Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp @ 845:df6caf649ff7
6700789: G1: Enable use of compressed oops with G1 heaps
Summary: Modifications to G1 so as to allow the use of compressed oops.
Reviewed-by: apetrusenko, coleenp, jmasa, kvn, never, phh, tonyp
| author | ysr |
|---|---|
| date | Tue, 14 Jul 2009 15:40:39 -0700 |
| parents | 315a5d70b295 |
| children | 0414c1049f15 |
| rev | line source |
|---|---|
| 342 | 1 /* |
| 579 | 2 * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved. |
| 342 | 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
| 20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
| 21 * have any questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 // Remembered set for a heap region. Represent a set of "cards" that | |
| 26 // contain pointers into the owner heap region. Cards are defined somewhat | |
| 27 // abstractly, in terms of what the "BlockOffsetTable" in use can parse. | |
| 28 | |
| 29 class G1CollectedHeap; | |
| 30 class G1BlockOffsetSharedArray; | |
| 31 class HeapRegion; | |
| 32 class HeapRegionRemSetIterator; | |
| 33 class PosParPRT; | |
| 34 class SparsePRT; | |
| 35 | |
| 36 | |
| 37 // The "_coarse_map" is a bitmap with one bit for each region, where set | |
| 38 // bits indicate that the corresponding region may contain some pointer | |
| 39 // into the owning region. | |
| 40 | |
| 41 // The "_fine_grain_entries" array is an open hash table of PerRegionTables | |
| 42 // (PRTs), indicating regions for which we're keeping the RS as a set of | |
| 43 // cards. The strategy is to cap the size of the fine-grain table, | |
| 44 // deleting an entry and setting the corresponding coarse-grained bit when | |
| 45 // we would overflow this cap. | |
| 46 | |
| 47 // We use a mixture of locking and lock-free techniques here. We allow | |
| 48 // threads to locate PRTs without locking, but threads attempting to alter | |
| 49 // a bucket list obtain a lock. This means that any failing attempt to | |
| 50 // find a PRT must be retried with the lock. It might seem dangerous that | |
| 51 // a read can find a PRT that is concurrently deleted. This is all right, | |
| 52 // because: | |
| 53 // | |
| 54 // 1) We only actually free PRT's at safe points (though we reuse them at | |
| 55 // other times). | |
| 56 // 2) We find PRT's in an attempt to add entries. If a PRT is deleted, | |
| 57 // it's _coarse_map bit is set, so the that we were attempting to add | |
| 58 // is represented. If a deleted PRT is re-used, a thread adding a bit, | |
| 59 // thinking the PRT is for a different region, does no harm. | |
| 60 | |
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61 class OtherRegionsTable VALUE_OBJ_CLASS_SPEC { |
| 342 | 62 friend class HeapRegionRemSetIterator; |
| 63 | |
| 64 G1CollectedHeap* _g1h; | |
| 65 Mutex _m; | |
| 66 HeapRegion* _hr; | |
| 67 | |
| 68 // These are protected by "_m". | |
| 69 BitMap _coarse_map; | |
| 70 size_t _n_coarse_entries; | |
| 71 static jint _n_coarsenings; | |
| 72 | |
| 73 PosParPRT** _fine_grain_regions; | |
| 74 size_t _n_fine_entries; | |
| 75 | |
| 76 #define SAMPLE_FOR_EVICTION 1 | |
| 77 #if SAMPLE_FOR_EVICTION | |
| 78 size_t _fine_eviction_start; | |
| 79 static size_t _fine_eviction_stride; | |
| 80 static size_t _fine_eviction_sample_size; | |
| 81 #endif | |
| 82 | |
| 83 SparsePRT _sparse_table; | |
| 84 | |
| 85 // These are static after init. | |
| 86 static size_t _max_fine_entries; | |
| 87 static size_t _mod_max_fine_entries_mask; | |
| 88 | |
| 89 // Requires "prt" to be the first element of the bucket list appropriate | |
| 90 // for "hr". If this list contains an entry for "hr", return it, | |
| 91 // otherwise return "NULL". | |
| 92 PosParPRT* find_region_table(size_t ind, HeapRegion* hr) const; | |
| 93 | |
| 94 // Find, delete, and return a candidate PosParPRT, if any exists, | |
| 95 // adding the deleted region to the coarse bitmap. Requires the caller | |
| 96 // to hold _m, and the fine-grain table to be full. | |
| 97 PosParPRT* delete_region_table(); | |
| 98 | |
| 99 // If a PRT for "hr" is in the bucket list indicated by "ind" (which must | |
| 100 // be the correct index for "hr"), delete it and return true; else return | |
| 101 // false. | |
| 102 bool del_single_region_table(size_t ind, HeapRegion* hr); | |
| 103 | |
| 104 static jint _cache_probes; | |
| 105 static jint _cache_hits; | |
| 106 | |
| 107 // Indexed by thread X heap region, to minimize thread contention. | |
| 108 static int** _from_card_cache; | |
| 109 static size_t _from_card_cache_max_regions; | |
| 110 static size_t _from_card_cache_mem_size; | |
| 111 | |
| 112 public: | |
| 113 OtherRegionsTable(HeapRegion* hr); | |
| 114 | |
| 115 HeapRegion* hr() const { return _hr; } | |
| 116 | |
| 117 // For now. Could "expand" some tables in the future, so that this made | |
| 118 // sense. | |
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119 void add_reference(OopOrNarrowOopStar from, int tid); |
| 342 | 120 |
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121 void add_reference(OopOrNarrowOopStar from) { |
| 342 | 122 return add_reference(from, 0); |
| 123 } | |
| 124 | |
| 125 // Removes any entries shown by the given bitmaps to contain only dead | |
| 126 // objects. | |
| 127 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); | |
| 128 | |
| 129 // Not const because it takes a lock. | |
| 130 size_t occupied() const; | |
| 131 size_t occ_fine() const; | |
| 132 size_t occ_coarse() const; | |
| 133 size_t occ_sparse() const; | |
| 134 | |
| 135 static jint n_coarsenings() { return _n_coarsenings; } | |
| 136 | |
| 137 // Returns size in bytes. | |
| 138 // Not const because it takes a lock. | |
| 139 size_t mem_size() const; | |
| 140 static size_t static_mem_size(); | |
| 141 static size_t fl_mem_size(); | |
| 142 | |
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143 bool contains_reference(OopOrNarrowOopStar from) const; |
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144 bool contains_reference_locked(OopOrNarrowOopStar from) const; |
| 342 | 145 |
| 146 void clear(); | |
| 147 | |
| 148 // Specifically clear the from_card_cache. | |
| 149 void clear_fcc(); | |
| 150 | |
| 151 // "from_hr" is being cleared; remove any entries from it. | |
| 152 void clear_incoming_entry(HeapRegion* from_hr); | |
| 153 | |
| 154 // Declare the heap size (in # of regions) to the OtherRegionsTable. | |
| 155 // (Uses it to initialize from_card_cache). | |
| 156 static void init_from_card_cache(size_t max_regions); | |
| 157 | |
| 158 // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. | |
| 159 // Make sure any entries for higher regions are invalid. | |
| 160 static void shrink_from_card_cache(size_t new_n_regs); | |
| 161 | |
| 162 static void print_from_card_cache(); | |
| 163 | |
| 164 }; | |
| 165 | |
| 166 | |
| 167 class HeapRegionRemSet : public CHeapObj { | |
| 168 friend class VMStructs; | |
| 169 friend class HeapRegionRemSetIterator; | |
| 170 | |
| 171 public: | |
| 172 enum Event { | |
| 173 Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd | |
| 174 }; | |
| 175 | |
| 176 private: | |
| 177 G1BlockOffsetSharedArray* _bosa; | |
| 178 G1BlockOffsetSharedArray* bosa() const { return _bosa; } | |
| 179 | |
| 180 OtherRegionsTable _other_regions; | |
| 181 | |
| 182 // One set bit for every region that has an entry for this one. | |
| 183 BitMap _outgoing_region_map; | |
| 184 | |
| 185 // Clear entries for the current region in any rem sets named in | |
| 186 // the _outgoing_region_map. | |
| 187 void clear_outgoing_entries(); | |
| 188 | |
| 189 enum ParIterState { Unclaimed, Claimed, Complete }; | |
| 190 ParIterState _iter_state; | |
| 191 | |
| 192 // Unused unless G1RecordHRRSOops is true. | |
| 193 | |
| 194 static const int MaxRecorded = 1000000; | |
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195 static OopOrNarrowOopStar* _recorded_oops; |
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196 static HeapWord** _recorded_cards; |
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197 static HeapRegion** _recorded_regions; |
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198 static int _n_recorded; |
| 342 | 199 |
| 200 static const int MaxRecordedEvents = 1000; | |
| 201 static Event* _recorded_events; | |
| 202 static int* _recorded_event_index; | |
| 203 static int _n_recorded_events; | |
| 204 | |
| 205 static void print_event(outputStream* str, Event evnt); | |
| 206 | |
| 207 public: | |
| 208 HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, | |
| 209 HeapRegion* hr); | |
| 210 | |
| 211 static int num_par_rem_sets(); | |
| 212 | |
| 213 HeapRegion* hr() const { | |
| 214 return _other_regions.hr(); | |
| 215 } | |
| 216 | |
| 217 size_t occupied() const { | |
| 218 return _other_regions.occupied(); | |
| 219 } | |
| 220 size_t occ_fine() const { | |
| 221 return _other_regions.occ_fine(); | |
| 222 } | |
| 223 size_t occ_coarse() const { | |
| 224 return _other_regions.occ_coarse(); | |
| 225 } | |
| 226 size_t occ_sparse() const { | |
| 227 return _other_regions.occ_sparse(); | |
| 228 } | |
| 229 | |
| 230 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } | |
| 231 | |
| 232 /* Used in the sequential case. Returns "true" iff this addition causes | |
| 233 the size limit to be reached. */ | |
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234 void add_reference(OopOrNarrowOopStar from) { |
| 342 | 235 _other_regions.add_reference(from); |
| 236 } | |
| 237 | |
| 238 /* Used in the parallel case. Returns "true" iff this addition causes | |
| 239 the size limit to be reached. */ | |
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240 void add_reference(OopOrNarrowOopStar from, int tid) { |
| 342 | 241 _other_regions.add_reference(from, tid); |
| 242 } | |
| 243 | |
| 244 // Records the fact that the current region contains an outgoing | |
| 245 // reference into "to_hr". | |
| 246 void add_outgoing_reference(HeapRegion* to_hr); | |
| 247 | |
| 248 // Removes any entries shown by the given bitmaps to contain only dead | |
| 249 // objects. | |
| 250 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); | |
| 251 | |
| 252 // The region is being reclaimed; clear its remset, and any mention of | |
| 253 // entries for this region in other remsets. | |
| 254 void clear(); | |
| 255 | |
| 256 // Forget any entries due to pointers from "from_hr". | |
| 257 void clear_incoming_entry(HeapRegion* from_hr) { | |
| 258 _other_regions.clear_incoming_entry(from_hr); | |
| 259 } | |
| 260 | |
| 261 #if 0 | |
| 262 virtual void cleanup() = 0; | |
| 263 #endif | |
| 264 | |
| 265 // Should be called from single-threaded code. | |
| 266 void init_for_par_iteration(); | |
| 267 // Attempt to claim the region. Returns true iff this call caused an | |
| 268 // atomic transition from Unclaimed to Claimed. | |
| 269 bool claim_iter(); | |
| 270 // Sets the iteration state to "complete". | |
| 271 void set_iter_complete(); | |
| 272 // Returns "true" iff the region's iteration is complete. | |
| 273 bool iter_is_complete(); | |
| 274 | |
| 275 // Initialize the given iterator to iterate over this rem set. | |
| 276 void init_iterator(HeapRegionRemSetIterator* iter) const; | |
| 277 | |
| 278 #if 0 | |
| 279 // Apply the "do_card" method to the start address of every card in the | |
| 280 // rem set. Returns false if some application of the closure aborted. | |
| 281 virtual bool card_iterate(CardClosure* iter) = 0; | |
| 282 #endif | |
| 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 | |
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304 bool contains_reference(OopOrNarrowOopStar from) const { |
| 342 | 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 // The second version may be called by parallel threads after then finish | |
| 311 // collection work. | |
| 312 static void cleanup(); | |
| 313 static void par_cleanup(); | |
| 314 | |
| 315 // Declare the heap size (in # of regions) to the HeapRegionRemSet(s). | |
| 316 // (Uses it to initialize from_card_cache). | |
| 317 static void init_heap(size_t max_regions) { | |
| 318 OtherRegionsTable::init_from_card_cache(max_regions); | |
| 319 } | |
| 320 | |
| 321 // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. | |
| 322 static void shrink_heap(size_t new_n_regs) { | |
| 323 OtherRegionsTable::shrink_from_card_cache(new_n_regs); | |
| 324 } | |
| 325 | |
| 326 #ifndef PRODUCT | |
| 327 static void print_from_card_cache() { | |
| 328 OtherRegionsTable::print_from_card_cache(); | |
| 329 } | |
| 330 #endif | |
| 331 | |
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332 static void record(HeapRegion* hr, OopOrNarrowOopStar f); |
| 342 | 333 static void print_recorded(); |
| 334 static void record_event(Event evnt); | |
| 335 | |
| 336 // Run unit tests. | |
| 337 #ifndef PRODUCT | |
| 338 static void test(); | |
| 339 #endif | |
| 340 | |
| 341 }; | |
| 342 | |
| 343 class HeapRegionRemSetIterator : public CHeapObj { | |
| 344 | |
| 345 // The region over which we're iterating. | |
| 346 const HeapRegionRemSet* _hrrs; | |
| 347 | |
| 348 // Local caching of HRRS fields. | |
| 349 const BitMap* _coarse_map; | |
| 350 PosParPRT** _fine_grain_regions; | |
| 351 | |
| 352 G1BlockOffsetSharedArray* _bosa; | |
| 353 G1CollectedHeap* _g1h; | |
| 354 | |
| 355 // The number yielded since initialization. | |
| 356 size_t _n_yielded_fine; | |
| 357 size_t _n_yielded_coarse; | |
| 358 size_t _n_yielded_sparse; | |
| 359 | |
| 360 // If true we're iterating over the coarse table; if false the fine | |
| 361 // table. | |
| 362 enum IterState { | |
| 363 Sparse, | |
| 364 Fine, | |
| 365 Coarse | |
| 366 }; | |
| 367 IterState _is; | |
| 368 | |
| 369 // In both kinds of iteration, heap offset of first card of current | |
| 370 // region. | |
| 371 size_t _cur_region_card_offset; | |
| 372 // Card offset within cur region. | |
| 373 size_t _cur_region_cur_card; | |
| 374 | |
| 375 // Coarse table iteration fields: | |
| 376 | |
| 377 // Current region index; | |
| 378 int _coarse_cur_region_index; | |
| 379 int _coarse_cur_region_cur_card; | |
| 380 | |
| 381 bool coarse_has_next(size_t& card_index); | |
| 382 | |
| 383 // Fine table iteration fields: | |
| 384 | |
| 385 // Index of bucket-list we're working on. | |
| 386 int _fine_array_index; | |
| 387 // Per Region Table we're doing within current bucket list. | |
| 388 PosParPRT* _fine_cur_prt; | |
| 389 | |
| 390 /* SparsePRT::*/ SparsePRTIter _sparse_iter; | |
| 391 | |
| 392 void fine_find_next_non_null_prt(); | |
| 393 | |
| 394 bool fine_has_next(); | |
| 395 bool fine_has_next(size_t& card_index); | |
| 396 | |
| 397 public: | |
| 398 // We require an iterator to be initialized before use, so the | |
| 399 // constructor does little. | |
| 400 HeapRegionRemSetIterator(); | |
| 401 | |
| 402 void initialize(const HeapRegionRemSet* hrrs); | |
| 403 | |
| 404 // If there remains one or more cards to be yielded, returns true and | |
| 405 // sets "card_index" to one of those cards (which is then considered | |
| 406 // yielded.) Otherwise, returns false (and leaves "card_index" | |
| 407 // undefined.) | |
| 408 bool has_next(size_t& card_index); | |
| 409 | |
| 410 size_t n_yielded_fine() { return _n_yielded_fine; } | |
| 411 size_t n_yielded_coarse() { return _n_yielded_coarse; } | |
| 412 size_t n_yielded_sparse() { return _n_yielded_sparse; } | |
| 413 size_t n_yielded() { | |
| 414 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); | |
| 415 } | |
| 416 }; | |
| 417 | |
| 418 #if 0 | |
| 419 class CardClosure: public Closure { | |
| 420 public: | |
| 421 virtual void do_card(HeapWord* card_start) = 0; | |
| 422 }; | |
| 423 | |
| 424 #endif |