1 /* 2 * Copyright (c) 2001, 2019, 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 #include "precompiled.hpp" 26 #include "gc/g1/g1BlockOffsetTable.inline.hpp" 27 #include "gc/g1/g1CollectedHeap.inline.hpp" 28 #include "gc/g1/g1ConcurrentRefine.hpp" 29 #include "gc/g1/heapRegionManager.inline.hpp" 30 #include "gc/g1/heapRegionRemSet.inline.hpp" 31 #include "gc/g1/sparsePRT.inline.hpp" 32 #include "memory/allocation.hpp" 33 #include "memory/padded.inline.hpp" 34 #include "oops/oop.inline.hpp" 35 #include "runtime/atomic.hpp" 36 #include "utilities/bitMap.inline.hpp" 37 #include "utilities/debug.hpp" 38 #include "utilities/formatBuffer.hpp" 39 #include "utilities/globalDefinitions.hpp" 40 #include "utilities/growableArray.hpp" 41 42 const char* HeapRegionRemSet::_state_strings[] = {"Untracked", "Updating", "Complete"}; 43 const char* HeapRegionRemSet::_short_state_strings[] = {"UNTRA", "UPDAT", "CMPLT"}; 44 45 PerRegionTable* PerRegionTable::alloc(HeapRegion* hr) { 46 PerRegionTable* fl = _free_list; 47 while (fl != NULL) { 48 PerRegionTable* nxt = fl->next(); 49 PerRegionTable* res = Atomic::cmpxchg(&_free_list, fl, nxt); 50 if (res == fl) { 51 fl->init(hr, true); 52 return fl; 53 } else { 54 fl = _free_list; 55 } 56 } 57 assert(fl == NULL, "Loop condition."); 58 return new PerRegionTable(hr); 59 } 60 61 PerRegionTable* volatile PerRegionTable::_free_list = NULL; 62 63 size_t OtherRegionsTable::_max_fine_entries = 0; 64 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0; 65 size_t OtherRegionsTable::_fine_eviction_stride = 0; 66 size_t OtherRegionsTable::_fine_eviction_sample_size = 0; 67 68 OtherRegionsTable::OtherRegionsTable(Mutex* m) : 69 _g1h(G1CollectedHeap::heap()), 70 _m(m), 71 _num_occupied(0), 72 _coarse_map(G1CollectedHeap::heap()->max_regions(), mtGC), 73 _n_coarse_entries(0), 74 _fine_grain_regions(NULL), 75 _n_fine_entries(0), 76 _first_all_fine_prts(NULL), 77 _last_all_fine_prts(NULL), 78 _fine_eviction_start(0), 79 _sparse_table() 80 { 81 typedef PerRegionTable* PerRegionTablePtr; 82 83 if (_max_fine_entries == 0) { 84 assert(_mod_max_fine_entries_mask == 0, "Both or none."); 85 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries); 86 _max_fine_entries = (size_t)1 << max_entries_log; 87 _mod_max_fine_entries_mask = _max_fine_entries - 1; 88 89 assert(_fine_eviction_sample_size == 0 90 && _fine_eviction_stride == 0, "All init at same time."); 91 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log); 92 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size; 93 } 94 95 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries, 96 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 97 98 if (_fine_grain_regions == NULL) { 99 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR, 100 "Failed to allocate _fine_grain_entries."); 101 } 102 103 for (size_t i = 0; i < _max_fine_entries; i++) { 104 _fine_grain_regions[i] = NULL; 105 } 106 } 107 108 void OtherRegionsTable::link_to_all(PerRegionTable* prt) { 109 // We always append to the beginning of the list for convenience; 110 // the order of entries in this list does not matter. 111 if (_first_all_fine_prts != NULL) { 112 assert(_first_all_fine_prts->prev() == NULL, "invariant"); 113 _first_all_fine_prts->set_prev(prt); 114 prt->set_next(_first_all_fine_prts); 115 } else { 116 // this is the first element we insert. Adjust the "last" pointer 117 _last_all_fine_prts = prt; 118 assert(prt->next() == NULL, "just checking"); 119 } 120 // the new element is always the first element without a predecessor 121 prt->set_prev(NULL); 122 _first_all_fine_prts = prt; 123 124 assert(prt->prev() == NULL, "just checking"); 125 assert(_first_all_fine_prts == prt, "just checking"); 126 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) || 127 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL), 128 "just checking"); 129 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL, 130 "just checking"); 131 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL, 132 "just checking"); 133 } 134 135 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) { 136 if (prt->prev() != NULL) { 137 assert(_first_all_fine_prts != prt, "just checking"); 138 prt->prev()->set_next(prt->next()); 139 // removing the last element in the list? 140 if (_last_all_fine_prts == prt) { 141 _last_all_fine_prts = prt->prev(); 142 } 143 } else { 144 assert(_first_all_fine_prts == prt, "just checking"); 145 _first_all_fine_prts = prt->next(); 146 // list is empty now? 147 if (_first_all_fine_prts == NULL) { 148 _last_all_fine_prts = NULL; 149 } 150 } 151 152 if (prt->next() != NULL) { 153 prt->next()->set_prev(prt->prev()); 154 } 155 156 prt->set_next(NULL); 157 prt->set_prev(NULL); 158 159 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) || 160 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL), 161 "just checking"); 162 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL, 163 "just checking"); 164 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL, 165 "just checking"); 166 } 167 168 CardIdx_t OtherRegionsTable::card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr) { 169 assert(hr->is_in_reserved(within_region), 170 "HeapWord " PTR_FORMAT " is outside of region %u [" PTR_FORMAT ", " PTR_FORMAT ")", 171 p2i(within_region), hr->hrm_index(), p2i(hr->bottom()), p2i(hr->end())); 172 CardIdx_t result = (CardIdx_t)(pointer_delta((HeapWord*)within_region, hr->bottom()) >> (CardTable::card_shift - LogHeapWordSize)); 173 return result; 174 } 175 176 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) { 177 // Note that this may be a continued H region. 178 HeapRegion* from_hr = _g1h->heap_region_containing(from); 179 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index(); 180 181 // If the region is already coarsened, return. 182 if (_coarse_map.at(from_hrm_ind)) { 183 assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from)); 184 return; 185 } 186 187 size_t num_added_by_coarsening = 0; 188 // Otherwise find a per-region table to add it to. 189 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask; 190 PerRegionTable* prt = find_region_table(ind, from_hr); 191 if (prt == NULL) { 192 MutexLocker x(_m, Mutex::_no_safepoint_check_flag); 193 // Confirm that it's really not there... 194 prt = find_region_table(ind, from_hr); 195 if (prt == NULL) { 196 197 CardIdx_t card_index = card_within_region(from, from_hr); 198 199 SparsePRT::AddCardResult result = _sparse_table.add_card(from_hrm_ind, card_index); 200 if (result != SparsePRT::overflow) { 201 if (result == SparsePRT::added) { 202 Atomic::inc(&_num_occupied, memory_order_relaxed); 203 } 204 assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from)); 205 return; 206 } 207 208 if (_n_fine_entries == _max_fine_entries) { 209 prt = delete_region_table(num_added_by_coarsening); 210 // There is no need to clear the links to the 'all' list here: 211 // prt will be reused immediately, i.e. remain in the 'all' list. 212 prt->init(from_hr, false /* clear_links_to_all_list */); 213 } else { 214 prt = PerRegionTable::alloc(from_hr); 215 link_to_all(prt); 216 } 217 218 PerRegionTable* first_prt = _fine_grain_regions[ind]; 219 prt->set_collision_list_next(first_prt); 220 // The assignment into _fine_grain_regions allows the prt to 221 // start being used concurrently. In addition to 222 // collision_list_next which must be visible (else concurrent 223 // parsing of the list, if any, may fail to see other entries), 224 // the content of the prt must be visible (else for instance 225 // some mark bits may not yet seem cleared or a 'later' update 226 // performed by a concurrent thread could be undone when the 227 // zeroing becomes visible). This requires store ordering. 228 Atomic::release_store(&_fine_grain_regions[ind], prt); 229 _n_fine_entries++; 230 231 // Transfer from sparse to fine-grain. The cards from the sparse table 232 // were already added to the total in _num_occupied. 233 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind); 234 assert(sprt_entry != NULL, "There should have been an entry"); 235 for (int i = 0; i < sprt_entry->num_valid_cards(); i++) { 236 CardIdx_t c = sprt_entry->card(i); 237 prt->add_card(c); 238 } 239 // Now we can delete the sparse entry. 240 bool res = _sparse_table.delete_entry(from_hrm_ind); 241 assert(res, "It should have been there."); 242 } 243 assert(prt != NULL && prt->hr() == from_hr, "consequence"); 244 } 245 // Note that we can't assert "prt->hr() == from_hr", because of the 246 // possibility of concurrent reuse. But see head comment of 247 // OtherRegionsTable for why this is OK. 248 assert(prt != NULL, "Inv"); 249 250 bool added = prt->add_reference(from); 251 if (prt->add_reference(from)) { 252 num_added_by_coarsening++; 253 } 254 Atomic::add(&_num_occupied, num_added_by_coarsening, memory_order_relaxed); 255 assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT (%d)", p2i(from), prt->contains_reference(from)); 256 } 257 258 PerRegionTable* 259 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const { 260 assert(ind < _max_fine_entries, "Preconditions."); 261 PerRegionTable* prt = _fine_grain_regions[ind]; 262 while (prt != NULL && prt->hr() != hr) { 263 prt = prt->collision_list_next(); 264 } 265 // Loop postcondition is the method postcondition. 266 return prt; 267 } 268 269 jint OtherRegionsTable::_n_coarsenings = 0; 270 271 PerRegionTable* OtherRegionsTable::delete_region_table(size_t& added_by_deleted) { 272 assert(_m->owned_by_self(), "Precondition"); 273 assert(_n_fine_entries == _max_fine_entries, "Precondition"); 274 PerRegionTable* max = NULL; 275 jint max_occ = 0; 276 PerRegionTable** max_prev = NULL; 277 size_t max_ind; 278 279 size_t i = _fine_eviction_start; 280 for (size_t k = 0; k < _fine_eviction_sample_size; k++) { 281 size_t ii = i; 282 // Make sure we get a non-NULL sample. 283 while (_fine_grain_regions[ii] == NULL) { 284 ii++; 285 if (ii == _max_fine_entries) ii = 0; 286 guarantee(ii != i, "We must find one."); 287 } 288 PerRegionTable** prev = &_fine_grain_regions[ii]; 289 PerRegionTable* cur = *prev; 290 while (cur != NULL) { 291 jint cur_occ = cur->occupied(); 292 if (max == NULL || cur_occ > max_occ) { 293 max = cur; 294 max_prev = prev; 295 max_ind = i; 296 max_occ = cur_occ; 297 } 298 prev = cur->collision_list_next_addr(); 299 cur = cur->collision_list_next(); 300 } 301 i = i + _fine_eviction_stride; 302 if (i >= _n_fine_entries) i = i - _n_fine_entries; 303 } 304 305 _fine_eviction_start++; 306 307 if (_fine_eviction_start >= _n_fine_entries) { 308 _fine_eviction_start -= _n_fine_entries; 309 } 310 311 guarantee(max != NULL, "Since _n_fine_entries > 0"); 312 guarantee(max_prev != NULL, "Since max != NULL."); 313 314 // Set the corresponding coarse bit. 315 size_t max_hrm_index = (size_t) max->hr()->hrm_index(); 316 if (!_coarse_map.at(max_hrm_index)) { 317 _coarse_map.at_put(max_hrm_index, true); 318 _n_coarse_entries++; 319 } 320 321 added_by_deleted = HeapRegion::CardsPerRegion - max_occ; 322 // Unsplice. 323 *max_prev = max->collision_list_next(); 324 Atomic::inc(&_n_coarsenings); 325 _n_fine_entries--; 326 return max; 327 } 328 329 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const { 330 return occupied() <= limit; 331 } 332 333 bool OtherRegionsTable::is_empty() const { 334 return occupied() == 0; 335 } 336 337 size_t OtherRegionsTable::occupied() const { 338 return _num_occupied; 339 } 340 341 size_t OtherRegionsTable::mem_size() const { 342 size_t sum = 0; 343 // all PRTs are of the same size so it is sufficient to query only one of them. 344 if (_first_all_fine_prts != NULL) { 345 assert(_last_all_fine_prts != NULL && 346 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant"); 347 sum += _first_all_fine_prts->mem_size() * _n_fine_entries; 348 } 349 sum += (sizeof(PerRegionTable*) * _max_fine_entries); 350 sum += (_coarse_map.size_in_words() * HeapWordSize); 351 sum += (_sparse_table.mem_size()); 352 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above. 353 return sum; 354 } 355 356 size_t OtherRegionsTable::static_mem_size() { 357 return G1FromCardCache::static_mem_size(); 358 } 359 360 size_t OtherRegionsTable::fl_mem_size() { 361 return PerRegionTable::fl_mem_size(); 362 } 363 364 void OtherRegionsTable::clear() { 365 // if there are no entries, skip this step 366 if (_first_all_fine_prts != NULL) { 367 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking"); 368 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts); 369 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0])); 370 } else { 371 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking"); 372 } 373 374 _first_all_fine_prts = _last_all_fine_prts = NULL; 375 _sparse_table.clear(); 376 if (_n_coarse_entries > 0) { 377 _coarse_map.clear(); 378 } 379 _n_fine_entries = 0; 380 _n_coarse_entries = 0; 381 382 _num_occupied = 0; 383 } 384 385 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const { 386 // Cast away const in this case. 387 MutexLocker x((Mutex*)_m, Mutex::_no_safepoint_check_flag); 388 return contains_reference_locked(from); 389 } 390 391 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const { 392 HeapRegion* hr = _g1h->heap_region_containing(from); 393 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index(); 394 // Is this region in the coarse map? 395 if (_coarse_map.at(hr_ind)) return true; 396 397 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask, 398 hr); 399 if (prt != NULL) { 400 return prt->contains_reference(from); 401 402 } else { 403 CardIdx_t card_index = card_within_region(from, hr); 404 return _sparse_table.contains_card(hr_ind, card_index); 405 } 406 } 407 408 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot, 409 HeapRegion* hr) 410 : _bot(bot), 411 _code_roots(), 412 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Mutex::_safepoint_check_never), 413 _other_regions(&_m), 414 _hr(hr), 415 _state(Untracked) 416 { 417 } 418 419 void HeapRegionRemSet::clear_fcc() { 420 G1FromCardCache::clear(_hr->hrm_index()); 421 } 422 423 void HeapRegionRemSet::setup_remset_size() { 424 const int LOG_M = 20; 425 guarantee(HeapRegion::LogOfHRGrainBytes >= LOG_M, "Code assumes the region size >= 1M, but is " SIZE_FORMAT "B", HeapRegion::GrainBytes); 426 427 int region_size_log_mb = HeapRegion::LogOfHRGrainBytes - LOG_M; 428 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) { 429 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * ((size_t)1 << (region_size_log_mb + 1)); 430 } 431 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) { 432 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1); 433 } 434 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity"); 435 } 436 437 void HeapRegionRemSet::clear(bool only_cardset) { 438 MutexLocker x(&_m, Mutex::_no_safepoint_check_flag); 439 clear_locked(only_cardset); 440 } 441 442 void HeapRegionRemSet::clear_locked(bool only_cardset) { 443 if (!only_cardset) { 444 _code_roots.clear(); 445 } 446 clear_fcc(); 447 _other_regions.clear(); 448 set_state_empty(); 449 assert(occupied() == 0, "Should be clear."); 450 } 451 452 // Code roots support 453 // 454 // The code root set is protected by two separate locking schemes 455 // When at safepoint the per-hrrs lock must be held during modifications 456 // except when doing a full gc. 457 // When not at safepoint the CodeCache_lock must be held during modifications. 458 // When concurrent readers access the contains() function 459 // (during the evacuation phase) no removals are allowed. 460 461 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) { 462 assert(nm != NULL, "sanity"); 463 assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()), 464 "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s", 465 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint())); 466 // Optimistic unlocked contains-check 467 if (!_code_roots.contains(nm)) { 468 MutexLocker ml(&_m, Mutex::_no_safepoint_check_flag); 469 add_strong_code_root_locked(nm); 470 } 471 } 472 473 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) { 474 assert(nm != NULL, "sanity"); 475 assert((CodeCache_lock->owned_by_self() || 476 (SafepointSynchronize::is_at_safepoint() && 477 (_m.owned_by_self() || Thread::current()->is_VM_thread()))), 478 "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s", 479 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), 480 BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread())); 481 _code_roots.add(nm); 482 } 483 484 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) { 485 assert(nm != NULL, "sanity"); 486 assert_locked_or_safepoint(CodeCache_lock); 487 488 MutexLocker ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag); 489 _code_roots.remove(nm); 490 491 // Check that there were no duplicates 492 guarantee(!_code_roots.contains(nm), "duplicate entry found"); 493 } 494 495 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const { 496 _code_roots.nmethods_do(blk); 497 } 498 499 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) { 500 _code_roots.clean(hr); 501 } 502 503 size_t HeapRegionRemSet::strong_code_roots_mem_size() { 504 return _code_roots.mem_size(); 505 }