--- a/src/hotspot/share/gc/cms/compactibleFreeListSpace.cpp Fri Nov 08 14:54:17 2019 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,3141 +0,0 @@
-/*
- * Copyright (c) 2001, 2019, 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/cmsHeap.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/genOopClosures.inline.hpp"
-#include "gc/shared/space.inline.hpp"
-#include "gc/shared/spaceDecorator.inline.hpp"
-#include "logging/log.hpp"
-#include "logging/logStream.hpp"
-#include "memory/allocation.inline.hpp"
-#include "memory/binaryTreeDictionary.inline.hpp"
-#include "memory/iterator.inline.hpp"
-#include "memory/resourceArea.hpp"
-#include "memory/universe.hpp"
-#include "oops/access.inline.hpp"
-#include "oops/compressedOops.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.hpp"
-#include "runtime/vmThread.hpp"
-#include "utilities/align.hpp"
-#include "utilities/copy.hpp"
-
-// Specialize for AdaptiveFreeList which tries to avoid
-// splitting a chunk of a size that is under populated in favor of
-// an over populated size. The general get_better_list() just returns
-// the current list.
-template <>
-TreeList<FreeChunk, AdaptiveFreeList<FreeChunk> >*
-TreeList<FreeChunk, AdaptiveFreeList<FreeChunk> >::get_better_list(
- BinaryTreeDictionary<FreeChunk, ::AdaptiveFreeList<FreeChunk> >* dictionary) {
- // A candidate chunk has been found. If it is already under
- // populated, get a chunk associated with the hint for this
- // chunk.
-
- TreeList<FreeChunk, ::AdaptiveFreeList<FreeChunk> >* curTL = this;
- if (curTL->surplus() <= 0) {
- /* Use the hint to find a size with a surplus, and reset the hint. */
- TreeList<FreeChunk, ::AdaptiveFreeList<FreeChunk> >* hintTL = this;
- while (hintTL->hint() != 0) {
- assert(hintTL->hint() > hintTL->size(),
- "hint points in the wrong direction");
- hintTL = dictionary->find_list(hintTL->hint());
- assert(curTL != hintTL, "Infinite loop");
- if (hintTL == NULL ||
- hintTL == curTL /* Should not happen but protect against it */ ) {
- // No useful hint. Set the hint to NULL and go on.
- curTL->set_hint(0);
- break;
- }
- assert(hintTL->size() > curTL->size(), "hint is inconsistent");
- if (hintTL->surplus() > 0) {
- // The hint led to a list that has a surplus. Use it.
- // Set the hint for the candidate to an overpopulated
- // size.
- curTL->set_hint(hintTL->size());
- // Change the candidate.
- curTL = hintTL;
- break;
- }
- }
- }
- return curTL;
-}
-
-void AFLBinaryTreeDictionary::dict_census_update(size_t size, bool split, bool birth) {
- TreeList<FreeChunk, AdaptiveFreeList<FreeChunk> >* nd = find_list(size);
- if (nd) {
- if (split) {
- if (birth) {
- nd->increment_split_births();
- nd->increment_surplus();
- } else {
- nd->increment_split_deaths();
- nd->decrement_surplus();
- }
- } else {
- if (birth) {
- nd->increment_coal_births();
- nd->increment_surplus();
- } else {
- nd->increment_coal_deaths();
- nd->decrement_surplus();
- }
- }
- }
- // A list for this size may not be found (nd == 0) if
- // This is a death where the appropriate list is now
- // empty and has been removed from the list.
- // This is a birth associated with a LinAB. The chunk
- // for the LinAB is not in the dictionary.
-}
-
-bool AFLBinaryTreeDictionary::coal_dict_over_populated(size_t size) {
- if (FLSAlwaysCoalesceLarge) return true;
-
- TreeList<FreeChunk, AdaptiveFreeList<FreeChunk> >* list_of_size = find_list(size);
- // None of requested size implies overpopulated.
- return list_of_size == NULL || list_of_size->coal_desired() <= 0 ||
- list_of_size->count() > list_of_size->coal_desired();
-}
-
-// For each list in the tree, calculate the desired, desired
-// coalesce, count before sweep, and surplus before sweep.
-class BeginSweepClosure : public AscendTreeCensusClosure<FreeChunk, AdaptiveFreeList<FreeChunk> > {
- double _percentage;
- float _inter_sweep_current;
- float _inter_sweep_estimate;
- float _intra_sweep_estimate;
-
- public:
- BeginSweepClosure(double p, float inter_sweep_current,
- float inter_sweep_estimate,
- float intra_sweep_estimate) :
- _percentage(p),
- _inter_sweep_current(inter_sweep_current),
- _inter_sweep_estimate(inter_sweep_estimate),
- _intra_sweep_estimate(intra_sweep_estimate) { }
-
- void do_list(AdaptiveFreeList<FreeChunk>* fl) {
- double coalSurplusPercent = _percentage;
- fl->compute_desired(_inter_sweep_current, _inter_sweep_estimate, _intra_sweep_estimate);
- fl->set_coal_desired((ssize_t)((double)fl->desired() * coalSurplusPercent));
- fl->set_before_sweep(fl->count());
- fl->set_bfr_surp(fl->surplus());
- }
-};
-
-void AFLBinaryTreeDictionary::begin_sweep_dict_census(double coalSurplusPercent,
- float inter_sweep_current, float inter_sweep_estimate, float intra_sweep_estimate) {
- BeginSweepClosure bsc(coalSurplusPercent, inter_sweep_current,
- inter_sweep_estimate,
- intra_sweep_estimate);
- bsc.do_tree(root());
-}
-
-// Calculate surpluses for the lists in the tree.
-class setTreeSurplusClosure : public AscendTreeCensusClosure<FreeChunk, AdaptiveFreeList<FreeChunk> > {
- double percentage;
- public:
- setTreeSurplusClosure(double v) { percentage = v; }
-
- void do_list(AdaptiveFreeList<FreeChunk>* fl) {
- double splitSurplusPercent = percentage;
- fl->set_surplus(fl->count() -
- (ssize_t)((double)fl->desired() * splitSurplusPercent));
- }
-};
-
-void AFLBinaryTreeDictionary::set_tree_surplus(double splitSurplusPercent) {
- setTreeSurplusClosure sts(splitSurplusPercent);
- sts.do_tree(root());
-}
-
-// Set hints for the lists in the tree.
-class setTreeHintsClosure : public DescendTreeCensusClosure<FreeChunk, AdaptiveFreeList<FreeChunk> > {
- size_t hint;
- public:
- setTreeHintsClosure(size_t v) { hint = v; }
-
- void do_list(AdaptiveFreeList<FreeChunk>* fl) {
- fl->set_hint(hint);
- assert(fl->hint() == 0 || fl->hint() > fl->size(),
- "Current hint is inconsistent");
- if (fl->surplus() > 0) {
- hint = fl->size();
- }
- }
-};
-
-void AFLBinaryTreeDictionary::set_tree_hints(void) {
- setTreeHintsClosure sth(0);
- sth.do_tree(root());
-}
-
-// Save count before previous sweep and splits and coalesces.
-class clearTreeCensusClosure : public AscendTreeCensusClosure<FreeChunk, AdaptiveFreeList<FreeChunk> > {
- void do_list(AdaptiveFreeList<FreeChunk>* fl) {
- 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 AFLBinaryTreeDictionary::clear_tree_census(void) {
- clearTreeCensusClosure ctc;
- ctc.do_tree(root());
-}
-
-// Do reporting and post sweep clean up.
-void AFLBinaryTreeDictionary::end_sweep_dict_census(double splitSurplusPercent) {
- // Does walking the tree 3 times hurt?
- set_tree_surplus(splitSurplusPercent);
- set_tree_hints();
- LogTarget(Trace, gc, freelist, stats) log;
- if (log.is_enabled()) {
- LogStream out(log);
- report_statistics(&out);
- }
- clear_tree_census();
-}
-
-// Print census information - counts, births, deaths, etc.
-// for each list in the tree. Also print some summary
-// information.
-class PrintTreeCensusClosure : public AscendTreeCensusClosure<FreeChunk, AdaptiveFreeList<FreeChunk> > {
- int _print_line;
- size_t _total_free;
- AdaptiveFreeList<FreeChunk> _total;
-
- public:
- PrintTreeCensusClosure() {
- _print_line = 0;
- _total_free = 0;
- }
- AdaptiveFreeList<FreeChunk>* total() { return &_total; }
- size_t total_free() { return _total_free; }
-
- void do_list(AdaptiveFreeList<FreeChunk>* fl) {
- LogStreamHandle(Debug, gc, freelist, census) out;
-
- if (++_print_line >= 40) {
- AdaptiveFreeList<FreeChunk>::print_labels_on(&out, "size");
- _print_line = 0;
- }
- fl->print_on(&out);
- _total_free += fl->count() * fl->size() ;
- total()->set_count( total()->count() + fl->count() );
- total()->set_bfr_surp( total()->bfr_surp() + fl->bfr_surp() );
- total()->set_surplus( total()->split_deaths() + 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_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());
- }
-};
-
-void AFLBinaryTreeDictionary::print_dict_census(outputStream* st) const {
-
- st->print_cr("BinaryTree");
- AdaptiveFreeList<FreeChunk>::print_labels_on(st, "size");
- PrintTreeCensusClosure ptc;
- ptc.do_tree(root());
-
- AdaptiveFreeList<FreeChunk>* total = ptc.total();
- AdaptiveFreeList<FreeChunk>::print_labels_on(st, " ");
- total->print_on(st, "TOTAL\t");
- st->print_cr("total_free(words): " SIZE_FORMAT_W(16) " growth: %8.5f deficit: %8.5f",
- ptc.total_free(),
- (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));
-}
-
-/////////////////////////////////////////////////////////////////////////
-//// 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 CompactibleFreeListSpace::_min_chunk_size_in_bytes = 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.
- _min_chunk_size_in_bytes = align_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) :
- _rescan_task_size(CardTable::card_size_in_words * BitsPerWord *
- CMSRescanMultiple),
- _marking_task_size(CardTable::card_size_in_words * BitsPerWord *
- CMSConcMarkMultiple),
- _bt(bs, mr),
- _collector(NULL),
- // 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_never),
- _preconsumptionDirtyCardClosure(NULL),
- _parDictionaryAllocLock(Mutex::leaf - 1, // == rank(ExpandHeap_lock) - 1
- "CompactibleFreeListSpace_dict_par_lock", true,
- Monitor::_safepoint_check_never)
-{
- assert(sizeof(FreeChunk) / BytesPerWord <= MinChunkSize,
- "FreeChunk is larger than expected");
- _bt.set_space(this);
- initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
-
- _dictionary = new AFLBinaryTreeDictionary(mr);
-
- 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();
-
- _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_never);
- DEBUG_ONLY(
- _indexedFreeList[i].set_protecting_lock(_indexedFreeListParLocks[i]);
- )
- }
- _dictionary->set_par_lock(&_parDictionaryAllocLock);
-
- _used_stable = 0;
-}
-
-// 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 = CMSHeap::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_raw();
- 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");
- }
-}
-
-size_t CompactibleFreeListSpace::obj_size(const HeapWord* addr) const {
- return adjustObjectSize(oop(addr)->size());
-}
-
-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.
- refillLinearAllocBlocksIfNeeded();
-}
-
-// 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::used_stable() const {
- return _used_stable;
-}
-
-void CompactibleFreeListSpace::recalculate_used_stable() {
- _used_stable = used();
-}
-
-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", BOOL_TO_STR(_fitStrategy));
-}
-
-void CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st)
-const {
- reportIndexedFreeListStatistics(st);
- st->print_cr("Layout of Indexed Freelists");
- st->print_cr("---------------------------");
- AdaptiveFreeList<FreeChunk>::print_labels_on(st, "size");
- for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
- _indexedFreeList[i].print_on(st);
- for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL; fc = fc->next()) {
- st->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);
- 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("=========================");
- st->print_cr("Block layout in CMS Heap:");
- st->print_cr("=========================");
- BlkPrintingClosure bpcl(c, this, c->markBitMap(), st);
- blk_iterate(&bpcl);
-
- st->print_cr("=======================================");
- st->print_cr("Order & Layout of Promotion Info Blocks");
- st->print_cr("=======================================");
- print_promo_info_blocks(st);
-
- st->print_cr("===========================");
- st->print_cr("Order of Indexed Free Lists");
- st->print_cr("=========================");
- print_indexed_free_lists(st);
-
- st->print_cr("=================================");
- st->print_cr("Order of Free Lists in Dictionary");
- st->print_cr("=================================");
- print_dictionary_free_lists(st);
-}
-
-
-void CompactibleFreeListSpace::reportFreeListStatistics(const char* title) const {
- assert_lock_strong(&_freelistLock);
- Log(gc, freelist, stats) log;
- if (!log.is_debug()) {
- return;
- }
- log.debug("%s", title);
-
- LogStream out(log.debug());
- _dictionary->report_statistics(&out);
-
- if (log.is_trace()) {
- LogStream trace_out(log.trace());
- reportIndexedFreeListStatistics(&trace_out);
- size_t total_size = totalSizeInIndexedFreeLists() +
- _dictionary->total_chunk_size(DEBUG_ONLY(freelistLock()));
- log.trace(" free=" SIZE_FORMAT " frag=%1.4f", total_size, flsFrag());
- }
-}
-
-void CompactibleFreeListSpace::reportIndexedFreeListStatistics(outputStream* st) const {
- assert_lock_strong(&_freelistLock);
- st->print_cr("Statistics for IndexedFreeLists:");
- st->print_cr("--------------------------------");
- size_t total_size = totalSizeInIndexedFreeLists();
- size_t free_blocks = numFreeBlocksInIndexedFreeLists();
- st->print_cr("Total Free Space: " SIZE_FORMAT, total_size);
- st->print_cr("Max Chunk Size: " SIZE_FORMAT, maxChunkSizeInIndexedFreeLists());
- st->print_cr("Number of Blocks: " SIZE_FORMAT, free_blocks);
- if (free_blocks != 0) {
- st->print_cr("Av. Block Size: " SIZE_FORMAT, 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);
- // 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 FreeListSpaceDCTOC : public FilteringDCTOC {
- CompactibleFreeListSpace* _cfls;
- CMSCollector* _collector;
- bool _parallel;
-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(OopIterateClosure);
- walk_mem_region_with_cl_DECL(FilteringClosure);
-
-public:
- FreeListSpaceDCTOC(CompactibleFreeListSpace* sp,
- CMSCollector* collector,
- OopIterateClosure* cl,
- CardTable::PrecisionStyle precision,
- HeapWord* boundary,
- bool parallel) :
- FilteringDCTOC(sp, cl, precision, boundary),
- _cfls(sp), _collector(collector), _parallel(parallel) {}
-};
-
-// We de-virtualize the block-related calls below, since we know that our
-// space is a CompactibleFreeListSpace.
-
-#define FreeListSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
-void FreeListSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \
- HeapWord* bottom, \
- HeapWord* top, \
- ClosureType* cl) { \
- if (_parallel) { \
- walk_mem_region_with_cl_par(mr, bottom, top, cl); \
- } else { \
- walk_mem_region_with_cl_nopar(mr, bottom, top, cl); \
- } \
-} \
-void FreeListSpaceDCTOC::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_size(cl, mr); \
- bottom += _cfls->adjustObjectSize(word_sz); \
- } else { \
- bottom += _cfls->CompactibleFreeListSpace::block_size(bottom); \
- } \
- } \
-} \
-void FreeListSpaceDCTOC::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_size(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.)
-FreeListSpaceDCTOC__walk_mem_region_with_cl_DEFN(OopIterateClosure)
-FreeListSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
-
-DirtyCardToOopClosure*
-CompactibleFreeListSpace::new_dcto_cl(OopIterateClosure* cl,
- CardTable::PrecisionStyle precision,
- HeapWord* boundary,
- bool parallel) {
- return new FreeListSpaceDCTOC(this, _collector, cl, precision, boundary, parallel);
-}
-
-
-// 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(OopIterateClosure* 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(), align_up(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(),align_up(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 {
- // Ensure klass read before size.
- Klass* k = oop(p)->klass_or_null_acquire();
- if (k != NULL) {
- assert(k->is_klass(), "Should really be klass oop.");
- oop o = (oop)p;
- assert(oopDesc::is_oop(o, true /* ignore mark word */), "Should be an oop.");
-
- 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 {
- // Ensure klass read before size.
- Klass* k = oop(p)->klass_or_null_acquire();
- if (k != NULL) {
- assert(k->is_klass(), "Should really be klass oop.");
- oop o = (oop)p;
- assert(oopDesc::is_oop(o), "Should be an oop");
-
- 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(oopDesc::is_oop(oop(p), 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_acquire();
- 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(oopDesc::is_oop(oop(p), 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(oopDesc::is_oop(oop(p), 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) {
- MutexLocker 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()");
-
- res = allocate_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));
- }
-
- // During GC we do not need to recalculate the stable used value for
- // every allocation in old gen. It is done once at the end of GC instead
- // for performance reasons.
- if (!CMSHeap::heap()->is_gc_active()) {
- recalculate_used_stable();
- }
-
- 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;
- 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(is_object_aligned(currSize), "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.
- MutexLocker 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);
- 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);
- 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);
- 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);
- _indexedFreeList[size].return_chunk_at_tail(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;
- {
- MutexLocker 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];
- }
- MutexLocker 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(is_object_aligned(hint), "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) {
- // The freeList lock is held, but multiple GC task threads might be executing in parallel.
- bool is_par = Thread::current()->is_GC_task_thread();
- if (is_par) _indexedFreeListParLocks[rem_sz]->lock_without_safepoint_check();
- 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();
- reportFreeListStatistics("Before GC:");
- refillLinearAllocBlocksIfNeeded();
-}
-
-void
-CompactibleFreeListSpace::gc_epilogue() {
- assert_locked();
- assert(_promoInfo.noPromotions(), "_promoInfo inconsistency");
- _promoInfo.stopTrackingPromotions();
- repairLinearAllocationBlocks();
- reportFreeListStatistics("After GC:");
-}
-
-// 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),
- " 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?");
- return _promoInfo.noPromotions();
-}
-
-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);
- }
-}
-
-void
-CompactibleFreeListSpace::refillLinearAllocBlock(LinearAllocBlock* blk) {
- assert_locked();
- assert(blk->_word_size == 0 && blk->_ptr == NULL,
- "linear allocation block should be empty");
- FreeChunk* fc;
- if (blk->_refillSize < SmallForDictionary &&
- (fc = getChunkFromIndexedFreeList(blk->_refillSize)) != NULL) {
- // A linAB's strategy might be to use small sizes to reduce
- // fragmentation but still get the benefits of allocation from a
- // linAB.
- } else {
- fc = getChunkFromDictionary(blk->_refillSize);
- }
- if (fc != NULL) {
- blk->_ptr = (HeapWord*)fc;
- blk->_word_size = fc->size();
- fc->dontCoalesce(); // to prevent sweeper from sweeping us up
- }
-}
-
-// Support for compaction
-void CompactibleFreeListSpace::prepare_for_compaction(CompactPoint* cp) {
- scan_and_forward(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];
- log_trace(gc, freelist)("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) {
- log_debug(gc, freelist)("CMS: Large block " PTR_FORMAT, p2i(dictionary()->find_largest_dict()));
- setFLSurplus();
- setFLHints();
- 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(oopDesc::is_oop(p), "Should be an oop");
- res = _sp->adjustObjectSize(p->size());
- if (_sp->obj_is_alive(addr)) {
- was_live = true;
- oopDesc::verify(p);
- }
- } 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) {
- Log(gc, verify) log;
- log.error("Livelock: no rank reduction!");
- log.error(" 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");
- LogStream ls(log.error());
- _sp->print_on(&ls);
- guarantee(false, "Verification failed.");
- }
- _last_addr = addr;
- _last_size = res;
- _last_was_obj = was_obj;
- _last_was_live = was_live;
- return res;
- }
-};
-
-class VerifyAllOopsClosure: public BasicOopIterateClosure {
- 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(oopDesc::is_oop(obj), "Should be an oop");
- oopDesc::verify(obj);
- 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(oopDesc::is_oop(obj), "Should be an oop");
- oopDesc::verify(obj);
- }
- }
-
- template <class T> void do_oop_work(T* p) {
- T heap_oop = RawAccess<>::oop_load(p);
- if (!CompressedOops::is_null(heap_oop)) {
- oop obj = CompressedOops::decode_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.
- CMSHeap::heap()->oop_iterate(&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);
- LogTarget(Debug, gc, freelist, census) log;
- if (!log.is_enabled()) {
- return;
- }
- AdaptiveFreeList<FreeChunk> total;
- log.print("end sweep# " SIZE_FORMAT, sweep_count);
- ResourceMark rm;
- LogStream ls(log);
- outputStream* out = &ls;
- AdaptiveFreeList<FreeChunk>::print_labels_on(out, "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(out, "size");
- }
- fl->print_on(out);
- 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(out, "TOTAL");
- log.print("Total free in indexed lists " SIZE_FORMAT " words", total_free);
- log.print("growth: %8.5f deficit: %8.5f",
- (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(out);
-}
-
-///////////////////////////////////////////////////////////////////////////
-// CompactibleFreeListSpaceLAB
-///////////////////////////////////////////////////////////////////////////
-
-#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 CompactibleFreeListSpaceLAB::_blocks_to_claim[] =
- VECTOR_257(AdaptiveWeightedAverage(OldPLABWeight, (float)CompactibleFreeListSpaceLAB::_default_dynamic_old_plab_size));
-size_t CompactibleFreeListSpaceLAB::_global_num_blocks[] = VECTOR_257(0);
-uint CompactibleFreeListSpaceLAB::_global_num_workers[] = VECTOR_257(0);
-
-CompactibleFreeListSpaceLAB::CompactibleFreeListSpaceLAB(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 CompactibleFreeListSpaceLAB::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* CompactibleFreeListSpaceLAB::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.
- MutexLocker 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 CompactibleFreeListSpaceLAB::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) {
- //
- // On a 32-bit VM, the denominator can become zero because of integer overflow,
- // which is why there is a cast to double.
- //
- size_t multiple = (size_t) (_num_blocks[word_sz]/(((double)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 CompactibleFreeListSpaceLAB::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;
- log_trace(gc, plab)("[" 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 CompactibleFreeListSpaceLAB::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");
- {
- // MutexLocker 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);
- }
- }
- log_trace(gc, plab)("%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);
- {
- MutexLocker 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();
- MutexLocker 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;
- {
- MutexLocker x(parDictionaryAllocLock(),
- Mutex::_no_safepoint_check_flag);
- while (n > 0) {
- fc = dictionary()->get_chunk(MAX2(n * word_sz, _dictionary->min_size()));
- 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) {
- MutexLocker 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(),
- "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.
- MutexLocker 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);
-}
-
-const size_t CompactibleFreeListSpace::max_flag_size_for_task_size() const {
- const size_t ergo_max = _old_gen->reserved().word_size() / (CardTable::card_size_in_words * BitsPerWord);
- return ergo_max;
-}
-
-// 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 > CardTable::card_size_in_words &&
- (task_size % CardTable::card_size_in_words == 0),
- "Otherwise arithmetic below would be incorrect");
- MemRegion span = _old_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 = align_down(low, CardTable::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() % CardTable::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);
-}