jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1EvacFailure.hpp@023652e49ac0 (annotated)

src/share/vm/gc_implementation/g1/g1EvacFailure.hpp@023652e49ac0 (annotated)

src/share/vm/gc_implementation/g1/g1EvacFailure.hpp

Fri, 23 Dec 2011 11:14:18 -0800

author: johnc
date: Fri, 23 Dec 2011 11:14:18 -0800
changeset 3412: 023652e49ac0
child 3416: 2ace1c4ee8da
permissions: -rw-r--r--

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

 /*
  * 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

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1EvacFailure.hpp@023652e49ac0 (annotated)

src/share/vm/gc_implementation/g1/g1EvacFailure.hpp