Mercurial > hg > truffle
diff src/share/vm/gc_implementation/g1/g1EvacFailure.hpp @ 4783:023652e49ac0
7121496: G1: do the per-region evacuation failure handling work in parallel
Summary: Parallelize the removal of self forwarding pointers etc. by wrapping in a HeapRegion closure, which is then wrapped inside an AbstractGangTask.
Reviewed-by: tonyp, iveresov
author | johnc |
---|---|
date | Fri, 23 Dec 2011 11:14:18 -0800 |
parents | |
children | 2ace1c4ee8da |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/g1/g1EvacFailure.hpp Fri Dec 23 11:14:18 2011 -0800 @@ -0,0 +1,228 @@ +/* + * Copyright (c) 2012, 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. + * + */ + +#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP +#define SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP + +#include "gc_implementation/g1/concurrentMark.inline.hpp" +#include "gc_implementation/g1/dirtyCardQueue.hpp" +#include "gc_implementation/g1/g1CollectedHeap.inline.hpp" +#include "gc_implementation/g1/g1_globals.hpp" +#include "gc_implementation/g1/g1OopClosures.inline.hpp" +#include "gc_implementation/g1/heapRegion.hpp" +#include "gc_implementation/g1/heapRegionRemSet.hpp" +#include "utilities/workgroup.hpp" + +// Closures and tasks associated with any self-forwarding pointers +// installed as a result of an evacuation failure. + +class UpdateRSetDeferred : public OopsInHeapRegionClosure { +private: + G1CollectedHeap* _g1; + DirtyCardQueue *_dcq; + CardTableModRefBS* _ct_bs; + +public: + UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) : + _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {} + + virtual void do_oop(narrowOop* p) { do_oop_work(p); } + virtual void do_oop( oop* p) { do_oop_work(p); } + template <class T> void do_oop_work(T* p) { + assert(_from->is_in_reserved(p), "paranoia"); + if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && + !_from->is_survivor()) { + size_t card_index = _ct_bs->index_for(p); + if (_ct_bs->mark_card_deferred(card_index)) { + _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index)); + } + } + } +}; + +class RemoveSelfForwardPtrObjClosure: public ObjectClosure { +private: + G1CollectedHeap* _g1; + ConcurrentMark* _cm; + HeapRegion* _hr; + size_t _prev_marked_bytes; + size_t _next_marked_bytes; + OopsInHeapRegionClosure *_update_rset_cl; +public: + RemoveSelfForwardPtrObjClosure(G1CollectedHeap* g1, ConcurrentMark* cm, + HeapRegion* hr, + OopsInHeapRegionClosure* update_rset_cl) : + _g1(g1), _cm(cm), _hr(hr), + _update_rset_cl(update_rset_cl), + _prev_marked_bytes(0), _next_marked_bytes(0) {} + + size_t prev_marked_bytes() { return _prev_marked_bytes; } + size_t next_marked_bytes() { return _next_marked_bytes; } + + // <original comment> + // The original idea here was to coalesce evacuated and dead objects. + // However that caused complications with the block offset table (BOT). + // In particular if there were two TLABs, one of them partially refined. + // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~| + // The BOT entries of the unrefined part of TLAB_2 point to the start + // of TLAB_2. If the last object of the TLAB_1 and the first object + // of TLAB_2 are coalesced, then the cards of the unrefined part + // would point into middle of the filler object. + // The current approach is to not coalesce and leave the BOT contents intact. + // </original comment> + // + // We now reset the BOT when we start the object iteration over the + // region and refine its entries for every object we come across. So + // the above comment is not really relevant and we should be able + // to coalesce dead objects if we want to. + void do_object(oop obj) { + HeapWord* obj_addr = (HeapWord*) obj; + assert(_hr->is_in(obj_addr), "sanity"); + size_t obj_size = obj->size(); + + _hr->update_bot_for_object(obj_addr, obj_size); + + if (obj->is_forwarded() && obj->forwardee() == obj) { + // The object failed to move. + assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs."); + _cm->markPrev(obj); + assert(_cm->isPrevMarked(obj), "Should be marked!"); + _prev_marked_bytes += (obj_size * HeapWordSize); + if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) { + _cm->markAndGrayObjectIfNecessary(obj); + } + obj->set_mark(markOopDesc::prototype()); + + // While we were processing RSet buffers during the collection, + // we actually didn't scan any cards on the collection set, + // since we didn't want to update remembered sets with entries + // that point into the collection set, given that live objects + // from the collection set are about to move and such entries + // will be stale very soon. + // This change also dealt with a reliability issue which + // involved scanning a card in the collection set and coming + // across an array that was being chunked and looking malformed. + // The problem is that, if evacuation fails, we might have + // remembered set entries missing given that we skipped cards on + // the collection set. So, we'll recreate such entries now. + + obj->oop_iterate(_update_rset_cl); + assert(_cm->isPrevMarked(obj), "Should be marked!"); + } else { + // The object has been either evacuated or is dead. Fill it with a + // dummy object. + MemRegion mr((HeapWord*)obj, obj_size); + CollectedHeap::fill_with_object(mr); + _cm->clearRangeBothMaps(mr); + } + } +}; + +class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure { + G1CollectedHeap* _g1h; + ConcurrentMark* _cm; + OopsInHeapRegionClosure *_update_rset_cl; + +public: + RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h, + OopsInHeapRegionClosure* update_rset_cl) : + _g1h(g1h), _update_rset_cl(update_rset_cl), + _cm(_g1h->concurrent_mark()) { } + + bool doHeapRegion(HeapRegion *hr) { + assert(!hr->isHumongous(), "sanity"); + assert(hr->in_collection_set(), "bad CS"); + + if (hr->claimHeapRegion(HeapRegion::ParEvacFailureClaimValue)) { + if (hr->evacuation_failed()) { + RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, _update_rset_cl); + + // In the common case (i.e. when there is no evacuation + // failure) we make sure that the following is done when + // the region is freed so that it is "ready-to-go" when it's + // re-allocated. However, when evacuation failure happens, a + // region will remain in the heap and might ultimately be added + // to a CSet in the future. So we have to be careful here and + // make sure the region's RSet is ready for parallel iteration + // whenever this might be required in the future. + hr->rem_set()->reset_for_par_iteration(); + hr->reset_bot(); + _update_rset_cl->set_region(hr); + hr->object_iterate(&rspc); + + // A number of manipulations to make the TAMS for this region + // be the current top, and the marked bytes be the ones observed + // in the iteration. + if (_cm->at_least_one_mark_complete()) { + // The comments below are the postconditions achieved by the + // calls. Note especially the last such condition, which says that + // the count of marked bytes has been properly restored. + hr->note_start_of_marking(false); + // _next_top_at_mark_start == top, _next_marked_bytes == 0 + hr->add_to_marked_bytes(rspc.prev_marked_bytes()); + // _next_marked_bytes == prev_marked_bytes. + hr->note_end_of_marking(); + // _prev_top_at_mark_start == top(), + // _prev_marked_bytes == prev_marked_bytes + } + // If there is no mark in progress, we modified the _next variables + // above needlessly, but harmlessly. + if (_g1h->mark_in_progress()) { + hr->note_start_of_marking(false); + // _next_top_at_mark_start == top, _next_marked_bytes == 0 + // _next_marked_bytes == next_marked_bytes. + } + } + } + return false; + } +}; + +class G1ParRemoveSelfForwardPtrsTask: public AbstractGangTask { +protected: + G1CollectedHeap* _g1h; + +public: + G1ParRemoveSelfForwardPtrsTask(G1CollectedHeap* g1h) : + AbstractGangTask("G1 Remove Self-forwarding Pointers"), + _g1h(g1h) { } + + void work(uint worker_id) { + UpdateRSetImmediate immediate_update(_g1h->g1_rem_set()); + DirtyCardQueue dcq(&_g1h->dirty_card_queue_set()); + UpdateRSetDeferred deferred_update(_g1h, &dcq); + + OopsInHeapRegionClosure *update_rset_cl = &deferred_update; + if (!G1DeferredRSUpdate) { + update_rset_cl = &immediate_update; + } + + RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, update_rset_cl); + + HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id); + _g1h->collection_set_iterate_from(hr, &rsfp_cl); + } +}; + +#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP