--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.cpp Wed May 13 15:16:06 2015 +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<FreeChunk>::DictionaryChoice dictionaryChoice) :
+ _dictionaryChoice(dictionaryChoice),
+ _adaptive_freelists(use_adaptive_freelists),
+ _bt(bs, mr),
+ // free list locks are in the range of values taken by _lockRank
+ // This range currently is [_leaf+2, _leaf+3]
+ // Note: this requires that CFLspace c'tors
+ // are called serially in the order in which the locks are
+ // are acquired in the program text. This is true today.
+ _freelistLock(_lockRank--, "CompactibleFreeListSpace._lock", true,
+ Monitor::_safepoint_check_sometimes),
+ _parDictionaryAllocLock(Mutex::leaf - 1, // == rank(ExpandHeap_lock) - 1
+ "CompactibleFreeListSpace._dict_par_lock", true,
+ Monitor::_safepoint_check_never),
+ _rescan_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord *
+ CMSRescanMultiple),
+ _marking_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord *
+ CMSConcMarkMultiple),
+ _collector(NULL),
+ _preconsumptionDirtyCardClosure(NULL)
+{
+ assert(sizeof(FreeChunk) / BytesPerWord <= MinChunkSize,
+ "FreeChunk is larger than expected");
+ _bt.set_space(this);
+ initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
+ // We have all of "mr", all of which we place in the dictionary
+ // as one big chunk. We'll need to decide here which of several
+ // possible alternative dictionary implementations to use. For
+ // now the choice is easy, since we have only one working
+ // implementation, namely, the simple binary tree (splaying
+ // temporarily disabled).
+ switch (dictionaryChoice) {
+ case FreeBlockDictionary<FreeChunk>::dictionaryBinaryTree:
+ _dictionary = new AFLBinaryTreeDictionary(mr);
+ break;
+ case FreeBlockDictionary<FreeChunk>::dictionarySplayTree:
+ case FreeBlockDictionary<FreeChunk>::dictionarySkipList:
+ default:
+ warning("dictionaryChoice: selected option not understood; using"
+ " default BinaryTreeDictionary implementation instead.");
+ }
+ assert(_dictionary != NULL, "CMS dictionary initialization");
+ // The indexed free lists are initially all empty and are lazily
+ // filled in on demand. Initialize the array elements to NULL.
+ initializeIndexedFreeListArray();
+
+ // Not using adaptive free lists assumes that allocation is first
+ // from the linAB's. Also a cms perm gen which can be compacted
+ // has to have the klass's klassKlass allocated at a lower
+ // address in the heap than the klass so that the klassKlass is
+ // moved to its new location before the klass is moved.
+ // Set the _refillSize for the linear allocation blocks
+ if (!use_adaptive_freelists) {
+ FreeChunk* fc = _dictionary->get_chunk(mr.word_size(),
+ FreeBlockDictionary<FreeChunk>::atLeast);
+ // The small linAB initially has all the space and will allocate
+ // a chunk of any size.
+ HeapWord* addr = (HeapWord*) fc;
+ _smallLinearAllocBlock.set(addr, fc->size() ,
+ 1024*SmallForLinearAlloc, fc->size());
+ // Note that _unallocated_block is not updated here.
+ // Allocations from the linear allocation block should
+ // update it.
+ } else {
+ _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc,
+ SmallForLinearAlloc);
+ }
+ // CMSIndexedFreeListReplenish should be at least 1
+ CMSIndexedFreeListReplenish = MAX2((uintx)1, CMSIndexedFreeListReplenish);
+ _promoInfo.setSpace(this);
+ if (UseCMSBestFit) {
+ _fitStrategy = FreeBlockBestFitFirst;
+ } else {
+ _fitStrategy = FreeBlockStrategyNone;
+ }
+ check_free_list_consistency();
+
+ // Initialize locks for parallel case.
+ for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+ _indexedFreeListParLocks[i] = new Mutex(Mutex::leaf - 1, // == ExpandHeap_lock - 1
+ "a freelist par lock", true, Mutex::_safepoint_check_sometimes);
+ DEBUG_ONLY(
+ _indexedFreeList[i].set_protecting_lock(_indexedFreeListParLocks[i]);
+ )
+ }
+ _dictionary->set_par_lock(&_parDictionaryAllocLock);
+}
+
+// Like CompactibleSpace forward() but always calls cross_threshold() to
+// update the block offset table. Removed initialize_threshold call because
+// CFLS does not use a block offset array for contiguous spaces.
+HeapWord* CompactibleFreeListSpace::forward(oop q, size_t size,
+ CompactPoint* cp, HeapWord* compact_top) {
+ // q is alive
+ // First check if we should switch compaction space
+ assert(this == cp->space, "'this' should be current compaction space.");
+ size_t compaction_max_size = pointer_delta(end(), compact_top);
+ assert(adjustObjectSize(size) == cp->space->adjust_object_size_v(size),
+ "virtual adjustObjectSize_v() method is not correct");
+ size_t adjusted_size = adjustObjectSize(size);
+ assert(compaction_max_size >= MinChunkSize || compaction_max_size == 0,
+ "no small fragments allowed");
+ assert(minimum_free_block_size() == MinChunkSize,
+ "for de-virtualized reference below");
+ // Can't leave a nonzero size, residual fragment smaller than MinChunkSize
+ if (adjusted_size + MinChunkSize > compaction_max_size &&
+ adjusted_size != compaction_max_size) {
+ do {
+ // switch to next compaction space
+ cp->space->set_compaction_top(compact_top);
+ cp->space = cp->space->next_compaction_space();
+ if (cp->space == NULL) {
+ cp->gen = GenCollectedHeap::heap()->young_gen();
+ assert(cp->gen != NULL, "compaction must succeed");
+ cp->space = cp->gen->first_compaction_space();
+ assert(cp->space != NULL, "generation must have a first compaction space");
+ }
+ compact_top = cp->space->bottom();
+ cp->space->set_compaction_top(compact_top);
+ // The correct adjusted_size may not be the same as that for this method
+ // (i.e., cp->space may no longer be "this" so adjust the size again.
+ // Use the virtual method which is not used above to save the virtual
+ // dispatch.
+ adjusted_size = cp->space->adjust_object_size_v(size);
+ compaction_max_size = pointer_delta(cp->space->end(), compact_top);
+ assert(cp->space->minimum_free_block_size() == 0, "just checking");
+ } while (adjusted_size > compaction_max_size);
+ }
+
+ // store the forwarding pointer into the mark word
+ if ((HeapWord*)q != compact_top) {
+ q->forward_to(oop(compact_top));
+ assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
+ } else {
+ // if the object isn't moving we can just set the mark to the default
+ // mark and handle it specially later on.
+ q->init_mark();
+ assert(q->forwardee() == NULL, "should be forwarded to NULL");
+ }
+
+ compact_top += adjusted_size;
+
+ // we need to update the offset table so that the beginnings of objects can be
+ // found during scavenge. Note that we are updating the offset table based on
+ // where the object will be once the compaction phase finishes.
+
+ // Always call cross_threshold(). A contiguous space can only call it when
+ // the compaction_top exceeds the current threshold but not for an
+ // non-contiguous space.
+ cp->threshold =
+ cp->space->cross_threshold(compact_top - adjusted_size, compact_top);
+ return compact_top;
+}
+
+// A modified copy of OffsetTableContigSpace::cross_threshold() with _offsets -> _bt
+// and use of single_block instead of alloc_block. The name here is not really
+// appropriate - maybe a more general name could be invented for both the
+// contiguous and noncontiguous spaces.
+
+HeapWord* CompactibleFreeListSpace::cross_threshold(HeapWord* start, HeapWord* the_end) {
+ _bt.single_block(start, the_end);
+ return end();
+}
+
+// Initialize them to NULL.
+void CompactibleFreeListSpace::initializeIndexedFreeListArray() {
+ for (size_t i = 0; i < IndexSetSize; i++) {
+ // Note that on platforms where objects are double word aligned,
+ // the odd array elements are not used. It is convenient, however,
+ // to map directly from the object size to the array element.
+ _indexedFreeList[i].reset(IndexSetSize);
+ _indexedFreeList[i].set_size(i);
+ assert(_indexedFreeList[i].count() == 0, "reset check failed");
+ assert(_indexedFreeList[i].head() == NULL, "reset check failed");
+ assert(_indexedFreeList[i].tail() == NULL, "reset check failed");
+ assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed");
+ }
+}
+
+void CompactibleFreeListSpace::resetIndexedFreeListArray() {
+ for (size_t i = 1; i < IndexSetSize; i++) {
+ assert(_indexedFreeList[i].size() == (size_t) i,
+ "Indexed free list sizes are incorrect");
+ _indexedFreeList[i].reset(IndexSetSize);
+ assert(_indexedFreeList[i].count() == 0, "reset check failed");
+ assert(_indexedFreeList[i].head() == NULL, "reset check failed");
+ assert(_indexedFreeList[i].tail() == NULL, "reset check failed");
+ assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed");
+ }
+}
+
+void CompactibleFreeListSpace::reset(MemRegion mr) {
+ resetIndexedFreeListArray();
+ dictionary()->reset();
+ if (BlockOffsetArrayUseUnallocatedBlock) {
+ assert(end() == mr.end(), "We are compacting to the bottom of CMS gen");
+ // Everything's allocated until proven otherwise.
+ _bt.set_unallocated_block(end());
+ }
+ if (!mr.is_empty()) {
+ assert(mr.word_size() >= MinChunkSize, "Chunk size is too small");
+ _bt.single_block(mr.start(), mr.word_size());
+ FreeChunk* fc = (FreeChunk*) mr.start();
+ fc->set_size(mr.word_size());
+ if (mr.word_size() >= IndexSetSize ) {
+ returnChunkToDictionary(fc);
+ } else {
+ _bt.verify_not_unallocated((HeapWord*)fc, fc->size());
+ _indexedFreeList[mr.word_size()].return_chunk_at_head(fc);
+ }
+ coalBirth(mr.word_size());
+ }
+ _promoInfo.reset();
+ _smallLinearAllocBlock._ptr = NULL;
+ _smallLinearAllocBlock._word_size = 0;
+}
+
+void CompactibleFreeListSpace::reset_after_compaction() {
+ // Reset the space to the new reality - one free chunk.
+ MemRegion mr(compaction_top(), end());
+ reset(mr);
+ // Now refill the linear allocation block(s) if possible.
+ if (_adaptive_freelists) {
+ refillLinearAllocBlocksIfNeeded();
+ } else {
+ // Place as much of mr in the linAB as we can get,
+ // provided it was big enough to go into the dictionary.
+ FreeChunk* fc = dictionary()->find_largest_dict();
+ if (fc != NULL) {
+ assert(fc->size() == mr.word_size(),
+ "Why was the chunk broken up?");
+ removeChunkFromDictionary(fc);
+ HeapWord* addr = (HeapWord*) fc;
+ _smallLinearAllocBlock.set(addr, fc->size() ,
+ 1024*SmallForLinearAlloc, fc->size());
+ // Note that _unallocated_block is not updated here.
+ }
+ }
+}
+
+// Walks the entire dictionary, returning a coterminal
+// chunk, if it exists. Use with caution since it involves
+// a potentially complete walk of a potentially large tree.
+FreeChunk* CompactibleFreeListSpace::find_chunk_at_end() {
+
+ assert_lock_strong(&_freelistLock);
+
+ return dictionary()->find_chunk_ends_at(end());
+}
+
+
+#ifndef PRODUCT
+void CompactibleFreeListSpace::initializeIndexedFreeListArrayReturnedBytes() {
+ for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+ _indexedFreeList[i].allocation_stats()->set_returned_bytes(0);
+ }
+}
+
+size_t CompactibleFreeListSpace::sumIndexedFreeListArrayReturnedBytes() {
+ size_t sum = 0;
+ for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+ sum += _indexedFreeList[i].allocation_stats()->returned_bytes();
+ }
+ return sum;
+}
+
+size_t CompactibleFreeListSpace::totalCountInIndexedFreeLists() const {
+ size_t count = 0;
+ for (size_t i = IndexSetStart; i < IndexSetSize; i++) {
+ debug_only(
+ ssize_t total_list_count = 0;
+ for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;
+ fc = fc->next()) {
+ total_list_count++;
+ }
+ assert(total_list_count == _indexedFreeList[i].count(),
+ "Count in list is incorrect");
+ )
+ count += _indexedFreeList[i].count();
+ }
+ return count;
+}
+
+size_t CompactibleFreeListSpace::totalCount() {
+ size_t num = totalCountInIndexedFreeLists();
+ num += dictionary()->total_count();
+ if (_smallLinearAllocBlock._word_size != 0) {
+ num++;
+ }
+ return num;
+}
+#endif
+
+bool CompactibleFreeListSpace::is_free_block(const HeapWord* p) const {
+ FreeChunk* fc = (FreeChunk*) p;
+ return fc->is_free();
+}
+
+size_t CompactibleFreeListSpace::used() const {
+ return capacity() - free();
+}
+
+size_t CompactibleFreeListSpace::free() const {
+ // "MT-safe, but not MT-precise"(TM), if you will: i.e.
+ // if you do this while the structures are in flux you
+ // may get an approximate answer only; for instance
+ // because there is concurrent allocation either
+ // directly by mutators or for promotion during a GC.
+ // It's "MT-safe", however, in the sense that you are guaranteed
+ // not to crash and burn, for instance, because of walking
+ // pointers that could disappear as you were walking them.
+ // The approximation is because the various components
+ // that are read below are not read atomically (and
+ // further the computation of totalSizeInIndexedFreeLists()
+ // is itself a non-atomic computation. The normal use of
+ // this is during a resize operation at the end of GC
+ // and at that time you are guaranteed to get the
+ // correct actual value. However, for instance, this is
+ // also read completely asynchronously by the "perf-sampler"
+ // that supports jvmstat, and you are apt to see the values
+ // flicker in such cases.
+ assert(_dictionary != NULL, "No _dictionary?");
+ return (_dictionary->total_chunk_size(DEBUG_ONLY(freelistLock())) +
+ totalSizeInIndexedFreeLists() +
+ _smallLinearAllocBlock._word_size) * HeapWordSize;
+}
+
+size_t CompactibleFreeListSpace::max_alloc_in_words() const {
+ assert(_dictionary != NULL, "No _dictionary?");
+ assert_locked();
+ size_t res = _dictionary->max_chunk_size();
+ res = MAX2(res, MIN2(_smallLinearAllocBlock._word_size,
+ (size_t) SmallForLinearAlloc - 1));
+ // XXX the following could potentially be pretty slow;
+ // should one, pessimistically for the rare cases when res
+ // calculated above is less than IndexSetSize,
+ // just return res calculated above? My reasoning was that
+ // those cases will be so rare that the extra time spent doesn't
+ // really matter....
+ // Note: do not change the loop test i >= res + IndexSetStride
+ // to i > res below, because i is unsigned and res may be zero.
+ for (size_t i = IndexSetSize - 1; i >= res + IndexSetStride;
+ i -= IndexSetStride) {
+ if (_indexedFreeList[i].head() != NULL) {
+ assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList");
+ return i;
+ }
+ }
+ return res;
+}
+
+void LinearAllocBlock::print_on(outputStream* st) const {
+ st->print_cr(" LinearAllocBlock: ptr = " PTR_FORMAT ", word_size = " SIZE_FORMAT
+ ", refillsize = " SIZE_FORMAT ", allocation_size_limit = " SIZE_FORMAT,
+ p2i(_ptr), _word_size, _refillSize, _allocation_size_limit);
+}
+
+void CompactibleFreeListSpace::print_on(outputStream* st) const {
+ st->print_cr("COMPACTIBLE FREELIST SPACE");
+ st->print_cr(" Space:");
+ Space::print_on(st);
+
+ st->print_cr("promoInfo:");
+ _promoInfo.print_on(st);
+
+ st->print_cr("_smallLinearAllocBlock");
+ _smallLinearAllocBlock.print_on(st);
+
+ // dump_memory_block(_smallLinearAllocBlock->_ptr, 128);
+
+ st->print_cr(" _fitStrategy = %s, _adaptive_freelists = %s",
+ _fitStrategy?"true":"false", _adaptive_freelists?"true":"false");
+}
+
+void CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st)
+const {
+ reportIndexedFreeListStatistics();
+ gclog_or_tty->print_cr("Layout of Indexed Freelists");
+ gclog_or_tty->print_cr("---------------------------");
+ AdaptiveFreeList<FreeChunk>::print_labels_on(st, "size");
+ for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+ _indexedFreeList[i].print_on(gclog_or_tty);
+ for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;
+ fc = fc->next()) {
+ gclog_or_tty->print_cr("\t[" PTR_FORMAT "," PTR_FORMAT ") %s",
+ p2i(fc), p2i((HeapWord*)fc + i),
+ fc->cantCoalesce() ? "\t CC" : "");
+ }
+ }
+}
+
+void CompactibleFreeListSpace::print_promo_info_blocks(outputStream* st)
+const {
+ _promoInfo.print_on(st);
+}
+
+void CompactibleFreeListSpace::print_dictionary_free_lists(outputStream* st)
+const {
+ _dictionary->report_statistics();
+ st->print_cr("Layout of Freelists in Tree");
+ st->print_cr("---------------------------");
+ _dictionary->print_free_lists(st);
+}
+
+class BlkPrintingClosure: public BlkClosure {
+ const CMSCollector* _collector;
+ const CompactibleFreeListSpace* _sp;
+ const CMSBitMap* _live_bit_map;
+ const bool _post_remark;
+ outputStream* _st;
+public:
+ BlkPrintingClosure(const CMSCollector* collector,
+ const CompactibleFreeListSpace* sp,
+ const CMSBitMap* live_bit_map,
+ outputStream* st):
+ _collector(collector),
+ _sp(sp),
+ _live_bit_map(live_bit_map),
+ _post_remark(collector->abstract_state() > CMSCollector::FinalMarking),
+ _st(st) { }
+ size_t do_blk(HeapWord* addr);
+};
+
+size_t BlkPrintingClosure::do_blk(HeapWord* addr) {
+ size_t sz = _sp->block_size_no_stall(addr, _collector);
+ assert(sz != 0, "Should always be able to compute a size");
+ if (_sp->block_is_obj(addr)) {
+ const bool dead = _post_remark && !_live_bit_map->isMarked(addr);
+ _st->print_cr(PTR_FORMAT ": %s object of size " SIZE_FORMAT "%s",
+ p2i(addr),
+ dead ? "dead" : "live",
+ sz,
+ (!dead && CMSPrintObjectsInDump) ? ":" : ".");
+ if (CMSPrintObjectsInDump && !dead) {
+ oop(addr)->print_on(_st);
+ _st->print_cr("--------------------------------------");
+ }
+ } else { // free block
+ _st->print_cr(PTR_FORMAT ": free block of size " SIZE_FORMAT "%s",
+ p2i(addr), sz, CMSPrintChunksInDump ? ":" : ".");
+ if (CMSPrintChunksInDump) {
+ ((FreeChunk*)addr)->print_on(_st);
+ _st->print_cr("--------------------------------------");
+ }
+ }
+ return sz;
+}
+
+void CompactibleFreeListSpace::dump_at_safepoint_with_locks(CMSCollector* c,
+ outputStream* st) {
+ st->print_cr("\n=========================");
+ st->print_cr("Block layout in CMS Heap:");
+ st->print_cr("=========================");
+ BlkPrintingClosure bpcl(c, this, c->markBitMap(), st);
+ blk_iterate(&bpcl);
+
+ st->print_cr("\n=======================================");
+ st->print_cr("Order & Layout of Promotion Info Blocks");
+ st->print_cr("=======================================");
+ print_promo_info_blocks(st);
+
+ st->print_cr("\n===========================");
+ st->print_cr("Order of Indexed Free Lists");
+ st->print_cr("=========================");
+ print_indexed_free_lists(st);
+
+ st->print_cr("\n=================================");
+ st->print_cr("Order of Free Lists in Dictionary");
+ st->print_cr("=================================");
+ print_dictionary_free_lists(st);
+}
+
+
+void CompactibleFreeListSpace::reportFreeListStatistics() const {
+ assert_lock_strong(&_freelistLock);
+ assert(PrintFLSStatistics != 0, "Reporting error");
+ _dictionary->report_statistics();
+ if (PrintFLSStatistics > 1) {
+ reportIndexedFreeListStatistics();
+ size_t total_size = totalSizeInIndexedFreeLists() +
+ _dictionary->total_chunk_size(DEBUG_ONLY(freelistLock()));
+ gclog_or_tty->print(" free=" SIZE_FORMAT " frag=%1.4f\n", total_size, flsFrag());
+ }
+}
+
+void CompactibleFreeListSpace::reportIndexedFreeListStatistics() const {
+ assert_lock_strong(&_freelistLock);
+ gclog_or_tty->print("Statistics for IndexedFreeLists:\n"
+ "--------------------------------\n");
+ size_t total_size = totalSizeInIndexedFreeLists();
+ size_t free_blocks = numFreeBlocksInIndexedFreeLists();
+ gclog_or_tty->print("Total Free Space: " SIZE_FORMAT "\n", total_size);
+ gclog_or_tty->print("Max Chunk Size: " SIZE_FORMAT "\n", maxChunkSizeInIndexedFreeLists());
+ gclog_or_tty->print("Number of Blocks: " SIZE_FORMAT "\n", free_blocks);
+ if (free_blocks != 0) {
+ gclog_or_tty->print("Av. Block Size: " SIZE_FORMAT "\n", total_size/free_blocks);
+ }
+}
+
+size_t CompactibleFreeListSpace::numFreeBlocksInIndexedFreeLists() const {
+ size_t res = 0;
+ for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+ debug_only(
+ ssize_t recount = 0;
+ for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;
+ fc = fc->next()) {
+ recount += 1;
+ }
+ assert(recount == _indexedFreeList[i].count(),
+ "Incorrect count in list");
+ )
+ res += _indexedFreeList[i].count();
+ }
+ return res;
+}
+
+size_t CompactibleFreeListSpace::maxChunkSizeInIndexedFreeLists() const {
+ for (size_t i = IndexSetSize - 1; i != 0; i -= IndexSetStride) {
+ if (_indexedFreeList[i].head() != NULL) {
+ assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList");
+ return (size_t)i;
+ }
+ }
+ return 0;
+}
+
+void CompactibleFreeListSpace::set_end(HeapWord* value) {
+ HeapWord* prevEnd = end();
+ assert(prevEnd != value, "unnecessary set_end call");
+ assert(prevEnd == NULL || !BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(),
+ "New end is below unallocated block");
+ _end = value;
+ if (prevEnd != NULL) {
+ // Resize the underlying block offset table.
+ _bt.resize(pointer_delta(value, bottom()));
+ if (value <= prevEnd) {
+ assert(!BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(),
+ "New end is below unallocated block");
+ } else {
+ // Now, take this new chunk and add it to the free blocks.
+ // Note that the BOT has not yet been updated for this block.
+ size_t newFcSize = pointer_delta(value, prevEnd);
+ // XXX This is REALLY UGLY and should be fixed up. XXX
+ if (!_adaptive_freelists && _smallLinearAllocBlock._ptr == NULL) {
+ // Mark the boundary of the new block in BOT
+ _bt.mark_block(prevEnd, value);
+ // put it all in the linAB
+ MutexLockerEx x(parDictionaryAllocLock(),
+ Mutex::_no_safepoint_check_flag);
+ _smallLinearAllocBlock._ptr = prevEnd;
+ _smallLinearAllocBlock._word_size = newFcSize;
+ repairLinearAllocBlock(&_smallLinearAllocBlock);
+ // Births of chunks put into a LinAB are not recorded. Births
+ // of chunks as they are allocated out of a LinAB are.
+ } else {
+ // Add the block to the free lists, if possible coalescing it
+ // with the last free block, and update the BOT and census data.
+ addChunkToFreeListsAtEndRecordingStats(prevEnd, newFcSize);
+ }
+ }
+ }
+}
+
+class FreeListSpace_DCTOC : public Filtering_DCTOC {
+ CompactibleFreeListSpace* _cfls;
+ CMSCollector* _collector;
+protected:
+ // Override.
+#define walk_mem_region_with_cl_DECL(ClosureType) \
+ virtual void walk_mem_region_with_cl(MemRegion mr, \
+ HeapWord* bottom, HeapWord* top, \
+ ClosureType* cl); \
+ void walk_mem_region_with_cl_par(MemRegion mr, \
+ HeapWord* bottom, HeapWord* top, \
+ ClosureType* cl); \
+ void walk_mem_region_with_cl_nopar(MemRegion mr, \
+ HeapWord* bottom, HeapWord* top, \
+ ClosureType* cl)
+ walk_mem_region_with_cl_DECL(ExtendedOopClosure);
+ walk_mem_region_with_cl_DECL(FilteringClosure);
+
+public:
+ FreeListSpace_DCTOC(CompactibleFreeListSpace* sp,
+ CMSCollector* collector,
+ ExtendedOopClosure* cl,
+ CardTableModRefBS::PrecisionStyle precision,
+ HeapWord* boundary) :
+ Filtering_DCTOC(sp, cl, precision, boundary),
+ _cfls(sp), _collector(collector) {}
+};
+
+// We de-virtualize the block-related calls below, since we know that our
+// space is a CompactibleFreeListSpace.
+
+#define FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
+void FreeListSpace_DCTOC::walk_mem_region_with_cl(MemRegion mr, \
+ HeapWord* bottom, \
+ HeapWord* top, \
+ ClosureType* cl) { \
+ bool is_par = 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<FreeChunk>* fl = &_indexedFreeList[i];
+ if (fl->head()) {
+ ret = getFromListGreater(fl, numWords);
+ assert(ret == NULL || ret->is_free(), "Should be returning a free chunk");
+ return ret;
+ }
+ }
+
+ currSize = MAX2((size_t)SmallForDictionary,
+ (size_t)(numWords + MinChunkSize));
+
+ /* Try to get a chunk that satisfies request, while avoiding
+ fragmentation that can't be handled. */
+ {
+ ret = dictionary()->get_chunk(currSize);
+ if (ret != NULL) {
+ assert(ret->size() - numWords >= MinChunkSize,
+ "Chunk is too small");
+ _bt.allocated((HeapWord*)ret, ret->size());
+ /* Carve returned chunk. */
+ (void) splitChunkAndReturnRemainder(ret, numWords);
+ /* Label this as no longer a free chunk. */
+ assert(ret->is_free(), "This chunk should be free");
+ ret->link_prev(NULL);
+ }
+ assert(ret == NULL || ret->is_free(), "Should be returning a free chunk");
+ return ret;
+ }
+ ShouldNotReachHere();
+}
+
+bool CompactibleFreeListSpace::verifyChunkInIndexedFreeLists(FreeChunk* fc) const {
+ assert(fc->size() < IndexSetSize, "Size of chunk is too large");
+ return _indexedFreeList[fc->size()].verify_chunk_in_free_list(fc);
+}
+
+bool CompactibleFreeListSpace::verify_chunk_is_linear_alloc_block(FreeChunk* fc) const {
+ assert((_smallLinearAllocBlock._ptr != (HeapWord*)fc) ||
+ (_smallLinearAllocBlock._word_size == fc->size()),
+ "Linear allocation block shows incorrect size");
+ return ((_smallLinearAllocBlock._ptr == (HeapWord*)fc) &&
+ (_smallLinearAllocBlock._word_size == fc->size()));
+}
+
+// Check if the purported free chunk is present either as a linear
+// allocation block, the size-indexed table of (smaller) free blocks,
+// or the larger free blocks kept in the binary tree dictionary.
+bool CompactibleFreeListSpace::verify_chunk_in_free_list(FreeChunk* fc) const {
+ if (verify_chunk_is_linear_alloc_block(fc)) {
+ return true;
+ } else if (fc->size() < IndexSetSize) {
+ return verifyChunkInIndexedFreeLists(fc);
+ } else {
+ return dictionary()->verify_chunk_in_free_list(fc);
+ }
+}
+
+#ifndef PRODUCT
+void CompactibleFreeListSpace::assert_locked() const {
+ CMSLockVerifier::assert_locked(freelistLock(), parDictionaryAllocLock());
+}
+
+void CompactibleFreeListSpace::assert_locked(const Mutex* lock) const {
+ CMSLockVerifier::assert_locked(lock);
+}
+#endif
+
+FreeChunk* CompactibleFreeListSpace::allocateScratch(size_t size) {
+ // In the parallel case, the main thread holds the free list lock
+ // on behalf the parallel threads.
+ FreeChunk* fc;
+ {
+ // If GC is parallel, this might be called by several threads.
+ // This should be rare enough that the locking overhead won't affect
+ // the sequential code.
+ MutexLockerEx x(parDictionaryAllocLock(),
+ Mutex::_no_safepoint_check_flag);
+ fc = getChunkFromDictionary(size);
+ }
+ if (fc != NULL) {
+ fc->dontCoalesce();
+ assert(fc->is_free(), "Should be free, but not coalescable");
+ // Verify that the block offset table shows this to
+ // be a single block, but not one which is unallocated.
+ _bt.verify_single_block((HeapWord*)fc, fc->size());
+ _bt.verify_not_unallocated((HeapWord*)fc, fc->size());
+ }
+ return fc;
+}
+
+oop CompactibleFreeListSpace::promote(oop obj, size_t obj_size) {
+ assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
+ assert_locked();
+
+ // if we are tracking promotions, then first ensure space for
+ // promotion (including spooling space for saving header if necessary).
+ // then allocate and copy, then track promoted info if needed.
+ // When tracking (see PromotionInfo::track()), the mark word may
+ // be displaced and in this case restoration of the mark word
+ // occurs in the (oop_since_save_marks_)iterate phase.
+ if (_promoInfo.tracking() && !_promoInfo.ensure_spooling_space()) {
+ return NULL;
+ }
+ // Call the allocate(size_t, bool) form directly to avoid the
+ // additional call through the allocate(size_t) form. Having
+ // the compile inline the call is problematic because allocate(size_t)
+ // is a virtual method.
+ HeapWord* res = allocate(adjustObjectSize(obj_size));
+ if (res != NULL) {
+ Copy::aligned_disjoint_words((HeapWord*)obj, res, obj_size);
+ // if we should be tracking promotions, do so.
+ if (_promoInfo.tracking()) {
+ _promoInfo.track((PromotedObject*)res);
+ }
+ }
+ return oop(res);
+}
+
+HeapWord*
+CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlock(size_t size) {
+ assert_locked();
+ assert(size >= MinChunkSize, "minimum chunk size");
+ assert(size < _smallLinearAllocBlock._allocation_size_limit,
+ "maximum from smallLinearAllocBlock");
+ return getChunkFromLinearAllocBlock(&_smallLinearAllocBlock, size);
+}
+
+HeapWord*
+CompactibleFreeListSpace::getChunkFromLinearAllocBlock(LinearAllocBlock *blk,
+ size_t size) {
+ assert_locked();
+ assert(size >= MinChunkSize, "too small");
+ HeapWord* res = NULL;
+ // Try to do linear allocation from blk, making sure that
+ if (blk->_word_size == 0) {
+ // We have probably been unable to fill this either in the prologue or
+ // when it was exhausted at the last linear allocation. Bail out until
+ // next time.
+ assert(blk->_ptr == NULL, "consistency check");
+ return NULL;
+ }
+ assert(blk->_word_size != 0 && blk->_ptr != NULL, "consistency check");
+ res = getChunkFromLinearAllocBlockRemainder(blk, size);
+ if (res != NULL) return res;
+
+ // about to exhaust this linear allocation block
+ if (blk->_word_size == size) { // exactly satisfied
+ res = blk->_ptr;
+ _bt.allocated(res, blk->_word_size);
+ } else if (size + MinChunkSize <= blk->_refillSize) {
+ size_t sz = blk->_word_size;
+ // Update _unallocated_block if the size is such that chunk would be
+ // returned to the indexed free list. All other chunks in the indexed
+ // free lists are allocated from the dictionary so that _unallocated_block
+ // has already been adjusted for them. Do it here so that the cost
+ // for all chunks added back to the indexed free lists.
+ if (sz < SmallForDictionary) {
+ _bt.allocated(blk->_ptr, sz);
+ }
+ // Return the chunk that isn't big enough, and then refill below.
+ addChunkToFreeLists(blk->_ptr, sz);
+ split_birth(sz);
+ // Don't keep statistics on adding back chunk from a LinAB.
+ } else {
+ // A refilled block would not satisfy the request.
+ return NULL;
+ }
+
+ blk->_ptr = NULL; blk->_word_size = 0;
+ refillLinearAllocBlock(blk);
+ assert(blk->_ptr == NULL || blk->_word_size >= size + MinChunkSize,
+ "block was replenished");
+ if (res != NULL) {
+ split_birth(size);
+ repairLinearAllocBlock(blk);
+ } else if (blk->_ptr != NULL) {
+ res = blk->_ptr;
+ size_t blk_size = blk->_word_size;
+ blk->_word_size -= size;
+ blk->_ptr += size;
+ split_birth(size);
+ repairLinearAllocBlock(blk);
+ // Update BOT last so that other (parallel) GC threads see a consistent
+ // view of the BOT and free blocks.
+ // Above must occur before BOT is updated below.
+ OrderAccess::storestore();
+ _bt.split_block(res, blk_size, size); // adjust block offset table
+ }
+ return res;
+}
+
+HeapWord* CompactibleFreeListSpace::getChunkFromLinearAllocBlockRemainder(
+ LinearAllocBlock* blk,
+ size_t size) {
+ assert_locked();
+ assert(size >= MinChunkSize, "too small");
+
+ HeapWord* res = NULL;
+ // This is the common case. Keep it simple.
+ if (blk->_word_size >= size + MinChunkSize) {
+ assert(blk->_ptr != NULL, "consistency check");
+ res = blk->_ptr;
+ // Note that the BOT is up-to-date for the linAB before allocation. It
+ // indicates the start of the linAB. The split_block() updates the
+ // BOT for the linAB after the allocation (indicates the start of the
+ // next chunk to be allocated).
+ size_t blk_size = blk->_word_size;
+ blk->_word_size -= size;
+ blk->_ptr += size;
+ split_birth(size);
+ repairLinearAllocBlock(blk);
+ // Update BOT last so that other (parallel) GC threads see a consistent
+ // view of the BOT and free blocks.
+ // Above must occur before BOT is updated below.
+ OrderAccess::storestore();
+ _bt.split_block(res, blk_size, size); // adjust block offset table
+ _bt.allocated(res, size);
+ }
+ return res;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::getChunkFromIndexedFreeList(size_t size) {
+ assert_locked();
+ assert(size < SmallForDictionary, "just checking");
+ FreeChunk* res;
+ res = _indexedFreeList[size].get_chunk_at_head();
+ if (res == NULL) {
+ res = getChunkFromIndexedFreeListHelper(size);
+ }
+ _bt.verify_not_unallocated((HeapWord*) res, size);
+ assert(res == NULL || res->size() == size, "Incorrect block size");
+ return res;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::getChunkFromIndexedFreeListHelper(size_t size,
+ bool replenish) {
+ assert_locked();
+ FreeChunk* fc = NULL;
+ if (size < SmallForDictionary) {
+ assert(_indexedFreeList[size].head() == NULL ||
+ _indexedFreeList[size].surplus() <= 0,
+ "List for this size should be empty or under populated");
+ // Try best fit in exact lists before replenishing the list
+ if (!bestFitFirst() || (fc = bestFitSmall(size)) == NULL) {
+ // Replenish list.
+ //
+ // Things tried that failed.
+ // Tried allocating out of the two LinAB's first before
+ // replenishing lists.
+ // Tried small linAB of size 256 (size in indexed list)
+ // and replenishing indexed lists from the small linAB.
+ //
+ FreeChunk* newFc = NULL;
+ const size_t replenish_size = CMSIndexedFreeListReplenish * size;
+ if (replenish_size < SmallForDictionary) {
+ // Do not replenish from an underpopulated size.
+ if (_indexedFreeList[replenish_size].surplus() > 0 &&
+ _indexedFreeList[replenish_size].head() != NULL) {
+ newFc = _indexedFreeList[replenish_size].get_chunk_at_head();
+ } else if (bestFitFirst()) {
+ newFc = bestFitSmall(replenish_size);
+ }
+ }
+ if (newFc == NULL && replenish_size > size) {
+ assert(CMSIndexedFreeListReplenish > 1, "ctl pt invariant");
+ newFc = getChunkFromIndexedFreeListHelper(replenish_size, false);
+ }
+ // Note: The stats update re split-death of block obtained above
+ // will be recorded below precisely when we know we are going to
+ // be actually splitting it into more than one pieces below.
+ if (newFc != NULL) {
+ if (replenish || CMSReplenishIntermediate) {
+ // Replenish this list and return one block to caller.
+ size_t i;
+ FreeChunk *curFc, *nextFc;
+ size_t num_blk = newFc->size() / size;
+ assert(num_blk >= 1, "Smaller than requested?");
+ assert(newFc->size() % size == 0, "Should be integral multiple of request");
+ if (num_blk > 1) {
+ // we are sure we will be splitting the block just obtained
+ // into multiple pieces; record the split-death of the original
+ splitDeath(replenish_size);
+ }
+ // carve up and link blocks 0, ..., num_blk - 2
+ // The last chunk is not added to the lists but is returned as the
+ // free chunk.
+ for (curFc = newFc, nextFc = (FreeChunk*)((HeapWord*)curFc + size),
+ i = 0;
+ i < (num_blk - 1);
+ curFc = nextFc, nextFc = (FreeChunk*)((HeapWord*)nextFc + size),
+ i++) {
+ curFc->set_size(size);
+ // Don't record this as a return in order to try and
+ // determine the "returns" from a GC.
+ _bt.verify_not_unallocated((HeapWord*) fc, size);
+ _indexedFreeList[size].return_chunk_at_tail(curFc, false);
+ _bt.mark_block((HeapWord*)curFc, size);
+ split_birth(size);
+ // Don't record the initial population of the indexed list
+ // as a split birth.
+ }
+
+ // check that the arithmetic was OK above
+ assert((HeapWord*)nextFc == (HeapWord*)newFc + num_blk*size,
+ "inconsistency in carving newFc");
+ curFc->set_size(size);
+ _bt.mark_block((HeapWord*)curFc, size);
+ split_birth(size);
+ fc = curFc;
+ } else {
+ // Return entire block to caller
+ fc = newFc;
+ }
+ }
+ }
+ } else {
+ // Get a free chunk from the free chunk dictionary to be returned to
+ // replenish the indexed free list.
+ fc = getChunkFromDictionaryExact(size);
+ }
+ // assert(fc == NULL || fc->is_free(), "Should be returning a free chunk");
+ return fc;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::getChunkFromDictionary(size_t size) {
+ assert_locked();
+ FreeChunk* fc = _dictionary->get_chunk(size,
+ FreeBlockDictionary<FreeChunk>::atLeast);
+ if (fc == NULL) {
+ return NULL;
+ }
+ _bt.allocated((HeapWord*)fc, fc->size());
+ if (fc->size() >= size + MinChunkSize) {
+ fc = splitChunkAndReturnRemainder(fc, size);
+ }
+ assert(fc->size() >= size, "chunk too small");
+ assert(fc->size() < size + MinChunkSize, "chunk too big");
+ _bt.verify_single_block((HeapWord*)fc, fc->size());
+ return fc;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::getChunkFromDictionaryExact(size_t size) {
+ assert_locked();
+ FreeChunk* fc = _dictionary->get_chunk(size,
+ FreeBlockDictionary<FreeChunk>::atLeast);
+ if (fc == NULL) {
+ return fc;
+ }
+ _bt.allocated((HeapWord*)fc, fc->size());
+ if (fc->size() == size) {
+ _bt.verify_single_block((HeapWord*)fc, size);
+ return fc;
+ }
+ assert(fc->size() > size, "get_chunk() guarantee");
+ if (fc->size() < size + MinChunkSize) {
+ // Return the chunk to the dictionary and go get a bigger one.
+ returnChunkToDictionary(fc);
+ fc = _dictionary->get_chunk(size + MinChunkSize,
+ FreeBlockDictionary<FreeChunk>::atLeast);
+ if (fc == NULL) {
+ return NULL;
+ }
+ _bt.allocated((HeapWord*)fc, fc->size());
+ }
+ assert(fc->size() >= size + MinChunkSize, "tautology");
+ fc = splitChunkAndReturnRemainder(fc, size);
+ assert(fc->size() == size, "chunk is wrong size");
+ _bt.verify_single_block((HeapWord*)fc, size);
+ return fc;
+}
+
+void
+CompactibleFreeListSpace::returnChunkToDictionary(FreeChunk* chunk) {
+ assert_locked();
+
+ size_t size = chunk->size();
+ _bt.verify_single_block((HeapWord*)chunk, size);
+ // adjust _unallocated_block downward, as necessary
+ _bt.freed((HeapWord*)chunk, size);
+ _dictionary->return_chunk(chunk);
+#ifndef PRODUCT
+ if (CMSCollector::abstract_state() != CMSCollector::Sweeping) {
+ TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >* tc = TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >::as_TreeChunk(chunk);
+ TreeList<FreeChunk, AdaptiveFreeList<FreeChunk> >* tl = tc->list();
+ tl->verify_stats();
+ }
+#endif // PRODUCT
+}
+
+void
+CompactibleFreeListSpace::returnChunkToFreeList(FreeChunk* fc) {
+ assert_locked();
+ size_t size = fc->size();
+ _bt.verify_single_block((HeapWord*) fc, size);
+ _bt.verify_not_unallocated((HeapWord*) fc, size);
+ if (_adaptive_freelists) {
+ _indexedFreeList[size].return_chunk_at_tail(fc);
+ } else {
+ _indexedFreeList[size].return_chunk_at_head(fc);
+ }
+#ifndef PRODUCT
+ if (CMSCollector::abstract_state() != CMSCollector::Sweeping) {
+ _indexedFreeList[size].verify_stats();
+ }
+#endif // PRODUCT
+}
+
+// Add chunk to end of last block -- if it's the largest
+// block -- and update BOT and census data. We would
+// of course have preferred to coalesce it with the
+// last block, but it's currently less expensive to find the
+// largest block than it is to find the last.
+void
+CompactibleFreeListSpace::addChunkToFreeListsAtEndRecordingStats(
+ HeapWord* chunk, size_t size) {
+ // check that the chunk does lie in this space!
+ assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!");
+ // One of the parallel gc task threads may be here
+ // whilst others are allocating.
+ Mutex* lock = &_parDictionaryAllocLock;
+ FreeChunk* ec;
+ {
+ MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
+ ec = dictionary()->find_largest_dict(); // get largest block
+ if (ec != NULL && ec->end() == (uintptr_t*) chunk) {
+ // It's a coterminal block - we can coalesce.
+ size_t old_size = ec->size();
+ coalDeath(old_size);
+ removeChunkFromDictionary(ec);
+ size += old_size;
+ } else {
+ ec = (FreeChunk*)chunk;
+ }
+ }
+ ec->set_size(size);
+ debug_only(ec->mangleFreed(size));
+ if (size < SmallForDictionary) {
+ lock = _indexedFreeListParLocks[size];
+ }
+ MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
+ addChunkAndRepairOffsetTable((HeapWord*)ec, size, true);
+ // record the birth under the lock since the recording involves
+ // manipulation of the list on which the chunk lives and
+ // if the chunk is allocated and is the last on the list,
+ // the list can go away.
+ coalBirth(size);
+}
+
+void
+CompactibleFreeListSpace::addChunkToFreeLists(HeapWord* chunk,
+ size_t size) {
+ // check that the chunk does lie in this space!
+ assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!");
+ assert_locked();
+ _bt.verify_single_block(chunk, size);
+
+ FreeChunk* fc = (FreeChunk*) chunk;
+ fc->set_size(size);
+ debug_only(fc->mangleFreed(size));
+ if (size < SmallForDictionary) {
+ returnChunkToFreeList(fc);
+ } else {
+ returnChunkToDictionary(fc);
+ }
+}
+
+void
+CompactibleFreeListSpace::addChunkAndRepairOffsetTable(HeapWord* chunk,
+ size_t size, bool coalesced) {
+ assert_locked();
+ assert(chunk != NULL, "null chunk");
+ if (coalesced) {
+ // repair BOT
+ _bt.single_block(chunk, size);
+ }
+ addChunkToFreeLists(chunk, size);
+}
+
+// We _must_ find the purported chunk on our free lists;
+// we assert if we don't.
+void
+CompactibleFreeListSpace::removeFreeChunkFromFreeLists(FreeChunk* fc) {
+ size_t size = fc->size();
+ assert_locked();
+ debug_only(verifyFreeLists());
+ if (size < SmallForDictionary) {
+ removeChunkFromIndexedFreeList(fc);
+ } else {
+ removeChunkFromDictionary(fc);
+ }
+ _bt.verify_single_block((HeapWord*)fc, size);
+ debug_only(verifyFreeLists());
+}
+
+void
+CompactibleFreeListSpace::removeChunkFromDictionary(FreeChunk* fc) {
+ size_t size = fc->size();
+ assert_locked();
+ assert(fc != NULL, "null chunk");
+ _bt.verify_single_block((HeapWord*)fc, size);
+ _dictionary->remove_chunk(fc);
+ // adjust _unallocated_block upward, as necessary
+ _bt.allocated((HeapWord*)fc, size);
+}
+
+void
+CompactibleFreeListSpace::removeChunkFromIndexedFreeList(FreeChunk* fc) {
+ assert_locked();
+ size_t size = fc->size();
+ _bt.verify_single_block((HeapWord*)fc, size);
+ NOT_PRODUCT(
+ if (FLSVerifyIndexTable) {
+ verifyIndexedFreeList(size);
+ }
+ )
+ _indexedFreeList[size].remove_chunk(fc);
+ NOT_PRODUCT(
+ if (FLSVerifyIndexTable) {
+ verifyIndexedFreeList(size);
+ }
+ )
+}
+
+FreeChunk* CompactibleFreeListSpace::bestFitSmall(size_t numWords) {
+ /* A hint is the next larger size that has a surplus.
+ Start search at a size large enough to guarantee that
+ the excess is >= MIN_CHUNK. */
+ size_t start = align_object_size(numWords + MinChunkSize);
+ if (start < IndexSetSize) {
+ AdaptiveFreeList<FreeChunk>* it = _indexedFreeList;
+ size_t hint = _indexedFreeList[start].hint();
+ while (hint < IndexSetSize) {
+ assert(hint % MinObjAlignment == 0, "hint should be aligned");
+ AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[hint];
+ if (fl->surplus() > 0 && fl->head() != NULL) {
+ // Found a list with surplus, reset original hint
+ // and split out a free chunk which is returned.
+ _indexedFreeList[start].set_hint(hint);
+ FreeChunk* res = getFromListGreater(fl, numWords);
+ assert(res == NULL || res->is_free(),
+ "Should be returning a free chunk");
+ return res;
+ }
+ hint = fl->hint(); /* keep looking */
+ }
+ /* None found. */
+ it[start].set_hint(IndexSetSize);
+ }
+ return NULL;
+}
+
+/* Requires fl->size >= numWords + MinChunkSize */
+FreeChunk* CompactibleFreeListSpace::getFromListGreater(AdaptiveFreeList<FreeChunk>* fl,
+ size_t numWords) {
+ FreeChunk *curr = fl->head();
+ size_t oldNumWords = curr->size();
+ assert(numWords >= MinChunkSize, "Word size is too small");
+ assert(curr != NULL, "List is empty");
+ assert(oldNumWords >= numWords + MinChunkSize,
+ "Size of chunks in the list is too small");
+
+ fl->remove_chunk(curr);
+ // recorded indirectly by splitChunkAndReturnRemainder -
+ // smallSplit(oldNumWords, numWords);
+ FreeChunk* new_chunk = splitChunkAndReturnRemainder(curr, numWords);
+ // Does anything have to be done for the remainder in terms of
+ // fixing the card table?
+ assert(new_chunk == NULL || new_chunk->is_free(),
+ "Should be returning a free chunk");
+ return new_chunk;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::splitChunkAndReturnRemainder(FreeChunk* chunk,
+ size_t new_size) {
+ assert_locked();
+ size_t size = chunk->size();
+ assert(size > new_size, "Split from a smaller block?");
+ assert(is_aligned(chunk), "alignment problem");
+ assert(size == adjustObjectSize(size), "alignment problem");
+ size_t rem_sz = size - new_size;
+ assert(rem_sz == adjustObjectSize(rem_sz), "alignment problem");
+ assert(rem_sz >= MinChunkSize, "Free chunk smaller than minimum");
+ FreeChunk* ffc = (FreeChunk*)((HeapWord*)chunk + new_size);
+ assert(is_aligned(ffc), "alignment problem");
+ ffc->set_size(rem_sz);
+ ffc->link_next(NULL);
+ ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads.
+ // Above must occur before BOT is updated below.
+ // adjust block offset table
+ OrderAccess::storestore();
+ assert(chunk->is_free() && ffc->is_free(), "Error");
+ _bt.split_block((HeapWord*)chunk, chunk->size(), new_size);
+ if (rem_sz < SmallForDictionary) {
+ bool is_par = (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<FreeChunk>* fl = &_indexedFreeList[i];
+ if (PrintFLSStatistics > 1) {
+ gclog_or_tty->print("size[" SIZE_FORMAT "] : ", i);
+ }
+ fl->compute_desired(inter_sweep_current, inter_sweep_estimate, intra_sweep_estimate);
+ fl->set_coal_desired((ssize_t)((double)fl->desired() * CMSSmallCoalSurplusPercent));
+ fl->set_before_sweep(fl->count());
+ fl->set_bfr_surp(fl->surplus());
+ }
+ _dictionary->begin_sweep_dict_census(CMSLargeCoalSurplusPercent,
+ inter_sweep_current,
+ inter_sweep_estimate,
+ intra_sweep_estimate);
+}
+
+void CompactibleFreeListSpace::setFLSurplus() {
+ assert_locked();
+ size_t i;
+ for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+ AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];
+ fl->set_surplus(fl->count() -
+ (ssize_t)((double)fl->desired() * CMSSmallSplitSurplusPercent));
+ }
+}
+
+void CompactibleFreeListSpace::setFLHints() {
+ assert_locked();
+ size_t i;
+ size_t h = IndexSetSize;
+ for (i = IndexSetSize - 1; i != 0; i -= IndexSetStride) {
+ AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];
+ fl->set_hint(h);
+ if (fl->surplus() > 0) {
+ h = i;
+ }
+ }
+}
+
+void CompactibleFreeListSpace::clearFLCensus() {
+ assert_locked();
+ size_t i;
+ for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+ AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];
+ fl->set_prev_sweep(fl->count());
+ fl->set_coal_births(0);
+ fl->set_coal_deaths(0);
+ fl->set_split_births(0);
+ fl->set_split_deaths(0);
+ }
+}
+
+void CompactibleFreeListSpace::endSweepFLCensus(size_t sweep_count) {
+ if (PrintFLSStatistics > 0) {
+ HeapWord* largestAddr = (HeapWord*) dictionary()->find_largest_dict();
+ gclog_or_tty->print_cr("CMS: Large block " PTR_FORMAT,
+ p2i(largestAddr));
+ }
+ setFLSurplus();
+ setFLHints();
+ if (PrintGC && PrintFLSCensus > 0) {
+ printFLCensus(sweep_count);
+ }
+ clearFLCensus();
+ assert_locked();
+ _dictionary->end_sweep_dict_census(CMSLargeSplitSurplusPercent);
+}
+
+bool CompactibleFreeListSpace::coalOverPopulated(size_t size) {
+ if (size < SmallForDictionary) {
+ AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+ return (fl->coal_desired() < 0) ||
+ ((int)fl->count() > fl->coal_desired());
+ } else {
+ return dictionary()->coal_dict_over_populated(size);
+ }
+}
+
+void CompactibleFreeListSpace::smallCoalBirth(size_t size) {
+ assert(size < SmallForDictionary, "Size too large for indexed list");
+ AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+ fl->increment_coal_births();
+ fl->increment_surplus();
+}
+
+void CompactibleFreeListSpace::smallCoalDeath(size_t size) {
+ assert(size < SmallForDictionary, "Size too large for indexed list");
+ AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+ fl->increment_coal_deaths();
+ fl->decrement_surplus();
+}
+
+void CompactibleFreeListSpace::coalBirth(size_t size) {
+ if (size < SmallForDictionary) {
+ smallCoalBirth(size);
+ } else {
+ dictionary()->dict_census_update(size,
+ false /* split */,
+ true /* birth */);
+ }
+}
+
+void CompactibleFreeListSpace::coalDeath(size_t size) {
+ if(size < SmallForDictionary) {
+ smallCoalDeath(size);
+ } else {
+ dictionary()->dict_census_update(size,
+ false /* split */,
+ false /* birth */);
+ }
+}
+
+void CompactibleFreeListSpace::smallSplitBirth(size_t size) {
+ assert(size < SmallForDictionary, "Size too large for indexed list");
+ AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+ fl->increment_split_births();
+ fl->increment_surplus();
+}
+
+void CompactibleFreeListSpace::smallSplitDeath(size_t size) {
+ assert(size < SmallForDictionary, "Size too large for indexed list");
+ AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+ fl->increment_split_deaths();
+ fl->decrement_surplus();
+}
+
+void CompactibleFreeListSpace::split_birth(size_t size) {
+ if (size < SmallForDictionary) {
+ smallSplitBirth(size);
+ } else {
+ dictionary()->dict_census_update(size,
+ true /* split */,
+ true /* birth */);
+ }
+}
+
+void CompactibleFreeListSpace::splitDeath(size_t size) {
+ if (size < SmallForDictionary) {
+ smallSplitDeath(size);
+ } else {
+ dictionary()->dict_census_update(size,
+ true /* split */,
+ false /* birth */);
+ }
+}
+
+void CompactibleFreeListSpace::split(size_t from, size_t to1) {
+ size_t to2 = from - to1;
+ splitDeath(from);
+ split_birth(to1);
+ split_birth(to2);
+}
+
+void CompactibleFreeListSpace::print() const {
+ print_on(tty);
+}
+
+void CompactibleFreeListSpace::prepare_for_verify() {
+ assert_locked();
+ repairLinearAllocationBlocks();
+ // Verify that the SpoolBlocks look like free blocks of
+ // appropriate sizes... To be done ...
+}
+
+class VerifyAllBlksClosure: public BlkClosure {
+ private:
+ const CompactibleFreeListSpace* _sp;
+ const MemRegion _span;
+ HeapWord* _last_addr;
+ size_t _last_size;
+ bool _last_was_obj;
+ bool _last_was_live;
+
+ public:
+ VerifyAllBlksClosure(const CompactibleFreeListSpace* sp,
+ MemRegion span) : _sp(sp), _span(span),
+ _last_addr(NULL), _last_size(0),
+ _last_was_obj(false), _last_was_live(false) { }
+
+ virtual size_t do_blk(HeapWord* addr) {
+ size_t res;
+ bool was_obj = false;
+ bool was_live = false;
+ if (_sp->block_is_obj(addr)) {
+ was_obj = true;
+ oop p = oop(addr);
+ guarantee(p->is_oop(), "Should be an oop");
+ res = _sp->adjustObjectSize(p->size());
+ if (_sp->obj_is_alive(addr)) {
+ was_live = true;
+ p->verify();
+ }
+ } else {
+ FreeChunk* fc = (FreeChunk*)addr;
+ res = fc->size();
+ if (FLSVerifyLists && !fc->cantCoalesce()) {
+ guarantee(_sp->verify_chunk_in_free_list(fc),
+ "Chunk should be on a free list");
+ }
+ }
+ if (res == 0) {
+ gclog_or_tty->print_cr("Livelock: no rank reduction!");
+ gclog_or_tty->print_cr(
+ " Current: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n"
+ " Previous: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n",
+ p2i(addr), res, was_obj ?"true":"false", was_live ?"true":"false",
+ p2i(_last_addr), _last_size, _last_was_obj?"true":"false", _last_was_live?"true":"false");
+ _sp->print_on(gclog_or_tty);
+ guarantee(false, "Seppuku!");
+ }
+ _last_addr = addr;
+ _last_size = res;
+ _last_was_obj = was_obj;
+ _last_was_live = was_live;
+ return res;
+ }
+};
+
+class VerifyAllOopsClosure: public OopClosure {
+ private:
+ const CMSCollector* _collector;
+ const CompactibleFreeListSpace* _sp;
+ const MemRegion _span;
+ const bool _past_remark;
+ const CMSBitMap* _bit_map;
+
+ protected:
+ void do_oop(void* p, oop obj) {
+ if (_span.contains(obj)) { // the interior oop points into CMS heap
+ if (!_span.contains(p)) { // reference from outside CMS heap
+ // Should be a valid object; the first disjunct below allows
+ // us to sidestep an assertion in block_is_obj() that insists
+ // that p be in _sp. Note that several generations (and spaces)
+ // are spanned by _span (CMS heap) above.
+ guarantee(!_sp->is_in_reserved(obj) ||
+ _sp->block_is_obj((HeapWord*)obj),
+ "Should be an object");
+ guarantee(obj->is_oop(), "Should be an oop");
+ obj->verify();
+ if (_past_remark) {
+ // Remark has been completed, the object should be marked
+ _bit_map->isMarked((HeapWord*)obj);
+ }
+ } else { // reference within CMS heap
+ if (_past_remark) {
+ // Remark has been completed -- so the referent should have
+ // been marked, if referring object is.
+ if (_bit_map->isMarked(_collector->block_start(p))) {
+ guarantee(_bit_map->isMarked((HeapWord*)obj), "Marking error?");
+ }
+ }
+ }
+ } else if (_sp->is_in_reserved(p)) {
+ // the reference is from FLS, and points out of FLS
+ guarantee(obj->is_oop(), "Should be an oop");
+ obj->verify();
+ }
+ }
+
+ template <class T> void do_oop_work(T* p) {
+ T heap_oop = oopDesc::load_heap_oop(p);
+ if (!oopDesc::is_null(heap_oop)) {
+ oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
+ do_oop(p, obj);
+ }
+ }
+
+ public:
+ VerifyAllOopsClosure(const CMSCollector* collector,
+ const CompactibleFreeListSpace* sp, MemRegion span,
+ bool past_remark, CMSBitMap* bit_map) :
+ _collector(collector), _sp(sp), _span(span),
+ _past_remark(past_remark), _bit_map(bit_map) { }
+
+ virtual void do_oop(oop* p) { VerifyAllOopsClosure::do_oop_work(p); }
+ virtual void do_oop(narrowOop* p) { VerifyAllOopsClosure::do_oop_work(p); }
+};
+
+void CompactibleFreeListSpace::verify() const {
+ assert_lock_strong(&_freelistLock);
+ verify_objects_initialized();
+ MemRegion span = _collector->_span;
+ bool past_remark = (_collector->abstract_state() ==
+ CMSCollector::Sweeping);
+
+ ResourceMark rm;
+ HandleMark hm;
+
+ // Check integrity of CFL data structures
+ _promoInfo.verify();
+ _dictionary->verify();
+ if (FLSVerifyIndexTable) {
+ verifyIndexedFreeLists();
+ }
+ // Check integrity of all objects and free blocks in space
+ {
+ VerifyAllBlksClosure cl(this, span);
+ ((CompactibleFreeListSpace*)this)->blk_iterate(&cl); // cast off const
+ }
+ // Check that all references in the heap to FLS
+ // are to valid objects in FLS or that references in
+ // FLS are to valid objects elsewhere in the heap
+ if (FLSVerifyAllHeapReferences)
+ {
+ VerifyAllOopsClosure cl(_collector, this, span, past_remark,
+ _collector->markBitMap());
+
+ // 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<FreeChunk, AdaptiveFreeList<FreeChunk> >::min_size() <= IndexSetSize),
+ "Some sizes can't be allocated without recourse to"
+ " linear allocation buffers");
+ assert((TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >::min_size()*HeapWordSize == sizeof(TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >)),
+ "else MIN_TREE_CHUNK_SIZE is wrong");
+ assert(IndexSetStart != 0, "IndexSetStart not initialized");
+ assert(IndexSetStride != 0, "IndexSetStride not initialized");
+}
+#endif
+
+void CompactibleFreeListSpace::printFLCensus(size_t sweep_count) const {
+ assert_lock_strong(&_freelistLock);
+ AdaptiveFreeList<FreeChunk> total;
+ gclog_or_tty->print("end sweep# " SIZE_FORMAT "\n", sweep_count);
+ AdaptiveFreeList<FreeChunk>::print_labels_on(gclog_or_tty, "size");
+ size_t total_free = 0;
+ for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+ const AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];
+ total_free += fl->count() * fl->size();
+ if (i % (40*IndexSetStride) == 0) {
+ AdaptiveFreeList<FreeChunk>::print_labels_on(gclog_or_tty, "size");
+ }
+ fl->print_on(gclog_or_tty);
+ total.set_bfr_surp( total.bfr_surp() + fl->bfr_surp() );
+ total.set_surplus( total.surplus() + fl->surplus() );
+ total.set_desired( total.desired() + fl->desired() );
+ total.set_prev_sweep( total.prev_sweep() + fl->prev_sweep() );
+ total.set_before_sweep(total.before_sweep() + fl->before_sweep());
+ total.set_count( total.count() + fl->count() );
+ total.set_coal_births( total.coal_births() + fl->coal_births() );
+ total.set_coal_deaths( total.coal_deaths() + fl->coal_deaths() );
+ total.set_split_births(total.split_births() + fl->split_births());
+ total.set_split_deaths(total.split_deaths() + fl->split_deaths());
+ }
+ total.print_on(gclog_or_tty, "TOTAL");
+ gclog_or_tty->print_cr("Total free in indexed lists "
+ SIZE_FORMAT " words", total_free);
+ gclog_or_tty->print("growth: %8.5f deficit: %8.5f\n",
+ (double)(total.split_births()+total.coal_births()-total.split_deaths()-total.coal_deaths())/
+ (total.prev_sweep() != 0 ? (double)total.prev_sweep() : 1.0),
+ (double)(total.desired() - total.count())/(total.desired() != 0 ? (double)total.desired() : 1.0));
+ _dictionary->print_dict_census();
+}
+
+///////////////////////////////////////////////////////////////////////////
+// CFLS_LAB
+///////////////////////////////////////////////////////////////////////////
+
+#define VECTOR_257(x) \
+ /* 1 2 3 4 5 6 7 8 9 1x 11 12 13 14 15 16 17 18 19 2x 21 22 23 24 25 26 27 28 29 3x 31 32 */ \
+ { x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \
+ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \
+ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \
+ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \
+ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \
+ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \
+ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \
+ x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, \
+ x }
+
+// Initialize with default setting for CMS, _not_
+// generic OldPLABSize, whose static default is different; if overridden at the
+// command-line, this will get reinitialized via a call to
+// modify_initialization() below.
+AdaptiveWeightedAverage CFLS_LAB::_blocks_to_claim[] =
+ VECTOR_257(AdaptiveWeightedAverage(OldPLABWeight, (float)CFLS_LAB::_default_dynamic_old_plab_size));
+size_t CFLS_LAB::_global_num_blocks[] = VECTOR_257(0);
+uint CFLS_LAB::_global_num_workers[] = VECTOR_257(0);
+
+CFLS_LAB::CFLS_LAB(CompactibleFreeListSpace* cfls) :
+ _cfls(cfls)
+{
+ assert(CompactibleFreeListSpace::IndexSetSize == 257, "Modify VECTOR_257() macro above");
+ for (size_t i = CompactibleFreeListSpace::IndexSetStart;
+ i < CompactibleFreeListSpace::IndexSetSize;
+ i += CompactibleFreeListSpace::IndexSetStride) {
+ _indexedFreeList[i].set_size(i);
+ _num_blocks[i] = 0;
+ }
+}
+
+static bool _CFLS_LAB_modified = false;
+
+void CFLS_LAB::modify_initialization(size_t n, unsigned wt) {
+ assert(!_CFLS_LAB_modified, "Call only once");
+ _CFLS_LAB_modified = true;
+ for (size_t i = CompactibleFreeListSpace::IndexSetStart;
+ i < CompactibleFreeListSpace::IndexSetSize;
+ i += CompactibleFreeListSpace::IndexSetStride) {
+ _blocks_to_claim[i].modify(n, wt, true /* force */);
+ }
+}
+
+HeapWord* CFLS_LAB::alloc(size_t word_sz) {
+ FreeChunk* res;
+ assert(word_sz == _cfls->adjustObjectSize(word_sz), "Error");
+ if (word_sz >= CompactibleFreeListSpace::IndexSetSize) {
+ // This locking manages sync with other large object allocations.
+ MutexLockerEx x(_cfls->parDictionaryAllocLock(),
+ Mutex::_no_safepoint_check_flag);
+ res = _cfls->getChunkFromDictionaryExact(word_sz);
+ if (res == NULL) return NULL;
+ } else {
+ AdaptiveFreeList<FreeChunk>* fl = &_indexedFreeList[word_sz];
+ if (fl->count() == 0) {
+ // Attempt to refill this local free list.
+ get_from_global_pool(word_sz, fl);
+ // If it didn't work, give up.
+ if (fl->count() == 0) return NULL;
+ }
+ res = fl->get_chunk_at_head();
+ assert(res != NULL, "Why was count non-zero?");
+ }
+ res->markNotFree();
+ assert(!res->is_free(), "shouldn't be marked free");
+ assert(oop(res)->klass_or_null() == NULL, "should look uninitialized");
+ // mangle a just allocated object with a distinct pattern.
+ debug_only(res->mangleAllocated(word_sz));
+ return (HeapWord*)res;
+}
+
+// Get a chunk of blocks of the right size and update related
+// book-keeping stats
+void CFLS_LAB::get_from_global_pool(size_t word_sz, AdaptiveFreeList<FreeChunk>* fl) {
+ // Get the #blocks we want to claim
+ size_t n_blks = (size_t)_blocks_to_claim[word_sz].average();
+ assert(n_blks > 0, "Error");
+ assert(ResizeOldPLAB || n_blks == OldPLABSize, "Error");
+ // In some cases, when the application has a phase change,
+ // there may be a sudden and sharp shift in the object survival
+ // profile, and updating the counts at the end of a scavenge
+ // may not be quick enough, giving rise to large scavenge pauses
+ // during these phase changes. It is beneficial to detect such
+ // changes on-the-fly during a scavenge and avoid such a phase-change
+ // pothole. The following code is a heuristic attempt to do that.
+ // It is protected by a product flag until we have gained
+ // enough experience with this heuristic and fine-tuned its behavior.
+ // WARNING: This might increase fragmentation if we overreact to
+ // small spikes, so some kind of historical smoothing based on
+ // previous experience with the greater reactivity might be useful.
+ // Lacking sufficient experience, CMSOldPLABResizeQuicker is disabled by
+ // default.
+ if (ResizeOldPLAB && CMSOldPLABResizeQuicker) {
+ size_t multiple = _num_blocks[word_sz]/(CMSOldPLABToleranceFactor*CMSOldPLABNumRefills*n_blks);
+ n_blks += CMSOldPLABReactivityFactor*multiple*n_blks;
+ n_blks = MIN2(n_blks, CMSOldPLABMax);
+ }
+ assert(n_blks > 0, "Error");
+ _cfls->par_get_chunk_of_blocks(word_sz, n_blks, fl);
+ // Update stats table entry for this block size
+ _num_blocks[word_sz] += fl->count();
+}
+
+void CFLS_LAB::compute_desired_plab_size() {
+ for (size_t i = CompactibleFreeListSpace::IndexSetStart;
+ i < CompactibleFreeListSpace::IndexSetSize;
+ i += CompactibleFreeListSpace::IndexSetStride) {
+ assert((_global_num_workers[i] == 0) == (_global_num_blocks[i] == 0),
+ "Counter inconsistency");
+ if (_global_num_workers[i] > 0) {
+ // Need to smooth wrt historical average
+ if (ResizeOldPLAB) {
+ _blocks_to_claim[i].sample(
+ MAX2(CMSOldPLABMin,
+ MIN2(CMSOldPLABMax,
+ _global_num_blocks[i]/(_global_num_workers[i]*CMSOldPLABNumRefills))));
+ }
+ // Reset counters for next round
+ _global_num_workers[i] = 0;
+ _global_num_blocks[i] = 0;
+ if (PrintOldPLAB) {
+ gclog_or_tty->print_cr("[" SIZE_FORMAT "]: " SIZE_FORMAT,
+ i, (size_t)_blocks_to_claim[i].average());
+ }
+ }
+ }
+}
+
+// If this is changed in the future to allow parallel
+// access, one would need to take the FL locks and,
+// depending on how it is used, stagger access from
+// parallel threads to reduce contention.
+void CFLS_LAB::retire(int tid) {
+ // We run this single threaded with the world stopped;
+ // so no need for locks and such.
+ NOT_PRODUCT(Thread* t = Thread::current();)
+ assert(Thread::current()->is_VM_thread(), "Error");
+ for (size_t i = CompactibleFreeListSpace::IndexSetStart;
+ i < CompactibleFreeListSpace::IndexSetSize;
+ i += CompactibleFreeListSpace::IndexSetStride) {
+ assert(_num_blocks[i] >= (size_t)_indexedFreeList[i].count(),
+ "Can't retire more than what we obtained");
+ if (_num_blocks[i] > 0) {
+ size_t num_retire = _indexedFreeList[i].count();
+ assert(_num_blocks[i] > num_retire, "Should have used at least one");
+ {
+ // MutexLockerEx x(_cfls->_indexedFreeListParLocks[i],
+ // Mutex::_no_safepoint_check_flag);
+
+ // Update globals stats for num_blocks used
+ _global_num_blocks[i] += (_num_blocks[i] - num_retire);
+ _global_num_workers[i]++;
+ assert(_global_num_workers[i] <= ParallelGCThreads, "Too big");
+ if (num_retire > 0) {
+ _cfls->_indexedFreeList[i].prepend(&_indexedFreeList[i]);
+ // Reset this list.
+ _indexedFreeList[i] = AdaptiveFreeList<FreeChunk>();
+ _indexedFreeList[i].set_size(i);
+ }
+ }
+ if (PrintOldPLAB) {
+ gclog_or_tty->print_cr("%d[" SIZE_FORMAT "]: " SIZE_FORMAT "/" SIZE_FORMAT "/" SIZE_FORMAT,
+ tid, i, num_retire, _num_blocks[i], (size_t)_blocks_to_claim[i].average());
+ }
+ // Reset stats for next round
+ _num_blocks[i] = 0;
+ }
+ }
+}
+
+// Used by par_get_chunk_of_blocks() for the chunks from the
+// indexed_free_lists. Looks for a chunk with size that is a multiple
+// of "word_sz" and if found, splits it into "word_sz" chunks and add
+// to the free list "fl". "n" is the maximum number of chunks to
+// be added to "fl".
+bool CompactibleFreeListSpace:: par_get_chunk_of_blocks_IFL(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl) {
+
+ // We'll try all multiples of word_sz in the indexed set, starting with
+ // word_sz itself and, if CMSSplitIndexedFreeListBlocks, try larger multiples,
+ // then try getting a big chunk and splitting it.
+ {
+ bool found;
+ int k;
+ size_t cur_sz;
+ for (k = 1, cur_sz = k * word_sz, found = false;
+ (cur_sz < CompactibleFreeListSpace::IndexSetSize) &&
+ (CMSSplitIndexedFreeListBlocks || k <= 1);
+ k++, cur_sz = k * word_sz) {
+ AdaptiveFreeList<FreeChunk> fl_for_cur_sz; // Empty.
+ fl_for_cur_sz.set_size(cur_sz);
+ {
+ MutexLockerEx x(_indexedFreeListParLocks[cur_sz],
+ Mutex::_no_safepoint_check_flag);
+ AdaptiveFreeList<FreeChunk>* gfl = &_indexedFreeList[cur_sz];
+ if (gfl->count() != 0) {
+ // nn is the number of chunks of size cur_sz that
+ // we'd need to split k-ways each, in order to create
+ // "n" chunks of size word_sz each.
+ const size_t nn = MAX2(n/k, (size_t)1);
+ gfl->getFirstNChunksFromList(nn, &fl_for_cur_sz);
+ found = true;
+ if (k > 1) {
+ // Update split death stats for the cur_sz-size blocks list:
+ // we increment the split death count by the number of blocks
+ // we just took from the cur_sz-size blocks list and which
+ // we will be splitting below.
+ ssize_t deaths = gfl->split_deaths() +
+ fl_for_cur_sz.count();
+ gfl->set_split_deaths(deaths);
+ }
+ }
+ }
+ // Now transfer fl_for_cur_sz to fl. Common case, we hope, is k = 1.
+ if (found) {
+ if (k == 1) {
+ fl->prepend(&fl_for_cur_sz);
+ } else {
+ // Divide each block on fl_for_cur_sz up k ways.
+ FreeChunk* fc;
+ while ((fc = fl_for_cur_sz.get_chunk_at_head()) != NULL) {
+ // Must do this in reverse order, so that anybody attempting to
+ // access the main chunk sees it as a single free block until we
+ // change it.
+ size_t fc_size = fc->size();
+ assert(fc->is_free(), "Error");
+ for (int i = k-1; i >= 0; i--) {
+ FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz);
+ assert((i != 0) ||
+ ((fc == ffc) && ffc->is_free() &&
+ (ffc->size() == k*word_sz) && (fc_size == word_sz)),
+ "Counting error");
+ ffc->set_size(word_sz);
+ ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads.
+ ffc->link_next(NULL);
+ // Above must occur before BOT is updated below.
+ OrderAccess::storestore();
+ // splitting from the right, fc_size == i * word_sz
+ _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */);
+ fc_size -= word_sz;
+ assert(fc_size == i*word_sz, "Error");
+ _bt.verify_not_unallocated((HeapWord*)ffc, word_sz);
+ _bt.verify_single_block((HeapWord*)fc, fc_size);
+ _bt.verify_single_block((HeapWord*)ffc, word_sz);
+ // Push this on "fl".
+ fl->return_chunk_at_head(ffc);
+ }
+ // TRAP
+ assert(fl->tail()->next() == NULL, "List invariant.");
+ }
+ }
+ // Update birth stats for this block size.
+ size_t num = fl->count();
+ MutexLockerEx x(_indexedFreeListParLocks[word_sz],
+ Mutex::_no_safepoint_check_flag);
+ ssize_t births = _indexedFreeList[word_sz].split_births() + num;
+ _indexedFreeList[word_sz].set_split_births(births);
+ return true;
+ }
+ }
+ return found;
+ }
+}
+
+FreeChunk* CompactibleFreeListSpace::get_n_way_chunk_to_split(size_t word_sz, size_t n) {
+
+ FreeChunk* fc = NULL;
+ FreeChunk* rem_fc = NULL;
+ size_t rem;
+ {
+ MutexLockerEx x(parDictionaryAllocLock(),
+ Mutex::_no_safepoint_check_flag);
+ while (n > 0) {
+ fc = dictionary()->get_chunk(MAX2(n * word_sz, _dictionary->min_size()),
+ FreeBlockDictionary<FreeChunk>::atLeast);
+ if (fc != NULL) {
+ break;
+ } else {
+ n--;
+ }
+ }
+ if (fc == NULL) return NULL;
+ // Otherwise, split up that block.
+ assert((ssize_t)n >= 1, "Control point invariant");
+ assert(fc->is_free(), "Error: should be a free block");
+ _bt.verify_single_block((HeapWord*)fc, fc->size());
+ const size_t nn = fc->size() / word_sz;
+ n = MIN2(nn, n);
+ assert((ssize_t)n >= 1, "Control point invariant");
+ rem = fc->size() - n * word_sz;
+ // If there is a remainder, and it's too small, allocate one fewer.
+ if (rem > 0 && rem < MinChunkSize) {
+ n--; rem += word_sz;
+ }
+ // Note that at this point we may have n == 0.
+ assert((ssize_t)n >= 0, "Control point invariant");
+
+ // If n is 0, the chunk fc that was found is not large
+ // enough to leave a viable remainder. We are unable to
+ // allocate even one block. Return fc to the
+ // dictionary and return, leaving "fl" empty.
+ if (n == 0) {
+ returnChunkToDictionary(fc);
+ return NULL;
+ }
+
+ _bt.allocated((HeapWord*)fc, fc->size(), true /* reducing */); // update _unallocated_blk
+ dictionary()->dict_census_update(fc->size(),
+ true /*split*/,
+ false /*birth*/);
+
+ // First return the remainder, if any.
+ // Note that we hold the lock until we decide if we're going to give
+ // back the remainder to the dictionary, since a concurrent allocation
+ // may otherwise see the heap as empty. (We're willing to take that
+ // hit if the block is a small block.)
+ if (rem > 0) {
+ size_t prefix_size = n * word_sz;
+ rem_fc = (FreeChunk*)((HeapWord*)fc + prefix_size);
+ rem_fc->set_size(rem);
+ rem_fc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads.
+ rem_fc->link_next(NULL);
+ // Above must occur before BOT is updated below.
+ assert((ssize_t)n > 0 && prefix_size > 0 && rem_fc > fc, "Error");
+ OrderAccess::storestore();
+ _bt.split_block((HeapWord*)fc, fc->size(), prefix_size);
+ assert(fc->is_free(), "Error");
+ fc->set_size(prefix_size);
+ if (rem >= IndexSetSize) {
+ returnChunkToDictionary(rem_fc);
+ dictionary()->dict_census_update(rem, true /*split*/, true /*birth*/);
+ rem_fc = NULL;
+ }
+ // Otherwise, return it to the small list below.
+ }
+ }
+ if (rem_fc != NULL) {
+ MutexLockerEx x(_indexedFreeListParLocks[rem],
+ Mutex::_no_safepoint_check_flag);
+ _bt.verify_not_unallocated((HeapWord*)rem_fc, rem_fc->size());
+ _indexedFreeList[rem].return_chunk_at_head(rem_fc);
+ smallSplitBirth(rem);
+ }
+ assert(n * word_sz == fc->size(),
+ err_msg("Chunk size " SIZE_FORMAT " is not exactly splittable by "
+ SIZE_FORMAT " sized chunks of size " SIZE_FORMAT,
+ fc->size(), n, word_sz));
+ return fc;
+}
+
+void CompactibleFreeListSpace:: par_get_chunk_of_blocks_dictionary(size_t word_sz, size_t targetted_number_of_chunks, AdaptiveFreeList<FreeChunk>* fl) {
+
+ FreeChunk* fc = get_n_way_chunk_to_split(word_sz, targetted_number_of_chunks);
+
+ if (fc == NULL) {
+ return;
+ }
+
+ size_t n = fc->size() / word_sz;
+
+ assert((ssize_t)n > 0, "Consistency");
+ // Now do the splitting up.
+ // Must do this in reverse order, so that anybody attempting to
+ // access the main chunk sees it as a single free block until we
+ // change it.
+ size_t fc_size = n * word_sz;
+ // All but first chunk in this loop
+ for (ssize_t i = n-1; i > 0; i--) {
+ FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz);
+ ffc->set_size(word_sz);
+ ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads.
+ ffc->link_next(NULL);
+ // Above must occur before BOT is updated below.
+ OrderAccess::storestore();
+ // splitting from the right, fc_size == (n - i + 1) * wordsize
+ _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */);
+ fc_size -= word_sz;
+ _bt.verify_not_unallocated((HeapWord*)ffc, ffc->size());
+ _bt.verify_single_block((HeapWord*)ffc, ffc->size());
+ _bt.verify_single_block((HeapWord*)fc, fc_size);
+ // Push this on "fl".
+ fl->return_chunk_at_head(ffc);
+ }
+ // First chunk
+ assert(fc->is_free() && fc->size() == n*word_sz, "Error: should still be a free block");
+ // The blocks above should show their new sizes before the first block below
+ fc->set_size(word_sz);
+ fc->link_prev(NULL); // idempotent wrt free-ness, see assert above
+ fc->link_next(NULL);
+ _bt.verify_not_unallocated((HeapWord*)fc, fc->size());
+ _bt.verify_single_block((HeapWord*)fc, fc->size());
+ fl->return_chunk_at_head(fc);
+
+ assert((ssize_t)n > 0 && (ssize_t)n == fl->count(), "Incorrect number of blocks");
+ {
+ // Update the stats for this block size.
+ MutexLockerEx x(_indexedFreeListParLocks[word_sz],
+ Mutex::_no_safepoint_check_flag);
+ const ssize_t births = _indexedFreeList[word_sz].split_births() + n;
+ _indexedFreeList[word_sz].set_split_births(births);
+ // ssize_t new_surplus = _indexedFreeList[word_sz].surplus() + n;
+ // _indexedFreeList[word_sz].set_surplus(new_surplus);
+ }
+
+ // TRAP
+ assert(fl->tail()->next() == NULL, "List invariant.");
+}
+
+void CompactibleFreeListSpace:: par_get_chunk_of_blocks(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl) {
+ assert(fl->count() == 0, "Precondition.");
+ assert(word_sz < CompactibleFreeListSpace::IndexSetSize,
+ "Precondition");
+
+ if (par_get_chunk_of_blocks_IFL(word_sz, n, fl)) {
+ // Got it
+ return;
+ }
+
+ // Otherwise, we'll split a block from the dictionary.
+ par_get_chunk_of_blocks_dictionary(word_sz, n, fl);
+}
+
+// Set up the space's par_seq_tasks structure for work claiming
+// for parallel rescan. See CMSParRemarkTask where this is currently used.
+// XXX Need to suitably abstract and generalize this and the next
+// method into one.
+void
+CompactibleFreeListSpace::
+initialize_sequential_subtasks_for_rescan(int n_threads) {
+ // The "size" of each task is fixed according to rescan_task_size.
+ assert(n_threads > 0, "Unexpected n_threads argument");
+ const size_t task_size = rescan_task_size();
+ size_t n_tasks = (used_region().word_size() + task_size - 1)/task_size;
+ assert((n_tasks == 0) == used_region().is_empty(), "n_tasks incorrect");
+ assert(n_tasks == 0 ||
+ ((used_region().start() + (n_tasks - 1)*task_size < used_region().end()) &&
+ (used_region().start() + n_tasks*task_size >= used_region().end())),
+ "n_tasks calculation incorrect");
+ SequentialSubTasksDone* pst = conc_par_seq_tasks();
+ assert(!pst->valid(), "Clobbering existing data?");
+ // Sets the condition for completion of the subtask (how many threads
+ // need to finish in order to be done).
+ pst->set_n_threads(n_threads);
+ pst->set_n_tasks((int)n_tasks);
+}
+
+// Set up the space's par_seq_tasks structure for work claiming
+// for parallel concurrent marking. See CMSConcMarkTask where this is currently used.
+void
+CompactibleFreeListSpace::
+initialize_sequential_subtasks_for_marking(int n_threads,
+ HeapWord* low) {
+ // The "size" of each task is fixed according to rescan_task_size.
+ assert(n_threads > 0, "Unexpected n_threads argument");
+ const size_t task_size = marking_task_size();
+ assert(task_size > CardTableModRefBS::card_size_in_words &&
+ (task_size % CardTableModRefBS::card_size_in_words == 0),
+ "Otherwise arithmetic below would be incorrect");
+ MemRegion span = _gen->reserved();
+ if (low != NULL) {
+ if (span.contains(low)) {
+ // Align low down to a card boundary so that
+ // we can use block_offset_careful() on span boundaries.
+ HeapWord* aligned_low = (HeapWord*)align_size_down((uintptr_t)low,
+ CardTableModRefBS::card_size);
+ // Clip span prefix at aligned_low
+ span = span.intersection(MemRegion(aligned_low, span.end()));
+ } else if (low > span.end()) {
+ span = MemRegion(low, low); // Null region
+ } // else use entire span
+ }
+ assert(span.is_empty() ||
+ ((uintptr_t)span.start() % CardTableModRefBS::card_size == 0),
+ "span should start at a card boundary");
+ size_t n_tasks = (span.word_size() + task_size - 1)/task_size;
+ assert((n_tasks == 0) == span.is_empty(), "Inconsistency");
+ assert(n_tasks == 0 ||
+ ((span.start() + (n_tasks - 1)*task_size < span.end()) &&
+ (span.start() + n_tasks*task_size >= span.end())),
+ "n_tasks calculation incorrect");
+ SequentialSubTasksDone* pst = conc_par_seq_tasks();
+ assert(!pst->valid(), "Clobbering existing data?");
+ // Sets the condition for completion of the subtask (how many threads
+ // need to finish in order to be done).
+ pst->set_n_threads(n_threads);
+ pst->set_n_tasks((int)n_tasks);
+}