_threads() == 0, |
| "Shouldn't be called if using parallel 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) |
| |
| bool CompactibleFreeListSpace::linearAllocationWouldFail() const { |
| 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->set_size(blk->_word_size); |
| fc->link_prev(NULL); // mark as free |
| fc->dontCoalesce(); |
| assert(fc->is_free(), "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 concurrent collection policy decisions. |
| bool CompactibleFreeListSpace::should_concurrent_collect() const { |
| // In the future we might want to add in fragmentation stats -- |
| // including erosion of the "mountain" into this decision as well. |
| return !adaptive_freelists() && linearAllocationWouldFail(); |
| } |
| |
| // Support for compaction |
| void CompactibleFreeListSpace::prepare_for_compaction(CompactPoint* cp) { |
| scan_and_forward(this, cp); |
| // 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. |
| } |
| |
| 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(this); |
| // See note about verification in prepare_for_compaction(). |
| } |
| |
| void CompactibleFreeListSpace::compact() { |
| scan_and_compact(this); |
| } |
| |
| // 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->total_chunk_size(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; |
| } |
| |
| void CompactibleFreeListSpace::beginSweepFLCensus( |
| float inter_sweep_current, |
| float inter_sweep_estimate, |
| float intra_sweep_estimate) { |
| assert_locked(); |
| size_t i; |
| for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
| AdaptiveFreeList<FreeChunk>* fl = &_indexedFreeList[i]; |
| if (PrintFLSStatistics > 1) { |
| gclog_or_tty->print("size[" SIZE_FORMAT "] : ", i); |
| } |
| fl->compute_desired(inter_sweep_current, inter_sweep_estimate, intra_sweep_estimate); |
| fl->set_coal_desired((ssize_t)((double)fl->desired() * CMSSmallCoalSurplusPercent)); |
| fl->set_before_sweep(fl->count()); |
| fl->set_bfr_surp(fl->surplus()); |
| } |
| _dictionary->begin_sweep_dict_census(CMSLargeCoalSurplusPercent, |
| inter_sweep_current, |
| inter_sweep_estimate, |
| intra_sweep_estimate); |
| } |
| |
| void CompactibleFreeListSpace::setFLSurplus() { |
| assert_locked(); |
| size_t i; |
| for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
| AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i]; |
| fl->set_surplus(fl->count() - |
| (ssize_t)((double)fl->desired() * CMSSmallSplitSurplusPercent)); |
| } |
| } |
| |
| void CompactibleFreeListSpace::setFLHints() { |
| assert_locked(); |
| size_t i; |
| size_t h = IndexSetSize; |
| for (i = IndexSetSize - 1; i != 0; i -= IndexSetStride) { |
| AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i]; |
| fl->set_hint(h); |
| if (fl->surplus() > 0) { |
| h = i; |
| } |
| } |
| } |
| |
| void CompactibleFreeListSpace::clearFLCensus() { |
| assert_locked(); |
| size_t i; |
| for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
| AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i]; |
| fl->set_prev_sweep(fl->count()); |
| fl->set_coal_births(0); |
| fl->set_coal_deaths(0); |
| fl->set_split_births(0); |
| fl->set_split_deaths(0); |
| } |
| } |
| |
| void CompactibleFreeListSpace::endSweepFLCensus(size_t sweep_count) { |
| if (PrintFLSStatistics > 0) { |
| HeapWord* largestAddr = (HeapWord*) dictionary()->find_largest_dict(); |
| gclog_or_tty->print_cr("CMS: Large block " PTR_FORMAT, |
| p2i(largestAddr)); |
| } |
| setFLSurplus(); |
| setFLHints(); |
| if (PrintGC && PrintFLSCensus > 0) { |
| printFLCensus(sweep_count); |
| } |
| clearFLCensus(); |
| assert_locked(); |
| _dictionary->end_sweep_dict_census(CMSLargeSplitSurplusPercent); |
| } |
| |
| bool CompactibleFreeListSpace::coalOverPopulated(size_t size) { |
| if (size < SmallForDictionary) { |
| AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size]; |
| return (fl->coal_desired() < 0) || |
| ((int)fl->count() > fl->coal_desired()); |
| } else { |
| return dictionary()->coal_dict_over_populated(size); |
| } |
| } |
| |
| void CompactibleFreeListSpace::smallCoalBirth(size_t size) { |
| assert(size < SmallForDictionary, "Size too large for indexed list"); |
| AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size]; |
| fl->increment_coal_births(); |
| fl->increment_surplus(); |
| } |
| |
| void CompactibleFreeListSpace::smallCoalDeath(size_t size) { |
| assert(size < SmallForDictionary, "Size too large for indexed list"); |
| AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size]; |
| fl->increment_coal_deaths(); |
| fl->decrement_surplus(); |
| } |
| |
| void CompactibleFreeListSpace::coalBirth(size_t size) { |
| if (size < SmallForDictionary) { |
| smallCoalBirth(size); |
| } else { |
| dictionary()->dict_census_update(size, |
| false /* split */, |
| true /* birth */); |
| } |
| } |
| |
| void CompactibleFreeListSpace::coalDeath(size_t size) { |
| if(size < SmallForDictionary) { |
| smallCoalDeath(size); |
| } else { |
| dictionary()->dict_census_update(size, |
| false /* split */, |
| false /* birth */); |
| } |
| } |
| |
| void CompactibleFreeListSpace::smallSplitBirth(size_t size) { |
| assert(size < SmallForDictionary, "Size too large for indexed list"); |
| AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size]; |
| fl->increment_split_births(); |
| fl->increment_surplus(); |
| } |
| |
| void CompactibleFreeListSpace::smallSplitDeath(size_t size) { |
| assert(size < SmallForDictionary, "Size too large for indexed list"); |
| AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size]; |
| fl->increment_split_deaths(); |
| fl->decrement_surplus(); |
| } |
| |
| void CompactibleFreeListSpace::split_birth(size_t size) { |
| if (size < SmallForDictionary) { |
| smallSplitBirth(size); |
| } else { |
| dictionary()->dict_census_update(size, |
| true /* split */, |
| true /* birth */); |
| } |
| } |
| |
| void CompactibleFreeListSpace::splitDeath(size_t size) { |
| if (size < SmallForDictionary) { |
| smallSplitDeath(size); |
| } else { |
| dictionary()->dict_census_update(size, |
| true /* split */, |
| false /* birth */); |
| } |
| } |
| |
| void CompactibleFreeListSpace::split(size_t from, size_t to1) { |
| size_t to2 = from - to1; |
| splitDeath(from); |
| split_birth(to1); |
| split_birth(to2); |
| } |
| |
| void CompactibleFreeListSpace::print() const { |
| print_on(tty); |
| } |
| |
| 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 { |
| private: |
| const CompactibleFreeListSpace* _sp; |
| const MemRegion _span; |
| HeapWord* _last_addr; |
| size_t _last_size; |
| bool _last_was_obj; |
| bool _last_was_live; |
| |
| public: |
| VerifyAllBlksClosure(const CompactibleFreeListSpace* sp, |
| MemRegion span) : _sp(sp), _span(span), |
| _last_addr(NULL), _last_size(0), |
| _last_was_obj(false), _last_was_live(false) { } |
| |
| virtual size_t do_blk(HeapWord* addr) { |
| size_t res; |
| bool was_obj = false; |
| bool was_live = false; |
| if (_sp->block_is_obj(addr)) { |
| was_obj = true; |
| oop p = oop(addr); |
| guarantee(p->is_oop(), "Should be an oop"); |
| res = _sp->adjustObjectSize(p->size()); |
| if (_sp->obj_is_alive(addr)) { |
| was_live = true; |
| p->verify(); |
| } |
| } else { |
| FreeChunk* fc = (FreeChunk*)addr; |
| res = fc->size(); |
| if (FLSVerifyLists && !fc->cantCoalesce()) { |
| guarantee(_sp->verify_chunk_in_free_list(fc), |
| "Chunk should be on a free list"); |
| } |
| } |
| if (res == 0) { |
| gclog_or_tty->print_cr("Livelock: no rank reduction!"); |
| gclog_or_tty->print_cr( |
| " Current: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n" |
| " Previous: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n", |
| p2i(addr), res, was_obj ?"true":"false", was_live ?"true":"false", |
| p2i(_last_addr), _last_size, _last_was_obj?"true":"false", _last_was_live?"true":"false"); |
| _sp->print_on(gclog_or_tty); |
| guarantee(false, "Seppuku!"); |
| } |
| _last_addr = addr; |
| _last_size = res; |
| _last_was_obj = was_obj; |
| _last_was_live = was_live; |
| return res; |
| } |
| }; |
| |
| class VerifyAllOopsClosure: public OopClosure { |
| private: |
| const CMSCollector* _collector; |
| const CompactibleFreeListSpace* _sp; |
| const MemRegion _span; |
| const bool _past_remark; |
| const CMSBitMap* _bit_map; |
| |
| protected: |
| void do_oop(void* p, oop obj) { |
| if (_span.contains(obj)) { // the interior oop points into CMS heap |
| if (!_span.contains(p)) { // 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(obj) || |
| _sp->block_is_obj((HeapWord*)obj), |
| "Should be an object"); |
| guarantee(obj->is_oop(), "Should be an oop"); |
| obj->verify(); |
| if (_past_remark) { |
| // Remark has been completed, the object should be marked |
| _bit_map->isMarked((HeapWord*)obj); |
| } |
| } 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(p))) { |
| guarantee(_bit_map->isMarked((HeapWord*)obj), "Marking error?"); |
| } |
| } |
| } |
| } else if (_sp->is_in_reserved(p)) { |
| // the reference is from FLS, and points out of FLS |
| guarantee(obj->is_oop(), "Should be an oop"); |
| obj->verify(); |
| } |
| } |
| |
| template <class T> void do_oop_work(T* p) { |
| T heap_oop = oopDesc::load_heap_oop(p); |
| if (!oopDesc::is_null(heap_oop)) { |
| oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
| do_oop(p, obj); |
| } |
| } |
| |
| public: |
| VerifyAllOopsClosure(const CMSCollector* collector, |
| const CompactibleFreeListSpace* sp, MemRegion span, |
| bool past_remark, CMSBitMap* bit_map) : |
| _collector(collector), _sp(sp), _span(span), |
| _past_remark(past_remark), _bit_map(bit_map) { } |
| |
| virtual void do_oop(oop* p) { VerifyAllOopsClosure::do_oop_work(p); } |
| virtual void do_oop(narrowOop* p) { VerifyAllOopsClosure::do_oop_work(p); } |
| }; |
| |
| void CompactibleFreeListSpace::verify() 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(); |
| |
| // Iterate over all oops in the heap. Uses the _no_header version |
| // since we are not interested in following the klass pointers. |
| ch->oop_iterate_no_header(&cl); |
| } |
| |
| 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 < IndexSetStart; i++) { |
| guarantee(_indexedFreeList[i].head() == NULL, "should be NULL"); |
| } |
| for (; i < IndexSetSize; i++) { |
| verifyIndexedFreeList(i); |
| } |
| } |
| |
| void CompactibleFreeListSpace::verifyIndexedFreeList(size_t size) const { |
| FreeChunk* fc = _indexedFreeList[size].head(); |
| FreeChunk* tail = _indexedFreeList[size].tail(); |
| size_t num = _indexedFreeList[size].count(); |
| size_t n = 0; |
| guarantee(((size >= IndexSetStart) && (size % IndexSetStride == 0)) || fc == NULL, |
| "Slot should have been empty"); |
| for (; fc != NULL; fc = fc->next(), n++) { |
| guarantee(fc->size() == size, "Size inconsistency"); |
| guarantee(fc->is_free(), "!free?"); |
| guarantee(fc->next() == NULL || fc->next()->prev() == fc, "Broken list"); |
| guarantee((fc->next() == NULL) == (fc == tail), "Incorrect tail"); |
| } |
| guarantee(n == num, "Incorrect count"); |
| } |
| |
| #ifndef PRODUCT |
| void CompactibleFreeListSpace::check_free_list_consistency() const { |
| assert((TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >::min_size() <= IndexSetSize), |
| "Some sizes can't be allocated without recourse to" |
| " linear allocation buffers"); |
| assert((TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >::min_size()*HeapWordSize == sizeof(TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >)), |
| "else MIN_TREE_CHUNK_SIZE is wrong"); |
| assert(IndexSetStart != 0, "IndexSetStart not initialized"); |
| assert(IndexSetStride != 0, "IndexSetStride not initialized"); |
| } |
| #endif |
| |
| void CompactibleFreeListSpace::printFLCensus(size_t sweep_count) const { |
| assert_lock_strong(&_freelistLock); |
| AdaptiveFreeList<FreeChunk> total; |
| gclog_or_tty->print("end sweep# " SIZE_FORMAT "\n", sweep_count); |
| AdaptiveFreeList<FreeChunk>::print_labels_on(gclog_or_tty, "size"); |
| size_t total_free = 0; |
| for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { |
| const AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i]; |
| total_free += fl->count() * fl->size(); |
| if (i % (40*IndexSetStride) == 0) { |
| AdaptiveFreeList<FreeChunk>::print_labels_on(gclog_or_tty, "size"); |
| } |
| fl->print_on(gclog_or_tty); |
| total.set_bfr_surp( total.bfr_surp() + fl->bfr_surp() ); |
| total.set_surplus( total.surplus() + fl->surplus() ); |
| total.set_desired( total.desired() + fl->desired() ); |
| total.set_prev_sweep( total.prev_sweep() + fl->prev_sweep() ); |
| total.set_before_sweep(total.before_sweep() + fl->before_sweep()); |
| total.set_count( total.count() + fl->count() ); |
| total.set_coal_births( total.coal_births() + fl->coal_births() ); |
| total.set_coal_deaths( total.coal_deaths() + fl->coal_deaths() ); |
| total.set_split_births(total.split_births() + fl->split_births()); |
| total.set_split_deaths(total.split_deaths() + fl->split_deaths()); |
| } |
| total.print_on(gclog_or_tty, "TOTAL"); |
| gclog_or_tty->print_cr("Total free in indexed lists " |
| SIZE_FORMAT " words", total_free); |
| gclog_or_tty->print("growth: %8.5f deficit: %8.5f\n", |
| (double)(total.split_births()+total.coal_births()-total.split_deaths()-total.coal_deaths())/ |
| (total.prev_sweep() != 0 ? (double)total.prev_sweep() : 1.0), |
| (double)(total.desired() - total.count())/(total.desired() != 0 ? (double)total.desired() : 1.0)); |
| _dictionary->print_dict_census(); |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // CFLS_LAB |
| /////////////////////////////////////////////////////////////////////////// |
| |
| #define VECTOR_257(x) \ |
| /* 1 2 3 4 5 6 7 8 9 1x 11 12 13 14 15 16 17 18 19 2x 21 22 23 24 25 26 27 28 29 3x 31 32 */ \ |
| { x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
| x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
| x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
| x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
| x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
| x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
| x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
| x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \ |
| x } |
| |
| // Initialize with default setting for CMS, _not_ |
| // generic OldPLABSize, whose static default is different; if overridden at the |
| // command-line, this will get reinitialized via a call to |
| // modify_initialization() below. |
| AdaptiveWeightedAverage CFLS_LAB::_blocks_to_claim[] = |
| VECTOR_257(AdaptiveWeightedAverage(OldPLABWeight, (float)CFLS_LAB::_default_dynamic_old_plab_size)); |
| size_t CFLS_LAB::_global_num_blocks[] = VECTOR_257(0); |
| uint CFLS_LAB::_global_num_workers[] = VECTOR_257(0); |
| |
| CFLS_LAB::CFLS_LAB(CompactibleFreeListSpace* cfls) : |
| _cfls(cfls) |
| { |
| assert(CompactibleFreeListSpace::IndexSetSize == 257, "Modify VECTOR_257() macro above"); |
| for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
| i < CompactibleFreeListSpace::IndexSetSize; |
| i += CompactibleFreeListSpace::IndexSetStride) { |
| _indexedFreeList[i].set_size(i); |
| _num_blocks[i] = 0; |
| } |
| } |
| |
| static bool _CFLS_LAB_modified = false; |
| |
| void CFLS_LAB::modify_initialization(size_t n, unsigned wt) { |
| assert(!_CFLS_LAB_modified, "Call only once"); |
| _CFLS_LAB_modified = true; |
| for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
| i < CompactibleFreeListSpace::IndexSetSize; |
| i += CompactibleFreeListSpace::IndexSetStride) { |
| _blocks_to_claim[i].modify(n, wt, true /* force */); |
| } |
| } |
| |
| HeapWord* CFLS_LAB::alloc(size_t word_sz) { |
| FreeChunk* res; |
| assert(word_sz == _cfls->adjustObjectSize(word_sz), "Error"); |
| 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 { |
| AdaptiveFreeList<FreeChunk>* fl = &_indexedFreeList[word_sz]; |
| if (fl->count() == 0) { |
| // Attempt to refill this local free list. |
| get_from_global_pool(word_sz, fl); |
| // If it didn't work, give up. |
| if (fl->count() == 0) return NULL; |
| } |
| res = fl->get_chunk_at_head(); |
| assert(res != NULL, "Why was count non-zero?"); |
| } |
| res->markNotFree(); |
| assert(!res->is_free(), "shouldn't be marked free"); |
| assert(oop(res)->klass_or_null() == NULL, "should look uninitialized"); |
| // mangle a just allocated object with a distinct pattern. |
| debug_only(res->mangleAllocated(word_sz)); |
| return (HeapWord*)res; |
| } |
| |
| // Get a chunk of blocks of the right size and update related |
| // book-keeping stats |
| void CFLS_LAB::get_from_global_pool(size_t word_sz, AdaptiveFreeList<FreeChunk>* fl) { |
| // Get the #blocks we want to claim |
| size_t n_blks = (size_t)_blocks_to_claim[word_sz].average(); |
| assert(n_blks > 0, "Error"); |
| assert(ResizeOldPLAB || n_blks == OldPLABSize, "Error"); |
| // In some cases, when the application has a phase change, |
| // there may be a sudden and sharp shift in the object survival |
| // profile, and updating the counts at the end of a scavenge |
| // may not be quick enough, giving rise to large scavenge pauses |
| // during these phase changes. It is beneficial to detect such |
| // changes on-the-fly during a scavenge and avoid such a phase-change |
| // pothole. The following code is a heuristic attempt to do that. |
| // It is protected by a product flag until we have gained |
| // enough experience with this heuristic and fine-tuned its behavior. |
| // WARNING: This might increase fragmentation if we overreact to |
| // small spikes, so some kind of historical smoothing based on |
| // previous experience with the greater reactivity might be useful. |
| // Lacking sufficient experience, CMSOldPLABResizeQuicker is disabled by |
| // default. |
| if (ResizeOldPLAB && CMSOldPLABResizeQuicker) { |
| size_t multiple = _num_blocks[word_sz]/(CMSOldPLABToleranceFactor*CMSOldPLABNumRefills*n_blks); |
| n_blks += CMSOldPLABReactivityFactor*multiple*n_blks; |
| n_blks = MIN2(n_blks, CMSOldPLABMax); |
| } |
| assert(n_blks > 0, "Error"); |
| _cfls->par_get_chunk_of_blocks(word_sz, n_blks, fl); |
| // Update stats table entry for this block size |
| _num_blocks[word_sz] += fl->count(); |
| } |
| |
| void CFLS_LAB::compute_desired_plab_size() { |
| for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
| i < CompactibleFreeListSpace::IndexSetSize; |
| i += CompactibleFreeListSpace::IndexSetStride) { |
| assert((_global_num_workers[i] == 0) == (_global_num_blocks[i] == 0), |
| "Counter inconsistency"); |
| if (_global_num_workers[i] > 0) { |
| // Need to smooth wrt historical average |
| if (ResizeOldPLAB) { |
| _blocks_to_claim[i].sample( |
| MAX2(CMSOldPLABMin, |
| MIN2(CMSOldPLABMax, |
| _global_num_blocks[i]/(_global_num_workers[i]*CMSOldPLABNumRefills)))); |
| } |
| // Reset counters for next round |
| _global_num_workers[i] = 0; |
| _global_num_blocks[i] = 0; |
| if (PrintOldPLAB) { |
| gclog_or_tty->print_cr("[" SIZE_FORMAT "]: " SIZE_FORMAT, |
| i, (size_t)_blocks_to_claim[i].average()); |
| } |
| } |
| } |
| } |
| |
| // If this is changed in the future to allow parallel |
| // access, one would need to take the FL locks and, |
| // depending on how it is used, stagger access from |
| // parallel threads to reduce contention. |
| void CFLS_LAB::retire(int tid) { |
| // We run this single threaded with the world stopped; |
| // so no need for locks and such. |
| NOT_PRODUCT(Thread* t = Thread::current();) |
| assert(Thread::current()->is_VM_thread(), "Error"); |
| for (size_t i = CompactibleFreeListSpace::IndexSetStart; |
| i < CompactibleFreeListSpace::IndexSetSize; |
| i += CompactibleFreeListSpace::IndexSetStride) { |
| assert(_num_blocks[i] >= (size_t)_indexedFreeList[i].count(), |
| "Can't retire more than what we obtained"); |
| if (_num_blocks[i] > 0) { |
| size_t num_retire = _indexedFreeList[i].count(); |
| assert(_num_blocks[i] > num_retire, "Should have used at least one"); |
| { |
| // MutexLockerEx x(_cfls->_indexedFreeListParLocks[i], |
| // Mutex::_no_safepoint_check_flag); |
| |
| // Update globals stats for num_blocks used |
| _global_num_blocks[i] += (_num_blocks[i] - num_retire); |
| _global_num_workers[i]++; |
| assert(_global_num_workers[i] <= ParallelGCThreads, "Too big"); |
| if (num_retire > 0) { |
| _cfls->_indexedFreeList[i].prepend(&_indexedFreeList[i]); |
| // Reset this list. |
| _indexedFreeList[i] = AdaptiveFreeList<FreeChunk>(); |
| _indexedFreeList[i].set_size(i); |
| } |
| } |
| if (PrintOldPLAB) { |
| gclog_or_tty->print_cr("%d[" SIZE_FORMAT "]: " SIZE_FORMAT "/" SIZE_FORMAT "/" SIZE_FORMAT, |
| tid, i, num_retire, _num_blocks[i], (size_t)_blocks_to_claim[i].average()); |
| } |
| // Reset stats for next round |
| _num_blocks[i] = 0; |
| } |
| } |
| } |
| |
| // Used by par_get_chunk_of_blocks() for the chunks from the |
| // indexed_free_lists. Looks for a chunk with size that is a multiple |
| // of "word_sz" and if found, splits it into "word_sz" chunks and add |
| // to the free list "fl". "n" is the maximum number of chunks to |
| // be added to "fl". |
| bool CompactibleFreeListSpace:: par_get_chunk_of_blocks_IFL(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl) { |
| |
| // We'll try all multiples of word_sz in the indexed set, starting with |
| // word_sz itself and, if CMSSplitIndexedFreeListBlocks, try larger multiples, |
| // then try getting a big chunk and splitting it. |
| { |
| bool found; |
| int k; |
| size_t cur_sz; |
| for (k = 1, cur_sz = k * word_sz, found = false; |
| (cur_sz < CompactibleFreeListSpace::IndexSetSize) && |
| (CMSSplitIndexedFreeListBlocks || k <= 1); |
| k++, cur_sz = k * word_sz) { |
| AdaptiveFreeList<FreeChunk> fl_for_cur_sz; // Empty. |
| fl_for_cur_sz.set_size(cur_sz); |
| { |
| MutexLockerEx x(_indexedFreeListParLocks[cur_sz], |
| Mutex::_no_safepoint_check_flag); |
| AdaptiveFreeList<FreeChunk>* gfl = &_indexedFreeList[cur_sz]; |
| if (gfl->count() != 0) { |
| // nn is the number of chunks of size cur_sz that |
| // we'd need to split k-ways each, in order to create |
| // "n" chunks of size word_sz each. |
| const size_t nn = MAX2(n/k, (size_t)1); |
| gfl->getFirstNChunksFromList(nn, &fl_for_cur_sz); |
| found = true; |
| if (k > 1) { |
| // Update split death stats for the cur_sz-size blocks list: |
| // we increment the split death count by the number of blocks |
| // we just took from the cur_sz-size blocks list and which |
| // we will be splitting below. |
| ssize_t deaths = gfl->split_deaths() + |
| fl_for_cur_sz.count(); |
| gfl->set_split_deaths(deaths); |
| } |
| } |
| } |
| // 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.get_chunk_at_head()) != 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(); |
| assert(fc->is_free(), "Error"); |
| for (int i = k-1; i >= 0; i--) { |
| FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz); |
| assert((i != 0) || |
| ((fc == ffc) && ffc->is_free() && |
| (ffc->size() == k*word_sz) && (fc_size == word_sz)), |
| "Counting error"); |
| ffc->set_size(word_sz); |
| ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads. |
| ffc->link_next(NULL); |
| // Above must occur before BOT is updated below. |
| OrderAccess::storestore(); |
| // splitting from the right, fc_size == i * word_sz |
| _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */); |
| fc_size -= word_sz; |
| assert(fc_size == i*word_sz, "Error"); |
| _bt.verify_not_unallocated((HeapWord*)ffc, word_sz); |
| _bt.verify_single_block((HeapWord*)fc, fc_size); |
| _bt.verify_single_block((HeapWord*)ffc, word_sz); |
| // Push this on "fl". |
| fl->return_chunk_at_head(ffc); |
| } |
| // TRAP |
| assert(fl->tail()->next() == NULL, "List invariant."); |
| } |
| } |
| // Update birth stats for this block size. |
| size_t num = fl->count(); |
| MutexLockerEx x(_indexedFreeListParLocks[word_sz], |
| Mutex::_no_safepoint_check_flag); |
| ssize_t births = _indexedFreeList[word_sz].split_births() + num; |
| _indexedFreeList[word_sz].set_split_births(births); |
| return true; |
| } |
| } |
| return found; |
| } |
| } |
| |
| FreeChunk* CompactibleFreeListSpace::get_n_way_chunk_to_split(size_t word_sz, size_t n) { |
| |
| FreeChunk* fc = NULL; |
| FreeChunk* rem_fc = NULL; |
| size_t rem; |
| { |
| MutexLockerEx x(parDictionaryAllocLock(), |
| Mutex::_no_safepoint_check_flag); |
| while (n > 0) { |
| fc = dictionary()->get_chunk(MAX2(n * word_sz, _dictionary->min_size()), |
| FreeBlockDictionary<FreeChunk>::atLeast); |
| if (fc != NULL) { |
| break; |
| } else { |
| n--; |
| } |
| } |
| if (fc == NULL) return NULL; |
| // Otherwise, split up that block. |
| assert((ssize_t)n >= 1, "Control point invariant"); |
| assert(fc->is_free(), "Error: should be a free block"); |
| _bt.verify_single_block((HeapWord*)fc, fc->size()); |
| const size_t nn = fc->size() / word_sz; |
| n = MIN2(nn, n); |
| assert((ssize_t)n >= 1, "Control point invariant"); |
| 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; |
| } |
| // Note that at this point we may have n == 0. |
| assert((ssize_t)n >= 0, "Control point invariant"); |
| |
| // If n is 0, the chunk fc that was found is not large |
| // enough to leave a viable remainder. We are unable to |
| // allocate even one block. Return fc to the |
| // dictionary and return, leaving "fl" empty. |
| if (n == 0) { |
| returnChunkToDictionary(fc); |
| return NULL; |
| } |
| |
| _bt.allocated((HeapWord*)fc, fc->size(), true /* reducing */); // update _unallocated_blk |
| dictionary()->dict_census_update(fc->size(), |
| true /*split*/, |
| false /*birth*/); |
| |
| // 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 concurrent allocation |
| // 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->set_size(rem); |
| rem_fc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads. |
| rem_fc->link_next(NULL); |
| // Above must occur before BOT is updated below. |
| assert((ssize_t)n > 0 && prefix_size > 0 && rem_fc > fc, "Error"); |
| OrderAccess::storestore(); |
| _bt.split_block((HeapWord*)fc, fc->size(), prefix_size); |
| assert(fc->is_free(), "Error"); |
| fc->set_size(prefix_size); |
| if (rem >= IndexSetSize) { |
| returnChunkToDictionary(rem_fc); |
| dictionary()->dict_census_update(rem, 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].return_chunk_at_head(rem_fc); |
| smallSplitBirth(rem); |
| } |
| assert(n * word_sz == fc->size(), |
| err_msg("Chunk size " SIZE_FORMAT " is not exactly splittable by " |
| SIZE_FORMAT " sized chunks of size " SIZE_FORMAT, |
| fc->size(), n, word_sz)); |
| return fc; |
| } |
| |
| void CompactibleFreeListSpace:: par_get_chunk_of_blocks_dictionary(size_t word_sz, size_t targetted_number_of_chunks, AdaptiveFreeList<FreeChunk>* fl) { |
| |
| FreeChunk* fc = get_n_way_chunk_to_split(word_sz, targetted_number_of_chunks); |
| |
| if (fc == NULL) { |
| return; |
| } |
| |
| size_t n = fc->size() / word_sz; |
| |
| assert((ssize_t)n > 0, "Consistency"); |
| // 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->set_size(word_sz); |
| ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads. |
| ffc->link_next(NULL); |
| // Above must occur before BOT is updated below. |
| OrderAccess::storestore(); |
| // splitting from the right, fc_size == (n - i + 1) * wordsize |
| _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */); |
| 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->return_chunk_at_head(ffc); |
| } |
| // First chunk |
| assert(fc->is_free() && fc->size() == n*word_sz, "Error: should still be a free block"); |
| // The blocks above should show their new sizes before the first block below |
| fc->set_size(word_sz); |
| fc->link_prev(NULL); // idempotent wrt free-ness, see assert above |
| fc->link_next(NULL); |
| _bt.verify_not_unallocated((HeapWord*)fc, fc->size()); |
| _bt.verify_single_block((HeapWord*)fc, fc->size()); |
| fl->return_chunk_at_head(fc); |
| |
| assert((ssize_t)n > 0 && (ssize_t)n == fl->count(), "Incorrect number of blocks"); |
| { |
| // Update the stats for this block size. |
| MutexLockerEx x(_indexedFreeListParLocks[word_sz], |
| Mutex::_no_safepoint_check_flag); |
| const ssize_t births = _indexedFreeList[word_sz].split_births() + n; |
| _indexedFreeList[word_sz].set_split_births(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."); |
| } |
| |
| void CompactibleFreeListSpace:: par_get_chunk_of_blocks(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl) { |
| assert(fl->count() == 0, "Precondition."); |
| assert(word_sz < CompactibleFreeListSpace::IndexSetSize, |
| "Precondition"); |
| |
| if (par_get_chunk_of_blocks_IFL(word_sz, n, fl)) { |
| // Got it |
| return; |
| } |
| |
| // Otherwise, we'll split a block from the dictionary. |
| par_get_chunk_of_blocks_dictionary(word_sz, n, fl); |
| } |
| |
| // 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((n_tasks == 0) == used_region().is_empty(), "n_tasks incorrect"); |
| assert(n_tasks == 0 || |
| ((used_region().start() + (n_tasks - 1)*task_size < used_region().end()) && |
| (used_region().start() + n_tasks*task_size >= used_region().end())), |
| "n_tasks calculation incorrect"); |
| SequentialSubTasksDone* pst = conc_par_seq_tasks(); |
| assert(!pst->valid(), "Clobbering existing data?"); |
| // Sets the condition for completion of the subtask (how many threads |
| // need to finish in order to be done). |
| pst->set_n_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_tasks calculation incorrect"); |
| SequentialSubTasksDone* pst = conc_par_seq_tasks(); |
| assert(!pst->valid(), "Clobbering existing data?"); |
| // Sets the condition for completion of the subtask (how many threads |
| // need to finish in order to be done). |
| pst->set_n_threads(n_threads); |
| pst->set_n_tasks((int)n_tasks); |
| } |