jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp@ff7b317d2af8 (annotated)

src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp@ff7b317d2af8 (annotated)

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

Mon, 21 Jul 2014 09:40:19 +0200

author: tschatzl
date: Mon, 21 Jul 2014 09:40:19 +0200
changeset 6927: ff7b317d2af8
parent 6925: 82693fb204a5
child 6928: 8cc89a893545
permissions: -rw-r--r--

8037344: Use the "next" field to iterate over fine remembered instead of using the hash table
Summary: After changes to the PerRegionTable where all these PRTs are linked together in an additional field, simplify iterating over all PRTs by using these links instead of walki
Reviewed-by: mgerdin, jwilhelm, 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
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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP
 #include "gc_implementation/g1/g1CodeCacheRemSet.hpp"
 #include "gc_implementation/g1/sparsePRT.hpp"
 // Remembered set for a heap region.  Represent a set of "cards" that
 // contain pointers into the owner heap region.  Cards are defined somewhat
 // abstractly, in terms of what the "BlockOffsetTable" in use can parse.
 class G1CollectedHeap;
 class G1BlockOffsetSharedArray;
 class HeapRegion;
 class HeapRegionRemSetIterator;
 class PerRegionTable;
 class SparsePRT;
 class nmethod;
 // Essentially a wrapper around SparsePRTCleanupTask. See
 // sparsePRT.hpp for more details.
 class HRRSCleanupTask : public SparsePRTCleanupTask {
 };
 // The FromCardCache remembers the most recently processed card on the heap on
 // a per-region and per-thread basis.
 class FromCardCache : public AllStatic {
  private:
   // Array of card indices. Indexed by thread X and heap region to minimize
   // thread contention.
   static int** _cache;
   static uint _max_regions;
   static size_t _static_mem_size;
  public:
   enum {
     InvalidCard = -1 // Card value of an invalid card, i.e. a card index not otherwise used.
   };
   static void clear(uint region_idx);
   // Returns true if the given card is in the cache at the given location, or
   // replaces the card at that location and returns false.
   static bool contains_or_replace(uint worker_id, uint region_idx, int card) {
     int card_in_cache = at(worker_id, region_idx);
     if (card_in_cache == card) {
       return true;
     } else {
       set(worker_id, region_idx, card);
       return false;
     }
   }
   static int at(uint worker_id, uint region_idx) {
     return _cache[worker_id][region_idx];
   }
   static void set(uint worker_id, uint region_idx, int val) {
     _cache[worker_id][region_idx] = val;
   }
   static void initialize(uint n_par_rs, uint max_num_regions);
   static void shrink(uint new_num_regions);
   static void print(outputStream* out = gclog_or_tty) PRODUCT_RETURN;
   static size_t static_mem_size() {
     return _static_mem_size;
   }
 };
 // The "_coarse_map" is a bitmap with one bit for each region, where set
 // bits indicate that the corresponding region may contain some pointer
 // into the owning region.
 // The "_fine_grain_entries" array is an open hash table of PerRegionTables
 // (PRTs), indicating regions for which we're keeping the RS as a set of
 // cards.  The strategy is to cap the size of the fine-grain table,
 // deleting an entry and setting the corresponding coarse-grained bit when
 // we would overflow this cap.
 // We use a mixture of locking and lock-free techniques here.  We allow
 // threads to locate PRTs without locking, but threads attempting to alter
 // a bucket list obtain a lock.  This means that any failing attempt to
 // find a PRT must be retried with the lock.  It might seem dangerous that
 // a read can find a PRT that is concurrently deleted.  This is all right,
 // because:
 //
 //   1) We only actually free PRT's at safe points (though we reuse them at
 //      other times).
 //   2) We find PRT's in an attempt to add entries.  If a PRT is deleted,
 //      it's _coarse_map bit is set, so the that we were attempting to add
 //      is represented.  If a deleted PRT is re-used, a thread adding a bit,
 //      thinking the PRT is for a different region, does no harm.
 class OtherRegionsTable VALUE_OBJ_CLASS_SPEC {
   friend class HeapRegionRemSetIterator;
   G1CollectedHeap* _g1h;
   Mutex*           _m;
   HeapRegion*      _hr;
   // These are protected by "_m".
   BitMap      _coarse_map;
   size_t      _n_coarse_entries;
   static jint _n_coarsenings;
   PerRegionTable** _fine_grain_regions;
   size_t           _n_fine_entries;
   // The fine grain remembered sets are doubly linked together using
   // their 'next' and 'prev' fields.
   // This allows fast bulk freeing of all the fine grain remembered
   // set entries, and fast finding of all of them without iterating
   // over the _fine_grain_regions table.
   PerRegionTable * _first_all_fine_prts;
   PerRegionTable * _last_all_fine_prts;
   // Used to sample a subset of the fine grain PRTs to determine which
   // PRT to evict and coarsen.
   size_t        _fine_eviction_start;
   static size_t _fine_eviction_stride;
   static size_t _fine_eviction_sample_size;
   SparsePRT   _sparse_table;
   // These are static after init.
   static size_t _max_fine_entries;
   static size_t _mod_max_fine_entries_mask;
   // Requires "prt" to be the first element of the bucket list appropriate
   // for "hr".  If this list contains an entry for "hr", return it,
   // otherwise return "NULL".
   PerRegionTable* find_region_table(size_t ind, HeapRegion* hr) const;
   // Find, delete, and return a candidate PerRegionTable, if any exists,
   // adding the deleted region to the coarse bitmap.  Requires the caller
   // to hold _m, and the fine-grain table to be full.
   PerRegionTable* delete_region_table();
   // If a PRT for "hr" is in the bucket list indicated by "ind" (which must
   // be the correct index for "hr"), delete it and return true; else return
   // false.
   bool del_single_region_table(size_t ind, HeapRegion* hr);
   // link/add the given fine grain remembered set into the "all" list
   void link_to_all(PerRegionTable * prt);
   // unlink/remove the given fine grain remembered set into the "all" list
   void unlink_from_all(PerRegionTable * prt);
 public:
   OtherRegionsTable(HeapRegion* hr, Mutex* m);
   HeapRegion* hr() const { return _hr; }
   // For now.  Could "expand" some tables in the future, so that this made
   // sense.
   void add_reference(OopOrNarrowOopStar from, int tid);
   // Removes any entries shown by the given bitmaps to contain only dead
   // objects.
   void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm);
   size_t occupied() const;
   size_t occ_fine() const;
   size_t occ_coarse() const;
   size_t occ_sparse() const;
   static jint n_coarsenings() { return _n_coarsenings; }
   // Returns size in bytes.
   // Not const because it takes a lock.
   size_t mem_size() const;
   static size_t static_mem_size();
   static size_t fl_mem_size();
   bool contains_reference(OopOrNarrowOopStar from) const;
   bool contains_reference_locked(OopOrNarrowOopStar from) const;
   void clear();
   // Specifically clear the from_card_cache.
   void clear_fcc();
   // "from_hr" is being cleared; remove any entries from it.
   void clear_incoming_entry(HeapRegion* from_hr);
   void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task);
   // Declare the heap size (in # of regions) to the OtherRegionsTable.
   // (Uses it to initialize from_card_cache).
   static void init_from_card_cache(uint max_regions);
   // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
   // Make sure any entries for higher regions are invalid.
   static void shrink_from_card_cache(uint new_num_regions);
   static void print_from_card_cache();
 };
 class HeapRegionRemSet : public CHeapObj<mtGC> {
   friend class VMStructs;
   friend class HeapRegionRemSetIterator;
 public:
   enum Event {
     Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd
   };
 private:
   G1BlockOffsetSharedArray* _bosa;
   G1BlockOffsetSharedArray* bosa() const { return _bosa; }
   // A set of code blobs (nmethods) whose code contains pointers into
   // the region that owns this RSet.
   G1CodeRootSet _code_roots;
   Mutex _m;
   OtherRegionsTable _other_regions;
   enum ParIterState { Unclaimed, Claimed, Complete };
   volatile ParIterState _iter_state;
   volatile jlong _iter_claimed;
   // Unused unless G1RecordHRRSOops is true.
   static const int MaxRecorded = 1000000;
   static OopOrNarrowOopStar* _recorded_oops;
   static HeapWord**          _recorded_cards;
   static HeapRegion**        _recorded_regions;
   static int                 _n_recorded;
   static const int MaxRecordedEvents = 1000;
   static Event*       _recorded_events;
   static int*         _recorded_event_index;
   static int          _n_recorded_events;
   static void print_event(outputStream* str, Event evnt);
 public:
   HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, HeapRegion* hr);
   static uint num_par_rem_sets();
   static void setup_remset_size();
   HeapRegion* hr() const {
     return _other_regions.hr();
   }
   size_t occupied() {
     MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
     return occupied_locked();
   }
   size_t occupied_locked() {
     return _other_regions.occupied();
   }
   size_t occ_fine() const {
     return _other_regions.occ_fine();
   }
   size_t occ_coarse() const {
     return _other_regions.occ_coarse();
   }
   size_t occ_sparse() const {
     return _other_regions.occ_sparse();
   }
   static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); }
   // Used in the sequential case.
   void add_reference(OopOrNarrowOopStar from) {
     _other_regions.add_reference(from, 0);
   }
   // Used in the parallel case.
   void add_reference(OopOrNarrowOopStar from, int tid) {
     _other_regions.add_reference(from, tid);
   }
   // Removes any entries shown by the given bitmaps to contain only dead
   // objects.
   void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm);
   // The region is being reclaimed; clear its remset, and any mention of
   // entries for this region in other remsets.
   void clear();
   void clear_locked();
   // Attempt to claim the region.  Returns true iff this call caused an
   // atomic transition from Unclaimed to Claimed.
   bool claim_iter();
   // Sets the iteration state to "complete".
   void set_iter_complete();
   // Returns "true" iff the region's iteration is complete.
   bool iter_is_complete();
   // Support for claiming blocks of cards during iteration
   size_t iter_claimed() const { return (size_t)_iter_claimed; }
   // Claim the next block of cards
   size_t iter_claimed_next(size_t step) {
     size_t current, next;
     do {
       current = iter_claimed();
       next = current + step;
     } while (Atomic::cmpxchg((jlong)next, &_iter_claimed, (jlong)current) != (jlong)current);
     return current;
   }
   void reset_for_par_iteration();
   bool verify_ready_for_par_iteration() {
     return (_iter_state == Unclaimed) && (_iter_claimed == 0);
   }
   // The actual # of bytes this hr_remset takes up.
   // Note also includes the strong code root set.
   size_t mem_size() {
     MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
     return _other_regions.mem_size()
       // This correction is necessary because the above includes the second
       // part.
       + (sizeof(this) - sizeof(OtherRegionsTable))
       + strong_code_roots_mem_size();
   }
   // Returns the memory occupancy of all static data structures associated
   // with remembered sets.
   static size_t static_mem_size() {
     return OtherRegionsTable::static_mem_size() + G1CodeRootSet::static_mem_size();
   }
   // Returns the memory occupancy of all free_list data structures associated
   // with remembered sets.
   static size_t fl_mem_size() {
     return OtherRegionsTable::fl_mem_size() + G1CodeRootSet::free_chunks_mem_size();
   }
   bool contains_reference(OopOrNarrowOopStar from) const {
     return _other_regions.contains_reference(from);
   }
   // Routines for managing the list of code roots that point into
   // the heap region that owns this RSet.
   void add_strong_code_root(nmethod* nm);
   void remove_strong_code_root(nmethod* nm);
   // During a collection, migrate the successfully evacuated strong
   // code roots that referenced into the region that owns this RSet
   // to the RSets of the new regions that they now point into.
   // Unsuccessfully evacuated code roots are not migrated.
   void migrate_strong_code_roots();
   // Applies blk->do_code_blob() to each of the entries in
   // the strong code roots list
   void strong_code_roots_do(CodeBlobClosure* blk) const;
   // Returns the number of elements in the strong code roots list
   size_t strong_code_roots_list_length() {
     return _code_roots.length();
   }
   // Returns true if the strong code roots contains the given
   // nmethod.
   bool strong_code_roots_list_contains(nmethod* nm) {
     return _code_roots.contains(nm);
   }
   // Returns the amount of memory, in bytes, currently
   // consumed by the strong code roots.
   size_t strong_code_roots_mem_size();
   void print() PRODUCT_RETURN;
   // Called during a stop-world phase to perform any deferred cleanups.
   static void cleanup();
   // Declare the heap size (in # of regions) to the HeapRegionRemSet(s).
   // (Uses it to initialize from_card_cache).
   static void init_heap(uint max_regions) {
     OtherRegionsTable::init_from_card_cache(max_regions);
   }
   // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
   static void shrink_heap(uint new_n_regs) {
     OtherRegionsTable::shrink_from_card_cache(new_n_regs);
   }
 #ifndef PRODUCT
   static void print_from_card_cache() {
     OtherRegionsTable::print_from_card_cache();
   }
 #endif
   static void record(HeapRegion* hr, OopOrNarrowOopStar f);
   static void print_recorded();
   static void record_event(Event evnt);
   // These are wrappers for the similarly-named methods on
   // SparsePRT. Look at sparsePRT.hpp for more details.
   static void reset_for_cleanup_tasks();
   void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task);
   static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task);
   // Run unit tests.
 #ifndef PRODUCT
   static void test_prt();
   static void test();
 #endif
 };
 class HeapRegionRemSetIterator : public StackObj {
  private:
   // The region RSet over which we are iterating.
   HeapRegionRemSet* _hrrs;
   // Local caching of HRRS fields.
   const BitMap*             _coarse_map;
   G1BlockOffsetSharedArray* _bosa;
   G1CollectedHeap*          _g1h;
   // The number of cards yielded since initialization.
   size_t _n_yielded_fine;
   size_t _n_yielded_coarse;
   size_t _n_yielded_sparse;
   // Indicates what granularity of table that we are currently iterating over.
   // We start iterating over the sparse table, progress to the fine grain
   // table, and then finish with the coarse table.
   enum IterState {
     Sparse,
     Fine,
     Coarse
   };
   IterState _is;
   // For both Coarse and Fine remembered set iteration this contains the
   // first card number of the heap region we currently iterate over.
   size_t _cur_region_card_offset;
   // Current region index for the Coarse remembered set iteration.
   int    _coarse_cur_region_index;
   size_t _coarse_cur_region_cur_card;
   bool coarse_has_next(size_t& card_index);
   // The PRT we are currently iterating over.
   PerRegionTable* _fine_cur_prt;
   // Card offset within the current PRT.
   size_t _cur_card_in_prt;
   // Update internal variables when switching to the given PRT.
   void switch_to_prt(PerRegionTable* prt);
   bool fine_has_next();
   bool fine_has_next(size_t& card_index);
   // The Sparse remembered set iterator.
   SparsePRTIter _sparse_iter;
  public:
   HeapRegionRemSetIterator(HeapRegionRemSet* hrrs);
   // If there remains one or more cards to be yielded, returns true and
   // sets "card_index" to one of those cards (which is then considered
   // yielded.)   Otherwise, returns false (and leaves "card_index"
   // undefined.)
   bool has_next(size_t& card_index);
   size_t n_yielded_fine() { return _n_yielded_fine; }
   size_t n_yielded_coarse() { return _n_yielded_coarse; }
   size_t n_yielded_sparse() { return _n_yielded_sparse; }
   size_t n_yielded() {
     return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse();
   }
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp@ff7b317d2af8 (annotated)

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