jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1RemSet.cpp@5f429ee79634 (annotated)

src/share/vm/gc_implementation/g1/g1RemSet.cpp@5f429ee79634 (annotated)

src/share/vm/gc_implementation/g1/g1RemSet.cpp

Mon, 09 Aug 2010 05:41:05 -0700

author: jcoomes
date: Mon, 09 Aug 2010 05:41:05 -0700
changeset 2064: 5f429ee79634
parent 2063: a03ae377b2e8
child 2188: 8b10f48633dc
permissions: -rw-r--r--

6966222: G1: simplify TaskQueue overflow handling
Reviewed-by: tonyp, ysr

 /*
  * Copyright (c) 2001, 2010, 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 "incls/_precompiled.incl"
 #include "incls/_g1RemSet.cpp.incl"
 #define CARD_REPEAT_HISTO 0
 #if CARD_REPEAT_HISTO
 static size_t ct_freq_sz;
 static jbyte* ct_freq = NULL;
 void init_ct_freq_table(size_t heap_sz_bytes) {
   if (ct_freq == NULL) {
     ct_freq_sz = heap_sz_bytes/CardTableModRefBS::card_size;
     ct_freq = new jbyte[ct_freq_sz];
     for (size_t j = 0; j < ct_freq_sz; j++) ct_freq[j] = 0;
   }
 }
 void ct_freq_note_card(size_t index) {
   assert(0 <= index && index < ct_freq_sz, "Bounds error.");
   if (ct_freq[index] < 100) { ct_freq[index]++; }
 }
 static IntHistogram card_repeat_count(10, 10);
 void ct_freq_update_histo_and_reset() {
   for (size_t j = 0; j < ct_freq_sz; j++) {
     card_repeat_count.add_entry(ct_freq[j]);
     ct_freq[j] = 0;
   }
 }
 #endif
 class IntoCSOopClosure: public OopsInHeapRegionClosure {
   OopsInHeapRegionClosure* _blk;
   G1CollectedHeap* _g1;
 public:
   IntoCSOopClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* blk) :
     _g1(g1), _blk(blk) {}
   void set_region(HeapRegion* from) {
     _blk->set_region(from);
   }
   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) {
     oop obj = oopDesc::load_decode_heap_oop(p);
     if (_g1->obj_in_cs(obj)) _blk->do_oop(p);
   }
   bool apply_to_weak_ref_discovered_field() { return true; }
   bool idempotent() { return true; }
 };
 class IntoCSRegionClosure: public HeapRegionClosure {
   IntoCSOopClosure _blk;
   G1CollectedHeap* _g1;
 public:
   IntoCSRegionClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* blk) :
     _g1(g1), _blk(g1, blk) {}
   bool doHeapRegion(HeapRegion* r) {
     if (!r->in_collection_set()) {
       _blk.set_region(r);
       if (r->isHumongous()) {
         if (r->startsHumongous()) {
           oop obj = oop(r->bottom());
           obj->oop_iterate(&_blk);
         }
       } else {
         r->oop_before_save_marks_iterate(&_blk);
       }
     }
     return false;
   }
 };
 void
 StupidG1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc,
                                             int worker_i) {
   IntoCSRegionClosure rc(_g1, oc);
   _g1->heap_region_iterate(&rc);
 }
 class VerifyRSCleanCardOopClosure: public OopClosure {
   G1CollectedHeap* _g1;
 public:
   VerifyRSCleanCardOopClosure(G1CollectedHeap* g1) : _g1(g1) {}
   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) {
     oop obj = oopDesc::load_decode_heap_oop(p);
     HeapRegion* to = _g1->heap_region_containing(obj);
     guarantee(to == NULL || !to->in_collection_set(),
               "Missed a rem set member.");
   }
 };
 HRInto_G1RemSet::HRInto_G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs)
   : G1RemSet(g1), _ct_bs(ct_bs), _g1p(_g1->g1_policy()),
     _cg1r(g1->concurrent_g1_refine()),
     _traversal_in_progress(false),
     _cset_rs_update_cl(NULL),
     _cards_scanned(NULL), _total_cards_scanned(0)
 {
   _seq_task = new SubTasksDone(NumSeqTasks);
   guarantee(n_workers() > 0, "There should be some workers");
   _cset_rs_update_cl = NEW_C_HEAP_ARRAY(OopsInHeapRegionClosure*, n_workers());
   for (uint i = 0; i < n_workers(); i++) {
     _cset_rs_update_cl[i] = NULL;
   }
 }
 HRInto_G1RemSet::~HRInto_G1RemSet() {
   delete _seq_task;
   for (uint i = 0; i < n_workers(); i++) {
     assert(_cset_rs_update_cl[i] == NULL, "it should be");
   }
   FREE_C_HEAP_ARRAY(OopsInHeapRegionClosure*, _cset_rs_update_cl);
 }
 void CountNonCleanMemRegionClosure::do_MemRegion(MemRegion mr) {
   if (_g1->is_in_g1_reserved(mr.start())) {
     _n += (int) ((mr.byte_size() / CardTableModRefBS::card_size));
     if (_start_first == NULL) _start_first = mr.start();
   }
 }
 class ScanRSClosure : public HeapRegionClosure {
   size_t _cards_done, _cards;
   G1CollectedHeap* _g1h;
   OopsInHeapRegionClosure* _oc;
   G1BlockOffsetSharedArray* _bot_shared;
   CardTableModRefBS *_ct_bs;
   int _worker_i;
   int _block_size;
   bool _try_claimed;
 public:
   ScanRSClosure(OopsInHeapRegionClosure* oc, int worker_i) :
     _oc(oc),
     _cards(0),
     _cards_done(0),
     _worker_i(worker_i),
     _try_claimed(false)
   {
     _g1h = G1CollectedHeap::heap();
     _bot_shared = _g1h->bot_shared();
     _ct_bs = (CardTableModRefBS*) (_g1h->barrier_set());
     _block_size = MAX2<int>(G1RSetScanBlockSize, 1);
   }
   void set_try_claimed() { _try_claimed = true; }
   void scanCard(size_t index, HeapRegion *r) {
     _cards_done++;
     DirtyCardToOopClosure* cl =
       r->new_dcto_closure(_oc,
                          CardTableModRefBS::Precise,
                          HeapRegionDCTOC::IntoCSFilterKind);
     // Set the "from" region in the closure.
     _oc->set_region(r);
     HeapWord* card_start = _bot_shared->address_for_index(index);
     HeapWord* card_end = card_start + G1BlockOffsetSharedArray::N_words;
     Space *sp = SharedHeap::heap()->space_containing(card_start);
     MemRegion sm_region;
     if (ParallelGCThreads > 0) {
       // first find the used area
       sm_region = sp->used_region_at_save_marks();
     } else {
       // The closure is not idempotent.  We shouldn't look at objects
       // allocated during the GC.
       sm_region = sp->used_region_at_save_marks();
     }
     MemRegion mr = sm_region.intersection(MemRegion(card_start,card_end));
     if (!mr.is_empty()) {
       cl->do_MemRegion(mr);
     }
   }
   void printCard(HeapRegion* card_region, size_t card_index,
                  HeapWord* card_start) {
     gclog_or_tty->print_cr("T %d Region [" PTR_FORMAT ", " PTR_FORMAT ") "
                            "RS names card %p: "
                            "[" PTR_FORMAT ", " PTR_FORMAT ")",
                            _worker_i,
                            card_region->bottom(), card_region->end(),
                            card_index,
                            card_start, card_start + G1BlockOffsetSharedArray::N_words);
   }
   bool doHeapRegion(HeapRegion* r) {
     assert(r->in_collection_set(), "should only be called on elements of CS.");
     HeapRegionRemSet* hrrs = r->rem_set();
     if (hrrs->iter_is_complete()) return false; // All done.
     if (!_try_claimed && !hrrs->claim_iter()) return false;
     _g1h->push_dirty_cards_region(r);
     // If we didn't return above, then
     //   _try_claimed || r->claim_iter()
     // is true: either we're supposed to work on claimed-but-not-complete
     // regions, or we successfully claimed the region.
     HeapRegionRemSetIterator* iter = _g1h->rem_set_iterator(_worker_i);
     hrrs->init_iterator(iter);
     size_t card_index;
     // We claim cards in block so as to recude the contention. The block size is determined by
     // the G1RSetScanBlockSize parameter.
     size_t jump_to_card = hrrs->iter_claimed_next(_block_size);
     for (size_t current_card = 0; iter->has_next(card_index); current_card++) {
       if (current_card >= jump_to_card + _block_size) {
         jump_to_card = hrrs->iter_claimed_next(_block_size);
       }
       if (current_card < jump_to_card) continue;
       HeapWord* card_start = _g1h->bot_shared()->address_for_index(card_index);
 #if 0
       gclog_or_tty->print("Rem set iteration yielded card [" PTR_FORMAT ", " PTR_FORMAT ").\n",
                           card_start, card_start + CardTableModRefBS::card_size_in_words);
 #endif
       HeapRegion* card_region = _g1h->heap_region_containing(card_start);
       assert(card_region != NULL, "Yielding cards not in the heap?");
       _cards++;
       if (!card_region->is_on_dirty_cards_region_list()) {
         _g1h->push_dirty_cards_region(card_region);
       }
        // If the card is dirty, then we will scan it during updateRS.
       if (!card_region->in_collection_set() && !_ct_bs->is_card_dirty(card_index)) {
         // We make the card as "claimed" lazily (so races are possible but they're benign),
         // which reduces the number of duplicate scans (the rsets of the regions in the cset
         // can intersect).
         if (!_ct_bs->is_card_claimed(card_index)) {
           _ct_bs->set_card_claimed(card_index);
           scanCard(card_index, card_region);
         }
       }
     }
     if (!_try_claimed) {
       hrrs->set_iter_complete();
     }
     return false;
   }
   // Set all cards back to clean.
   void cleanup() {_g1h->cleanUpCardTable();}
   size_t cards_done() { return _cards_done;}
   size_t cards_looked_up() { return _cards;}
 };
 // We want the parallel threads to start their scanning at
 // different collection set regions to avoid contention.
 // If we have:
 //          n collection set regions
 //          p threads
 // Then thread t will start at region t * floor (n/p)
 HeapRegion* HRInto_G1RemSet::calculateStartRegion(int worker_i) {
   HeapRegion* result = _g1p->collection_set();
   if (ParallelGCThreads > 0) {
     size_t cs_size = _g1p->collection_set_size();
     int n_workers = _g1->workers()->total_workers();
     size_t cs_spans = cs_size / n_workers;
     size_t ind      = cs_spans * worker_i;
     for (size_t i = 0; i < ind; i++)
       result = result->next_in_collection_set();
   }
   return result;
 }
 void HRInto_G1RemSet::scanRS(OopsInHeapRegionClosure* oc, int worker_i) {
   double rs_time_start = os::elapsedTime();
   HeapRegion *startRegion = calculateStartRegion(worker_i);
   ScanRSClosure scanRScl(oc, worker_i);
   _g1->collection_set_iterate_from(startRegion, &scanRScl);
   scanRScl.set_try_claimed();
   _g1->collection_set_iterate_from(startRegion, &scanRScl);
   double scan_rs_time_sec = os::elapsedTime() - rs_time_start;
   assert( _cards_scanned != NULL, "invariant" );
   _cards_scanned[worker_i] = scanRScl.cards_done();
   _g1p->record_scan_rs_time(worker_i, scan_rs_time_sec * 1000.0);
 }
 // Closure used for updating RSets and recording references that
 // point into the collection set. Only called during an
 // evacuation pause.
 class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure {
   G1RemSet* _g1rs;
   DirtyCardQueue* _into_cset_dcq;
 public:
   RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h,
                                               DirtyCardQueue* into_cset_dcq) :
     _g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq)
   {}
   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
     // The only time we care about recording cards that
     // contain references that point into the collection set
     // is during RSet updating within an evacuation pause.
     // In this case worker_i should be the id of a GC worker thread.
     assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
     assert(worker_i < (int) DirtyCardQueueSet::num_par_ids(), "should be a GC worker");
     if (_g1rs->concurrentRefineOneCard(card_ptr, worker_i, true)) {
       // 'card_ptr' contains references that point into the collection
       // set. We need to record the card in the DCQS
       // (G1CollectedHeap::into_cset_dirty_card_queue_set())
       // that's used for that purpose.
       //
       // Enqueue the card
       _into_cset_dcq->enqueue(card_ptr);
     }
     return true;
   }
 };
 void HRInto_G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, int worker_i) {
   double start = os::elapsedTime();
   // Apply the given closure to all remaining log entries.
   RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq);
   _g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i);
   // Now there should be no dirty cards.
   if (G1RSLogCheckCardTable) {
     CountNonCleanMemRegionClosure cl(_g1);
     _ct_bs->mod_card_iterate(&cl);
     // XXX This isn't true any more: keeping cards of young regions
     // marked dirty broke it.  Need some reasonable fix.
     guarantee(cl.n() == 0, "Card table should be clean.");
   }
   _g1p->record_update_rs_time(worker_i, (os::elapsedTime() - start) * 1000.0);
 }
 #ifndef PRODUCT
 class PrintRSClosure : public HeapRegionClosure {
   int _count;
 public:
   PrintRSClosure() : _count(0) {}
   bool doHeapRegion(HeapRegion* r) {
     HeapRegionRemSet* hrrs = r->rem_set();
     _count += (int) hrrs->occupied();
     if (hrrs->occupied() == 0) {
       gclog_or_tty->print("Heap Region [" PTR_FORMAT ", " PTR_FORMAT ") "
                           "has no remset entries\n",
                           r->bottom(), r->end());
     } else {
       gclog_or_tty->print("Printing rem set for heap region [" PTR_FORMAT ", " PTR_FORMAT ")\n",
                           r->bottom(), r->end());
       r->print();
       hrrs->print();
       gclog_or_tty->print("\nDone printing rem set\n");
     }
     return false;
   }
   int occupied() {return _count;}
 };
 #endif
 class CountRSSizeClosure: public HeapRegionClosure {
   size_t _n;
   size_t _tot;
   size_t _max;
   HeapRegion* _max_r;
   enum {
     N = 20,
     MIN = 6
   };
   int _histo[N];
 public:
   CountRSSizeClosure() : _n(0), _tot(0), _max(0), _max_r(NULL) {
     for (int i = 0; i < N; i++) _histo[i] = 0;
   }
   bool doHeapRegion(HeapRegion* r) {
     if (!r->continuesHumongous()) {
       size_t occ = r->rem_set()->occupied();
       _n++;
       _tot += occ;
       if (occ > _max) {
         _max = occ;
         _max_r = r;
       }
       // Fit it into a histo bin.
       int s = 1 << MIN;
       int i = 0;
       while (occ > (size_t) s && i < (N-1)) {
         s = s << 1;
         i++;
       }
       _histo[i]++;
     }
     return false;
   }
   size_t n() { return _n; }
   size_t tot() { return _tot; }
   size_t mx() { return _max; }
   HeapRegion* mxr() { return _max_r; }
   void print_histo() {
     int mx = N;
     while (mx >= 0) {
       if (_histo[mx-1] > 0) break;
       mx--;
     }
     gclog_or_tty->print_cr("Number of regions with given RS sizes:");
     gclog_or_tty->print_cr("           <= %8d   %8d", 1 << MIN, _histo[0]);
     for (int i = 1; i < mx-1; i++) {
       gclog_or_tty->print_cr("  %8d  - %8d   %8d",
                     (1 << (MIN + i - 1)) + 1,
 << (MIN + i),
                     _histo[i]);
     }
     gclog_or_tty->print_cr("            > %8d   %8d", (1 << (MIN+mx-2))+1, _histo[mx-1]);
   }
 };
 void HRInto_G1RemSet::cleanupHRRS() {
   HeapRegionRemSet::cleanup();
 }
 void
 HRInto_G1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc,
                                              int worker_i) {
 #if CARD_REPEAT_HISTO
   ct_freq_update_histo_and_reset();
 #endif
   if (worker_i == 0) {
     _cg1r->clear_and_record_card_counts();
   }
   // Make this into a command-line flag...
   if (G1RSCountHisto && (ParallelGCThreads == 0 || worker_i == 0)) {
     CountRSSizeClosure count_cl;
     _g1->heap_region_iterate(&count_cl);
     gclog_or_tty->print_cr("Avg of %d RS counts is %f, max is %d, "
                   "max region is " PTR_FORMAT,
                   count_cl.n(), (float)count_cl.tot()/(float)count_cl.n(),
                   count_cl.mx(), count_cl.mxr());
     count_cl.print_histo();
   }
   // We cache the value of 'oc' closure into the appropriate slot in the
   // _cset_rs_update_cl for this worker
   assert(worker_i < (int)n_workers(), "sanity");
   _cset_rs_update_cl[worker_i] = oc;
   // A DirtyCardQueue that is used to hold cards containing references
   // that point into the collection set. This DCQ is associated with a
   // special DirtyCardQueueSet (see g1CollectedHeap.hpp).  Under normal
   // circumstances (i.e. the pause successfully completes), these cards
   // are just discarded (there's no need to update the RSets of regions
   // that were in the collection set - after the pause these regions
   // are wholly 'free' of live objects. In the event of an evacuation
   // failure the cards/buffers in this queue set are:
   // * passed to the DirtyCardQueueSet that is used to manage deferred
   //   RSet updates, or
   // * scanned for references that point into the collection set
   //   and the RSet of the corresponding region in the collection set
   //   is updated immediately.
   DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
   assert((ParallelGCThreads > 0) || worker_i == 0, "invariant");
   // The two flags below were introduced temporarily to serialize
   // the updating and scanning of remembered sets. There are some
   // race conditions when these two operations are done in parallel
   // and they are causing failures. When we resolve said race
   // conditions, we'll revert back to parallel remembered set
   // updating and scanning. See CRs 6677707 and 6677708.
   if (G1UseParallelRSetUpdating || (worker_i == 0)) {
     updateRS(&into_cset_dcq, worker_i);
   } else {
     _g1p->record_update_rs_processed_buffers(worker_i, 0.0);
     _g1p->record_update_rs_time(worker_i, 0.0);
   }
   if (G1UseParallelRSetScanning || (worker_i == 0)) {
     scanRS(oc, worker_i);
   } else {
     _g1p->record_scan_rs_time(worker_i, 0.0);
   }
   // We now clear the cached values of _cset_rs_update_cl for this worker
   _cset_rs_update_cl[worker_i] = NULL;
 }
 void HRInto_G1RemSet::
 prepare_for_oops_into_collection_set_do() {
 #if G1_REM_SET_LOGGING
   PrintRSClosure cl;
   _g1->collection_set_iterate(&cl);
 #endif
   cleanupHRRS();
   ConcurrentG1Refine* cg1r = _g1->concurrent_g1_refine();
   _g1->set_refine_cte_cl_concurrency(false);
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   dcqs.concatenate_logs();
   assert(!_traversal_in_progress, "Invariant between iterations.");
   set_traversal(true);
   if (ParallelGCThreads > 0) {
     _seq_task->set_par_threads((int)n_workers());
   }
   guarantee( _cards_scanned == NULL, "invariant" );
   _cards_scanned = NEW_C_HEAP_ARRAY(size_t, n_workers());
   for (uint i = 0; i < n_workers(); ++i) {
     _cards_scanned[i] = 0;
   }
   _total_cards_scanned = 0;
 }
 class cleanUpIteratorsClosure : public HeapRegionClosure {
   bool doHeapRegion(HeapRegion *r) {
     HeapRegionRemSet* hrrs = r->rem_set();
     hrrs->init_for_par_iteration();
     return false;
   }
 };
 // This closure, applied to a DirtyCardQueueSet, is used to immediately
 // update the RSets for the regions in the CSet. For each card it iterates
 // through the oops which coincide with that card. It scans the reference
 // fields in each oop; when it finds an oop that points into the collection
 // set, the RSet for the region containing the referenced object is updated.
 // Note: _par_traversal_in_progress in the G1RemSet must be FALSE; otherwise
 // the UpdateRSetImmediate closure will cause cards to be enqueued on to
 // the DCQS that we're iterating over, causing an infinite loop.
 class UpdateRSetCardTableEntryIntoCSetClosure: public CardTableEntryClosure {
   G1CollectedHeap* _g1;
   CardTableModRefBS* _ct_bs;
 public:
   UpdateRSetCardTableEntryIntoCSetClosure(G1CollectedHeap* g1,
                                           CardTableModRefBS* bs):
     _g1(g1), _ct_bs(bs)
   { }
   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
     // Construct the region representing the card.
     HeapWord* start = _ct_bs->addr_for(card_ptr);
     // And find the region containing it.
     HeapRegion* r = _g1->heap_region_containing(start);
     assert(r != NULL, "unexpected null");
     // Scan oops in the card looking for references into the collection set
     HeapWord* end   = _ct_bs->addr_for(card_ptr + 1);
     MemRegion scanRegion(start, end);
     UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set());
     FilterIntoCSClosure update_rs_cset_oop_cl(NULL, _g1, &update_rs_cl);
     FilterOutOfRegionClosure filter_then_update_rs_cset_oop_cl(r, &update_rs_cset_oop_cl);
     // We can pass false as the "filter_young" parameter here as:
     // * we should be in a STW pause,
     // * the DCQS to which this closure is applied is used to hold
     //   references that point into the collection set from the prior
     //   RSet updating,
     // * the post-write barrier shouldn't be logging updates to young
     //   regions (but there is a situation where this can happen - see
     //   the comment in HRInto_G1RemSet::concurrentRefineOneCard below -
     //   that should not be applicable here), and
     // * during actual RSet updating, the filtering of cards in young
     //   regions in HeapRegion::oops_on_card_seq_iterate_careful is
     //   employed.
     // As a result, when this closure is applied to "refs into cset"
     // DCQS, we shouldn't see any cards in young regions.
     update_rs_cl.set_region(r);
     HeapWord* stop_point =
       r->oops_on_card_seq_iterate_careful(scanRegion,
                                         &filter_then_update_rs_cset_oop_cl,
                                         false /* filter_young */);
     // Since this is performed in the event of an evacuation failure, we
     // we shouldn't see a non-null stop point
     assert(stop_point == NULL, "saw an unallocated region");
     return true;
   }
 };
 void HRInto_G1RemSet::cleanup_after_oops_into_collection_set_do() {
   guarantee( _cards_scanned != NULL, "invariant" );
   _total_cards_scanned = 0;
   for (uint i = 0; i < n_workers(); ++i)
     _total_cards_scanned += _cards_scanned[i];
   FREE_C_HEAP_ARRAY(size_t, _cards_scanned);
   _cards_scanned = NULL;
   // Cleanup after copy
 #if G1_REM_SET_LOGGING
   PrintRSClosure cl;
   _g1->heap_region_iterate(&cl);
 #endif
   _g1->set_refine_cte_cl_concurrency(true);
   cleanUpIteratorsClosure iterClosure;
   _g1->collection_set_iterate(&iterClosure);
   // Set all cards back to clean.
   _g1->cleanUpCardTable();
   set_traversal(false);
   DirtyCardQueueSet& into_cset_dcqs = _g1->into_cset_dirty_card_queue_set();
   int into_cset_n_buffers = into_cset_dcqs.completed_buffers_num();
   if (_g1->evacuation_failed()) {
     // Restore remembered sets for the regions pointing into the collection set.
     if (G1DeferredRSUpdate) {
       // If deferred RS updates are enabled then we just need to transfer
       // the completed buffers from (a) the DirtyCardQueueSet used to hold
       // cards that contain references that point into the collection set
       // to (b) the DCQS used to hold the deferred RS updates
       _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs);
     } else {
       CardTableModRefBS* bs = (CardTableModRefBS*)_g1->barrier_set();
       UpdateRSetCardTableEntryIntoCSetClosure update_rs_cset_immediate(_g1, bs);
       int n_completed_buffers = 0;
       while (into_cset_dcqs.apply_closure_to_completed_buffer(&update_rs_cset_immediate,
 , 0, true)) {
         n_completed_buffers++;
       }
       assert(n_completed_buffers == into_cset_n_buffers, "missed some buffers");
     }
   }
   // Free any completed buffers in the DirtyCardQueueSet used to hold cards
   // which contain references that point into the collection.
   _g1->into_cset_dirty_card_queue_set().clear();
   assert(_g1->into_cset_dirty_card_queue_set().completed_buffers_num() == 0,
          "all buffers should be freed");
   _g1->into_cset_dirty_card_queue_set().clear_n_completed_buffers();
   assert(!_traversal_in_progress, "Invariant between iterations.");
 }
 class UpdateRSObjectClosure: public ObjectClosure {
   UpdateRSOopClosure* _update_rs_oop_cl;
 public:
   UpdateRSObjectClosure(UpdateRSOopClosure* update_rs_oop_cl) :
     _update_rs_oop_cl(update_rs_oop_cl) {}
   void do_object(oop obj) {
     obj->oop_iterate(_update_rs_oop_cl);
   }
 };
 class ScrubRSClosure: public HeapRegionClosure {
   G1CollectedHeap* _g1h;
   BitMap* _region_bm;
   BitMap* _card_bm;
   CardTableModRefBS* _ctbs;
 public:
   ScrubRSClosure(BitMap* region_bm, BitMap* card_bm) :
     _g1h(G1CollectedHeap::heap()),
     _region_bm(region_bm), _card_bm(card_bm),
     _ctbs(NULL)
   {
     ModRefBarrierSet* bs = _g1h->mr_bs();
     guarantee(bs->is_a(BarrierSet::CardTableModRef), "Precondition");
     _ctbs = (CardTableModRefBS*)bs;
   }
   bool doHeapRegion(HeapRegion* r) {
     if (!r->continuesHumongous()) {
       r->rem_set()->scrub(_ctbs, _region_bm, _card_bm);
     }
     return false;
   }
 };
 void HRInto_G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm) {
   ScrubRSClosure scrub_cl(region_bm, card_bm);
   _g1->heap_region_iterate(&scrub_cl);
 }
 void HRInto_G1RemSet::scrub_par(BitMap* region_bm, BitMap* card_bm,
                                 int worker_num, int claim_val) {
   ScrubRSClosure scrub_cl(region_bm, card_bm);
   _g1->heap_region_par_iterate_chunked(&scrub_cl, worker_num, claim_val);
 }
 static IntHistogram out_of_histo(50, 50);
 class TriggerClosure : public OopClosure {
   bool _trigger;
 public:
   TriggerClosure() : _trigger(false) { }
   bool value() const { return _trigger; }
   template <class T> void do_oop_nv(T* p) { _trigger = true; }
   virtual void do_oop(oop* p)        { do_oop_nv(p); }
   virtual void do_oop(narrowOop* p)  { do_oop_nv(p); }
 };
 class InvokeIfNotTriggeredClosure: public OopClosure {
   TriggerClosure* _t;
   OopClosure* _oc;
 public:
   InvokeIfNotTriggeredClosure(TriggerClosure* t, OopClosure* oc):
     _t(t), _oc(oc) { }
   template <class T> void do_oop_nv(T* p) {
     if (!_t->value()) _oc->do_oop(p);
   }
   virtual void do_oop(oop* p)        { do_oop_nv(p); }
   virtual void do_oop(narrowOop* p)  { do_oop_nv(p); }
 };
 class Mux2Closure : public OopClosure {
   OopClosure* _c1;
   OopClosure* _c2;
 public:
   Mux2Closure(OopClosure *c1, OopClosure *c2) : _c1(c1), _c2(c2) { }
   template <class T> void do_oop_nv(T* p) {
     _c1->do_oop(p); _c2->do_oop(p);
   }
   virtual void do_oop(oop* p)        { do_oop_nv(p); }
   virtual void do_oop(narrowOop* p)  { do_oop_nv(p); }
 };
 bool HRInto_G1RemSet::concurrentRefineOneCard_impl(jbyte* card_ptr, int worker_i,
                                                    bool check_for_refs_into_cset) {
   // Construct the region representing the card.
   HeapWord* start = _ct_bs->addr_for(card_ptr);
   // And find the region containing it.
   HeapRegion* r = _g1->heap_region_containing(start);
   assert(r != NULL, "unexpected null");
   HeapWord* end   = _ct_bs->addr_for(card_ptr + 1);
   MemRegion dirtyRegion(start, end);
 #if CARD_REPEAT_HISTO
   init_ct_freq_table(_g1->g1_reserved_obj_bytes());
   ct_freq_note_card(_ct_bs->index_for(start));
 #endif
   UpdateRSOopClosure update_rs_oop_cl(this, worker_i);
   update_rs_oop_cl.set_from(r);
   TriggerClosure trigger_cl;
   FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl);
   InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl);
   Mux2Closure mux(&invoke_cl, &update_rs_oop_cl);
   FilterOutOfRegionClosure filter_then_update_rs_oop_cl(r,
                         (check_for_refs_into_cset ?
                                 (OopClosure*)&mux :
                                 (OopClosure*)&update_rs_oop_cl));
   // Undirty the card.
   *card_ptr = CardTableModRefBS::clean_card_val();
   // We must complete this write before we do any of the reads below.
   OrderAccess::storeload();
   // And process it, being careful of unallocated portions of TLAB's.
   // The region for the current card may be a young region. The
   // current card may have been a card that was evicted from the
   // card cache. When the card was inserted into the cache, we had
   // determined that its region was non-young. While in the cache,
   // the region may have been freed during a cleanup pause, reallocated
   // and tagged as young.
   //
   // We wish to filter out cards for such a region but the current
   // thread, if we're running conucrrently, may "see" the young type
   // change at any time (so an earlier "is_young" check may pass or
   // fail arbitrarily). We tell the iteration code to perform this
   // filtering when it has been determined that there has been an actual
   // allocation in this region and making it safe to check the young type.
   bool filter_young = true;
   HeapWord* stop_point =
     r->oops_on_card_seq_iterate_careful(dirtyRegion,
                                         &filter_then_update_rs_oop_cl,
                                         filter_young);
   // If stop_point is non-null, then we encountered an unallocated region
   // (perhaps the unfilled portion of a TLAB.)  For now, we'll dirty the
   // card and re-enqueue: if we put off the card until a GC pause, then the
   // unallocated portion will be filled in.  Alternatively, we might try
   // the full complexity of the technique used in "regular" precleaning.
   if (stop_point != NULL) {
     // The card might have gotten re-dirtied and re-enqueued while we
     // worked.  (In fact, it's pretty likely.)
     if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
       *card_ptr = CardTableModRefBS::dirty_card_val();
       MutexLockerEx x(Shared_DirtyCardQ_lock,
                       Mutex::_no_safepoint_check_flag);
       DirtyCardQueue* sdcq =
         JavaThread::dirty_card_queue_set().shared_dirty_card_queue();
       sdcq->enqueue(card_ptr);
     }
   } else {
     out_of_histo.add_entry(filter_then_update_rs_oop_cl.out_of_region());
     _conc_refine_cards++;
   }
   return trigger_cl.value();
 }
 bool HRInto_G1RemSet::concurrentRefineOneCard(jbyte* card_ptr, int worker_i,
                                               bool check_for_refs_into_cset) {
   // If the card is no longer dirty, nothing to do.
   if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
     // No need to return that this card contains refs that point
     // into the collection set.
     return false;
   }
   // Construct the region representing the card.
   HeapWord* start = _ct_bs->addr_for(card_ptr);
   // And find the region containing it.
   HeapRegion* r = _g1->heap_region_containing(start);
   if (r == NULL) {
     guarantee(_g1->is_in_permanent(start), "Or else where?");
     // Again no need to return that this card contains refs that
     // point into the collection set.
     return false;  // Not in the G1 heap (might be in perm, for example.)
   }
   // Why do we have to check here whether a card is on a young region,
   // given that we dirty young regions and, as a result, the
   // post-barrier is supposed to filter them out and never to enqueue
   // them? When we allocate a new region as the "allocation region" we
   // actually dirty its cards after we release the lock, since card
   // dirtying while holding the lock was a performance bottleneck. So,
   // as a result, it is possible for other threads to actually
   // allocate objects in the region (after the acquire the lock)
   // before all the cards on the region are dirtied. This is unlikely,
   // and it doesn't happen often, but it can happen. So, the extra
   // check below filters out those cards.
   if (r->is_young()) {
     return false;
   }
   // While we are processing RSet buffers during the collection, we
   // actually don't want to scan any cards on the collection set,
   // since we don't want to update remebered 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 deals with a reliability issue which
   // involves scanning a card in the collection set and coming across
   // an array that was being chunked and looking malformed. Note,
   // however, that if evacuation fails, we have to scan any objects
   // that were not moved and create any missing entries.
   if (r->in_collection_set()) {
     return false;
   }
   // Should we defer processing the card?
   //
   // Previously the result from the insert_cache call would be
   // either card_ptr (implying that card_ptr was currently "cold"),
   // null (meaning we had inserted the card ptr into the "hot"
   // cache, which had some headroom), or a "hot" card ptr
   // extracted from the "hot" cache.
   //
   // Now that the _card_counts cache in the ConcurrentG1Refine
   // instance is an evicting hash table, the result we get back
   // could be from evicting the card ptr in an already occupied
   // bucket (in which case we have replaced the card ptr in the
   // bucket with card_ptr and "defer" is set to false). To avoid
   // having a data structure (updates to which would need a lock)
   // to hold these unprocessed dirty cards, we need to immediately
   // process card_ptr. The actions needed to be taken on return
   // from cache_insert are summarized in the following table:
   //
   // res      defer   action
   // --------------------------------------------------------------
   // null     false   card evicted from _card_counts & replaced with
   //                  card_ptr; evicted ptr added to hot cache.
   //                  No need to process res; immediately process card_ptr
   //
   // null     true    card not evicted from _card_counts; card_ptr added
   //                  to hot cache.
   //                  Nothing to do.
   //
   // non-null false   card evicted from _card_counts & replaced with
   //                  card_ptr; evicted ptr is currently "cold" or
   //                  caused an eviction from the hot cache.
   //                  Immediately process res; process card_ptr.
   //
   // non-null true    card not evicted from _card_counts; card_ptr is
   //                  currently cold, or caused an eviction from hot
   //                  cache.
   //                  Immediately process res; no need to process card_ptr.
   jbyte* res = card_ptr;
   bool defer = false;
   // This gets set to true if the card being refined has references
   // that point into the collection set.
   bool oops_into_cset = false;
   if (_cg1r->use_cache()) {
     jbyte* res = _cg1r->cache_insert(card_ptr, &defer);
     if (res != NULL && (res != card_ptr || defer)) {
       start = _ct_bs->addr_for(res);
       r = _g1->heap_region_containing(start);
       if (r == NULL) {
         assert(_g1->is_in_permanent(start), "Or else where?");
       } else {
         // Checking whether the region we got back from the cache
         // is young here is inappropriate. The region could have been
         // freed, reallocated and tagged as young while in the cache.
         // Hence we could see its young type change at any time.
         //
         // Process card pointer we get back from the hot card cache. This
         // will check whether the region containing the card is young
         // _after_ checking that the region has been allocated from.
         oops_into_cset = concurrentRefineOneCard_impl(res, worker_i,
                                                       false /* check_for_refs_into_cset */);
         // The above call to concurrentRefineOneCard_impl is only
         // performed if the hot card cache is enabled. This cache is
         // disabled during an evacuation pause - which is the only
         // time when we need know if the card contains references
         // that point into the collection set. Also when the hot card
         // cache is enabled, this code is executed by the concurrent
         // refine threads - rather than the GC worker threads - and
         // concurrentRefineOneCard_impl will return false.
         assert(!oops_into_cset, "should not see true here");
       }
     }
   }
   if (!defer) {
     oops_into_cset =
       concurrentRefineOneCard_impl(card_ptr, worker_i, check_for_refs_into_cset);
     // We should only be detecting that the card contains references
     // that point into the collection set if the current thread is
     // a GC worker thread.
     assert(!oops_into_cset || SafepointSynchronize::is_at_safepoint(),
            "invalid result at non safepoint");
   }
   return oops_into_cset;
 }
 class HRRSStatsIter: public HeapRegionClosure {
   size_t _occupied;
   size_t _total_mem_sz;
   size_t _max_mem_sz;
   HeapRegion* _max_mem_sz_region;
 public:
   HRRSStatsIter() :
     _occupied(0),
     _total_mem_sz(0),
     _max_mem_sz(0),
     _max_mem_sz_region(NULL)
   {}
   bool doHeapRegion(HeapRegion* r) {
     if (r->continuesHumongous()) return false;
     size_t mem_sz = r->rem_set()->mem_size();
     if (mem_sz > _max_mem_sz) {
       _max_mem_sz = mem_sz;
       _max_mem_sz_region = r;
     }
     _total_mem_sz += mem_sz;
     size_t occ = r->rem_set()->occupied();
     _occupied += occ;
     return false;
   }
   size_t total_mem_sz() { return _total_mem_sz; }
   size_t max_mem_sz() { return _max_mem_sz; }
   size_t occupied() { return _occupied; }
   HeapRegion* max_mem_sz_region() { return _max_mem_sz_region; }
 };
 class PrintRSThreadVTimeClosure : public ThreadClosure {
 public:
   virtual void do_thread(Thread *t) {
     ConcurrentG1RefineThread* crt = (ConcurrentG1RefineThread*) t;
     gclog_or_tty->print("    %5.2f", crt->vtime_accum());
   }
 };
 void HRInto_G1RemSet::print_summary_info() {
   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 #if CARD_REPEAT_HISTO
   gclog_or_tty->print_cr("\nG1 card_repeat count histogram: ");
   gclog_or_tty->print_cr("  # of repeats --> # of cards with that number.");
   card_repeat_count.print_on(gclog_or_tty);
 #endif
   if (FILTEROUTOFREGIONCLOSURE_DOHISTOGRAMCOUNT) {
     gclog_or_tty->print_cr("\nG1 rem-set out-of-region histogram: ");
     gclog_or_tty->print_cr("  # of CS ptrs --> # of cards with that number.");
     out_of_histo.print_on(gclog_or_tty);
   }
   gclog_or_tty->print_cr("\n Concurrent RS processed %d cards",
                          _conc_refine_cards);
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   jint tot_processed_buffers =
     dcqs.processed_buffers_mut() + dcqs.processed_buffers_rs_thread();
   gclog_or_tty->print_cr("  Of %d completed buffers:", tot_processed_buffers);
   gclog_or_tty->print_cr("     %8d (%5.1f%%) by conc RS threads.",
                 dcqs.processed_buffers_rs_thread(),
 .0*(float)dcqs.processed_buffers_rs_thread()/
                 (float)tot_processed_buffers);
   gclog_or_tty->print_cr("     %8d (%5.1f%%) by mutator threads.",
                 dcqs.processed_buffers_mut(),
 .0*(float)dcqs.processed_buffers_mut()/
                 (float)tot_processed_buffers);
   gclog_or_tty->print_cr("  Conc RS threads times(s)");
   PrintRSThreadVTimeClosure p;
   gclog_or_tty->print("     ");
   g1->concurrent_g1_refine()->threads_do(&p);
   gclog_or_tty->print_cr("");
   if (G1UseHRIntoRS) {
     HRRSStatsIter blk;
     g1->heap_region_iterate(&blk);
     gclog_or_tty->print_cr("  Total heap region rem set sizes = " SIZE_FORMAT "K."
                            "  Max = " SIZE_FORMAT "K.",
                            blk.total_mem_sz()/K, blk.max_mem_sz()/K);
     gclog_or_tty->print_cr("  Static structures = " SIZE_FORMAT "K,"
                            " free_lists = " SIZE_FORMAT "K.",
                            HeapRegionRemSet::static_mem_size()/K,
                            HeapRegionRemSet::fl_mem_size()/K);
     gclog_or_tty->print_cr("    %d occupied cards represented.",
                            blk.occupied());
     gclog_or_tty->print_cr("    Max sz region = [" PTR_FORMAT ", " PTR_FORMAT " )"
                            ", cap = " SIZE_FORMAT "K, occ = " SIZE_FORMAT "K.",
                            blk.max_mem_sz_region()->bottom(), blk.max_mem_sz_region()->end(),
                            (blk.max_mem_sz_region()->rem_set()->mem_size() + K - 1)/K,
                            (blk.max_mem_sz_region()->rem_set()->occupied() + K - 1)/K);
     gclog_or_tty->print_cr("    Did %d coarsenings.",
                   HeapRegionRemSet::n_coarsenings());
   }
 }
 void HRInto_G1RemSet::prepare_for_verify() {
   if (G1HRRSFlushLogBuffersOnVerify &&
       (VerifyBeforeGC || VerifyAfterGC)
       &&  !_g1->full_collection()) {
     cleanupHRRS();
     _g1->set_refine_cte_cl_concurrency(false);
     if (SafepointSynchronize::is_at_safepoint()) {
       DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
       dcqs.concatenate_logs();
     }
     bool cg1r_use_cache = _cg1r->use_cache();
     _cg1r->set_use_cache(false);
     DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
     updateRS(&into_cset_dcq, 0);
     _g1->into_cset_dirty_card_queue_set().clear();
     _cg1r->set_use_cache(cg1r_use_cache);
     assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1RemSet.cpp@5f429ee79634 (annotated)

src/share/vm/gc_implementation/g1/g1RemSet.cpp