jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp@e7d0505c8a30 (annotated)

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

Fri, 10 Oct 2014 15:51:58 +0200

author: tschatzl
date: Fri, 10 Oct 2014 15:51:58 +0200
changeset 7257: e7d0505c8a30
parent 7208: 7baf47cb97cb
child 7535: 7ae4e26cb1e0
child 7828: cbc7c4c9e11c
permissions: -rw-r--r--

8059758: Footprint regressions with JDK-8038423
Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.
Reviewed-by: 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
  * questions.
  *
  */
 #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 invalidate(uint start_idx, size_t 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);
   // Returns whether this remembered set (and all sub-sets) contain no entries.
   bool is_empty() const;
   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();
   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 initialize(uint max_regions);
   // Declares that regions between start_idx <= i < start_idx + num_regions are
   // not in use. Make sure that any entries for these regions are invalid.
   static void invalidate(uint start_idx, size_t 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();
   }
   bool is_empty() const {
     return (strong_code_roots_list_length() == 0) && _other_regions.is_empty();
   }
   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(HeapRegionRemSet) - 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();
   }
   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 add_strong_code_root_locked(nmethod* nm);
   void remove_strong_code_root(nmethod* nm);
   // Applies blk->do_code_blob() to each of the entries in
   // the strong code roots list
   void strong_code_roots_do(CodeBlobClosure* blk) const;
   void clean_strong_code_roots(HeapRegion* hr);
   // Returns the number of elements in the strong code roots list
   size_t strong_code_roots_list_length() const {
     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::initialize(max_regions);
   }
   static void invalidate(uint start_idx, uint num_regions) {
     OtherRegionsTable::invalidate(start_idx, num_regions);
   }
 #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@e7d0505c8a30 (annotated)

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