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 "_coarse_map" is a bitmap with one bit for each region, where set 49 // bits indicate that the corresponding region may contain some pointer 50 // into the owning region. 51 52 // The "_fine_grain_entries" array is an open hash table of PerRegionTables 53 // (PRTs), indicating regions for which we're keeping the RS as a set of 54 // cards. The strategy is to cap the size of the fine-grain table, 55 // deleting an entry and setting the corresponding coarse-grained bit when 56 // we would overflow this cap. 57 58 // We use a mixture of locking and lock-free techniques here. We allow 59 // threads to locate PRTs without locking, but threads attempting to alter 60 // a bucket list obtain a lock. This means that any failing attempt to 61 // find a PRT must be retried with the lock. It might seem dangerous that 62 // a read can find a PRT that is concurrently deleted. This is all right, 63 // because: 64 // 65 // 1) We only actually free PRT's at safe points (though we reuse them at 66 // other times). 67 // 2) We find PRT's in an attempt to add entries. If a PRT is deleted, 68 // it's _coarse_map bit is set, so the that we were attempting to add 69 // is represented. If a deleted PRT is re-used, a thread adding a bit, 70 // thinking the PRT is for a different region, does no harm. 71 72 class OtherRegionsTable VALUE_OBJ_CLASS_SPEC { 73 friend class HeapRegionRemSetIterator; 74 75 G1CollectedHeap* _g1h; 76 Mutex* _m; 77 HeapRegion* _hr; 78 79 // These are protected by "_m". 80 BitMap _coarse_map; 81 size_t _n_coarse_entries; 82 static jint _n_coarsenings; 83 84 PerRegionTable** _fine_grain_regions; 85 size_t _n_fine_entries; 86 87 // The fine grain remembered sets are doubly linked together using 88 // their 'next' and 'prev' fields. 89 // This allows fast bulk freeing of all the fine grain remembered 90 // set entries, and fast finding of all of them without iterating 91 // over the _fine_grain_regions table. 92 PerRegionTable * _first_all_fine_prts; 93 PerRegionTable * _last_all_fine_prts; 94 95 // Used to sample a subset of the fine grain PRTs to determine which 96 // PRT to evict and coarsen. 97 size_t _fine_eviction_start; 98 static size_t _fine_eviction_stride; 99 static size_t _fine_eviction_sample_size; 100 101 SparsePRT _sparse_table; 102 103 // These are static after init. 104 static size_t _max_fine_entries; 105 static size_t _mod_max_fine_entries_mask; 106 107 // Requires "prt" to be the first element of the bucket list appropriate 108 // for "hr". If this list contains an entry for "hr", return it, 109 // otherwise return "NULL". 110 PerRegionTable* find_region_table(size_t ind, HeapRegion* hr) const; 111 112 // Find, delete, and return a candidate PerRegionTable, if any exists, 113 // adding the deleted region to the coarse bitmap. Requires the caller 114 // to hold _m, and the fine-grain table to be full. 115 PerRegionTable* delete_region_table(); 116 117 // If a PRT for "hr" is in the bucket list indicated by "ind" (which must 118 // be the correct index for "hr"), delete it and return true; else return 119 // false. 120 bool del_single_region_table(size_t ind, HeapRegion* hr); 121 122 // Indexed by thread X heap region, to minimize thread contention. 123 static int** _from_card_cache; 124 static size_t _from_card_cache_max_regions; 125 static size_t _from_card_cache_mem_size; 126 127 // link/add the given fine grain remembered set into the "all" list 128 void link_to_all(PerRegionTable * prt); 129 // unlink/remove the given fine grain remembered set into the "all" list 130 void unlink_from_all(PerRegionTable * prt); 131 132 public: 133 OtherRegionsTable(HeapRegion* hr, Mutex* m); 134 135 HeapRegion* hr() const { return _hr; } 136 137 // For now. Could "expand" some tables in the future, so that this made 138 // sense. 139 void add_reference(OopOrNarrowOopStar from, int tid); 140 141 // Removes any entries shown by the given bitmaps to contain only dead 142 // objects. 143 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); 144 145 size_t occupied() const; 146 size_t occ_fine() const; 147 size_t occ_coarse() const; 148 size_t occ_sparse() const; 149 150 static jint n_coarsenings() { return _n_coarsenings; } 151 152 // Returns size in bytes. 153 // Not const because it takes a lock. 154 size_t mem_size() const; 155 static size_t static_mem_size(); 156 static size_t fl_mem_size(); 157 158 bool contains_reference(OopOrNarrowOopStar from) const; 159 bool contains_reference_locked(OopOrNarrowOopStar from) const; 160 161 void clear(); 162 void clear_locked(); 163 164 // Specifically clear the from_card_cache. 165 void clear_fcc(); 166 167 // "from_hr" is being cleared; remove any entries from it. 168 void clear_incoming_entry(HeapRegion* from_hr); 169 170 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 171 172 // Declare the heap size (in # of regions) to the OtherRegionsTable. 173 // (Uses it to initialize from_card_cache). 174 static void init_from_card_cache(size_t max_regions); 175 176 // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. 177 // Make sure any entries for higher regions are invalid. 178 static void shrink_from_card_cache(size_t new_n_regs); 179 180 static void print_from_card_cache(); 181 }; 182 183 class HeapRegionRemSet : public CHeapObj<mtGC> { 184 friend class VMStructs; 185 friend class HeapRegionRemSetIterator; 186 187 public: 188 enum Event { 189 Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd 190 }; 191 192 private: 193 G1BlockOffsetSharedArray* _bosa; 194 G1BlockOffsetSharedArray* bosa() const { return _bosa; } 195 196 // A set of code blobs (nmethods) whose code contains pointers into 197 // the region that owns this RSet. 198 G1CodeRootSet _code_roots; 199 200 Mutex _m; 201 202 OtherRegionsTable _other_regions; 203 204 enum ParIterState { Unclaimed, Claimed, Complete }; 205 volatile ParIterState _iter_state; 206 volatile jlong _iter_claimed; 207 208 // Unused unless G1RecordHRRSOops is true. 209 210 static const int MaxRecorded = 1000000; 211 static OopOrNarrowOopStar* _recorded_oops; 212 static HeapWord** _recorded_cards; 213 static HeapRegion** _recorded_regions; 214 static int _n_recorded; 215 216 static const int MaxRecordedEvents = 1000; 217 static Event* _recorded_events; 218 static int* _recorded_event_index; 219 static int _n_recorded_events; 220 221 static void print_event(outputStream* str, Event evnt); 222 223 public: 224 HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, HeapRegion* hr); 225 226 static int num_par_rem_sets(); 227 static void setup_remset_size(); 228 229 HeapRegion* hr() const { 230 return _other_regions.hr(); 231 } 232 233 size_t occupied() { 234 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 235 return occupied_locked(); 236 } 237 size_t occupied_locked() { 238 return _other_regions.occupied(); 239 } 240 size_t occ_fine() const { 241 return _other_regions.occ_fine(); 242 } 243 size_t occ_coarse() const { 244 return _other_regions.occ_coarse(); 245 } 246 size_t occ_sparse() const { 247 return _other_regions.occ_sparse(); 248 } 249 250 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } 251 252 // Used in the sequential case. 253 void add_reference(OopOrNarrowOopStar from) { 254 _other_regions.add_reference(from, 0); 255 } 256 257 // Used in the parallel case. 258 void add_reference(OopOrNarrowOopStar from, int tid) { 259 _other_regions.add_reference(from, tid); 260 } 261 262 // Removes any entries shown by the given bitmaps to contain only dead 263 // objects. 264 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); 265 266 // The region is being reclaimed; clear its remset, and any mention of 267 // entries for this region in other remsets. 268 void clear(); 269 void clear_locked(); 270 271 // Attempt to claim the region. Returns true iff this call caused an 272 // atomic transition from Unclaimed to Claimed. 273 bool claim_iter(); 274 // Sets the iteration state to "complete". 275 void set_iter_complete(); 276 // Returns "true" iff the region's iteration is complete. 277 bool iter_is_complete(); 278 279 // Support for claiming blocks of cards during iteration 280 size_t iter_claimed() const { return (size_t)_iter_claimed; } 281 // Claim the next block of cards 282 size_t iter_claimed_next(size_t step) { 283 size_t current, next; 284 do { 285 current = iter_claimed(); 286 next = current + step; 287 } while (Atomic::cmpxchg((jlong)next, &_iter_claimed, (jlong)current) != (jlong)current); 288 return current; 289 } 290 void reset_for_par_iteration(); 291 292 bool verify_ready_for_par_iteration() { 293 return (_iter_state == Unclaimed) && (_iter_claimed == 0); 294 } 295 296 // The actual # of bytes this hr_remset takes up. 297 // Note also includes the strong code root set. 298 size_t mem_size() { 299 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 300 return _other_regions.mem_size() 301 // This correction is necessary because the above includes the second 302 // part. 303 + (sizeof(this) - sizeof(OtherRegionsTable)) 304 + strong_code_roots_mem_size(); 305 } 306 307 // Returns the memory occupancy of all static data structures associated 308 // with remembered sets. 309 static size_t static_mem_size() { 310 return OtherRegionsTable::static_mem_size() + G1CodeRootSet::static_mem_size(); 311 } 312 313 // Returns the memory occupancy of all free_list data structures associated 314 // with remembered sets. 315 static size_t fl_mem_size() { 316 return OtherRegionsTable::fl_mem_size() + G1CodeRootSet::fl_mem_size(); 317 } 318 319 bool contains_reference(OopOrNarrowOopStar from) const { 320 return _other_regions.contains_reference(from); 321 } 322 323 // Routines for managing the list of code roots that point into 324 // the heap region that owns this RSet. 325 void add_strong_code_root(nmethod* nm); 326 void remove_strong_code_root(nmethod* nm); 327 328 // During a collection, migrate the successfully evacuated strong 329 // code roots that referenced into the region that owns this RSet 330 // to the RSets of the new regions that they now point into. 331 // Unsuccessfully evacuated code roots are not migrated. 332 void migrate_strong_code_roots(); 333 334 // Applies blk->do_code_blob() to each of the entries in 335 // the strong code roots list 336 void strong_code_roots_do(CodeBlobClosure* blk) const; 337 338 // Returns the number of elements in the strong code roots list 339 size_t strong_code_roots_list_length() { 340 return _code_roots.length(); 341 } 342 343 // Returns true if the strong code roots contains the given 344 // nmethod. 345 bool strong_code_roots_list_contains(nmethod* nm) { 346 return _code_roots.contains(nm); 347 } 348 349 // Returns the amount of memory, in bytes, currently 350 // consumed by the strong code roots. 351 size_t strong_code_roots_mem_size(); 352 353 void print() PRODUCT_RETURN; 354 355 // Called during a stop-world phase to perform any deferred cleanups. 356 static void cleanup(); 357 358 // Declare the heap size (in # of regions) to the HeapRegionRemSet(s). 359 // (Uses it to initialize from_card_cache). 360 static void init_heap(uint max_regions) { 361 G1CodeRootSet::initialize(); 362 OtherRegionsTable::init_from_card_cache((size_t) max_regions); 363 } 364 365 // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. 366 static void shrink_heap(uint new_n_regs) { 367 OtherRegionsTable::shrink_from_card_cache((size_t) new_n_regs); 368 } 369 370 #ifndef PRODUCT 371 static void print_from_card_cache() { 372 OtherRegionsTable::print_from_card_cache(); 373 } 374 #endif 375 376 static void record(HeapRegion* hr, OopOrNarrowOopStar f); 377 static void print_recorded(); 378 static void record_event(Event evnt); 379 380 // These are wrappers for the similarly-named methods on 381 // SparsePRT. Look at sparsePRT.hpp for more details. 382 static void reset_for_cleanup_tasks(); 383 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 384 static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task); 385 386 // Run unit tests. 387 #ifndef PRODUCT 388 static void test_prt(); 389 static void test(); 390 #endif 391 }; 392 393 class HeapRegionRemSetIterator : public StackObj { 394 395 // The region RSet over which we're iterating. 396 HeapRegionRemSet* _hrrs; 397 398 // Local caching of HRRS fields. 399 const BitMap* _coarse_map; 400 PerRegionTable** _fine_grain_regions; 401 402 G1BlockOffsetSharedArray* _bosa; 403 G1CollectedHeap* _g1h; 404 405 // The number yielded since initialization. 406 size_t _n_yielded_fine; 407 size_t _n_yielded_coarse; 408 size_t _n_yielded_sparse; 409 410 // Indicates what granularity of table that we're currently iterating over. 411 // We start iterating over the sparse table, progress to the fine grain 412 // table, and then finish with the coarse table. 413 // See HeapRegionRemSetIterator::has_next(). 414 enum IterState { 415 Sparse, 416 Fine, 417 Coarse 418 }; 419 IterState _is; 420 421 // In both kinds of iteration, heap offset of first card of current 422 // region. 423 size_t _cur_region_card_offset; 424 // Card offset within cur region. 425 size_t _cur_region_cur_card; 426 427 // Coarse table iteration fields: 428 429 // Current region index; 430 int _coarse_cur_region_index; 431 size_t _coarse_cur_region_cur_card; 432 433 bool coarse_has_next(size_t& card_index); 434 435 // Fine table iteration fields: 436 437 // Index of bucket-list we're working on. 438 int _fine_array_index; 439 440 // Per Region Table we're doing within current bucket list. 441 PerRegionTable* _fine_cur_prt; 442 443 /* SparsePRT::*/ SparsePRTIter _sparse_iter; 444 445 void fine_find_next_non_null_prt(); 446 447 bool fine_has_next(); 448 bool fine_has_next(size_t& card_index); 449 450 public: 451 // We require an iterator to be initialized before use, so the 452 // constructor does little. 453 HeapRegionRemSetIterator(HeapRegionRemSet* hrrs); 454 455 // If there remains one or more cards to be yielded, returns true and 456 // sets "card_index" to one of those cards (which is then considered 457 // yielded.) Otherwise, returns false (and leaves "card_index" 458 // undefined.) 459 bool has_next(size_t& card_index); 460 461 size_t n_yielded_fine() { return _n_yielded_fine; } 462 size_t n_yielded_coarse() { return _n_yielded_coarse; } 463 size_t n_yielded_sparse() { return _n_yielded_sparse; } 464 size_t n_yielded() { 465 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); 466 } 467 }; 468 469 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP