1 /* 2 * Copyright (c) 2001, 2015, 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_G1_HEAPREGIONREMSET_HPP 26 #define SHARE_VM_GC_G1_HEAPREGIONREMSET_HPP 27 28 #include "gc/g1/g1CodeCacheRemSet.hpp" 29 #include "gc/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 invalidate(uint start_idx, size_t 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 // link/add the given fine grain remembered set into the "all" list 166 void link_to_all(PerRegionTable * prt); 167 // unlink/remove the given fine grain remembered set into the "all" list 168 void unlink_from_all(PerRegionTable * prt); 169 170 bool contains_reference_locked(OopOrNarrowOopStar from) const; 171 172 // Clear the from_card_cache entries for this region. 173 void clear_fcc(); 174 public: 175 // Create a new remembered set for the given heap region. The given mutex should 176 // be used to ensure consistency. 177 OtherRegionsTable(HeapRegion* hr, Mutex* m); 178 179 // For now. Could "expand" some tables in the future, so that this made 180 // sense. 181 void add_reference(OopOrNarrowOopStar from, uint tid); 182 183 // Returns whether the remembered set contains the given reference. 184 bool contains_reference(OopOrNarrowOopStar from) const; 185 186 // Returns whether this remembered set (and all sub-sets) have an occupancy 187 // that is less or equal than the given occupancy. 188 bool occupancy_less_or_equal_than(size_t limit) const; 189 190 // Removes any entries shown by the given bitmaps to contain only dead 191 // objects. Not thread safe. 192 // Set bits in the bitmaps indicate that the given region or card is live. 193 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); 194 195 // Returns whether this remembered set (and all sub-sets) does not contain any entry. 196 bool is_empty() const; 197 198 // Returns the number of cards contained in this remembered set. 199 size_t occupied() const; 200 size_t occ_fine() const; 201 size_t occ_coarse() const; 202 size_t occ_sparse() const; 203 204 static jint n_coarsenings() { return _n_coarsenings; } 205 206 // Returns size of the actual remembered set containers in bytes. 207 size_t mem_size() const; 208 // Returns the size of static data in bytes. 209 static size_t static_mem_size(); 210 // Returns the size of the free list content in bytes. 211 static size_t fl_mem_size(); 212 213 // Clear the entire contents of this remembered set. 214 void clear(); 215 216 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 217 }; 218 219 class HeapRegionRemSet : public CHeapObj<mtGC> { 220 friend class VMStructs; 221 friend class HeapRegionRemSetIterator; 222 223 public: 224 enum Event { 225 Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd 226 }; 227 228 private: 229 G1BlockOffsetSharedArray* _bosa; 230 231 // A set of code blobs (nmethods) whose code contains pointers into 232 // the region that owns this RSet. 233 G1CodeRootSet _code_roots; 234 235 Mutex _m; 236 237 OtherRegionsTable _other_regions; 238 239 enum ParIterState { Unclaimed, Claimed, Complete }; 240 volatile ParIterState _iter_state; 241 volatile size_t _iter_claimed; 242 243 // Unused unless G1RecordHRRSOops is true. 244 245 static const int MaxRecorded = 1000000; 246 static OopOrNarrowOopStar* _recorded_oops; 247 static HeapWord** _recorded_cards; 248 static HeapRegion** _recorded_regions; 249 static int _n_recorded; 250 251 static const int MaxRecordedEvents = 1000; 252 static Event* _recorded_events; 253 static int* _recorded_event_index; 254 static int _n_recorded_events; 255 256 static void print_event(outputStream* str, Event evnt); 257 258 public: 259 HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, HeapRegion* hr); 260 261 static uint num_par_rem_sets(); 262 static void setup_remset_size(); 263 264 bool is_empty() const { 265 return (strong_code_roots_list_length() == 0) && _other_regions.is_empty(); 266 } 267 268 bool occupancy_less_or_equal_than(size_t occ) const { 269 return (strong_code_roots_list_length() == 0) && _other_regions.occupancy_less_or_equal_than(occ); 270 } 271 272 size_t occupied() { 273 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 274 return occupied_locked(); 275 } 276 size_t occupied_locked() { 277 return _other_regions.occupied(); 278 } 279 size_t occ_fine() const { 280 return _other_regions.occ_fine(); 281 } 282 size_t occ_coarse() const { 283 return _other_regions.occ_coarse(); 284 } 285 size_t occ_sparse() const { 286 return _other_regions.occ_sparse(); 287 } 288 289 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } 290 291 // Used in the sequential case. 292 void add_reference(OopOrNarrowOopStar from) { 293 _other_regions.add_reference(from, 0); 294 } 295 296 // Used in the parallel case. 297 void add_reference(OopOrNarrowOopStar from, uint tid) { 298 _other_regions.add_reference(from, tid); 299 } 300 301 // Removes any entries in the remembered set shown by the given bitmaps to 302 // contain only dead objects. Not thread safe. 303 // One bits in the bitmaps indicate that the given region or card is live. 304 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); 305 306 // The region is being reclaimed; clear its remset, and any mention of 307 // entries for this region in other remsets. 308 void clear(); 309 void clear_locked(); 310 311 // Attempt to claim the region. Returns true iff this call caused an 312 // atomic transition from Unclaimed to Claimed. 313 bool claim_iter(); 314 // Sets the iteration state to "complete". 315 void set_iter_complete(); 316 // Returns "true" iff the region's iteration is complete. 317 bool iter_is_complete(); 318 319 // Support for claiming blocks of cards during iteration 320 size_t iter_claimed() const { return _iter_claimed; } 321 // Claim the next block of cards 322 size_t iter_claimed_next(size_t step) { 323 return Atomic::add(step, &_iter_claimed) - step; 324 } 325 326 void reset_for_par_iteration(); 327 328 bool verify_ready_for_par_iteration() { 329 return (_iter_state == Unclaimed) && (_iter_claimed == 0); 330 } 331 332 // The actual # of bytes this hr_remset takes up. 333 // Note also includes the strong code root set. 334 size_t mem_size() { 335 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 336 return _other_regions.mem_size() 337 // This correction is necessary because the above includes the second 338 // part. 339 + (sizeof(HeapRegionRemSet) - sizeof(OtherRegionsTable)) 340 + strong_code_roots_mem_size(); 341 } 342 343 // Returns the memory occupancy of all static data structures associated 344 // with remembered sets. 345 static size_t static_mem_size() { 346 return OtherRegionsTable::static_mem_size() + G1CodeRootSet::static_mem_size(); 347 } 348 349 // Returns the memory occupancy of all free_list data structures associated 350 // with remembered sets. 351 static size_t fl_mem_size() { 352 return OtherRegionsTable::fl_mem_size(); 353 } 354 355 bool contains_reference(OopOrNarrowOopStar from) const { 356 return _other_regions.contains_reference(from); 357 } 358 359 // Routines for managing the list of code roots that point into 360 // the heap region that owns this RSet. 361 void add_strong_code_root(nmethod* nm); 362 void add_strong_code_root_locked(nmethod* nm); 363 void remove_strong_code_root(nmethod* nm); 364 365 // Applies blk->do_code_blob() to each of the entries in 366 // the strong code roots list 367 void strong_code_roots_do(CodeBlobClosure* blk) const; 368 369 void clean_strong_code_roots(HeapRegion* hr); 370 371 // Returns the number of elements in the strong code roots list 372 size_t strong_code_roots_list_length() const { 373 return _code_roots.length(); 374 } 375 376 // Returns true if the strong code roots contains the given 377 // nmethod. 378 bool strong_code_roots_list_contains(nmethod* nm) { 379 return _code_roots.contains(nm); 380 } 381 382 // Returns the amount of memory, in bytes, currently 383 // consumed by the strong code roots. 384 size_t strong_code_roots_mem_size(); 385 386 void print() PRODUCT_RETURN; 387 388 // Called during a stop-world phase to perform any deferred cleanups. 389 static void cleanup(); 390 391 // Declare the heap size (in # of regions) to the HeapRegionRemSet(s). 392 // (Uses it to initialize from_card_cache). 393 static void init_heap(uint max_regions) { 394 FromCardCache::initialize(num_par_rem_sets(), max_regions); 395 } 396 397 static void invalidate_from_card_cache(uint start_idx, size_t num_regions) { 398 FromCardCache::invalidate(start_idx, num_regions); 399 } 400 401 #ifndef PRODUCT 402 static void print_from_card_cache() { 403 FromCardCache::print(); 404 } 405 #endif 406 407 static void record(HeapRegion* hr, OopOrNarrowOopStar f); 408 static void print_recorded(); 409 static void record_event(Event evnt); 410 411 // These are wrappers for the similarly-named methods on 412 // SparsePRT. Look at sparsePRT.hpp for more details. 413 static void reset_for_cleanup_tasks(); 414 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 415 static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task); 416 417 // Run unit tests. 418 #ifndef PRODUCT 419 static void test_prt(); 420 static void test(); 421 #endif 422 }; 423 424 class HeapRegionRemSetIterator : public StackObj { 425 private: 426 // The region RSet over which we are iterating. 427 HeapRegionRemSet* _hrrs; 428 429 // Local caching of HRRS fields. 430 const BitMap* _coarse_map; 431 432 G1BlockOffsetSharedArray* _bosa; 433 G1CollectedHeap* _g1h; 434 435 // The number of cards yielded since initialization. 436 size_t _n_yielded_fine; 437 size_t _n_yielded_coarse; 438 size_t _n_yielded_sparse; 439 440 // Indicates what granularity of table that we are currently iterating over. 441 // We start iterating over the sparse table, progress to the fine grain 442 // table, and then finish with the coarse table. 443 enum IterState { 444 Sparse, 445 Fine, 446 Coarse 447 }; 448 IterState _is; 449 450 // For both Coarse and Fine remembered set iteration this contains the 451 // first card number of the heap region we currently iterate over. 452 size_t _cur_region_card_offset; 453 454 // Current region index for the Coarse remembered set iteration. 455 int _coarse_cur_region_index; 456 size_t _coarse_cur_region_cur_card; 457 458 bool coarse_has_next(size_t& card_index); 459 460 // The PRT we are currently iterating over. 461 PerRegionTable* _fine_cur_prt; 462 // Card offset within the current PRT. 463 size_t _cur_card_in_prt; 464 465 // Update internal variables when switching to the given PRT. 466 void switch_to_prt(PerRegionTable* prt); 467 bool fine_has_next(); 468 bool fine_has_next(size_t& card_index); 469 470 // The Sparse remembered set iterator. 471 SparsePRTIter _sparse_iter; 472 473 public: 474 HeapRegionRemSetIterator(HeapRegionRemSet* hrrs); 475 476 // If there remains one or more cards to be yielded, returns true and 477 // sets "card_index" to one of those cards (which is then considered 478 // yielded.) Otherwise, returns false (and leaves "card_index" 479 // undefined.) 480 bool has_next(size_t& card_index); 481 482 size_t n_yielded_fine() { return _n_yielded_fine; } 483 size_t n_yielded_coarse() { return _n_yielded_coarse; } 484 size_t n_yielded_sparse() { return _n_yielded_sparse; } 485 size_t n_yielded() { 486 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); 487 } 488 }; 489 490 #endif // SHARE_VM_GC_G1_HEAPREGIONREMSET_HPP