1 /* 2 * Copyright (c) 2001, 2016, 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/g1FromCardCache.hpp" 30 #include "gc/g1/sparsePRT.hpp" 31 32 // Remembered set for a heap region. Represent a set of "cards" that 33 // contain pointers into the owner heap region. Cards are defined somewhat 34 // abstractly, in terms of what the "BlockOffsetTable" in use can parse. 35 36 class G1CollectedHeap; 37 class G1BlockOffsetTable; 38 class G1CardLiveData; 39 class HeapRegion; 40 class HeapRegionRemSetIterator; 41 class PerRegionTable; 42 class SparsePRT; 43 class nmethod; 44 45 // Essentially a wrapper around SparsePRTCleanupTask. See 46 // sparsePRT.hpp for more details. 47 class HRRSCleanupTask : public SparsePRTCleanupTask { 48 }; 49 50 // The "_coarse_map" is a bitmap with one bit for each region, where set 51 // bits indicate that the corresponding region may contain some pointer 52 // into the owning region. 53 54 // The "_fine_grain_entries" array is an open hash table of PerRegionTables 55 // (PRTs), indicating regions for which we're keeping the RS as a set of 56 // cards. The strategy is to cap the size of the fine-grain table, 57 // deleting an entry and setting the corresponding coarse-grained bit when 58 // we would overflow this cap. 59 60 // We use a mixture of locking and lock-free techniques here. We allow 61 // threads to locate PRTs without locking, but threads attempting to alter 62 // a bucket list obtain a lock. This means that any failing attempt to 63 // find a PRT must be retried with the lock. It might seem dangerous that 64 // a read can find a PRT that is concurrently deleted. This is all right, 65 // because: 66 // 67 // 1) We only actually free PRT's at safe points (though we reuse them at 68 // other times). 69 // 2) We find PRT's in an attempt to add entries. If a PRT is deleted, 70 // it's _coarse_map bit is set, so the that we were attempting to add 71 // is represented. If a deleted PRT is re-used, a thread adding a bit, 72 // thinking the PRT is for a different region, does no harm. 73 74 class OtherRegionsTable VALUE_OBJ_CLASS_SPEC { 75 friend class HeapRegionRemSetIterator; 76 77 G1CollectedHeap* _g1h; 78 Mutex* _m; 79 HeapRegion* _hr; 80 81 // These are protected by "_m". 82 CHeapBitMap _coarse_map; 83 size_t _n_coarse_entries; 84 static jint _n_coarsenings; 85 86 PerRegionTable** _fine_grain_regions; 87 size_t _n_fine_entries; 88 89 // The fine grain remembered sets are doubly linked together using 90 // their 'next' and 'prev' fields. 91 // This allows fast bulk freeing of all the fine grain remembered 92 // set entries, and fast finding of all of them without iterating 93 // over the _fine_grain_regions table. 94 PerRegionTable * _first_all_fine_prts; 95 PerRegionTable * _last_all_fine_prts; 96 97 // Used to sample a subset of the fine grain PRTs to determine which 98 // PRT to evict and coarsen. 99 size_t _fine_eviction_start; 100 static size_t _fine_eviction_stride; 101 static size_t _fine_eviction_sample_size; 102 103 SparsePRT _sparse_table; 104 105 // These are static after init. 106 static size_t _max_fine_entries; 107 static size_t _mod_max_fine_entries_mask; 108 109 // Requires "prt" to be the first element of the bucket list appropriate 110 // for "hr". If this list contains an entry for "hr", return it, 111 // otherwise return "NULL". 112 PerRegionTable* find_region_table(size_t ind, HeapRegion* hr) const; 113 114 // Find, delete, and return a candidate PerRegionTable, if any exists, 115 // adding the deleted region to the coarse bitmap. Requires the caller 116 // to hold _m, and the fine-grain table to be full. 117 PerRegionTable* delete_region_table(); 118 119 // link/add the given fine grain remembered set into the "all" list 120 void link_to_all(PerRegionTable * prt); 121 // unlink/remove the given fine grain remembered set into the "all" list 122 void unlink_from_all(PerRegionTable * prt); 123 124 bool contains_reference_locked(OopOrNarrowOopStar from) const; 125 126 // Clear the from_card_cache entries for this region. 127 void clear_fcc(); 128 public: 129 // Create a new remembered set for the given heap region. The given mutex should 130 // be used to ensure consistency. 131 OtherRegionsTable(HeapRegion* hr, Mutex* m); 132 133 // For now. Could "expand" some tables in the future, so that this made 134 // sense. 135 void add_reference(OopOrNarrowOopStar from, uint tid); 136 137 // Returns whether the remembered set contains the given reference. 138 bool contains_reference(OopOrNarrowOopStar from) const; 139 140 // Returns whether this remembered set (and all sub-sets) have an occupancy 141 // that is less or equal than the given occupancy. 142 bool occupancy_less_or_equal_than(size_t limit) const; 143 144 // Removes any entries shown by the given bitmaps to contain only dead 145 // objects. Not thread safe. 146 // Set bits in the bitmaps indicate that the given region or card is live. 147 void scrub(G1CardLiveData* live_data); 148 149 // Returns whether this remembered set (and all sub-sets) does not contain any entry. 150 bool is_empty() const; 151 152 // Returns the number of cards contained in this remembered set. 153 size_t occupied() const; 154 size_t occ_fine() const; 155 size_t occ_coarse() const; 156 size_t occ_sparse() const; 157 158 static jint n_coarsenings() { return _n_coarsenings; } 159 160 // Returns size of the actual remembered set containers in bytes. 161 size_t mem_size() const; 162 // Returns the size of static data in bytes. 163 static size_t static_mem_size(); 164 // Returns the size of the free list content in bytes. 165 static size_t fl_mem_size(); 166 167 // Clear the entire contents of this remembered set. 168 void clear(); 169 170 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 171 }; 172 173 class HeapRegionRemSet : public CHeapObj<mtGC> { 174 friend class VMStructs; 175 friend class HeapRegionRemSetIterator; 176 177 private: 178 G1BlockOffsetTable* _bot; 179 180 // A set of code blobs (nmethods) whose code contains pointers into 181 // the region that owns this RSet. 182 G1CodeRootSet _code_roots; 183 184 Mutex _m; 185 186 OtherRegionsTable _other_regions; 187 188 public: 189 HeapRegionRemSet(G1BlockOffsetTable* bot, HeapRegion* hr); 190 191 static void setup_remset_size(); 192 193 bool is_empty() const { 194 return (strong_code_roots_list_length() == 0) && _other_regions.is_empty(); 195 } 196 197 bool occupancy_less_or_equal_than(size_t occ) const { 198 return (strong_code_roots_list_length() == 0) && _other_regions.occupancy_less_or_equal_than(occ); 199 } 200 201 size_t occupied() { 202 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 203 return occupied_locked(); 204 } 205 size_t occupied_locked() { 206 return _other_regions.occupied(); 207 } 208 size_t occ_fine() const { 209 return _other_regions.occ_fine(); 210 } 211 size_t occ_coarse() const { 212 return _other_regions.occ_coarse(); 213 } 214 size_t occ_sparse() const { 215 return _other_regions.occ_sparse(); 216 } 217 218 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } 219 220 // Used in the sequential case. 221 void add_reference(OopOrNarrowOopStar from) { 222 _other_regions.add_reference(from, 0); 223 } 224 225 // Used in the parallel case. 226 void add_reference(OopOrNarrowOopStar from, uint tid) { 227 _other_regions.add_reference(from, tid); 228 } 229 230 // Removes any entries in the remembered set shown by the given card live data to 231 // contain only dead objects. Not thread safe. 232 void scrub(G1CardLiveData* live_data); 233 234 // The region is being reclaimed; clear its remset, and any mention of 235 // entries for this region in other remsets. 236 void clear(); 237 void clear_locked(); 238 239 // The actual # of bytes this hr_remset takes up. 240 // Note also includes the strong code root set. 241 size_t mem_size() { 242 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 243 return _other_regions.mem_size() 244 // This correction is necessary because the above includes the second 245 // part. 246 + (sizeof(HeapRegionRemSet) - sizeof(OtherRegionsTable)) 247 + strong_code_roots_mem_size(); 248 } 249 250 // Returns the memory occupancy of all static data structures associated 251 // with remembered sets. 252 static size_t static_mem_size() { 253 return OtherRegionsTable::static_mem_size() + G1CodeRootSet::static_mem_size(); 254 } 255 256 // Returns the memory occupancy of all free_list data structures associated 257 // with remembered sets. 258 static size_t fl_mem_size() { 259 return OtherRegionsTable::fl_mem_size(); 260 } 261 262 bool contains_reference(OopOrNarrowOopStar from) const { 263 return _other_regions.contains_reference(from); 264 } 265 266 // Routines for managing the list of code roots that point into 267 // the heap region that owns this RSet. 268 void add_strong_code_root(nmethod* nm); 269 void add_strong_code_root_locked(nmethod* nm); 270 void remove_strong_code_root(nmethod* nm); 271 272 // Applies blk->do_code_blob() to each of the entries in 273 // the strong code roots list 274 void strong_code_roots_do(CodeBlobClosure* blk) const; 275 276 void clean_strong_code_roots(HeapRegion* hr); 277 278 // Returns the number of elements in the strong code roots list 279 size_t strong_code_roots_list_length() const { 280 return _code_roots.length(); 281 } 282 283 // Returns true if the strong code roots contains the given 284 // nmethod. 285 bool strong_code_roots_list_contains(nmethod* nm) { 286 return _code_roots.contains(nm); 287 } 288 289 // Returns the amount of memory, in bytes, currently 290 // consumed by the strong code roots. 291 size_t strong_code_roots_mem_size(); 292 293 void print() PRODUCT_RETURN; 294 295 // Called during a stop-world phase to perform any deferred cleanups. 296 static void cleanup(); 297 298 static void invalidate_from_card_cache(uint start_idx, size_t num_regions) { 299 G1FromCardCache::invalidate(start_idx, num_regions); 300 } 301 302 #ifndef PRODUCT 303 static void print_from_card_cache() { 304 G1FromCardCache::print(); 305 } 306 #endif 307 308 // These are wrappers for the similarly-named methods on 309 // SparsePRT. Look at sparsePRT.hpp for more details. 310 static void reset_for_cleanup_tasks(); 311 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 312 static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task); 313 314 // Run unit tests. 315 #ifndef PRODUCT 316 static void test(); 317 #endif 318 }; 319 320 class HeapRegionRemSetIterator : public StackObj { 321 private: 322 // The region RSet over which we are iterating. 323 HeapRegionRemSet* _hrrs; 324 325 // Local caching of HRRS fields. 326 const BitMap* _coarse_map; 327 328 G1BlockOffsetTable* _bot; 329 G1CollectedHeap* _g1h; 330 331 // The number of cards yielded since initialization. 332 size_t _n_yielded_fine; 333 size_t _n_yielded_coarse; 334 size_t _n_yielded_sparse; 335 336 // Indicates what granularity of table that we are currently iterating over. 337 // We start iterating over the sparse table, progress to the fine grain 338 // table, and then finish with the coarse table. 339 enum IterState { 340 Sparse, 341 Fine, 342 Coarse 343 }; 344 IterState _is; 345 346 // For both Coarse and Fine remembered set iteration this contains the 347 // first card number of the heap region we currently iterate over. 348 size_t _cur_region_card_offset; 349 350 // Current region index for the Coarse remembered set iteration. 351 int _coarse_cur_region_index; 352 size_t _coarse_cur_region_cur_card; 353 354 bool coarse_has_next(size_t& card_index); 355 356 // The PRT we are currently iterating over. 357 PerRegionTable* _fine_cur_prt; 358 // Card offset within the current PRT. 359 size_t _cur_card_in_prt; 360 361 // Update internal variables when switching to the given PRT. 362 void switch_to_prt(PerRegionTable* prt); 363 bool fine_has_next(); 364 bool fine_has_next(size_t& card_index); 365 366 // The Sparse remembered set iterator. 367 SparsePRTIter _sparse_iter; 368 369 public: 370 HeapRegionRemSetIterator(HeapRegionRemSet* hrrs); 371 372 // If there remains one or more cards to be yielded, returns true and 373 // sets "card_index" to one of those cards (which is then considered 374 // yielded.) Otherwise, returns false (and leaves "card_index" 375 // undefined.) 376 bool has_next(size_t& card_index); 377 378 size_t n_yielded_fine() { return _n_yielded_fine; } 379 size_t n_yielded_coarse() { return _n_yielded_coarse; } 380 size_t n_yielded_sparse() { return _n_yielded_sparse; } 381 size_t n_yielded() { 382 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); 383 } 384 }; 385 386 #endif // SHARE_VM_GC_G1_HEAPREGIONREMSET_HPP