Mercurial > hg > graal-compiler
annotate src/share/vm/memory/cardTableModRefBS.hpp @ 3287:c48ad6ab8bdf
7037276: Unnecessary double traversal of dirty card windows
Summary: Short-circuited an unnecessary double traversal of dirty card windows when iterating younger refs. Also renamed some cardtable methods for more clarity.
Reviewed-by: jmasa, stefank, poonam
| author | ysr |
|---|---|
| date | Wed, 20 Apr 2011 19:19:30 -0700 |
| parents | c69b1043dfb1 |
| children | 063382f9b575 |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved. |
| 0 | 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. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #ifndef SHARE_VM_MEMORY_CARDTABLEMODREFBS_HPP |
| 26 #define SHARE_VM_MEMORY_CARDTABLEMODREFBS_HPP | |
| 27 | |
| 28 #include "memory/modRefBarrierSet.hpp" | |
| 29 #include "oops/oop.hpp" | |
| 30 #include "oops/oop.inline2.hpp" | |
| 31 | |
| 0 | 32 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and |
| 33 // enumerate ref fields that have been modified (since the last | |
| 34 // enumeration.) | |
| 35 | |
| 36 // As it currently stands, this barrier is *imprecise*: when a ref field in | |
| 37 // an object "o" is modified, the card table entry for the card containing | |
| 38 // the head of "o" is dirtied, not necessarily the card containing the | |
| 39 // modified field itself. For object arrays, however, the barrier *is* | |
| 40 // precise; only the card containing the modified element is dirtied. | |
| 41 // Any MemRegionClosures used to scan dirty cards should take these | |
| 42 // considerations into account. | |
| 43 | |
| 44 class Generation; | |
| 45 class OopsInGenClosure; | |
| 46 class DirtyCardToOopClosure; | |
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47 class ClearNoncleanCardWrapper; |
| 0 | 48 |
| 49 class CardTableModRefBS: public ModRefBarrierSet { | |
| 50 // Some classes get to look at some private stuff. | |
| 51 friend class BytecodeInterpreter; | |
| 52 friend class VMStructs; | |
| 53 friend class CardTableRS; | |
| 54 friend class CheckForUnmarkedOops; // Needs access to raw card bytes. | |
| 1692 | 55 friend class SharkBuilder; |
| 0 | 56 #ifndef PRODUCT |
| 57 // For debugging. | |
| 58 friend class GuaranteeNotModClosure; | |
| 59 #endif | |
| 60 protected: | |
| 61 | |
| 62 enum CardValues { | |
| 63 clean_card = -1, | |
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64 // The mask contains zeros in places for all other values. |
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65 clean_card_mask = clean_card - 31, |
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66 |
| 0 | 67 dirty_card = 0, |
| 68 precleaned_card = 1, | |
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69 claimed_card = 2, |
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70 deferred_card = 4, |
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71 last_card = 8, |
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72 CT_MR_BS_last_reserved = 16 |
| 0 | 73 }; |
| 74 | |
| 75 // dirty and precleaned are equivalent wrt younger_refs_iter. | |
| 76 static bool card_is_dirty_wrt_gen_iter(jbyte cv) { | |
| 77 return cv == dirty_card || cv == precleaned_card; | |
| 78 } | |
| 79 | |
| 80 // Returns "true" iff the value "cv" will cause the card containing it | |
| 81 // to be scanned in the current traversal. May be overridden by | |
| 82 // subtypes. | |
| 83 virtual bool card_will_be_scanned(jbyte cv) { | |
| 84 return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv); | |
| 85 } | |
| 86 | |
| 87 // Returns "true" iff the value "cv" may have represented a dirty card at | |
| 88 // some point. | |
| 89 virtual bool card_may_have_been_dirty(jbyte cv) { | |
| 90 return card_is_dirty_wrt_gen_iter(cv); | |
| 91 } | |
| 92 | |
| 93 // The declaration order of these const fields is important; see the | |
| 94 // constructor before changing. | |
| 95 const MemRegion _whole_heap; // the region covered by the card table | |
| 96 const size_t _guard_index; // index of very last element in the card | |
| 97 // table; it is set to a guard value | |
| 98 // (last_card) and should never be modified | |
| 99 const size_t _last_valid_index; // index of the last valid element | |
| 100 const size_t _page_size; // page size used when mapping _byte_map | |
| 101 const size_t _byte_map_size; // in bytes | |
| 102 jbyte* _byte_map; // the card marking array | |
| 103 | |
| 104 int _cur_covered_regions; | |
| 105 // The covered regions should be in address order. | |
| 106 MemRegion* _covered; | |
| 107 // The committed regions correspond one-to-one to the covered regions. | |
| 108 // They represent the card-table memory that has been committed to service | |
| 109 // the corresponding covered region. It may be that committed region for | |
| 110 // one covered region corresponds to a larger region because of page-size | |
| 111 // roundings. Thus, a committed region for one covered region may | |
| 112 // actually extend onto the card-table space for the next covered region. | |
| 113 MemRegion* _committed; | |
| 114 | |
| 115 // The last card is a guard card, and we commit the page for it so | |
| 116 // we can use the card for verification purposes. We make sure we never | |
| 117 // uncommit the MemRegion for that page. | |
| 118 MemRegion _guard_region; | |
| 119 | |
| 120 protected: | |
| 121 // Initialization utilities; covered_words is the size of the covered region | |
| 122 // in, um, words. | |
| 123 inline size_t cards_required(size_t covered_words); | |
| 124 inline size_t compute_byte_map_size(); | |
| 125 | |
| 126 // Finds and return the index of the region, if any, to which the given | |
| 127 // region would be contiguous. If none exists, assign a new region and | |
| 128 // returns its index. Requires that no more than the maximum number of | |
| 129 // covered regions defined in the constructor are ever in use. | |
| 130 int find_covering_region_by_base(HeapWord* base); | |
| 131 | |
| 132 // Same as above, but finds the region containing the given address | |
| 133 // instead of starting at a given base address. | |
| 134 int find_covering_region_containing(HeapWord* addr); | |
| 135 | |
| 136 // Resize one of the regions covered by the remembered set. | |
| 137 void resize_covered_region(MemRegion new_region); | |
| 138 | |
| 139 // Returns the leftmost end of a committed region corresponding to a | |
| 140 // covered region before covered region "ind", or else "NULL" if "ind" is | |
| 141 // the first covered region. | |
| 142 HeapWord* largest_prev_committed_end(int ind) const; | |
| 143 | |
| 144 // Returns the part of the region mr that doesn't intersect with | |
| 145 // any committed region other than self. Used to prevent uncommitting | |
| 146 // regions that are also committed by other regions. Also protects | |
| 147 // against uncommitting the guard region. | |
| 148 MemRegion committed_unique_to_self(int self, MemRegion mr) const; | |
| 149 | |
| 150 // Mapping from address to card marking array entry | |
| 151 jbyte* byte_for(const void* p) const { | |
| 152 assert(_whole_heap.contains(p), | |
| 153 "out of bounds access to card marking array"); | |
| 154 jbyte* result = &byte_map_base[uintptr_t(p) >> card_shift]; | |
| 155 assert(result >= _byte_map && result < _byte_map + _byte_map_size, | |
| 156 "out of bounds accessor for card marking array"); | |
| 157 return result; | |
| 158 } | |
| 159 | |
| 160 // The card table byte one after the card marking array | |
| 161 // entry for argument address. Typically used for higher bounds | |
| 162 // for loops iterating through the card table. | |
| 163 jbyte* byte_after(const void* p) const { | |
| 164 return byte_for(p) + 1; | |
| 165 } | |
| 166 | |
| 167 // Iterate over the portion of the card-table which covers the given | |
| 168 // region mr in the given space and apply cl to any dirty sub-regions | |
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169 // of mr. Dirty cards are _not_ cleared by the iterator method itself, |
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170 // but closures may arrange to do so on their own should they so wish. |
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171 void non_clean_card_iterate_serial(MemRegion mr, MemRegionClosure* cl); |
| 0 | 172 |
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173 // A variant of the above that will operate in a parallel mode if |
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174 // worker threads are available, and clear the dirty cards as it |
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175 // processes them. |
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176 // ClearNoncleanCardWrapper cl must wrap the DirtyCardToOopClosure dcto_cl, |
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177 // which may itself be modified by the method. |
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178 void non_clean_card_iterate_possibly_parallel(Space* sp, MemRegion mr, |
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179 DirtyCardToOopClosure* dcto_cl, |
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180 ClearNoncleanCardWrapper* cl); |
| 0 | 181 |
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182 private: |
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183 // Work method used to implement non_clean_card_iterate_possibly_parallel() |
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184 // above in the parallel case. |
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185 void non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr, |
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186 DirtyCardToOopClosure* dcto_cl, |
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187 ClearNoncleanCardWrapper* cl, |
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188 int n_threads); |
| 0 | 189 |
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190 protected: |
| 0 | 191 // Dirty the bytes corresponding to "mr" (not all of which must be |
| 192 // covered.) | |
| 193 void dirty_MemRegion(MemRegion mr); | |
| 194 | |
| 195 // Clear (to clean_card) the bytes entirely contained within "mr" (not | |
| 196 // all of which must be covered.) | |
| 197 void clear_MemRegion(MemRegion mr); | |
| 198 | |
| 199 // *** Support for parallel card scanning. | |
| 200 | |
| 201 enum SomeConstantsForParallelism { | |
| 202 StridesPerThread = 2, | |
| 203 CardsPerStrideChunk = 256 | |
| 204 }; | |
| 205 | |
| 206 // This is an array, one element per covered region of the card table. | |
| 207 // Each entry is itself an array, with one element per chunk in the | |
| 208 // covered region. Each entry of these arrays is the lowest non-clean | |
| 209 // card of the corresponding chunk containing part of an object from the | |
| 210 // previous chunk, or else NULL. | |
| 211 typedef jbyte* CardPtr; | |
| 212 typedef CardPtr* CardArr; | |
| 213 CardArr* _lowest_non_clean; | |
| 214 size_t* _lowest_non_clean_chunk_size; | |
| 215 uintptr_t* _lowest_non_clean_base_chunk_index; | |
| 216 int* _last_LNC_resizing_collection; | |
| 217 | |
| 218 // Initializes "lowest_non_clean" to point to the array for the region | |
| 219 // covering "sp", and "lowest_non_clean_base_chunk_index" to the chunk | |
| 220 // index of the corresponding to the first element of that array. | |
| 221 // Ensures that these arrays are of sufficient size, allocating if necessary. | |
| 222 // May be called by several threads concurrently. | |
| 223 void get_LNC_array_for_space(Space* sp, | |
| 224 jbyte**& lowest_non_clean, | |
| 225 uintptr_t& lowest_non_clean_base_chunk_index, | |
| 226 size_t& lowest_non_clean_chunk_size); | |
| 227 | |
| 228 // Returns the number of chunks necessary to cover "mr". | |
| 229 size_t chunks_to_cover(MemRegion mr) { | |
| 230 return (size_t)(addr_to_chunk_index(mr.last()) - | |
| 231 addr_to_chunk_index(mr.start()) + 1); | |
| 232 } | |
| 233 | |
| 234 // Returns the index of the chunk in a stride which | |
| 235 // covers the given address. | |
| 236 uintptr_t addr_to_chunk_index(const void* addr) { | |
| 237 uintptr_t card = (uintptr_t) byte_for(addr); | |
| 238 return card / CardsPerStrideChunk; | |
| 239 } | |
| 240 | |
| 241 // Apply cl, which must either itself apply dcto_cl or be dcto_cl, | |
| 242 // to the cards in the stride (of n_strides) within the given space. | |
| 243 void process_stride(Space* sp, | |
| 244 MemRegion used, | |
| 245 jint stride, int n_strides, | |
| 246 DirtyCardToOopClosure* dcto_cl, | |
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247 ClearNoncleanCardWrapper* cl, |
| 0 | 248 jbyte** lowest_non_clean, |
| 249 uintptr_t lowest_non_clean_base_chunk_index, | |
| 250 size_t lowest_non_clean_chunk_size); | |
| 251 | |
| 252 // Makes sure that chunk boundaries are handled appropriately, by | |
| 253 // adjusting the min_done of dcto_cl, and by using a special card-table | |
| 254 // value to indicate how min_done should be set. | |
| 255 void process_chunk_boundaries(Space* sp, | |
| 256 DirtyCardToOopClosure* dcto_cl, | |
| 257 MemRegion chunk_mr, | |
| 258 MemRegion used, | |
| 259 jbyte** lowest_non_clean, | |
| 260 uintptr_t lowest_non_clean_base_chunk_index, | |
| 261 size_t lowest_non_clean_chunk_size); | |
| 262 | |
| 263 public: | |
| 264 // Constants | |
| 265 enum SomePublicConstants { | |
| 266 card_shift = 9, | |
| 267 card_size = 1 << card_shift, | |
| 268 card_size_in_words = card_size / sizeof(HeapWord) | |
| 269 }; | |
| 270 | |
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271 static int clean_card_val() { return clean_card; } |
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272 static int clean_card_mask_val() { return clean_card_mask; } |
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273 static int dirty_card_val() { return dirty_card; } |
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274 static int claimed_card_val() { return claimed_card; } |
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275 static int precleaned_card_val() { return precleaned_card; } |
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276 static int deferred_card_val() { return deferred_card; } |
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277 |
| 0 | 278 // For RTTI simulation. |
| 279 bool is_a(BarrierSet::Name bsn) { | |
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280 return bsn == BarrierSet::CardTableModRef || ModRefBarrierSet::is_a(bsn); |
| 0 | 281 } |
| 282 | |
| 283 CardTableModRefBS(MemRegion whole_heap, int max_covered_regions); | |
| 284 | |
| 285 // *** Barrier set functions. | |
| 286 | |
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287 bool has_write_ref_pre_barrier() { return false; } |
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288 |
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289 inline bool write_ref_needs_barrier(void* field, oop new_val) { |
| 0 | 290 // Note that this assumes the perm gen is the highest generation |
| 291 // in the address space | |
| 292 return new_val != NULL && !new_val->is_perm(); | |
| 293 } | |
| 294 | |
| 295 // Record a reference update. Note that these versions are precise! | |
| 296 // The scanning code has to handle the fact that the write barrier may be | |
| 297 // either precise or imprecise. We make non-virtual inline variants of | |
| 298 // these functions here for performance. | |
| 299 protected: | |
| 300 void write_ref_field_work(oop obj, size_t offset, oop newVal); | |
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301 virtual void write_ref_field_work(void* field, oop newVal); |
| 0 | 302 public: |
| 303 | |
| 304 bool has_write_ref_array_opt() { return true; } | |
| 305 bool has_write_region_opt() { return true; } | |
| 306 | |
| 307 inline void inline_write_region(MemRegion mr) { | |
| 308 dirty_MemRegion(mr); | |
| 309 } | |
| 310 protected: | |
| 311 void write_region_work(MemRegion mr) { | |
| 312 inline_write_region(mr); | |
| 313 } | |
| 314 public: | |
| 315 | |
| 316 inline void inline_write_ref_array(MemRegion mr) { | |
| 317 dirty_MemRegion(mr); | |
| 318 } | |
| 319 protected: | |
| 320 void write_ref_array_work(MemRegion mr) { | |
| 321 inline_write_ref_array(mr); | |
| 322 } | |
| 323 public: | |
| 324 | |
| 325 bool is_aligned(HeapWord* addr) { | |
| 326 return is_card_aligned(addr); | |
| 327 } | |
| 328 | |
| 329 // *** Card-table-barrier-specific things. | |
| 330 | |
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331 template <class T> inline void inline_write_ref_field_pre(T* field, oop newVal) {} |
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332 |
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333 template <class T> inline void inline_write_ref_field(T* field, oop newVal) { |
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334 jbyte* byte = byte_for((void*)field); |
| 0 | 335 *byte = dirty_card; |
| 336 } | |
| 337 | |
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338 // These are used by G1, when it uses the card table as a temporary data |
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339 // structure for card claiming. |
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340 bool is_card_dirty(size_t card_index) { |
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341 return _byte_map[card_index] == dirty_card_val(); |
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342 } |
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343 |
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344 void mark_card_dirty(size_t card_index) { |
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345 _byte_map[card_index] = dirty_card_val(); |
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346 } |
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347 |
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348 bool is_card_claimed(size_t card_index) { |
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349 jbyte val = _byte_map[card_index]; |
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350 return (val & (clean_card_mask_val() | claimed_card_val())) == claimed_card_val(); |
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351 } |
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352 |
| 1261 | 353 void set_card_claimed(size_t card_index) { |
| 354 jbyte val = _byte_map[card_index]; | |
| 355 if (val == clean_card_val()) { | |
| 356 val = (jbyte)claimed_card_val(); | |
| 357 } else { | |
| 358 val |= (jbyte)claimed_card_val(); | |
| 359 } | |
| 360 _byte_map[card_index] = val; | |
| 361 } | |
| 362 | |
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363 bool claim_card(size_t card_index); |
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364 |
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365 bool is_card_clean(size_t card_index) { |
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366 return _byte_map[card_index] == clean_card_val(); |
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367 } |
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368 |
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369 bool is_card_deferred(size_t card_index) { |
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370 jbyte val = _byte_map[card_index]; |
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371 return (val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val(); |
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372 } |
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373 |
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374 bool mark_card_deferred(size_t card_index); |
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375 |
| 0 | 376 // Card marking array base (adjusted for heap low boundary) |
| 377 // This would be the 0th element of _byte_map, if the heap started at 0x0. | |
| 378 // But since the heap starts at some higher address, this points to somewhere | |
| 379 // before the beginning of the actual _byte_map. | |
| 380 jbyte* byte_map_base; | |
| 381 | |
| 382 // Return true if "p" is at the start of a card. | |
| 383 bool is_card_aligned(HeapWord* p) { | |
| 384 jbyte* pcard = byte_for(p); | |
| 385 return (addr_for(pcard) == p); | |
| 386 } | |
| 387 | |
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388 HeapWord* align_to_card_boundary(HeapWord* p) { |
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389 jbyte* pcard = byte_for(p + card_size_in_words - 1); |
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390 return addr_for(pcard); |
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391 } |
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392 |
| 0 | 393 // The kinds of precision a CardTableModRefBS may offer. |
| 394 enum PrecisionStyle { | |
| 395 Precise, | |
| 396 ObjHeadPreciseArray | |
| 397 }; | |
| 398 | |
| 399 // Tells what style of precision this card table offers. | |
| 400 PrecisionStyle precision() { | |
| 401 return ObjHeadPreciseArray; // Only one supported for now. | |
| 402 } | |
| 403 | |
| 404 // ModRefBS functions. | |
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405 virtual void invalidate(MemRegion mr, bool whole_heap = false); |
| 0 | 406 void clear(MemRegion mr); |
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407 void dirty(MemRegion mr); |
| 0 | 408 |
| 409 // *** Card-table-RemSet-specific things. | |
| 410 | |
| 411 // Invoke "cl.do_MemRegion" on a set of MemRegions that collectively | |
| 412 // includes all the modified cards (expressing each card as a | |
| 413 // MemRegion). Thus, several modified cards may be lumped into one | |
| 414 // region. The regions are non-overlapping, and are visited in | |
| 415 // *decreasing* address order. (This order aids with imprecise card | |
| 416 // marking, where a dirty card may cause scanning, and summarization | |
| 417 // marking, of objects that extend onto subsequent cards.) | |
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418 void mod_card_iterate(MemRegionClosure* cl) { |
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419 non_clean_card_iterate_serial(_whole_heap, cl); |
| 0 | 420 } |
| 421 | |
| 422 // Like the "mod_cards_iterate" above, except only invokes the closure | |
| 423 // for cards within the MemRegion "mr" (which is required to be | |
| 424 // card-aligned and sized.) | |
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425 void mod_card_iterate(MemRegion mr, MemRegionClosure* cl) { |
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426 non_clean_card_iterate_serial(mr, cl); |
| 0 | 427 } |
| 428 | |
| 429 static uintx ct_max_alignment_constraint(); | |
| 430 | |
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431 // Apply closure "cl" to the dirty cards containing some part of |
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432 // MemRegion "mr". |
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433 void dirty_card_iterate(MemRegion mr, MemRegionClosure* cl); |
| 0 | 434 |
| 435 // Return the MemRegion corresponding to the first maximal run | |
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436 // of dirty cards lying completely within MemRegion mr. |
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437 // If reset is "true", then sets those card table entries to the given |
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438 // value. |
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439 MemRegion dirty_card_range_after_reset(MemRegion mr, bool reset, |
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440 int reset_val); |
| 0 | 441 |
| 442 // Set all the dirty cards in the given region to precleaned state. | |
| 443 void preclean_dirty_cards(MemRegion mr); | |
| 444 | |
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445 // Provide read-only access to the card table array. |
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446 const jbyte* byte_for_const(const void* p) const { |
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447 return byte_for(p); |
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448 } |
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449 const jbyte* byte_after_const(const void* p) const { |
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450 return byte_after(p); |
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451 } |
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452 |
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453 // Mapping from card marking array entry to address of first word |
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454 HeapWord* addr_for(const jbyte* p) const { |
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455 assert(p >= _byte_map && p < _byte_map + _byte_map_size, |
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456 "out of bounds access to card marking array"); |
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457 size_t delta = pointer_delta(p, byte_map_base, sizeof(jbyte)); |
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458 HeapWord* result = (HeapWord*) (delta << card_shift); |
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459 assert(_whole_heap.contains(result), |
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460 "out of bounds accessor from card marking array"); |
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461 return result; |
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462 } |
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463 |
| 0 | 464 // Mapping from address to card marking array index. |
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465 size_t index_for(void* p) { |
| 0 | 466 assert(_whole_heap.contains(p), |
| 467 "out of bounds access to card marking array"); | |
| 468 return byte_for(p) - _byte_map; | |
| 469 } | |
| 470 | |
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471 const jbyte* byte_for_index(const size_t card_index) const { |
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472 return _byte_map + card_index; |
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473 } |
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474 |
| 0 | 475 void verify(); |
| 476 void verify_guard(); | |
| 477 | |
| 478 void verify_clean_region(MemRegion mr) PRODUCT_RETURN; | |
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479 void verify_dirty_region(MemRegion mr) PRODUCT_RETURN; |
| 0 | 480 |
| 481 static size_t par_chunk_heapword_alignment() { | |
| 482 return CardsPerStrideChunk * card_size_in_words; | |
| 483 } | |
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484 |
| 0 | 485 }; |
| 486 | |
| 487 class CardTableRS; | |
| 488 | |
| 489 // A specialization for the CardTableRS gen rem set. | |
| 490 class CardTableModRefBSForCTRS: public CardTableModRefBS { | |
| 491 CardTableRS* _rs; | |
| 492 protected: | |
| 493 bool card_will_be_scanned(jbyte cv); | |
| 494 bool card_may_have_been_dirty(jbyte cv); | |
| 495 public: | |
| 496 CardTableModRefBSForCTRS(MemRegion whole_heap, | |
| 497 int max_covered_regions) : | |
| 498 CardTableModRefBS(whole_heap, max_covered_regions) {} | |
| 499 | |
| 500 void set_CTRS(CardTableRS* rs) { _rs = rs; } | |
| 501 }; | |
| 1972 | 502 |
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503 |
| 1972 | 504 #endif // SHARE_VM_MEMORY_CARDTABLEMODREFBS_HPP |