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 private: 224 G1BlockOffsetSharedArray* _bosa; 225 226 // A set of code blobs (nmethods) whose code contains pointers into 227 // the region that owns this RSet. 228 G1CodeRootSet _code_roots; 229 230 Mutex _m; 231 232 OtherRegionsTable _other_regions; 233 234 enum ParIterState { Unclaimed, Claimed, Complete }; 235 volatile ParIterState _iter_state; 236 volatile size_t _iter_claimed; 237 238 public: 239 HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, HeapRegion* hr); 240 241 static uint num_par_rem_sets(); 242 static void setup_remset_size(); 243 244 bool is_empty() const { 245 return (strong_code_roots_list_length() == 0) && _other_regions.is_empty(); 246 } 247 248 bool occupancy_less_or_equal_than(size_t occ) const { 249 return (strong_code_roots_list_length() == 0) && _other_regions.occupancy_less_or_equal_than(occ); 250 } 251 252 size_t occupied() { 253 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 254 return occupied_locked(); 255 } 256 size_t occupied_locked() { 257 return _other_regions.occupied(); 258 } 259 size_t occ_fine() const { 260 return _other_regions.occ_fine(); 261 } 262 size_t occ_coarse() const { 263 return _other_regions.occ_coarse(); 264 } 265 size_t occ_sparse() const { 266 return _other_regions.occ_sparse(); 267 } 268 269 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } 270 271 // Used in the sequential case. 272 void add_reference(OopOrNarrowOopStar from) { 273 _other_regions.add_reference(from, 0); 274 } 275 276 // Used in the parallel case. 277 void add_reference(OopOrNarrowOopStar from, uint tid) { 278 _other_regions.add_reference(from, tid); 279 } 280 281 // Removes any entries in the remembered set shown by the given bitmaps to 282 // contain only dead objects. Not thread safe. 283 // One bits in the bitmaps indicate that the given region or card is live. 284 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); 285 286 // The region is being reclaimed; clear its remset, and any mention of 287 // entries for this region in other remsets. 288 void clear(); 289 void clear_locked(); 290 291 // Attempt to claim the region. Returns true iff this call caused an 292 // atomic transition from Unclaimed to Claimed. 293 bool claim_iter(); 294 // Sets the iteration state to "complete". 295 void set_iter_complete(); 296 // Returns "true" iff the region's iteration is complete. 297 bool iter_is_complete(); 298 299 // Support for claiming blocks of cards during iteration 300 size_t iter_claimed() const { return _iter_claimed; } 301 // Claim the next block of cards 302 size_t iter_claimed_next(size_t step) { 303 return Atomic::add(step, &_iter_claimed) - step; 304 } 305 306 void reset_for_par_iteration(); 307 308 bool verify_ready_for_par_iteration() { 309 return (_iter_state == Unclaimed) && (_iter_claimed == 0); 310 } 311 312 // The actual # of bytes this hr_remset takes up. 313 // Note also includes the strong code root set. 314 size_t mem_size() { 315 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 316 return _other_regions.mem_size() 317 // This correction is necessary because the above includes the second 318 // part. 319 + (sizeof(HeapRegionRemSet) - sizeof(OtherRegionsTable)) 320 + strong_code_roots_mem_size(); 321 } 322 323 // Returns the memory occupancy of all static data structures associated 324 // with remembered sets. 325 static size_t static_mem_size() { 326 return OtherRegionsTable::static_mem_size() + G1CodeRootSet::static_mem_size(); 327 } 328 329 // Returns the memory occupancy of all free_list data structures associated 330 // with remembered sets. 331 static size_t fl_mem_size() { 332 return OtherRegionsTable::fl_mem_size(); 333 } 334 335 bool contains_reference(OopOrNarrowOopStar from) const { 336 return _other_regions.contains_reference(from); 337 } 338 339 // Routines for managing the list of code roots that point into 340 // the heap region that owns this RSet. 341 void add_strong_code_root(nmethod* nm); 342 void add_strong_code_root_locked(nmethod* nm); 343 void remove_strong_code_root(nmethod* nm); 344 345 // Applies blk->do_code_blob() to each of the entries in 346 // the strong code roots list 347 void strong_code_roots_do(CodeBlobClosure* blk) const; 348 349 void clean_strong_code_roots(HeapRegion* hr); 350 351 // Returns the number of elements in the strong code roots list 352 size_t strong_code_roots_list_length() const { 353 return _code_roots.length(); 354 } 355 356 // Returns true if the strong code roots contains the given 357 // nmethod. 358 bool strong_code_roots_list_contains(nmethod* nm) { 359 return _code_roots.contains(nm); 360 } 361 362 // Returns the amount of memory, in bytes, currently 363 // consumed by the strong code roots. 364 size_t strong_code_roots_mem_size(); 365 366 void print() PRODUCT_RETURN; 367 368 // Called during a stop-world phase to perform any deferred cleanups. 369 static void cleanup(); 370 371 // Declare the heap size (in # of regions) to the HeapRegionRemSet(s). 372 // (Uses it to initialize from_card_cache). 373 static void init_heap(uint max_regions) { 374 FromCardCache::initialize(num_par_rem_sets(), max_regions); 375 } 376 377 static void invalidate_from_card_cache(uint start_idx, size_t num_regions) { 378 FromCardCache::invalidate(start_idx, num_regions); 379 } 380 381 #ifndef PRODUCT 382 static void print_from_card_cache() { 383 FromCardCache::print(); 384 } 385 #endif 386 387 // These are wrappers for the similarly-named methods on 388 // SparsePRT. Look at sparsePRT.hpp for more details. 389 static void reset_for_cleanup_tasks(); 390 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 391 static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task); 392 393 // Run unit tests. 394 #ifndef PRODUCT 395 static void test_prt(); 396 static void test(); 397 #endif 398 }; 399 400 class HeapRegionRemSetIterator : public StackObj { 401 private: 402 // The region RSet over which we are iterating. 403 HeapRegionRemSet* _hrrs; 404 405 // Local caching of HRRS fields. 406 const BitMap* _coarse_map; 407 408 G1BlockOffsetSharedArray* _bosa; 409 G1CollectedHeap* _g1h; 410 411 // The number of cards yielded since initialization. 412 size_t _n_yielded_fine; 413 size_t _n_yielded_coarse; 414 size_t _n_yielded_sparse; 415 416 // Indicates what granularity of table that we are currently iterating over. 417 // We start iterating over the sparse table, progress to the fine grain 418 // table, and then finish with the coarse table. 419 enum IterState { 420 Sparse, 421 Fine, 422 Coarse 423 }; 424 IterState _is; 425 426 // For both Coarse and Fine remembered set iteration this contains the 427 // first card number of the heap region we currently iterate over. 428 size_t _cur_region_card_offset; 429 430 // Current region index for the Coarse remembered set iteration. 431 int _coarse_cur_region_index; 432 size_t _coarse_cur_region_cur_card; 433 434 bool coarse_has_next(size_t& card_index); 435 436 // The PRT we are currently iterating over. 437 PerRegionTable* _fine_cur_prt; 438 // Card offset within the current PRT. 439 size_t _cur_card_in_prt; 440 441 // Update internal variables when switching to the given PRT. 442 void switch_to_prt(PerRegionTable* prt); 443 bool fine_has_next(); 444 bool fine_has_next(size_t& card_index); 445 446 // The Sparse remembered set iterator. 447 SparsePRTIter _sparse_iter; 448 449 public: 450 HeapRegionRemSetIterator(HeapRegionRemSet* hrrs); 451 452 // If there remains one or more cards to be yielded, returns true and 453 // sets "card_index" to one of those cards (which is then considered 454 // yielded.) Otherwise, returns false (and leaves "card_index" 455 // undefined.) 456 bool has_next(size_t& card_index); 457 458 size_t n_yielded_fine() { return _n_yielded_fine; } 459 size_t n_yielded_coarse() { return _n_yielded_coarse; } 460 size_t n_yielded_sparse() { return _n_yielded_sparse; } 461 size_t n_yielded() { 462 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); 463 } 464 }; 465 466 #endif // SHARE_VM_GC_G1_HEAPREGIONREMSET_HPP