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annotate src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp @ 1710:94251661de76
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Reviewed-by: ysr
author | jcoomes |
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date | Mon, 09 Aug 2010 18:03:50 -0700 |
parents | c18cbe5936b8 |
children | f95d63e2154a |
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342 | 1 /* |
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2 * Copyright (c) 2001, 2009, Oracle and/or its affiliates. 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
342 | 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 enum ParIterState { Unclaimed, Claimed, Complete }; | |
1261 | 183 volatile ParIterState _iter_state; |
184 volatile jlong _iter_claimed; | |
342 | 185 |
186 // Unused unless G1RecordHRRSOops is true. | |
187 | |
188 static const int MaxRecorded = 1000000; | |
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189 static OopOrNarrowOopStar* _recorded_oops; |
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190 static HeapWord** _recorded_cards; |
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191 static HeapRegion** _recorded_regions; |
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192 static int _n_recorded; |
342 | 193 |
194 static const int MaxRecordedEvents = 1000; | |
195 static Event* _recorded_events; | |
196 static int* _recorded_event_index; | |
197 static int _n_recorded_events; | |
198 | |
199 static void print_event(outputStream* str, Event evnt); | |
200 | |
201 public: | |
202 HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, | |
203 HeapRegion* hr); | |
204 | |
205 static int num_par_rem_sets(); | |
1261 | 206 static void setup_remset_size(); |
342 | 207 |
208 HeapRegion* hr() const { | |
209 return _other_regions.hr(); | |
210 } | |
211 | |
212 size_t occupied() const { | |
213 return _other_regions.occupied(); | |
214 } | |
215 size_t occ_fine() const { | |
216 return _other_regions.occ_fine(); | |
217 } | |
218 size_t occ_coarse() const { | |
219 return _other_regions.occ_coarse(); | |
220 } | |
221 size_t occ_sparse() const { | |
222 return _other_regions.occ_sparse(); | |
223 } | |
224 | |
225 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } | |
226 | |
227 /* Used in the sequential case. Returns "true" iff this addition causes | |
228 the size limit to be reached. */ | |
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229 void add_reference(OopOrNarrowOopStar from) { |
342 | 230 _other_regions.add_reference(from); |
231 } | |
232 | |
233 /* Used in the parallel case. Returns "true" iff this addition causes | |
234 the size limit to be reached. */ | |
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235 void add_reference(OopOrNarrowOopStar from, int tid) { |
342 | 236 _other_regions.add_reference(from, tid); |
237 } | |
238 | |
239 // Removes any entries shown by the given bitmaps to contain only dead | |
240 // objects. | |
241 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); | |
242 | |
243 // The region is being reclaimed; clear its remset, and any mention of | |
244 // entries for this region in other remsets. | |
245 void clear(); | |
246 | |
247 // Forget any entries due to pointers from "from_hr". | |
248 void clear_incoming_entry(HeapRegion* from_hr) { | |
249 _other_regions.clear_incoming_entry(from_hr); | |
250 } | |
251 | |
252 #if 0 | |
253 virtual void cleanup() = 0; | |
254 #endif | |
255 | |
256 // Should be called from single-threaded code. | |
257 void init_for_par_iteration(); | |
258 // Attempt to claim the region. Returns true iff this call caused an | |
259 // atomic transition from Unclaimed to Claimed. | |
260 bool claim_iter(); | |
261 // Sets the iteration state to "complete". | |
262 void set_iter_complete(); | |
263 // Returns "true" iff the region's iteration is complete. | |
264 bool iter_is_complete(); | |
265 | |
1261 | 266 // Support for claiming blocks of cards during iteration |
267 void set_iter_claimed(size_t x) { _iter_claimed = (jlong)x; } | |
268 size_t iter_claimed() const { return (size_t)_iter_claimed; } | |
269 // Claim the next block of cards | |
270 size_t iter_claimed_next(size_t step) { | |
271 size_t current, next; | |
272 do { | |
273 current = iter_claimed(); | |
274 next = current + step; | |
275 } while (Atomic::cmpxchg((jlong)next, &_iter_claimed, (jlong)current) != (jlong)current); | |
276 return current; | |
277 } | |
278 | |
342 | 279 // Initialize the given iterator to iterate over this rem set. |
280 void init_iterator(HeapRegionRemSetIterator* iter) const; | |
281 | |
282 #if 0 | |
283 // Apply the "do_card" method to the start address of every card in the | |
284 // rem set. Returns false if some application of the closure aborted. | |
285 virtual bool card_iterate(CardClosure* iter) = 0; | |
286 #endif | |
287 | |
288 // The actual # of bytes this hr_remset takes up. | |
289 size_t mem_size() { | |
290 return _other_regions.mem_size() | |
291 // This correction is necessary because the above includes the second | |
292 // part. | |
293 + sizeof(this) - sizeof(OtherRegionsTable); | |
294 } | |
295 | |
296 // Returns the memory occupancy of all static data structures associated | |
297 // with remembered sets. | |
298 static size_t static_mem_size() { | |
299 return OtherRegionsTable::static_mem_size(); | |
300 } | |
301 | |
302 // Returns the memory occupancy of all free_list data structures associated | |
303 // with remembered sets. | |
304 static size_t fl_mem_size() { | |
305 return OtherRegionsTable::fl_mem_size(); | |
306 } | |
307 | |
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308 bool contains_reference(OopOrNarrowOopStar from) const { |
342 | 309 return _other_regions.contains_reference(from); |
310 } | |
311 void print() const; | |
312 | |
313 // Called during a stop-world phase to perform any deferred cleanups. | |
314 // The second version may be called by parallel threads after then finish | |
315 // collection work. | |
316 static void cleanup(); | |
317 static void par_cleanup(); | |
318 | |
319 // Declare the heap size (in # of regions) to the HeapRegionRemSet(s). | |
320 // (Uses it to initialize from_card_cache). | |
321 static void init_heap(size_t max_regions) { | |
322 OtherRegionsTable::init_from_card_cache(max_regions); | |
323 } | |
324 | |
325 // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. | |
326 static void shrink_heap(size_t new_n_regs) { | |
327 OtherRegionsTable::shrink_from_card_cache(new_n_regs); | |
328 } | |
329 | |
330 #ifndef PRODUCT | |
331 static void print_from_card_cache() { | |
332 OtherRegionsTable::print_from_card_cache(); | |
333 } | |
334 #endif | |
335 | |
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336 static void record(HeapRegion* hr, OopOrNarrowOopStar f); |
342 | 337 static void print_recorded(); |
338 static void record_event(Event evnt); | |
339 | |
340 // Run unit tests. | |
341 #ifndef PRODUCT | |
342 static void test(); | |
343 #endif | |
344 | |
345 }; | |
346 | |
347 class HeapRegionRemSetIterator : public CHeapObj { | |
348 | |
349 // The region over which we're iterating. | |
350 const HeapRegionRemSet* _hrrs; | |
351 | |
352 // Local caching of HRRS fields. | |
353 const BitMap* _coarse_map; | |
354 PosParPRT** _fine_grain_regions; | |
355 | |
356 G1BlockOffsetSharedArray* _bosa; | |
357 G1CollectedHeap* _g1h; | |
358 | |
359 // The number yielded since initialization. | |
360 size_t _n_yielded_fine; | |
361 size_t _n_yielded_coarse; | |
362 size_t _n_yielded_sparse; | |
363 | |
364 // If true we're iterating over the coarse table; if false the fine | |
365 // table. | |
366 enum IterState { | |
367 Sparse, | |
368 Fine, | |
369 Coarse | |
370 }; | |
371 IterState _is; | |
372 | |
373 // In both kinds of iteration, heap offset of first card of current | |
374 // region. | |
375 size_t _cur_region_card_offset; | |
376 // Card offset within cur region. | |
377 size_t _cur_region_cur_card; | |
378 | |
379 // Coarse table iteration fields: | |
380 | |
381 // Current region index; | |
382 int _coarse_cur_region_index; | |
383 int _coarse_cur_region_cur_card; | |
384 | |
385 bool coarse_has_next(size_t& card_index); | |
386 | |
387 // Fine table iteration fields: | |
388 | |
389 // Index of bucket-list we're working on. | |
390 int _fine_array_index; | |
391 // Per Region Table we're doing within current bucket list. | |
392 PosParPRT* _fine_cur_prt; | |
393 | |
394 /* SparsePRT::*/ SparsePRTIter _sparse_iter; | |
395 | |
396 void fine_find_next_non_null_prt(); | |
397 | |
398 bool fine_has_next(); | |
399 bool fine_has_next(size_t& card_index); | |
400 | |
401 public: | |
402 // We require an iterator to be initialized before use, so the | |
403 // constructor does little. | |
404 HeapRegionRemSetIterator(); | |
405 | |
406 void initialize(const HeapRegionRemSet* hrrs); | |
407 | |
408 // If there remains one or more cards to be yielded, returns true and | |
409 // sets "card_index" to one of those cards (which is then considered | |
410 // yielded.) Otherwise, returns false (and leaves "card_index" | |
411 // undefined.) | |
412 bool has_next(size_t& card_index); | |
413 | |
414 size_t n_yielded_fine() { return _n_yielded_fine; } | |
415 size_t n_yielded_coarse() { return _n_yielded_coarse; } | |
416 size_t n_yielded_sparse() { return _n_yielded_sparse; } | |
417 size_t n_yielded() { | |
418 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); | |
419 } | |
420 }; | |
421 | |
422 #if 0 | |
423 class CardClosure: public Closure { | |
424 public: | |
425 virtual void do_card(HeapWord* card_start) = 0; | |
426 }; | |
427 | |
428 #endif |