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 80 // These are protected by "_m". 81 CHeapBitMap _coarse_map; 82 size_t _n_coarse_entries; 83 static jint _n_coarsenings; 84 85 PerRegionTable** _fine_grain_regions; 86 size_t _n_fine_entries; 87 88 // The fine grain remembered sets are doubly linked together using 89 // their 'next' and 'prev' fields. 90 // This allows fast bulk freeing of all the fine grain remembered 91 // set entries, and fast finding of all of them without iterating 92 // over the _fine_grain_regions table. 93 PerRegionTable * _first_all_fine_prts; 94 PerRegionTable * _last_all_fine_prts; 95 96 // Used to sample a subset of the fine grain PRTs to determine which 97 // PRT to evict and coarsen. 98 size_t _fine_eviction_start; 99 static size_t _fine_eviction_stride; 100 static size_t _fine_eviction_sample_size; 101 102 SparsePRT _sparse_table; 103 104 // These are static after init. 105 static size_t _max_fine_entries; 106 static size_t _mod_max_fine_entries_mask; 107 108 // Requires "prt" to be the first element of the bucket list appropriate 109 // for "hr". If this list contains an entry for "hr", return it, 110 // otherwise return "NULL". 111 PerRegionTable* find_region_table(size_t ind, HeapRegion* hr) const; 112 113 // Find, delete, and return a candidate PerRegionTable, if any exists, 114 // adding the deleted region to the coarse bitmap. Requires the caller 115 // to hold _m, and the fine-grain table to be full. 116 PerRegionTable* delete_region_table(); 117 118 // link/add the given fine grain remembered set into the "all" list 119 void link_to_all(PerRegionTable * prt); 120 // unlink/remove the given fine grain remembered set into the "all" list 121 void unlink_from_all(PerRegionTable * prt); 122 123 bool contains_reference_locked(OopOrNarrowOopStar from) const; 124 125 public: 126 // Create a new remembered set. The given mutex is used to ensure consistency. 127 OtherRegionsTable(Mutex* m); 128 129 // Returns the card index of the given within_region pointer relative to the bottom 130 // of the given heap region. 131 static CardIdx_t card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr); 132 // Adds the reference from "from to this remembered set. 133 void add_reference(OopOrNarrowOopStar from, uint tid); 134 135 // Returns whether the remembered set contains the given reference. 136 bool contains_reference(OopOrNarrowOopStar from) const; 137 138 // Returns whether this remembered set (and all sub-sets) have an occupancy 139 // that is less or equal than the given occupancy. 140 bool occupancy_less_or_equal_than(size_t limit) const; 141 142 // Returns whether this remembered set (and all sub-sets) does not contain any entry. 143 bool is_empty() const; 144 145 // Returns the number of cards contained in this remembered set. 146 size_t occupied() const; 147 size_t occ_fine() const; 148 size_t occ_coarse() const; 149 size_t occ_sparse() const; 150 151 static jint n_coarsenings() { return _n_coarsenings; } 152 153 // Returns size of the actual remembered set containers in bytes. 154 size_t mem_size() const; 155 // Returns the size of static data in bytes. 156 static size_t static_mem_size(); 157 // Returns the size of the free list content in bytes. 158 static size_t fl_mem_size(); 159 160 // Clear the entire contents of this remembered set. 161 void clear(); 162 163 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 164 }; 165 166 class HeapRegionRemSet : public CHeapObj<mtGC> { 167 friend class VMStructs; 168 friend class HeapRegionRemSetIterator; 169 170 private: 171 G1BlockOffsetTable* _bot; 172 173 // A set of code blobs (nmethods) whose code contains pointers into 174 // the region that owns this RSet. 175 G1CodeRootSet _code_roots; 176 177 Mutex _m; 178 179 OtherRegionsTable _other_regions; 180 181 HeapRegion* _hr; 182 183 void clear_fcc(); 184 185 public: 186 HeapRegionRemSet(G1BlockOffsetTable* bot, HeapRegion* hr); 187 188 static void setup_remset_size(); 189 190 bool cardset_is_empty() const { 191 return _other_regions.is_empty(); 192 } 193 194 bool is_empty() const { 195 return (strong_code_roots_list_length() == 0) && cardset_is_empty(); 196 } 197 198 bool occupancy_less_or_equal_than(size_t occ) const { 199 return (strong_code_roots_list_length() == 0) && _other_regions.occupancy_less_or_equal_than(occ); 200 } 201 202 size_t occupied() { 203 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 204 return occupied_locked(); 205 } 206 size_t occupied_locked() { 207 return _other_regions.occupied(); 208 } 209 size_t occ_fine() const { 210 return _other_regions.occ_fine(); 211 } 212 size_t occ_coarse() const { 213 return _other_regions.occ_coarse(); 214 } 215 size_t occ_sparse() const { 216 return _other_regions.occ_sparse(); 217 } 218 219 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } 220 221 private: 222 enum RemSetState { 223 Untracked, 224 Updating, 225 Complete 226 }; 227 228 RemSetState _state; 229 230 static const char* _state_strings[]; 231 static const char* _short_state_strings[]; 232 public: 233 234 const char* get_state_str() const { return _state_strings[_state]; } 235 const char* get_short_state_str() const { return _short_state_strings[_state]; } 236 237 bool is_tracked() { return _state != Untracked; } 238 bool is_updating() { return _state == Updating; } 239 bool is_complete() { return _state == Complete; } 240 241 void set_state_empty() { 242 guarantee(SafepointSynchronize::is_at_safepoint() || !is_tracked(), "Should only set to Untracked during safepoint but is %s.", get_state_str()); 243 if (_state == Untracked) { 244 return; 245 } 246 clear_fcc(); 247 _state = Untracked; 248 } 249 250 void set_state_updating() { 251 guarantee(SafepointSynchronize::is_at_safepoint() && !is_tracked(), "Should only set to Updating from Untracked during safepoint but is %s", get_state_str()); 252 clear_fcc(); 253 _state = Updating; 254 } 255 256 void set_state_complete() { 257 clear_fcc(); 258 _state = Complete; 259 } 260 261 // Used in the sequential case. 262 void add_reference(OopOrNarrowOopStar from) { 263 add_reference(from, 0); 264 } 265 266 // Used in the parallel case. 267 void add_reference(OopOrNarrowOopStar from, uint tid) { 268 RemSetState state = _state; 269 if (state == Untracked) { 270 return; 271 } 272 273 uint cur_idx = _hr->hrm_index(); 274 uintptr_t from_card = uintptr_t(from) >> CardTable::card_shift; 275 276 if (G1FromCardCache::contains_or_replace(tid, cur_idx, from_card)) { 277 assert(contains_reference(from), "We just found " PTR_FORMAT " in the FromCardCache", p2i(from)); 278 return; 279 } 280 281 _other_regions.add_reference(from, tid); 282 } 283 284 // The region is being reclaimed; clear its remset, and any mention of 285 // entries for this region in other remsets. 286 void clear(bool only_cardset = false); 287 void clear_locked(bool only_cardset = false); 288 289 // The actual # of bytes this hr_remset takes up. 290 // Note also includes the strong code root set. 291 size_t mem_size() { 292 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 293 return _other_regions.mem_size() 294 // This correction is necessary because the above includes the second 295 // part. 296 + (sizeof(HeapRegionRemSet) - sizeof(OtherRegionsTable)) 297 + strong_code_roots_mem_size(); 298 } 299 300 // Returns the memory occupancy of all static data structures associated 301 // with remembered sets. 302 static size_t static_mem_size() { 303 return OtherRegionsTable::static_mem_size() + G1CodeRootSet::static_mem_size(); 304 } 305 306 // Returns the memory occupancy of all free_list data structures associated 307 // with remembered sets. 308 static size_t fl_mem_size() { 309 return OtherRegionsTable::fl_mem_size(); 310 } 311 312 bool contains_reference(OopOrNarrowOopStar from) const { 313 return _other_regions.contains_reference(from); 314 } 315 316 // Routines for managing the list of code roots that point into 317 // the heap region that owns this RSet. 318 void add_strong_code_root(nmethod* nm); 319 void add_strong_code_root_locked(nmethod* nm); 320 void remove_strong_code_root(nmethod* nm); 321 322 // Applies blk->do_code_blob() to each of the entries in 323 // the strong code roots list 324 void strong_code_roots_do(CodeBlobClosure* blk) const; 325 326 void clean_strong_code_roots(HeapRegion* hr); 327 328 // Returns the number of elements in the strong code roots list 329 size_t strong_code_roots_list_length() const { 330 return _code_roots.length(); 331 } 332 333 // Returns true if the strong code roots contains the given 334 // nmethod. 335 bool strong_code_roots_list_contains(nmethod* nm) { 336 return _code_roots.contains(nm); 337 } 338 339 // Returns the amount of memory, in bytes, currently 340 // consumed by the strong code roots. 341 size_t strong_code_roots_mem_size(); 342 343 // Called during a stop-world phase to perform any deferred cleanups. 344 static void cleanup(); 345 346 static void invalidate_from_card_cache(uint start_idx, size_t num_regions) { 347 G1FromCardCache::invalidate(start_idx, num_regions); 348 } 349 350 #ifndef PRODUCT 351 static void print_from_card_cache() { 352 G1FromCardCache::print(); 353 } 354 #endif 355 356 // These are wrappers for the similarly-named methods on 357 // SparsePRT. Look at sparsePRT.hpp for more details. 358 static void reset_for_cleanup_tasks(); 359 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); 360 static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task); 361 362 // Run unit tests. 363 #ifndef PRODUCT 364 static void test(); 365 #endif 366 }; 367 368 class HeapRegionRemSetIterator : public StackObj { 369 private: 370 // The region RSet over which we are iterating. 371 HeapRegionRemSet* _hrrs; 372 373 // Local caching of HRRS fields. 374 const BitMap* _coarse_map; 375 376 G1BlockOffsetTable* _bot; 377 G1CollectedHeap* _g1h; 378 379 // The number of cards yielded since initialization. 380 size_t _n_yielded_fine; 381 size_t _n_yielded_coarse; 382 size_t _n_yielded_sparse; 383 384 // Indicates what granularity of table that we are currently iterating over. 385 // We start iterating over the sparse table, progress to the fine grain 386 // table, and then finish with the coarse table. 387 enum IterState { 388 Sparse, 389 Fine, 390 Coarse 391 }; 392 IterState _is; 393 394 // For both Coarse and Fine remembered set iteration this contains the 395 // first card number of the heap region we currently iterate over. 396 size_t _cur_region_card_offset; 397 398 // Current region index for the Coarse remembered set iteration. 399 int _coarse_cur_region_index; 400 size_t _coarse_cur_region_cur_card; 401 402 bool coarse_has_next(size_t& card_index); 403 404 // The PRT we are currently iterating over. 405 PerRegionTable* _fine_cur_prt; 406 // Card offset within the current PRT. 407 size_t _cur_card_in_prt; 408 409 // Update internal variables when switching to the given PRT. 410 void switch_to_prt(PerRegionTable* prt); 411 bool fine_has_next(); 412 bool fine_has_next(size_t& card_index); 413 414 // The Sparse remembered set iterator. 415 SparsePRTIter _sparse_iter; 416 417 public: 418 HeapRegionRemSetIterator(HeapRegionRemSet* hrrs); 419 420 // If there remains one or more cards to be yielded, returns true and 421 // sets "card_index" to one of those cards (which is then considered 422 // yielded.) Otherwise, returns false (and leaves "card_index" 423 // undefined.) 424 bool has_next(size_t& card_index); 425 426 size_t n_yielded_fine() { return _n_yielded_fine; } 427 size_t n_yielded_coarse() { return _n_yielded_coarse; } 428 size_t n_yielded_sparse() { return _n_yielded_sparse; } 429 size_t n_yielded() { 430 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); 431 } 432 }; 433 434 #endif // SHARE_VM_GC_G1_HEAPREGIONREMSET_HPP