--- old/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp 2015-05-12 11:53:31.810480278 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,3026 +0,0 @@ -/* - * 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/genCollectedHeap.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::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::dictionaryBinaryTree: - _dictionary = new AFLBinaryTreeDictionary(mr); - break; - case FreeBlockDictionary::dictionarySplayTree: - case FreeBlockDictionary::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::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::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 = GenCollectedHeap::heap()->n_par_threads() > 0; \ - if (is_par) { \ - assert(GenCollectedHeap::heap()->n_par_threads() == \ - GenCollectedHeap::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"); - 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* 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::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::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::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 >* tc = TreeChunk >::as_TreeChunk(chunk); - TreeList >* 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* it = _indexedFreeList; - size_t hint = _indexedFreeList[start].hint(); - while (hint < IndexSetSize) { - assert(hint % MinObjAlignment == 0, "hint should be aligned"); - AdaptiveFreeList *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* 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 = (GenCollectedHeap::heap()->n_par_threads() > 0); - if (is_par) _indexedFreeListParLocks[rem_sz]->lock(); - assert(!is_par || - (GenCollectedHeap::heap()->n_par_threads() == - GenCollectedHeap::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(GenCollectedHeap::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(GenCollectedHeap::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* 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 *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 *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 *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 *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 *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 *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 *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 *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 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()); - - // Iterate over all oops in the heap. Uses the _no_header version - // since we are not interested in following the klass pointers. - GenCollectedHeap::heap()->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 >::min_size() <= IndexSetSize), - "Some sizes can't be allocated without recourse to" - " linear allocation buffers"); - assert((TreeChunk >::min_size()*HeapWordSize == sizeof(TreeChunk >)), - "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 total; - gclog_or_tty->print("end sweep# " SIZE_FORMAT "\n", sweep_count); - AdaptiveFreeList::print_labels_on(gclog_or_tty, "size"); - size_t total_free = 0; - for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { - const AdaptiveFreeList *fl = &_indexedFreeList[i]; - total_free += fl->count() * fl->size(); - if (i % (40*IndexSetStride) == 0) { - AdaptiveFreeList::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* 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* 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(); - _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* 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 fl_for_cur_sz; // Empty. - fl_for_cur_sz.set_size(cur_sz); - { - MutexLockerEx x(_indexedFreeListParLocks[cur_sz], - Mutex::_no_safepoint_check_flag); - AdaptiveFreeList* 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::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* 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* 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); -} --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/cms/compactibleFreeListSpace.cpp 2015-05-12 11:53:31.632472836 +0200 @@ -0,0 +1,3026 @@ +/* + * 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/cms/cmsLockVerifier.hpp" +#include "gc/cms/compactibleFreeListSpace.hpp" +#include "gc/cms/concurrentMarkSweepGeneration.inline.hpp" +#include "gc/cms/concurrentMarkSweepThread.hpp" +#include "gc/shared/blockOffsetTable.inline.hpp" +#include "gc/shared/collectedHeap.inline.hpp" +#include "gc/shared/genCollectedHeap.hpp" +#include "gc/shared/liveRange.hpp" +#include "gc/shared/space.inline.hpp" +#include "gc/shared/spaceDecorator.hpp" +#include "memory/allocation.inline.hpp" +#include "memory/resourceArea.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::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::dictionaryBinaryTree: + _dictionary = new AFLBinaryTreeDictionary(mr); + break; + case FreeBlockDictionary::dictionarySplayTree: + case FreeBlockDictionary::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::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::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 = GenCollectedHeap::heap()->n_par_threads() > 0; \ + if (is_par) { \ + assert(GenCollectedHeap::heap()->n_par_threads() == \ + GenCollectedHeap::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"); + 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* 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::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::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::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 >* tc = TreeChunk >::as_TreeChunk(chunk); + TreeList >* 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* it = _indexedFreeList; + size_t hint = _indexedFreeList[start].hint(); + while (hint < IndexSetSize) { + assert(hint % MinObjAlignment == 0, "hint should be aligned"); + AdaptiveFreeList *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* 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 = (GenCollectedHeap::heap()->n_par_threads() > 0); + if (is_par) _indexedFreeListParLocks[rem_sz]->lock(); + assert(!is_par || + (GenCollectedHeap::heap()->n_par_threads() == + GenCollectedHeap::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(GenCollectedHeap::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(GenCollectedHeap::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* 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 *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 *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 *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 *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 *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 *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 *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 *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 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()); + + // Iterate over all oops in the heap. Uses the _no_header version + // since we are not interested in following the klass pointers. + GenCollectedHeap::heap()->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 >::min_size() <= IndexSetSize), + "Some sizes can't be allocated without recourse to" + " linear allocation buffers"); + assert((TreeChunk >::min_size()*HeapWordSize == sizeof(TreeChunk >)), + "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 total; + gclog_or_tty->print("end sweep# " SIZE_FORMAT "\n", sweep_count); + AdaptiveFreeList::print_labels_on(gclog_or_tty, "size"); + size_t total_free = 0; + for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) { + const AdaptiveFreeList *fl = &_indexedFreeList[i]; + total_free += fl->count() * fl->size(); + if (i % (40*IndexSetStride) == 0) { + AdaptiveFreeList::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* 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* 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(); + _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* 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 fl_for_cur_sz; // Empty. + fl_for_cur_sz.set_size(cur_sz); + { + MutexLockerEx x(_indexedFreeListParLocks[cur_sz], + Mutex::_no_safepoint_check_flag); + AdaptiveFreeList* 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::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* 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* 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); +}