1 /* 2 * Copyright (c) 2001, 2012, 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/sparsePRT.hpp" 29 30 // Remembered set for a heap region. Represent a set of "cards" that 31 // contain pointers into the owner heap region. Cards are defined somewhat 32 // abstractly, in terms of what the "BlockOffsetTable" in use can parse. 33 34 class G1CollectedHeap; 35 class G1BlockOffsetSharedArray; 36 class HeapRegion; 37 class HeapRegionRemSetIterator; 38 class PerRegionTable; 39 class SparsePRT; 40 41 // Essentially a wrapper around SparsePRTCleanupTask. See 42 // sparsePRT.hpp for more details. 43 class HRRSCleanupTask : public SparsePRTCleanupTask { 44 }; 45 46 // The "_coarse_map" is a bitmap with one bit for each region, where set 47 // bits indicate that the corresponding region may contain some pointer 48 // into the owning region. 49 50 // The "_fine_grain_entries" array is an open hash table of PerRegionTables 51 // (PRTs), indicating regions for which we're keeping the RS as a set of 52 // cards. The strategy is to cap the size of the fine-grain table, 53 // deleting an entry and setting the corresponding coarse-grained bit when 54 // we would overflow this cap. 55 56 // We use a mixture of locking and lock-free techniques here. We allow 57 // threads to locate PRTs without locking, but threads attempting to alter 58 // a bucket list obtain a lock. This means that any failing attempt to 59 // find a PRT must be retried with the lock. It might seem dangerous that 60 // a read can find a PRT that is concurrently deleted. This is all right, 61 // because: 62 // 63 // 1) We only actually free PRT's at safe points (though we reuse them at 64 // other times). 65 // 2) We find PRT's in an attempt to add entries. If a PRT is deleted, 66 // it's _coarse_map bit is set, so the that we were attempting to add 67 // is represented. If a deleted PRT is re-used, a thread adding a bit, 68 // thinking the PRT is for a different region, does no harm. 69 70 class OtherRegionsTable VALUE_OBJ_CLASS_SPEC { 71 friend class HeapRegionRemSetIterator; 72 73 G1CollectedHeap* _g1h; 74 Mutex _m; 75 HeapRegion* _hr; 76 77 // These are protected by "_m". 78 BitMap _coarse_map; 79 size_t _n_coarse_entries; 80 static jint _n_coarsenings; 81 82 PerRegionTable** _fine_grain_regions; 83 size_t _n_fine_entries; 84 85 // The fine grain remembered sets are doubly linked together using 86 // their 'next' and 'prev' fields. 87 // This allows fast bulk freeing of all the fine grain remembered 88 // set entries, and fast finding of all of them without iterating 89 // over the _fine_grain_regions table. 90 PerRegionTable * _first_all_fine_prts; 91 PerRegionTable * _last_all_fine_prts; 92 93 // Used to sample a subset of the fine grain PRTs to determine which 94 // PRT to evict and coarsen. 95 size_t _fine_eviction_start; 96 static size_t _fine_eviction_stride; 97 static size_t _fine_eviction_sample_size; 98 99 SparsePRT _sparse_table; 100 101 // These are static after init. 102 static size_t _max_fine_entries; 103 static size_t _mod_max_fine_entries_mask; 104 105 // Requires "prt" to be the first element of the bucket list appropriate 106 // for "hr". If this list contains an entry for "hr", return it, 107 // otherwise return "NULL". 108 PerRegionTable* find_region_table(size_t ind, HeapRegion* hr) const; 109 110 // Find, delete, and return a candidate PerRegionTable, if any exists, 111 // adding the deleted region to the coarse bitmap. Requires the caller 112 // to hold _m, and the fine-grain table to be full. 113 PerRegionTable* delete_region_table(); 114 115 // If a PRT for "hr" is in the bucket list indicated by "ind" (which must 116 // be the correct index for "hr"), delete it and return true; else return 117 // false. 118 bool del_single_region_table(size_t ind, HeapRegion* hr); 119 120 // Indexed by thread X heap region, to minimize thread contention. 121 static int** _from_card_cache; 122 static size_t _from_card_cache_max_regions; 123 static size_t _from_card_cache_mem_size; 124 125 // link/add the given fine grain remembered set into the "all" list 126 void link_to_all(PerRegionTable * prt); 127 // unlink/remove the given fine grain remembered set into the "all" list 128 void unlink_from_all(PerRegionTable * prt); 129 130 public: 131 OtherRegionsTable(HeapRegion* hr); 132 133 HeapRegion* hr() const { return _hr; } 134 135 // For now. Could "expand" some tables in the future, so that this made 136 // sense. 137 void add_reference(OopOrNarrowOopStar from, int tid); 138 139 // Removes any entries shown by the given bitmaps to contain only dead 140 // objects. 141 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); 142 143 // Not const because it takes a lock. 144 size_t occupied() const; 145 size_t occ_fine() const; 146 size_t occ_coarse() const; 147 size_t occ_sparse() const; 148 149 static jint n_coarsenings() { return _n_coarsenings; } 150 151 // Returns size in bytes. 152 // Not const because it takes a lock. 153 size_t mem_size() const; 154 static size_t static_mem_size(); 155 static size_t fl_mem_size(); 156 157 bool contains_reference(OopOrNarrowOopStar from) const; 158 bool contains_reference_locked(OopOrNarrowOopStar from) const; 159 160 void clear(); 161 162 // Specifically clear the from_card_cache. 163 void clear_fcc(); 164 165 // "from_hr" is being cleared; remove any entries from it. 166 void clear_incoming_entry(HeapRegion* from_hr); 167 168 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 169 170 // Declare the heap size (in # of regions) to the OtherRegionsTable. 171 // (Uses it to initialize from_card_cache). 172 static void init_from_card_cache(size_t max_regions); 173 174 // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. 175 // Make sure any entries for higher regions are invalid. 176 static void shrink_from_card_cache(size_t new_n_regs); 177 178 static void print_from_card_cache(); 179 }; 180 181 class HeapRegionRemSet : public CHeapObj<mtGC> { 182 friend class VMStructs; 183 friend class HeapRegionRemSetIterator; 184 185 public: 186 enum Event { 187 Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd 188 }; 189 190 private: 191 G1BlockOffsetSharedArray* _bosa; 192 G1BlockOffsetSharedArray* bosa() const { return _bosa; } 193 194 OtherRegionsTable _other_regions; 195 196 enum ParIterState { Unclaimed, Claimed, Complete }; 197 volatile ParIterState _iter_state; 198 volatile jlong _iter_claimed; 199 200 // Unused unless G1RecordHRRSOops is true. 201 202 static const int MaxRecorded = 1000000; 203 static OopOrNarrowOopStar* _recorded_oops; 204 static HeapWord** _recorded_cards; 205 static HeapRegion** _recorded_regions; 206 static int _n_recorded; 207 208 static const int MaxRecordedEvents = 1000; 209 static Event* _recorded_events; 210 static int* _recorded_event_index; 211 static int _n_recorded_events; 212 213 static void print_event(outputStream* str, Event evnt); 214 215 public: 216 HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, 217 HeapRegion* hr); 218 219 static int num_par_rem_sets(); 220 static void setup_remset_size(); 221 222 HeapRegion* hr() const { 223 return _other_regions.hr(); 224 } 225 226 size_t occupied() const { 227 return _other_regions.occupied(); 228 } 229 size_t occ_fine() const { 230 return _other_regions.occ_fine(); 231 } 232 size_t occ_coarse() const { 233 return _other_regions.occ_coarse(); 234 } 235 size_t occ_sparse() const { 236 return _other_regions.occ_sparse(); 237 } 238 239 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } 240 241 // Used in the sequential case. 242 void add_reference(OopOrNarrowOopStar from) { 243 _other_regions.add_reference(from, 0); 244 } 245 246 // Used in the parallel case. 247 void add_reference(OopOrNarrowOopStar from, int tid) { 248 _other_regions.add_reference(from, tid); 249 } 250 251 // Removes any entries shown by the given bitmaps to contain only dead 252 // objects. 253 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); 254 255 // The region is being reclaimed; clear its remset, and any mention of 256 // entries for this region in other remsets. 257 void clear(); 258 259 // Attempt to claim the region. Returns true iff this call caused an 260 // atomic transition from Unclaimed to Claimed. 261 bool claim_iter(); 262 // Sets the iteration state to "complete". 263 void set_iter_complete(); 264 // Returns "true" iff the region's iteration is complete. 265 bool iter_is_complete(); 266 267 // Support for claiming blocks of cards during iteration 268 size_t iter_claimed() const { return (size_t)_iter_claimed; } 269 // Claim the next block of cards 270 size_t iter_claimed_next(size_t step) { 271 size_t current, next; 272 do { 273 current = iter_claimed(); 274 next = current + step; 275 } while (Atomic::cmpxchg((jlong)next, &_iter_claimed, (jlong)current) != (jlong)current); 276 return current; 277 } 278 void reset_for_par_iteration(); 279 280 bool verify_ready_for_par_iteration() { 281 return (_iter_state == Unclaimed) && (_iter_claimed == 0); 282 } 283 284 // The actual # of bytes this hr_remset takes up. 285 size_t mem_size() { 286 return _other_regions.mem_size() 287 // This correction is necessary because the above includes the second 288 // part. 289 + sizeof(this) - sizeof(OtherRegionsTable); 290 } 291 292 // Returns the memory occupancy of all static data structures associated 293 // with remembered sets. 294 static size_t static_mem_size() { 295 return OtherRegionsTable::static_mem_size(); 296 } 297 298 // Returns the memory occupancy of all free_list data structures associated 299 // with remembered sets. 300 static size_t fl_mem_size() { 301 return OtherRegionsTable::fl_mem_size(); 302 } 303 304 bool contains_reference(OopOrNarrowOopStar from) const { 305 return _other_regions.contains_reference(from); 306 } 307 void print() const; 308 309 // Called during a stop-world phase to perform any deferred cleanups. 310 static void cleanup(); 311 312 // Declare the heap size (in # of regions) to the HeapRegionRemSet(s). 313 // (Uses it to initialize from_card_cache). 314 static void init_heap(uint max_regions) { 315 OtherRegionsTable::init_from_card_cache((size_t) max_regions); 316 } 317 318 // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. 319 static void shrink_heap(uint new_n_regs) { 320 OtherRegionsTable::shrink_from_card_cache((size_t) new_n_regs); 321 } 322 323 #ifndef PRODUCT 324 static void print_from_card_cache() { 325 OtherRegionsTable::print_from_card_cache(); 326 } 327 #endif 328 329 static void record(HeapRegion* hr, OopOrNarrowOopStar f); 330 static void print_recorded(); 331 static void record_event(Event evnt); 332 333 // These are wrappers for the similarly-named methods on 334 // SparsePRT. Look at sparsePRT.hpp for more details. 335 static void reset_for_cleanup_tasks(); 336 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 337 static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task); 338 339 // Run unit tests. 340 #ifndef PRODUCT 341 static void test(); 342 #endif 343 }; 344 345 class HeapRegionRemSetIterator : public StackObj { 346 347 // The region RSet over which we're iterating. 348 const HeapRegionRemSet* _hrrs; 349 350 // Local caching of HRRS fields. 351 const BitMap* _coarse_map; 352 PerRegionTable** _fine_grain_regions; 353 354 G1BlockOffsetSharedArray* _bosa; 355 G1CollectedHeap* _g1h; 356 357 // The number yielded since initialization. 358 size_t _n_yielded_fine; 359 size_t _n_yielded_coarse; 360 size_t _n_yielded_sparse; 361 362 // Indicates what granularity of table that we're currently iterating over. 363 // We start iterating over the sparse table, progress to the fine grain 364 // table, and then finish with the coarse table. 365 // See HeapRegionRemSetIterator::has_next(). 366 enum IterState { 367 Sparse, 368 Fine, 369 Coarse 370 }; 371 IterState _is; 372 373 // In both kinds of iteration, heap offset of first card of current 374 // region. 375 size_t _cur_region_card_offset; 376 // Card offset within cur region. 377 size_t _cur_region_cur_card; 378 379 // Coarse table iteration fields: 380 381 // Current region index; 382 int _coarse_cur_region_index; 383 size_t _coarse_cur_region_cur_card; 384 385 bool coarse_has_next(size_t& card_index); 386 387 // Fine table iteration fields: 388 389 // Index of bucket-list we're working on. 390 int _fine_array_index; 391 392 // Per Region Table we're doing within current bucket list. 393 PerRegionTable* _fine_cur_prt; 394 395 /* SparsePRT::*/ SparsePRTIter _sparse_iter; 396 397 void fine_find_next_non_null_prt(); 398 399 bool fine_has_next(); 400 bool fine_has_next(size_t& card_index); 401 402 public: 403 // We require an iterator to be initialized before use, so the 404 // constructor does little. 405 HeapRegionRemSetIterator(const HeapRegionRemSet* hrrs); 406 407 // If there remains one or more cards to be yielded, returns true and 408 // sets "card_index" to one of those cards (which is then considered 409 // yielded.) Otherwise, returns false (and leaves "card_index" 410 // undefined.) 411 bool has_next(size_t& card_index); 412 413 size_t n_yielded_fine() { return _n_yielded_fine; } 414 size_t n_yielded_coarse() { return _n_yielded_coarse; } 415 size_t n_yielded_sparse() { return _n_yielded_sparse; } 416 size_t n_yielded() { 417 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); 418 } 419 }; 420 421 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP