1 /* 2 * Copyright (c) 2001, 2015, 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_CONCURRENTMARK_INLINE_HPP 26 #define SHARE_VM_GC_G1_CONCURRENTMARK_INLINE_HPP 27 28 #include "gc/g1/concurrentMark.hpp" 29 #include "gc/g1/g1CollectedHeap.inline.hpp" 30 #include "gc/shared/taskqueue.inline.hpp" 31 32 // Utility routine to set an exclusive range of cards on the given 33 // card liveness bitmap 34 inline void ConcurrentMark::set_card_bitmap_range(BitMap* card_bm, 35 BitMap::idx_t start_idx, 36 BitMap::idx_t end_idx, 37 bool is_par) { 38 39 // Set the exclusive bit range [start_idx, end_idx). 40 assert((end_idx - start_idx) > 0, "at least one card"); 41 assert(end_idx <= card_bm->size(), "sanity"); 42 43 // Silently clip the end index 44 end_idx = MIN2(end_idx, card_bm->size()); 45 46 // For small ranges use a simple loop; otherwise use set_range or 47 // use par_at_put_range (if parallel). The range is made up of the 48 // cards that are spanned by an object/mem region so 8 cards will 49 // allow up to object sizes up to 4K to be handled using the loop. 50 if ((end_idx - start_idx) <= 8) { 51 for (BitMap::idx_t i = start_idx; i < end_idx; i += 1) { 52 if (is_par) { 53 card_bm->par_set_bit(i); 54 } else { 55 card_bm->set_bit(i); 56 } 57 } 58 } else { 59 // Note BitMap::par_at_put_range() and BitMap::set_range() are exclusive. 60 if (is_par) { 61 card_bm->par_at_put_range(start_idx, end_idx, true); 62 } else { 63 card_bm->set_range(start_idx, end_idx); 64 } 65 } 66 } 67 68 // Returns the index in the liveness accounting card bitmap 69 // for the given address 70 inline BitMap::idx_t ConcurrentMark::card_bitmap_index_for(HeapWord* addr) { 71 // Below, the term "card num" means the result of shifting an address 72 // by the card shift -- address 0 corresponds to card number 0. One 73 // must subtract the card num of the bottom of the heap to obtain a 74 // card table index. 75 intptr_t card_num = intptr_t(uintptr_t(addr) >> CardTableModRefBS::card_shift); 76 return card_num - heap_bottom_card_num(); 77 } 78 79 // Counts the given memory region in the given task/worker 80 // counting data structures. 81 inline void ConcurrentMark::count_region(MemRegion mr, HeapRegion* hr, 82 size_t* marked_bytes_array, 83 BitMap* task_card_bm) { 84 G1CollectedHeap* g1h = _g1h; 85 CardTableModRefBS* ct_bs = g1h->g1_barrier_set(); 86 87 HeapWord* start = mr.start(); 88 HeapWord* end = mr.end(); 89 size_t region_size_bytes = mr.byte_size(); 90 uint index = hr->hrm_index(); 91 92 assert(hr == g1h->heap_region_containing(start), "sanity"); 93 assert(marked_bytes_array != NULL, "pre-condition"); 94 assert(task_card_bm != NULL, "pre-condition"); 95 96 // Add to the task local marked bytes for this region. 97 marked_bytes_array[index] += region_size_bytes; 98 99 BitMap::idx_t start_idx = card_bitmap_index_for(start); 100 BitMap::idx_t end_idx = card_bitmap_index_for(end); 101 102 // Note: if we're looking at the last region in heap - end 103 // could be actually just beyond the end of the heap; end_idx 104 // will then correspond to a (non-existent) card that is also 105 // just beyond the heap. 106 if (g1h->is_in_g1_reserved(end) && !ct_bs->is_card_aligned(end)) { 107 // end of region is not card aligned - increment to cover 108 // all the cards spanned by the region. 109 end_idx += 1; 110 } 111 // The card bitmap is task/worker specific => no need to use 112 // the 'par' BitMap routines. 113 // Set bits in the exclusive bit range [start_idx, end_idx). 114 set_card_bitmap_range(task_card_bm, start_idx, end_idx, false /* is_par */); 115 } 116 117 // Counts the given object in the given task/worker counting data structures. 118 inline void ConcurrentMark::count_object(oop obj, 119 HeapRegion* hr, 120 size_t* marked_bytes_array, 121 BitMap* task_card_bm, 122 size_t word_size) { 123 assert(!hr->is_continues_humongous(), "Cannot enter count_object with continues humongous"); 124 if (!hr->is_starts_humongous()) { 125 MemRegion mr((HeapWord*)obj, word_size); 126 count_region(mr, hr, marked_bytes_array, task_card_bm); 127 } else { 128 do { 129 MemRegion mr(hr->bottom(), hr->top()); 130 count_region(mr, hr, marked_bytes_array, task_card_bm); 131 hr = _g1h->next_region_in_humongous(hr); 132 } while (hr != NULL); 133 } 134 } 135 136 // Attempts to mark the given object and, if successful, counts 137 // the object in the given task/worker counting structures. 138 inline bool ConcurrentMark::par_mark_and_count(oop obj, 139 HeapRegion* hr, 140 size_t* marked_bytes_array, 141 BitMap* task_card_bm) { 142 if (_nextMarkBitMap->parMark((HeapWord*)obj)) { 143 // Update the task specific count data for the object. 144 count_object(obj, hr, marked_bytes_array, task_card_bm, obj->size()); 145 return true; 146 } 147 return false; 148 } 149 150 // Attempts to mark the given object and, if successful, counts 151 // the object in the task/worker counting structures for the 152 // given worker id. 153 inline bool ConcurrentMark::par_mark_and_count(oop obj, 154 size_t word_size, 155 HeapRegion* hr, 156 uint worker_id) { 157 if (_nextMarkBitMap->parMark((HeapWord*)obj)) { 158 size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id); 159 BitMap* task_card_bm = count_card_bitmap_for(worker_id); 160 count_object(obj, hr, marked_bytes_array, task_card_bm, word_size); 161 return true; 162 } 163 return false; 164 } 165 166 inline bool CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) { 167 HeapWord* start_addr = MAX2(startWord(), mr.start()); 168 HeapWord* end_addr = MIN2(endWord(), mr.end()); 169 170 if (end_addr > start_addr) { 171 // Right-open interval [start-offset, end-offset). 172 BitMap::idx_t start_offset = heapWordToOffset(start_addr); 173 BitMap::idx_t end_offset = heapWordToOffset(end_addr); 174 175 start_offset = _bm.get_next_one_offset(start_offset, end_offset); 176 while (start_offset < end_offset) { 177 if (!cl->do_bit(start_offset)) { 178 return false; 179 } 180 HeapWord* next_addr = MIN2(nextObject(offsetToHeapWord(start_offset)), end_addr); 181 BitMap::idx_t next_offset = heapWordToOffset(next_addr); 182 start_offset = _bm.get_next_one_offset(next_offset, end_offset); 183 } 184 } 185 return true; 186 } 187 188 inline bool CMBitMapRO::iterate(BitMapClosure* cl) { 189 MemRegion mr(startWord(), sizeInWords()); 190 return iterate(cl, mr); 191 } 192 193 #define check_mark(addr) \ 194 assert(_bmStartWord <= (addr) && (addr) < (_bmStartWord + _bmWordSize), \ 195 "outside underlying space?"); \ 196 assert(G1CollectedHeap::heap()->is_in_exact(addr), \ 197 "Trying to access not available bitmap " PTR_FORMAT \ 198 " corresponding to " PTR_FORMAT " (%u)", \ 199 p2i(this), p2i(addr), G1CollectedHeap::heap()->addr_to_region(addr)); 200 201 inline void CMBitMap::mark(HeapWord* addr) { 202 check_mark(addr); 203 _bm.set_bit(heapWordToOffset(addr)); 204 } 205 206 inline void CMBitMap::clear(HeapWord* addr) { 207 check_mark(addr); 208 _bm.clear_bit(heapWordToOffset(addr)); 209 } 210 211 inline bool CMBitMap::parMark(HeapWord* addr) { 212 check_mark(addr); 213 return _bm.par_set_bit(heapWordToOffset(addr)); 214 } 215 216 inline bool CMBitMap::parClear(HeapWord* addr) { 217 check_mark(addr); 218 return _bm.par_clear_bit(heapWordToOffset(addr)); 219 } 220 221 #undef check_mark 222 223 template<typename Fn> 224 inline void CMMarkStack::iterate(Fn fn) { 225 assert(_saved_index == _index, "saved index: %d index: %d", _saved_index, _index); 226 for (int i = 0; i < _index; ++i) { 227 fn(_base[i]); 228 } 229 } 230 231 // It scans an object and visits its children. 232 inline void CMTask::scan_object(oop obj) { process_grey_object<true>(obj); } 233 234 inline void CMTask::push(oop obj) { 235 HeapWord* objAddr = (HeapWord*) obj; 236 assert(_g1h->is_in_g1_reserved(objAddr), "invariant"); 237 assert(!_g1h->is_on_master_free_list( 238 _g1h->heap_region_containing((HeapWord*) objAddr)), "invariant"); 239 assert(!_g1h->is_obj_ill(obj), "invariant"); 240 assert(_nextMarkBitMap->isMarked(objAddr), "invariant"); 241 242 if (!_task_queue->push(obj)) { 243 // The local task queue looks full. We need to push some entries 244 // to the global stack. 245 move_entries_to_global_stack(); 246 247 // this should succeed since, even if we overflow the global 248 // stack, we should have definitely removed some entries from the 249 // local queue. So, there must be space on it. 250 bool success = _task_queue->push(obj); 251 assert(success, "invariant"); 252 } 253 } 254 255 inline bool CMTask::is_below_finger(oop obj, HeapWord* global_finger) const { 256 // If obj is above the global finger, then the mark bitmap scan 257 // will find it later, and no push is needed. Similarly, if we have 258 // a current region and obj is between the local finger and the 259 // end of the current region, then no push is needed. The tradeoff 260 // of checking both vs only checking the global finger is that the 261 // local check will be more accurate and so result in fewer pushes, 262 // but may also be a little slower. 263 HeapWord* objAddr = (HeapWord*)obj; 264 if (_finger != NULL) { 265 // We have a current region. 266 267 // Finger and region values are all NULL or all non-NULL. We 268 // use _finger to check since we immediately use its value. 269 assert(_curr_region != NULL, "invariant"); 270 assert(_region_limit != NULL, "invariant"); 271 assert(_region_limit <= global_finger, "invariant"); 272 273 // True if obj is less than the local finger, or is between 274 // the region limit and the global finger. 275 if (objAddr < _finger) { 276 return true; 277 } else if (objAddr < _region_limit) { 278 return false; 279 } // Else check global finger. 280 } 281 // Check global finger. 282 return objAddr < global_finger; 283 } 284 285 template<bool scan> 286 inline void CMTask::process_grey_object(oop obj) { 287 assert(scan || obj->is_typeArray(), "Skipping scan of grey non-typeArray"); 288 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant"); 289 290 size_t obj_size = obj->size(); 291 _words_scanned += obj_size; 292 293 if (scan) { 294 obj->oop_iterate(_cm_oop_closure); 295 } 296 check_limits(); 297 } 298 299 300 301 inline void CMTask::make_reference_grey(oop obj, HeapRegion* hr) { 302 if (_cm->par_mark_and_count(obj, hr, _marked_bytes_array, _card_bm)) { 303 // No OrderAccess:store_load() is needed. It is implicit in the 304 // CAS done in CMBitMap::parMark() call in the routine above. 305 HeapWord* global_finger = _cm->finger(); 306 307 // We only need to push a newly grey object on the mark 308 // stack if it is in a section of memory the mark bitmap 309 // scan has already examined. Mark bitmap scanning 310 // maintains progress "fingers" for determining that. 311 // 312 // Notice that the global finger might be moving forward 313 // concurrently. This is not a problem. In the worst case, we 314 // mark the object while it is above the global finger and, by 315 // the time we read the global finger, it has moved forward 316 // past this object. In this case, the object will probably 317 // be visited when a task is scanning the region and will also 318 // be pushed on the stack. So, some duplicate work, but no 319 // correctness problems. 320 if (is_below_finger(obj, global_finger)) { 321 if (obj->is_typeArray()) { 322 // Immediately process arrays of primitive types, rather 323 // than pushing on the mark stack. This keeps us from 324 // adding humongous objects to the mark stack that might 325 // be reclaimed before the entry is processed - see 326 // selection of candidates for eager reclaim of humongous 327 // objects. The cost of the additional type test is 328 // mitigated by avoiding a trip through the mark stack, 329 // by only doing a bookkeeping update and avoiding the 330 // actual scan of the object - a typeArray contains no 331 // references, and the metadata is built-in. 332 process_grey_object<false>(obj); 333 } else { 334 push(obj); 335 } 336 } 337 } 338 } 339 340 inline void CMTask::deal_with_reference(oop obj) { 341 increment_refs_reached(); 342 343 HeapWord* objAddr = (HeapWord*) obj; 344 assert(obj->is_oop_or_null(true /* ignore mark word */), "Expected an oop or NULL at " PTR_FORMAT, p2i(obj)); 345 if (_g1h->is_in_g1_reserved(objAddr)) { 346 assert(obj != NULL, "null check is implicit"); 347 if (!_nextMarkBitMap->isMarked(objAddr)) { 348 // Only get the containing region if the object is not marked on the 349 // bitmap (otherwise, it's a waste of time since we won't do 350 // anything with it). 351 HeapRegion* hr = _g1h->heap_region_containing(obj); 352 if (!hr->obj_allocated_since_next_marking(obj)) { 353 make_reference_grey(obj, hr); 354 } 355 } 356 } 357 } 358 359 inline void ConcurrentMark::markPrev(oop p) { 360 assert(!_prevMarkBitMap->isMarked((HeapWord*) p), "sanity"); 361 // Note we are overriding the read-only view of the prev map here, via 362 // the cast. 363 ((CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p); 364 } 365 366 inline void ConcurrentMark::grayRoot(oop obj, size_t word_size, 367 uint worker_id, HeapRegion* hr) { 368 assert(obj != NULL, "pre-condition"); 369 HeapWord* addr = (HeapWord*) obj; 370 if (hr == NULL) { 371 hr = _g1h->heap_region_containing(addr); 372 } else { 373 assert(hr->is_in(addr), "pre-condition"); 374 } 375 assert(hr != NULL, "sanity"); 376 // Given that we're looking for a region that contains an object 377 // header it's impossible to get back a HC region. 378 assert(!hr->is_continues_humongous(), "sanity"); 379 380 if (addr < hr->next_top_at_mark_start()) { 381 if (!_nextMarkBitMap->isMarked(addr)) { 382 par_mark_and_count(obj, word_size, hr, worker_id); 383 } 384 } 385 } 386 387 #endif // SHARE_VM_GC_G1_CONCURRENTMARK_INLINE_HPP