1 /* 2 * Copyright (c) 2001, 2018, 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 { 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 public: 127 // Clear the from_card_cache entries for this region. 128 void clear_fcc(); 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 // Returns the card index of the given within_region pointer relative to the bottom 134 // of the given heap region. 135 static CardIdx_t card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr); 136 // Adds the reference from "from to this remembered set. 137 void add_reference(OopOrNarrowOopStar from, uint tid); 138 139 // Returns whether the remembered set contains the given reference. 140 bool contains_reference(OopOrNarrowOopStar from) const; 141 142 // Returns whether this remembered set (and all sub-sets) have an occupancy 143 // that is less or equal than the given occupancy. 144 bool occupancy_less_or_equal_than(size_t limit) const; 145 146 // Returns whether this remembered set (and all sub-sets) does not contain any entry. 147 bool is_empty() const; 148 149 // Returns the number of cards contained in this remembered set. 150 size_t occupied() const; 151 size_t occ_fine() const; 152 size_t occ_coarse() const; 153 size_t occ_sparse() const; 154 155 static jint n_coarsenings() { return _n_coarsenings; } 156 157 // Returns size of the actual remembered set containers in bytes. 158 size_t mem_size() const; 159 // Returns the size of static data in bytes. 160 static size_t static_mem_size(); 161 // Returns the size of the free list content in bytes. 162 static size_t fl_mem_size(); 163 164 // Clear the entire contents of this remembered set. 165 void clear(); 166 167 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 168 }; 169 170 class HeapRegionRemSet : public CHeapObj<mtGC> { 171 friend class VMStructs; 172 friend class HeapRegionRemSetIterator; 173 174 private: 175 G1BlockOffsetTable* _bot; 176 177 // A set of code blobs (nmethods) whose code contains pointers into 178 // the region that owns this RSet. 179 G1CodeRootSet _code_roots; 180 181 Mutex _m; 182 183 OtherRegionsTable _other_regions; 184 185 public: 186 HeapRegionRemSet(G1BlockOffsetTable* bot, HeapRegion* hr); 187 188 static void setup_remset_size(); 189 190 bool is_empty() const { 191 return (strong_code_roots_list_length() == 0) && _other_regions.is_empty(); 192 } 193 194 bool occupancy_less_or_equal_than(size_t occ) const { 195 return (strong_code_roots_list_length() == 0) && _other_regions.occupancy_less_or_equal_than(occ); 196 } 197 198 size_t occupied() { 199 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 200 return occupied_locked(); 201 } 202 size_t occupied_locked() { 203 return _other_regions.occupied(); 204 } 205 size_t occ_fine() const { 206 return _other_regions.occ_fine(); 207 } 208 size_t occ_coarse() const { 209 return _other_regions.occ_coarse(); 210 } 211 size_t occ_sparse() const { 212 return _other_regions.occ_sparse(); 213 } 214 215 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } 216 217 private: 218 enum RemSetState { 219 Untracked, 220 Updating, 221 Complete 222 }; 223 224 RemSetState _state; 225 226 static const char* _state_strings[]; 227 public: 228 229 const char* get_state_str() const { return _state_strings[_state]; } 230 231 bool is_tracked() { return _state != Untracked; } 232 bool is_updating() { return _state == Updating; } 233 bool is_complete() { return _state == Complete; } 234 235 void set_state_empty() { 236 guarantee(SafepointSynchronize::is_at_safepoint() || !is_tracked(), "Should only set to Untracked during safepoint but is %s.", get_state_str()); 237 if (_state == Untracked) { 238 return; 239 } 240 _other_regions.clear_fcc(); 241 _state = Untracked; 242 } 243 244 void set_state_updating() { 245 guarantee(SafepointSynchronize::is_at_safepoint() && !is_tracked(), "Should only set to Updating from Untracked during safepoint but is %s", get_state_str()); 246 _other_regions.clear_fcc(); 247 _state = Updating; 248 } 249 250 void set_state_complete() { 251 _other_regions.clear_fcc(); 252 _state = Complete; 253 } 254 255 // Used in the sequential case. 256 void add_reference(OopOrNarrowOopStar from) { 257 add_reference(from, 0); 258 } 259 260 // Used in the parallel case. 261 void add_reference(OopOrNarrowOopStar from, uint tid) { 262 RemSetState state = _state; 263 if (state == Untracked) { 264 return; 265 } 266 _other_regions.add_reference(from, tid); 267 } 268 269 // The region is being reclaimed; clear its remset, and any mention of 270 // entries for this region in other remsets. 271 void clear(bool only_cardset = false); 272 void clear_locked(bool only_cardset = false); 273 274 // The actual # of bytes this hr_remset takes up. 275 // Note also includes the strong code root set. 276 size_t mem_size() { 277 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 278 return _other_regions.mem_size() 279 // This correction is necessary because the above includes the second 280 // part. 281 + (sizeof(HeapRegionRemSet) - sizeof(OtherRegionsTable)) 282 + strong_code_roots_mem_size(); 283 } 284 285 // Returns the memory occupancy of all static data structures associated 286 // with remembered sets. 287 static size_t static_mem_size() { 288 return OtherRegionsTable::static_mem_size() + G1CodeRootSet::static_mem_size(); 289 } 290 291 // Returns the memory occupancy of all free_list data structures associated 292 // with remembered sets. 293 static size_t fl_mem_size() { 294 return OtherRegionsTable::fl_mem_size(); 295 } 296 297 bool contains_reference(OopOrNarrowOopStar from) const { 298 return _other_regions.contains_reference(from); 299 } 300 301 // Routines for managing the list of code roots that point into 302 // the heap region that owns this RSet. 303 void add_strong_code_root(nmethod* nm); 304 void add_strong_code_root_locked(nmethod* nm); 305 void remove_strong_code_root(nmethod* nm); 306 307 // Applies blk->do_code_blob() to each of the entries in 308 // the strong code roots list 309 void strong_code_roots_do(CodeBlobClosure* blk) const; 310 311 void clean_strong_code_roots(HeapRegion* hr); 312 313 // Returns the number of elements in the strong code roots list 314 size_t strong_code_roots_list_length() const { 315 return _code_roots.length(); 316 } 317 318 // Returns true if the strong code roots contains the given 319 // nmethod. 320 bool strong_code_roots_list_contains(nmethod* nm) { 321 return _code_roots.contains(nm); 322 } 323 324 // Returns the amount of memory, in bytes, currently 325 // consumed by the strong code roots. 326 size_t strong_code_roots_mem_size(); 327 328 // Called during a stop-world phase to perform any deferred cleanups. 329 static void cleanup(); 330 331 static void invalidate_from_card_cache(uint start_idx, size_t num_regions) { 332 G1FromCardCache::invalidate(start_idx, num_regions); 333 } 334 335 #ifndef PRODUCT 336 static void print_from_card_cache() { 337 G1FromCardCache::print(); 338 } 339 #endif 340 341 // These are wrappers for the similarly-named methods on 342 // SparsePRT. Look at sparsePRT.hpp for more details. 343 static void reset_for_cleanup_tasks(); 344 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 345 static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task); 346 347 // Run unit tests. 348 #ifndef PRODUCT 349 static void test(); 350 #endif 351 }; 352 353 class HeapRegionRemSetIterator : public StackObj { 354 private: 355 // The region RSet over which we are iterating. 356 HeapRegionRemSet* _hrrs; 357 358 // Local caching of HRRS fields. 359 const BitMap* _coarse_map; 360 361 G1BlockOffsetTable* _bot; 362 G1CollectedHeap* _g1h; 363 364 // The number of cards yielded since initialization. 365 size_t _n_yielded_fine; 366 size_t _n_yielded_coarse; 367 size_t _n_yielded_sparse; 368 369 // Indicates what granularity of table that we are currently iterating over. 370 // We start iterating over the sparse table, progress to the fine grain 371 // table, and then finish with the coarse table. 372 enum IterState { 373 Sparse, 374 Fine, 375 Coarse 376 }; 377 IterState _is; 378 379 // For both Coarse and Fine remembered set iteration this contains the 380 // first card number of the heap region we currently iterate over. 381 size_t _cur_region_card_offset; 382 383 // Current region index for the Coarse remembered set iteration. 384 int _coarse_cur_region_index; 385 size_t _coarse_cur_region_cur_card; 386 387 bool coarse_has_next(size_t& card_index); 388 389 // The PRT we are currently iterating over. 390 PerRegionTable* _fine_cur_prt; 391 // Card offset within the current PRT. 392 size_t _cur_card_in_prt; 393 394 // Update internal variables when switching to the given PRT. 395 void switch_to_prt(PerRegionTable* prt); 396 bool fine_has_next(); 397 bool fine_has_next(size_t& card_index); 398 399 // The Sparse remembered set iterator. 400 SparsePRTIter _sparse_iter; 401 402 public: 403 HeapRegionRemSetIterator(HeapRegionRemSet* hrrs); 404 405 // If there remains one or more cards to be yielded, returns true and 406 // sets "card_index" to one of those cards (which is then considered 407 // yielded.) Otherwise, returns false (and leaves "card_index" 408 // undefined.) 409 bool has_next(size_t& card_index); 410 411 size_t n_yielded_fine() { return _n_yielded_fine; } 412 size_t n_yielded_coarse() { return _n_yielded_coarse; } 413 size_t n_yielded_sparse() { return _n_yielded_sparse; } 414 size_t n_yielded() { 415 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); 416 } 417 }; 418 419 #endif // SHARE_VM_GC_G1_HEAPREGIONREMSET_HPP