rev 6670 : fast reclaim main patch

   1 /*
   2  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP
  27 
  28 #include "gc_implementation/g1/g1CodeCacheRemSet.hpp"
  29 #include "gc_implementation/g1/sparsePRT.hpp"
  30 
  31 // Remembered set for a heap region.  Represent a set of "cards" that
  32 // contain pointers into the owner heap region.  Cards are defined somewhat
  33 // abstractly, in terms of what the "BlockOffsetTable" in use can parse.
  34 
  35 class G1CollectedHeap;
  36 class G1BlockOffsetSharedArray;
  37 class HeapRegion;
  38 class HeapRegionRemSetIterator;
  39 class PerRegionTable;
  40 class SparsePRT;
  41 class nmethod;
  42 
  43 // Essentially a wrapper around SparsePRTCleanupTask. See
  44 // sparsePRT.hpp for more details.
  45 class HRRSCleanupTask : public SparsePRTCleanupTask {
  46 };
  47 
  48 // The FromCardCache remembers the most recently processed card on the heap on
  49 // a per-region and per-thread basis.
  50 class FromCardCache : public AllStatic {
  51  private:
  52   // Array of card indices. Indexed by thread X and heap region to minimize
  53   // thread contention.
  54   static int** _cache;
  55   static uint _max_regions;
  56   static size_t _static_mem_size;
  57 
  58  public:
  59   enum {
  60     InvalidCard = -1 // Card value of an invalid card, i.e. a card index not otherwise used.
  61   };
  62 
  63   static void clear(uint region_idx);
  64 
  65   // Returns true if the given card is in the cache at the given location, or
  66   // replaces the card at that location and returns false.
  67   static bool contains_or_replace(uint worker_id, uint region_idx, int card) {
  68     int card_in_cache = at(worker_id, region_idx);
  69     if (card_in_cache == card) {
  70       return true;
  71     } else {
  72       set(worker_id, region_idx, card);
  73       return false;
  74     }
  75   }
  76 
  77   static int at(uint worker_id, uint region_idx) {
  78     return _cache[worker_id][region_idx];
  79   }
  80 
  81   static void set(uint worker_id, uint region_idx, int val) {
  82     _cache[worker_id][region_idx] = val;
  83   }
  84 
  85   static void initialize(uint n_par_rs, uint max_num_regions);
  86 
  87   static void shrink(uint new_num_regions);
  88 
  89   static void print(outputStream* out = gclog_or_tty) PRODUCT_RETURN;
  90 
  91   static size_t static_mem_size() {
  92     return _static_mem_size;
  93   }
  94 };
  95 
  96 // The "_coarse_map" is a bitmap with one bit for each region, where set
  97 // bits indicate that the corresponding region may contain some pointer
  98 // into the owning region.
  99 
 100 // The "_fine_grain_entries" array is an open hash table of PerRegionTables
 101 // (PRTs), indicating regions for which we're keeping the RS as a set of
 102 // cards.  The strategy is to cap the size of the fine-grain table,
 103 // deleting an entry and setting the corresponding coarse-grained bit when
 104 // we would overflow this cap.
 105 
 106 // We use a mixture of locking and lock-free techniques here.  We allow
 107 // threads to locate PRTs without locking, but threads attempting to alter
 108 // a bucket list obtain a lock.  This means that any failing attempt to
 109 // find a PRT must be retried with the lock.  It might seem dangerous that
 110 // a read can find a PRT that is concurrently deleted.  This is all right,
 111 // because:
 112 //
 113 //   1) We only actually free PRT's at safe points (though we reuse them at
 114 //      other times).
 115 //   2) We find PRT's in an attempt to add entries.  If a PRT is deleted,
 116 //      it's _coarse_map bit is set, so the that we were attempting to add
 117 //      is represented.  If a deleted PRT is re-used, a thread adding a bit,
 118 //      thinking the PRT is for a different region, does no harm.
 119 
 120 class OtherRegionsTable VALUE_OBJ_CLASS_SPEC {
 121   friend class HeapRegionRemSetIterator;
 122 
 123   G1CollectedHeap* _g1h;
 124   Mutex*           _m;
 125   HeapRegion*      _hr;
 126 
 127   // These are protected by "_m".
 128   BitMap      _coarse_map;
 129   size_t      _n_coarse_entries;
 130   static jint _n_coarsenings;
 131 
 132   PerRegionTable** _fine_grain_regions;
 133   size_t           _n_fine_entries;
 134 
 135   // The fine grain remembered sets are doubly linked together using
 136   // their 'next' and 'prev' fields.
 137   // This allows fast bulk freeing of all the fine grain remembered
 138   // set entries, and fast finding of all of them without iterating
 139   // over the _fine_grain_regions table.
 140   PerRegionTable * _first_all_fine_prts;
 141   PerRegionTable * _last_all_fine_prts;
 142 
 143   // Used to sample a subset of the fine grain PRTs to determine which
 144   // PRT to evict and coarsen.
 145   size_t        _fine_eviction_start;
 146   static size_t _fine_eviction_stride;
 147   static size_t _fine_eviction_sample_size;
 148 
 149   SparsePRT   _sparse_table;
 150 
 151   // These are static after init.
 152   static size_t _max_fine_entries;
 153   static size_t _mod_max_fine_entries_mask;
 154 
 155   // Requires "prt" to be the first element of the bucket list appropriate
 156   // for "hr".  If this list contains an entry for "hr", return it,
 157   // otherwise return "NULL".
 158   PerRegionTable* find_region_table(size_t ind, HeapRegion* hr) const;
 159 
 160   // Find, delete, and return a candidate PerRegionTable, if any exists,
 161   // adding the deleted region to the coarse bitmap.  Requires the caller
 162   // to hold _m, and the fine-grain table to be full.
 163   PerRegionTable* delete_region_table();
 164 
 165   // If a PRT for "hr" is in the bucket list indicated by "ind" (which must
 166   // be the correct index for "hr"), delete it and return true; else return
 167   // false.
 168   bool del_single_region_table(size_t ind, HeapRegion* hr);
 169 
 170   // link/add the given fine grain remembered set into the "all" list
 171   void link_to_all(PerRegionTable * prt);
 172   // unlink/remove the given fine grain remembered set into the "all" list
 173   void unlink_from_all(PerRegionTable * prt);
 174 
 175 public:
 176   OtherRegionsTable(HeapRegion* hr, Mutex* m);
 177 
 178   HeapRegion* hr() const { return _hr; }
 179 
 180   // For now.  Could "expand" some tables in the future, so that this made
 181   // sense.
 182   void add_reference(OopOrNarrowOopStar from, int tid);
 183 
 184   // Removes any entries shown by the given bitmaps to contain only dead
 185   // objects.
 186   void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm);
 187 
 188   // Returns whether this remembered set (and all sub-sets) contain no entries.
 189   bool is_empty() const;
 190 
 191   size_t occupied() const;
 192   size_t occ_fine() const;
 193   size_t occ_coarse() const;
 194   size_t occ_sparse() const;
 195 
 196   static jint n_coarsenings() { return _n_coarsenings; }
 197 
 198   // Returns size in bytes.
 199   // Not const because it takes a lock.
 200   size_t mem_size() const;
 201   static size_t static_mem_size();
 202   static size_t fl_mem_size();
 203 
 204   bool contains_reference(OopOrNarrowOopStar from) const;
 205   bool contains_reference_locked(OopOrNarrowOopStar from) const;
 206 
 207   void clear();
 208 
 209   // Specifically clear the from_card_cache.
 210   void clear_fcc();
 211 
 212   void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task);
 213 
 214   // Declare the heap size (in # of regions) to the OtherRegionsTable.
 215   // (Uses it to initialize from_card_cache).
 216   static void init_from_card_cache(uint max_regions);
 217 
 218   // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
 219   // Make sure any entries for higher regions are invalid.
 220   static void shrink_from_card_cache(uint new_num_regions);
 221 
 222   static void print_from_card_cache();
 223 };
 224 
 225 class HeapRegionRemSet : public CHeapObj<mtGC> {
 226   friend class VMStructs;
 227   friend class HeapRegionRemSetIterator;
 228 
 229 public:
 230   enum Event {
 231     Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd
 232   };
 233 
 234 private:
 235   G1BlockOffsetSharedArray* _bosa;
 236   G1BlockOffsetSharedArray* bosa() const { return _bosa; }
 237 
 238   // A set of code blobs (nmethods) whose code contains pointers into
 239   // the region that owns this RSet.
 240   G1CodeRootSet _code_roots;
 241 
 242   Mutex _m;
 243 
 244   OtherRegionsTable _other_regions;
 245 
 246   enum ParIterState { Unclaimed, Claimed, Complete };
 247   volatile ParIterState _iter_state;
 248   volatile size_t _iter_claimed;
 249 
 250   // Unused unless G1RecordHRRSOops is true.
 251 
 252   static const int MaxRecorded = 1000000;
 253   static OopOrNarrowOopStar* _recorded_oops;
 254   static HeapWord**          _recorded_cards;
 255   static HeapRegion**        _recorded_regions;
 256   static int                 _n_recorded;
 257 
 258   static const int MaxRecordedEvents = 1000;
 259   static Event*       _recorded_events;
 260   static int*         _recorded_event_index;
 261   static int          _n_recorded_events;
 262 
 263   static void print_event(outputStream* str, Event evnt);
 264 
 265 public:
 266   HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, HeapRegion* hr);
 267 
 268   static uint num_par_rem_sets();
 269   static void setup_remset_size();
 270 
 271   HeapRegion* hr() const {
 272     return _other_regions.hr();
 273   }
 274 
 275   bool is_empty() const {
 276     return (strong_code_roots_list_length() == 0) && _other_regions.is_empty();
 277   }
 278 
 279   size_t occupied() {
 280     MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
 281     return occupied_locked();
 282   }
 283   size_t occupied_locked() {
 284     return _other_regions.occupied();
 285   }
 286   size_t occ_fine() const {
 287     return _other_regions.occ_fine();
 288   }
 289   size_t occ_coarse() const {
 290     return _other_regions.occ_coarse();
 291   }
 292   size_t occ_sparse() const {
 293     return _other_regions.occ_sparse();
 294   }
 295 
 296   static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); }
 297 
 298   // Used in the sequential case.
 299   void add_reference(OopOrNarrowOopStar from) {
 300     _other_regions.add_reference(from, 0);
 301   }
 302 
 303   // Used in the parallel case.
 304   void add_reference(OopOrNarrowOopStar from, int tid) {
 305     _other_regions.add_reference(from, tid);
 306   }
 307 
 308   // Removes any entries shown by the given bitmaps to contain only dead
 309   // objects.
 310   void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm);
 311 
 312   // The region is being reclaimed; clear its remset, and any mention of
 313   // entries for this region in other remsets.
 314   void clear();
 315   void clear_locked();
 316 
 317   // Attempt to claim the region.  Returns true iff this call caused an
 318   // atomic transition from Unclaimed to Claimed.
 319   bool claim_iter();
 320   // Sets the iteration state to "complete".
 321   void set_iter_complete();
 322   // Returns "true" iff the region's iteration is complete.
 323   bool iter_is_complete();
 324 
 325   // Support for claiming blocks of cards during iteration
 326   size_t iter_claimed() const { return _iter_claimed; }
 327   // Claim the next block of cards
 328   size_t iter_claimed_next(size_t step) {
 329     return Atomic::add(step, &_iter_claimed) - step;
 330   }
 331 
 332   void reset_for_par_iteration();
 333 
 334   bool verify_ready_for_par_iteration() {
 335     return (_iter_state == Unclaimed) && (_iter_claimed == 0);
 336   }
 337 
 338   // The actual # of bytes this hr_remset takes up.
 339   // Note also includes the strong code root set.
 340   size_t mem_size() {
 341     MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
 342     return _other_regions.mem_size()
 343       // This correction is necessary because the above includes the second
 344       // part.
 345       + (sizeof(HeapRegionRemSet) - sizeof(OtherRegionsTable))
 346       + strong_code_roots_mem_size();
 347   }
 348 
 349   // Returns the memory occupancy of all static data structures associated
 350   // with remembered sets.
 351   static size_t static_mem_size() {
 352     return OtherRegionsTable::static_mem_size() + G1CodeRootSet::free_chunks_static_mem_size();
 353   }
 354 
 355   // Returns the memory occupancy of all free_list data structures associated
 356   // with remembered sets.
 357   static size_t fl_mem_size() {
 358     return OtherRegionsTable::fl_mem_size() + G1CodeRootSet::free_chunks_mem_size();
 359   }
 360 
 361   bool contains_reference(OopOrNarrowOopStar from) const {
 362     return _other_regions.contains_reference(from);
 363   }
 364 
 365   // Routines for managing the list of code roots that point into
 366   // the heap region that owns this RSet.
 367   void add_strong_code_root(nmethod* nm);
 368   void remove_strong_code_root(nmethod* nm);
 369 
 370   // During a collection, migrate the successfully evacuated strong
 371   // code roots that referenced into the region that owns this RSet
 372   // to the RSets of the new regions that they now point into.
 373   // Unsuccessfully evacuated code roots are not migrated.
 374   void migrate_strong_code_roots();
 375 
 376   // Applies blk->do_code_blob() to each of the entries in
 377   // the strong code roots list
 378   void strong_code_roots_do(CodeBlobClosure* blk) const;
 379 
 380   // Returns the number of elements in the strong code roots list
 381   size_t strong_code_roots_list_length() const {
 382     return _code_roots.length();
 383   }
 384 
 385   // Returns true if the strong code roots contains the given
 386   // nmethod.
 387   bool strong_code_roots_list_contains(nmethod* nm) {
 388     return _code_roots.contains(nm);
 389   }
 390 
 391   // Returns the amount of memory, in bytes, currently
 392   // consumed by the strong code roots.
 393   size_t strong_code_roots_mem_size();
 394 
 395   void print() PRODUCT_RETURN;
 396 
 397   // Called during a stop-world phase to perform any deferred cleanups.
 398   static void cleanup();
 399 
 400   // Declare the heap size (in # of regions) to the HeapRegionRemSet(s).
 401   // (Uses it to initialize from_card_cache).
 402   static void init_heap(uint max_regions) {
 403     OtherRegionsTable::init_from_card_cache(max_regions);
 404   }
 405 
 406   // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
 407   static void shrink_heap(uint new_n_regs) {
 408     OtherRegionsTable::shrink_from_card_cache(new_n_regs);
 409   }
 410 
 411 #ifndef PRODUCT
 412   static void print_from_card_cache() {
 413     OtherRegionsTable::print_from_card_cache();
 414   }
 415 #endif
 416 
 417   static void record(HeapRegion* hr, OopOrNarrowOopStar f);
 418   static void print_recorded();
 419   static void record_event(Event evnt);
 420 
 421   // These are wrappers for the similarly-named methods on
 422   // SparsePRT. Look at sparsePRT.hpp for more details.
 423   static void reset_for_cleanup_tasks();
 424   void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task);
 425   static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task);
 426 
 427   // Run unit tests.
 428 #ifndef PRODUCT
 429   static void test_prt();
 430   static void test();
 431 #endif
 432 };
 433 
 434 class HeapRegionRemSetIterator : public StackObj {
 435  private:
 436   // The region RSet over which we are iterating.
 437   HeapRegionRemSet* _hrrs;
 438 
 439   // Local caching of HRRS fields.
 440   const BitMap*             _coarse_map;
 441 
 442   G1BlockOffsetSharedArray* _bosa;
 443   G1CollectedHeap*          _g1h;
 444 
 445   // The number of cards yielded since initialization.
 446   size_t _n_yielded_fine;
 447   size_t _n_yielded_coarse;
 448   size_t _n_yielded_sparse;
 449 
 450   // Indicates what granularity of table that we are currently iterating over.
 451   // We start iterating over the sparse table, progress to the fine grain
 452   // table, and then finish with the coarse table.
 453   enum IterState {
 454     Sparse,
 455     Fine,
 456     Coarse
 457   };
 458   IterState _is;
 459 
 460   // For both Coarse and Fine remembered set iteration this contains the
 461   // first card number of the heap region we currently iterate over.
 462   size_t _cur_region_card_offset;
 463 
 464   // Current region index for the Coarse remembered set iteration.
 465   int    _coarse_cur_region_index;
 466   size_t _coarse_cur_region_cur_card;
 467 
 468   bool coarse_has_next(size_t& card_index);
 469 
 470   // The PRT we are currently iterating over.
 471   PerRegionTable* _fine_cur_prt;
 472   // Card offset within the current PRT.
 473   size_t _cur_card_in_prt;
 474 
 475   // Update internal variables when switching to the given PRT.
 476   void switch_to_prt(PerRegionTable* prt);
 477   bool fine_has_next();
 478   bool fine_has_next(size_t& card_index);
 479 
 480   // The Sparse remembered set iterator.
 481   SparsePRTIter _sparse_iter;
 482 
 483  public:
 484   HeapRegionRemSetIterator(HeapRegionRemSet* hrrs);
 485 
 486   // If there remains one or more cards to be yielded, returns true and
 487   // sets "card_index" to one of those cards (which is then considered
 488   // yielded.)   Otherwise, returns false (and leaves "card_index"
 489   // undefined.)
 490   bool has_next(size_t& card_index);
 491 
 492   size_t n_yielded_fine() { return _n_yielded_fine; }
 493   size_t n_yielded_coarse() { return _n_yielded_coarse; }
 494   size_t n_yielded_sparse() { return _n_yielded_sparse; }
 495   size_t n_yielded() {
 496     return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse();
 497   }
 498 };
 499 
 500 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP
--- EOF ---