jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1RemSet.cpp@7df07d855c8e (annotated)

src/share/vm/gc_implementation/g1/g1RemSet.cpp@7df07d855c8e (annotated)

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

Mon, 21 Jul 2014 09:59:46 +0200

author: tschatzl
date: Mon, 21 Jul 2014 09:59:46 +0200
changeset 7007: 7df07d855c8e
parent 6969: 02e61cf08ab3
child 7049: eec72fa4b108
permissions: -rw-r--r--

8048085: Aborting marking just before remark results in useless additional clearing of the next mark bitmap
Summary: Skip clearing the next bitmap if we just recently aborted since the full GC already clears this bitmap.
Reviewed-by: brutisso

 /*
  * Copyright (c) 2001, 2014, 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_implementation/g1/concurrentG1Refine.hpp"
 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
 #include "gc_implementation/g1/g1HotCardCache.hpp"
 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
 #include "gc_implementation/g1/g1RemSet.inline.hpp"
 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
 #include "gc_implementation/g1/heapRegionRemSet.hpp"
 #include "memory/iterator.hpp"
 #include "oops/oop.inline.hpp"
 #include "utilities/intHisto.hpp"
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 #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
 G1RemSet::G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs)
   : _g1(g1), _conc_refine_cards(0),
     _ct_bs(ct_bs), _g1p(_g1->g1_policy()),
     _cg1r(g1->concurrent_g1_refine()),
     _cset_rs_update_cl(NULL),
     _cards_scanned(NULL), _total_cards_scanned(0),
     _prev_period_summary()
 {
   _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(), mtGC);
   for (uint i = 0; i < n_workers(); i++) {
     _cset_rs_update_cl[i] = NULL;
   }
   if (G1SummarizeRSetStats) {
     _prev_period_summary.initialize(this);
   }
 }
 G1RemSet::~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, mtGC);
 }
 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;
   CodeBlobToOopClosure* _code_root_cl;
   G1BlockOffsetSharedArray* _bot_shared;
   G1SATBCardTableModRefBS *_ct_bs;
   double _strong_code_root_scan_time_sec;
   uint   _worker_i;
   int    _block_size;
   bool   _try_claimed;
 public:
   ScanRSClosure(OopsInHeapRegionClosure* oc,
                 CodeBlobToOopClosure* code_root_cl,
                 uint worker_i) :
     _oc(oc),
     _code_root_cl(code_root_cl),
     _strong_code_root_scan_time_sec(0.0),
     _cards(0),
     _cards_done(0),
     _worker_i(worker_i),
     _try_claimed(false)
   {
     _g1h = G1CollectedHeap::heap();
     _bot_shared = _g1h->bot_shared();
     _ct_bs = _g1h->g1_barrier_set();
     _block_size = MAX2<int>(G1RSetScanBlockSize, 1);
   }
   void set_try_claimed() { _try_claimed = true; }
   void scanCard(size_t index, HeapRegion *r) {
     // Stack allocate the DirtyCardToOopClosure instance
     HeapRegionDCTOC cl(_g1h, r, _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 = sp->used_region_at_save_marks();
     MemRegion mr = sm_region.intersection(MemRegion(card_start,card_end));
     if (!mr.is_empty() && !_ct_bs->is_card_claimed(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).
       _ct_bs->set_card_claimed(index);
       _cards_done++;
       cl.do_MemRegion(mr);
     }
   }
   void printCard(HeapRegion* card_region, size_t card_index,
                  HeapWord* card_start) {
     gclog_or_tty->print_cr("T " UINT32_FORMAT " 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);
   }
   void scan_strong_code_roots(HeapRegion* r) {
     double scan_start = os::elapsedTime();
     r->strong_code_roots_do(_code_root_cl);
     _strong_code_root_scan_time_sec += (os::elapsedTime() - scan_start);
   }
   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;
     // If we ever free the collection set concurrently, we should also
     // clear the card table concurrently therefore we won't need to
     // add regions of the collection set to the dirty cards region.
     _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(hrrs);
     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)) {
         scanCard(card_index, card_region);
       }
     }
     if (!_try_claimed) {
       // Scan the strong code root list attached to the current region
       scan_strong_code_roots(r);
       hrrs->set_iter_complete();
     }
     return false;
   }
   double strong_code_root_scan_time_sec() {
     return _strong_code_root_scan_time_sec;
   }
   size_t cards_done() { return _cards_done;}
   size_t cards_looked_up() { return _cards;}
 };
 void G1RemSet::scanRS(OopsInHeapRegionClosure* oc,
                       CodeBlobToOopClosure* code_root_cl,
                       uint worker_i) {
   double rs_time_start = os::elapsedTime();
   HeapRegion *startRegion = _g1->start_cset_region_for_worker(worker_i);
   ScanRSClosure scanRScl(oc, code_root_cl, 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)
                             - scanRScl.strong_code_root_scan_time_sec();
   assert(_cards_scanned != NULL, "invariant");
   _cards_scanned[worker_i] = scanRScl.cards_done();
   _g1p->phase_times()->record_scan_rs_time(worker_i, scan_rs_time_sec * 1000.0);
   _g1p->phase_times()->record_strong_code_root_scan_time(worker_i,
                                                          scanRScl.strong_code_root_scan_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, uint 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 < (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), "should be a GC worker");
     if (_g1rs->refine_card(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 G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, uint 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->phase_times()->record_update_rs_time(worker_i, (os::elapsedTime() - start) * 1000.0);
 }
 void G1RemSet::cleanupHRRS() {
   HeapRegionRemSet::cleanup();
 }
 void G1RemSet::oops_into_collection_set_do(OopsInHeapRegionClosure* oc,
                                            CodeBlobToOopClosure* code_root_cl,
                                            uint worker_i) {
 #if CARD_REPEAT_HISTO
   ct_freq_update_histo_and_reset();
 #endif
   // We cache the value of 'oc' closure into the appropriate slot in the
   // _cset_rs_update_cl for this worker
   assert(worker_i < 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->phase_times()->record_update_rs_processed_buffers(worker_i, 0);
     _g1p->phase_times()->record_update_rs_time(worker_i, 0.0);
   }
   if (G1UseParallelRSetScanning || (worker_i == 0)) {
     scanRS(oc, code_root_cl, worker_i);
   } else {
     _g1p->phase_times()->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 G1RemSet::prepare_for_oops_into_collection_set_do() {
   cleanupHRRS();
   ConcurrentG1Refine* cg1r = _g1->concurrent_g1_refine();
   _g1->set_refine_cte_cl_concurrency(false);
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   dcqs.concatenate_logs();
   guarantee( _cards_scanned == NULL, "invariant" );
   _cards_scanned = NEW_C_HEAP_ARRAY(size_t, n_workers(), mtGC);
   for (uint i = 0; i < n_workers(); ++i) {
     _cards_scanned[i] = 0;
   }
   _total_cards_scanned = 0;
 }
 // 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.
 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, uint 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
     // Don't use addr_for(card_ptr + 1) which can ask for
     // a card beyond the heap.  This is not safe without a perm
     // gen.
     HeapWord* end   = start + CardTableModRefBS::card_size_in_words;
     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 G1RemSet::refine_card() 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 */,
                                           NULL  /* card_ptr */);
     // 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 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, mtGC);
   _cards_scanned = NULL;
   // Cleanup after copy
   _g1->set_refine_cte_cl_concurrency(true);
   // Set all cards back to clean.
   _g1->cleanUpCardTable();
   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()) {
     double restore_remembered_set_start = os::elapsedTime();
     // 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");
     }
     _g1->g1_policy()->phase_times()->record_evac_fail_restore_remsets((os::elapsedTime() - restore_remembered_set_start) * 1000.0);
   }
   // 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();
 }
 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(_g1h->g1_barrier_set()) {}
   bool doHeapRegion(HeapRegion* r) {
     if (!r->continuesHumongous()) {
       r->rem_set()->scrub(_ctbs, _region_bm, _card_bm);
     }
     return false;
   }
 };
 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm) {
   ScrubRSClosure scrub_cl(region_bm, card_bm);
   _g1->heap_region_iterate(&scrub_cl);
 }
 void G1RemSet::scrub_par(BitMap* region_bm, BitMap* card_bm,
                                 uint worker_num, int claim_val) {
   ScrubRSClosure scrub_cl(region_bm, card_bm);
   _g1->heap_region_par_iterate_chunked(&scrub_cl,
                                        worker_num,
                                        n_workers(),
                                        claim_val);
 }
 G1TriggerClosure::G1TriggerClosure() :
   _triggered(false) { }
 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl,
                                                              OopClosure* oop_cl)  :
   _trigger_cl(t_cl), _oop_cl(oop_cl) { }
 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) :
   _c1(c1), _c2(c2) { }
 G1UpdateRSOrPushRefOopClosure::
 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h,
                               G1RemSet* rs,
                               OopsInHeapRegionClosure* push_ref_cl,
                               bool record_refs_into_cset,
                               uint worker_i) :
   _g1(g1h), _g1_rem_set(rs), _from(NULL),
   _record_refs_into_cset(record_refs_into_cset),
   _push_ref_cl(push_ref_cl), _worker_i(worker_i) { }
 // Returns true if the given card contains references that point
 // into the collection set, if we're checking for such references;
 // false otherwise.
 bool G1RemSet::refine_card(jbyte* card_ptr, uint 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) {
     // 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;
   }
   // The result from the hot card cache insert call is either:
   //   * pointer to the current card
   //     (implying that the current card is not 'hot'),
   //   * null
   //     (meaning we had inserted the card ptr into the "hot" card cache,
   //     which had some headroom),
   //   * a pointer to a "hot" card that was evicted from the "hot" cache.
   //
   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
   if (hot_card_cache->use_cache()) {
     assert(!check_for_refs_into_cset, "sanity");
     assert(!SafepointSynchronize::is_at_safepoint(), "sanity");
     card_ptr = hot_card_cache->insert(card_ptr);
     if (card_ptr == NULL) {
       // There was no eviction. Nothing to do.
       return false;
     }
     start = _ct_bs->addr_for(card_ptr);
     r = _g1->heap_region_containing(start);
     if (r == NULL) {
       // Not in the G1 heap
       return false;
     }
     // 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.
   }
   // Don't use addr_for(card_ptr + 1) which can ask for
   // a card beyond the heap.  This is not safe without a perm
   // gen at the upper end of the heap.
   HeapWord* end   = start + CardTableModRefBS::card_size_in_words;
   MemRegion dirtyRegion(start, end);
 #if CARD_REPEAT_HISTO
   init_ct_freq_table(_g1->max_capacity());
   ct_freq_note_card(_ct_bs->index_for(start));
 #endif
   OopsInHeapRegionClosure* oops_in_heap_closure = NULL;
   if (check_for_refs_into_cset) {
     // ConcurrentG1RefineThreads have worker numbers larger than what
     // _cset_rs_update_cl[] is set up to handle. But those threads should
     // only be active outside of a collection which means that when they
     // reach here they should have check_for_refs_into_cset == false.
     assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length");
     oops_in_heap_closure = _cset_rs_update_cl[worker_i];
   }
   G1UpdateRSOrPushRefOopClosure update_rs_oop_cl(_g1,
                                                  _g1->g1_rem_set(),
                                                  oops_in_heap_closure,
                                                  check_for_refs_into_cset,
                                                  worker_i);
   update_rs_oop_cl.set_from(r);
   G1TriggerClosure trigger_cl;
   FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl);
   G1InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl);
   G1Mux2Closure 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));
   // 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 concurrently, 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,
                                         card_ptr);
   // 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 {
     _conc_refine_cards++;
   }
   // This gets set to true if the card being refined has
   // references that point into the collection set.
   bool has_refs_into_cset = trigger_cl.triggered();
   // 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(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(),
            "invalid result at non safepoint");
   return has_refs_into_cset;
 }
 void G1RemSet::print_periodic_summary_info(const char* header) {
   G1RemSetSummary current;
   current.initialize(this);
   _prev_period_summary.subtract_from(&current);
   print_summary_info(&_prev_period_summary, header);
   _prev_period_summary.set(&current);
 }
 void G1RemSet::print_summary_info() {
   G1RemSetSummary current;
   current.initialize(this);
   print_summary_info(&current, " Cumulative RS summary");
 }
 void G1RemSet::print_summary_info(G1RemSetSummary * summary, const char * header) {
   assert(summary != NULL, "just checking");
   if (header != NULL) {
     gclog_or_tty->print_cr("%s", header);
   }
 #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
   summary->print_on(gclog_or_tty);
 }
 void G1RemSet::prepare_for_verify() {
   if (G1HRRSFlushLogBuffersOnVerify &&
       (VerifyBeforeGC || VerifyAfterGC)
       &&  (!_g1->full_collection() || G1VerifyRSetsDuringFullGC)) {
     cleanupHRRS();
     _g1->set_refine_cte_cl_concurrency(false);
     if (SafepointSynchronize::is_at_safepoint()) {
       DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
       dcqs.concatenate_logs();
     }
     G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
     bool use_hot_card_cache = hot_card_cache->use_cache();
     hot_card_cache->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();
     hot_card_cache->set_use_cache(use_hot_card_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@7df07d855c8e (annotated)

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