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 #include "precompiled.hpp" 26 #include "gc/g1/concurrentG1Refine.hpp" 27 #include "gc/g1/g1BlockOffsetTable.inline.hpp" 28 #include "gc/g1/g1CollectedHeap.inline.hpp" 29 #include "gc/g1/heapRegionManager.inline.hpp" 30 #include "gc/g1/heapRegionRemSet.hpp" 31 #include "gc/shared/space.inline.hpp" 32 #include "memory/allocation.hpp" 33 #include "memory/padded.inline.hpp" 34 #include "oops/oop.inline.hpp" 35 #include "runtime/atomic.inline.hpp" 36 #include "utilities/bitMap.inline.hpp" 37 #include "utilities/globalDefinitions.hpp" 38 #include "utilities/growableArray.hpp" 39 40 class PerRegionTable: public CHeapObj<mtGC> { 41 friend class OtherRegionsTable; 42 friend class HeapRegionRemSetIterator; 43 44 HeapRegion* _hr; 45 BitMap _bm; 46 jint _occupied; 47 48 // next pointer for free/allocated 'all' list 49 PerRegionTable* _next; 50 51 // prev pointer for the allocated 'all' list 52 PerRegionTable* _prev; 53 54 // next pointer in collision list 55 PerRegionTable * _collision_list_next; 56 57 // Global free list of PRTs 58 static PerRegionTable* _free_list; 59 60 protected: 61 // We need access in order to union things into the base table. 62 BitMap* bm() { return &_bm; } 63 64 void recount_occupied() { 65 _occupied = (jint) bm()->count_one_bits(); 66 } 67 68 PerRegionTable(HeapRegion* hr) : 69 _hr(hr), 70 _occupied(0), 71 _bm(HeapRegion::CardsPerRegion, false /* in-resource-area */), 72 _collision_list_next(NULL), _next(NULL), _prev(NULL) 73 {} 74 75 void add_card_work(CardIdx_t from_card, bool par) { 76 if (!_bm.at(from_card)) { 77 if (par) { 78 if (_bm.par_at_put(from_card, 1)) { 79 Atomic::inc(&_occupied); 80 } 81 } else { 82 _bm.at_put(from_card, 1); 83 _occupied++; 84 } 85 } 86 } 87 88 void add_reference_work(OopOrNarrowOopStar from, bool par) { 89 // Must make this robust in case "from" is not in "_hr", because of 90 // concurrency. 91 92 log_develop(gc, remset)(" PRT::Add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").", 93 p2i(from), 94 UseCompressedOops 95 ? p2i(oopDesc::load_decode_heap_oop((narrowOop*)from)) 96 : p2i(oopDesc::load_decode_heap_oop((oop*)from))); 97 98 HeapRegion* loc_hr = hr(); 99 // If the test below fails, then this table was reused concurrently 100 // with this operation. This is OK, since the old table was coarsened, 101 // and adding a bit to the new table is never incorrect. 102 // If the table used to belong to a continues humongous region and is 103 // now reused for the corresponding start humongous region, we need to 104 // make sure that we detect this. Thus, we call is_in_reserved_raw() 105 // instead of just is_in_reserved() here. 106 if (loc_hr->is_in_reserved_raw(from)) { 107 size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom()); 108 CardIdx_t from_card = (CardIdx_t) 109 hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize); 110 111 assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion, 112 "Must be in range."); 113 add_card_work(from_card, par); 114 } 115 } 116 117 public: 118 119 HeapRegion* hr() const { return _hr; } 120 121 jint occupied() const { 122 // Overkill, but if we ever need it... 123 // guarantee(_occupied == _bm.count_one_bits(), "Check"); 124 return _occupied; 125 } 126 127 void init(HeapRegion* hr, bool clear_links_to_all_list) { 128 if (clear_links_to_all_list) { 129 set_next(NULL); 130 set_prev(NULL); 131 } 132 _hr = hr; 133 _collision_list_next = NULL; 134 _occupied = 0; 135 _bm.clear(); 136 } 137 138 void add_reference(OopOrNarrowOopStar from) { 139 add_reference_work(from, /*parallel*/ true); 140 } 141 142 void seq_add_reference(OopOrNarrowOopStar from) { 143 add_reference_work(from, /*parallel*/ false); 144 } 145 146 void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) { 147 HeapWord* hr_bot = hr()->bottom(); 148 size_t hr_first_card_index = ctbs->index_for(hr_bot); 149 bm()->set_intersection_at_offset(*card_bm, hr_first_card_index); 150 recount_occupied(); 151 } 152 153 void add_card(CardIdx_t from_card_index) { 154 add_card_work(from_card_index, /*parallel*/ true); 155 } 156 157 void seq_add_card(CardIdx_t from_card_index) { 158 add_card_work(from_card_index, /*parallel*/ false); 159 } 160 161 // (Destructively) union the bitmap of the current table into the given 162 // bitmap (which is assumed to be of the same size.) 163 void union_bitmap_into(BitMap* bm) { 164 bm->set_union(_bm); 165 } 166 167 // Mem size in bytes. 168 size_t mem_size() const { 169 return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize; 170 } 171 172 // Requires "from" to be in "hr()". 173 bool contains_reference(OopOrNarrowOopStar from) const { 174 assert(hr()->is_in_reserved(from), "Precondition."); 175 size_t card_ind = pointer_delta(from, hr()->bottom(), 176 CardTableModRefBS::card_size); 177 return _bm.at(card_ind); 178 } 179 180 // Bulk-free the PRTs from prt to last, assumes that they are 181 // linked together using their _next field. 182 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) { 183 while (true) { 184 PerRegionTable* fl = _free_list; 185 last->set_next(fl); 186 PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl); 187 if (res == fl) { 188 return; 189 } 190 } 191 ShouldNotReachHere(); 192 } 193 194 static void free(PerRegionTable* prt) { 195 bulk_free(prt, prt); 196 } 197 198 // Returns an initialized PerRegionTable instance. 199 static PerRegionTable* alloc(HeapRegion* hr) { 200 PerRegionTable* fl = _free_list; 201 while (fl != NULL) { 202 PerRegionTable* nxt = fl->next(); 203 PerRegionTable* res = 204 (PerRegionTable*) 205 Atomic::cmpxchg_ptr(nxt, &_free_list, fl); 206 if (res == fl) { 207 fl->init(hr, true); 208 return fl; 209 } else { 210 fl = _free_list; 211 } 212 } 213 assert(fl == NULL, "Loop condition."); 214 return new PerRegionTable(hr); 215 } 216 217 PerRegionTable* next() const { return _next; } 218 void set_next(PerRegionTable* next) { _next = next; } 219 PerRegionTable* prev() const { return _prev; } 220 void set_prev(PerRegionTable* prev) { _prev = prev; } 221 222 // Accessor and Modification routines for the pointer for the 223 // singly linked collision list that links the PRTs within the 224 // OtherRegionsTable::_fine_grain_regions hash table. 225 // 226 // It might be useful to also make the collision list doubly linked 227 // to avoid iteration over the collisions list during scrubbing/deletion. 228 // OTOH there might not be many collisions. 229 230 PerRegionTable* collision_list_next() const { 231 return _collision_list_next; 232 } 233 234 void set_collision_list_next(PerRegionTable* next) { 235 _collision_list_next = next; 236 } 237 238 PerRegionTable** collision_list_next_addr() { 239 return &_collision_list_next; 240 } 241 242 static size_t fl_mem_size() { 243 PerRegionTable* cur = _free_list; 244 size_t res = 0; 245 while (cur != NULL) { 246 res += cur->mem_size(); 247 cur = cur->next(); 248 } 249 return res; 250 } 251 252 static void test_fl_mem_size(); 253 }; 254 255 PerRegionTable* PerRegionTable::_free_list = NULL; 256 257 size_t OtherRegionsTable::_max_fine_entries = 0; 258 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0; 259 size_t OtherRegionsTable::_fine_eviction_stride = 0; 260 size_t OtherRegionsTable::_fine_eviction_sample_size = 0; 261 262 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) : 263 _g1h(G1CollectedHeap::heap()), 264 _hr(hr), _m(m), 265 _coarse_map(G1CollectedHeap::heap()->max_regions(), 266 false /* in-resource-area */), 267 _fine_grain_regions(NULL), 268 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL), 269 _n_fine_entries(0), _n_coarse_entries(0), 270 _fine_eviction_start(0), 271 _sparse_table(hr) 272 { 273 typedef PerRegionTable* PerRegionTablePtr; 274 275 if (_max_fine_entries == 0) { 276 assert(_mod_max_fine_entries_mask == 0, "Both or none."); 277 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries); 278 _max_fine_entries = (size_t)1 << max_entries_log; 279 _mod_max_fine_entries_mask = _max_fine_entries - 1; 280 281 assert(_fine_eviction_sample_size == 0 282 && _fine_eviction_stride == 0, "All init at same time."); 283 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log); 284 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size; 285 } 286 287 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries, 288 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 289 290 if (_fine_grain_regions == NULL) { 291 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR, 292 "Failed to allocate _fine_grain_entries."); 293 } 294 295 for (size_t i = 0; i < _max_fine_entries; i++) { 296 _fine_grain_regions[i] = NULL; 297 } 298 } 299 300 void OtherRegionsTable::link_to_all(PerRegionTable* prt) { 301 // We always append to the beginning of the list for convenience; 302 // the order of entries in this list does not matter. 303 if (_first_all_fine_prts != NULL) { 304 assert(_first_all_fine_prts->prev() == NULL, "invariant"); 305 _first_all_fine_prts->set_prev(prt); 306 prt->set_next(_first_all_fine_prts); 307 } else { 308 // this is the first element we insert. Adjust the "last" pointer 309 _last_all_fine_prts = prt; 310 assert(prt->next() == NULL, "just checking"); 311 } 312 // the new element is always the first element without a predecessor 313 prt->set_prev(NULL); 314 _first_all_fine_prts = prt; 315 316 assert(prt->prev() == NULL, "just checking"); 317 assert(_first_all_fine_prts == prt, "just checking"); 318 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) || 319 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL), 320 "just checking"); 321 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL, 322 "just checking"); 323 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL, 324 "just checking"); 325 } 326 327 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) { 328 if (prt->prev() != NULL) { 329 assert(_first_all_fine_prts != prt, "just checking"); 330 prt->prev()->set_next(prt->next()); 331 // removing the last element in the list? 332 if (_last_all_fine_prts == prt) { 333 _last_all_fine_prts = prt->prev(); 334 } 335 } else { 336 assert(_first_all_fine_prts == prt, "just checking"); 337 _first_all_fine_prts = prt->next(); 338 // list is empty now? 339 if (_first_all_fine_prts == NULL) { 340 _last_all_fine_prts = NULL; 341 } 342 } 343 344 if (prt->next() != NULL) { 345 prt->next()->set_prev(prt->prev()); 346 } 347 348 prt->set_next(NULL); 349 prt->set_prev(NULL); 350 351 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) || 352 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL), 353 "just checking"); 354 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL, 355 "just checking"); 356 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL, 357 "just checking"); 358 } 359 360 int** FromCardCache::_cache = NULL; 361 uint FromCardCache::_max_regions = 0; 362 size_t FromCardCache::_static_mem_size = 0; 363 364 void FromCardCache::initialize(uint n_par_rs, uint max_num_regions) { 365 guarantee(_cache == NULL, "Should not call this multiple times"); 366 367 _max_regions = max_num_regions; 368 _cache = Padded2DArray<int, mtGC>::create_unfreeable(n_par_rs, 369 _max_regions, 370 &_static_mem_size); 371 372 invalidate(0, _max_regions); 373 } 374 375 void FromCardCache::invalidate(uint start_idx, size_t new_num_regions) { 376 guarantee((size_t)start_idx + new_num_regions <= max_uintx, 377 "Trying to invalidate beyond maximum region, from %u size " SIZE_FORMAT, 378 start_idx, new_num_regions); 379 for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) { 380 uint end_idx = (start_idx + (uint)new_num_regions); 381 assert(end_idx <= _max_regions, "Must be within max."); 382 for (uint j = start_idx; j < end_idx; j++) { 383 set(i, j, InvalidCard); 384 } 385 } 386 } 387 388 #ifndef PRODUCT 389 void FromCardCache::print(outputStream* out) { 390 for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) { 391 for (uint j = 0; j < _max_regions; j++) { 392 out->print_cr("_from_card_cache[%u][%u] = %d.", 393 i, j, at(i, j)); 394 } 395 } 396 } 397 #endif 398 399 void FromCardCache::clear(uint region_idx) { 400 uint num_par_remsets = HeapRegionRemSet::num_par_rem_sets(); 401 for (uint i = 0; i < num_par_remsets; i++) { 402 set(i, region_idx, InvalidCard); 403 } 404 } 405 406 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) { 407 uint cur_hrm_ind = _hr->hrm_index(); 408 409 log_develop(gc, remset)("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").", 410 p2i(from), 411 UseCompressedOops 412 ? p2i(oopDesc::load_decode_heap_oop((narrowOop*)from)) 413 : p2i(oopDesc::load_decode_heap_oop((oop*)from))); 414 415 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift); 416 417 log_develop(gc, remset)("Table for [" PTR_FORMAT "...): card %d (cache = %d)", 418 p2i(_hr->bottom()), from_card, 419 FromCardCache::at(tid, cur_hrm_ind)); 420 421 if (FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) { 422 log_develop(gc, remset)(" from-card cache hit."); 423 assert(contains_reference(from), "We just added it!"); 424 return; 425 } 426 427 // Note that this may be a continued H region. 428 HeapRegion* from_hr = _g1h->heap_region_containing_raw(from); 429 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index(); 430 431 // If the region is already coarsened, return. 432 if (_coarse_map.at(from_hrm_ind)) { 433 log_develop(gc, remset)(" coarse map hit."); 434 assert(contains_reference(from), "We just added it!"); 435 return; 436 } 437 438 // Otherwise find a per-region table to add it to. 439 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask; 440 PerRegionTable* prt = find_region_table(ind, from_hr); 441 if (prt == NULL) { 442 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag); 443 // Confirm that it's really not there... 444 prt = find_region_table(ind, from_hr); 445 if (prt == NULL) { 446 447 uintptr_t from_hr_bot_card_index = 448 uintptr_t(from_hr->bottom()) 449 >> CardTableModRefBS::card_shift; 450 CardIdx_t card_index = from_card - from_hr_bot_card_index; 451 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion, 452 "Must be in range."); 453 if (G1HRRSUseSparseTable && 454 _sparse_table.add_card(from_hrm_ind, card_index)) { 455 log_develop(gc, remset)(" added card to sparse table."); 456 assert(contains_reference_locked(from), "We just added it!"); 457 return; 458 } else { 459 log_develop(gc, remset)(" [tid %u] sparse table entry overflow(f: %d, t: %u)", 460 tid, from_hrm_ind, cur_hrm_ind); 461 } 462 463 if (_n_fine_entries == _max_fine_entries) { 464 prt = delete_region_table(); 465 // There is no need to clear the links to the 'all' list here: 466 // prt will be reused immediately, i.e. remain in the 'all' list. 467 prt->init(from_hr, false /* clear_links_to_all_list */); 468 } else { 469 prt = PerRegionTable::alloc(from_hr); 470 link_to_all(prt); 471 } 472 473 PerRegionTable* first_prt = _fine_grain_regions[ind]; 474 prt->set_collision_list_next(first_prt); 475 // The assignment into _fine_grain_regions allows the prt to 476 // start being used concurrently. In addition to 477 // collision_list_next which must be visible (else concurrent 478 // parsing of the list, if any, may fail to see other entries), 479 // the content of the prt must be visible (else for instance 480 // some mark bits may not yet seem cleared or a 'later' update 481 // performed by a concurrent thread could be undone when the 482 // zeroing becomes visible). This requires store ordering. 483 OrderAccess::release_store_ptr((volatile PerRegionTable*)&_fine_grain_regions[ind], prt); 484 _n_fine_entries++; 485 486 if (G1HRRSUseSparseTable) { 487 // Transfer from sparse to fine-grain. 488 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind); 489 assert(sprt_entry != NULL, "There should have been an entry"); 490 for (int i = 0; i < SparsePRTEntry::cards_num(); i++) { 491 CardIdx_t c = sprt_entry->card(i); 492 if (c != SparsePRTEntry::NullEntry) { 493 prt->add_card(c); 494 } 495 } 496 // Now we can delete the sparse entry. 497 bool res = _sparse_table.delete_entry(from_hrm_ind); 498 assert(res, "It should have been there."); 499 } 500 } 501 assert(prt != NULL && prt->hr() == from_hr, "consequence"); 502 } 503 // Note that we can't assert "prt->hr() == from_hr", because of the 504 // possibility of concurrent reuse. But see head comment of 505 // OtherRegionsTable for why this is OK. 506 assert(prt != NULL, "Inv"); 507 508 prt->add_reference(from); 509 assert(contains_reference(from), "We just added it!"); 510 } 511 512 PerRegionTable* 513 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const { 514 assert(ind < _max_fine_entries, "Preconditions."); 515 PerRegionTable* prt = _fine_grain_regions[ind]; 516 while (prt != NULL && prt->hr() != hr) { 517 prt = prt->collision_list_next(); 518 } 519 // Loop postcondition is the method postcondition. 520 return prt; 521 } 522 523 jint OtherRegionsTable::_n_coarsenings = 0; 524 525 PerRegionTable* OtherRegionsTable::delete_region_table() { 526 assert(_m->owned_by_self(), "Precondition"); 527 assert(_n_fine_entries == _max_fine_entries, "Precondition"); 528 PerRegionTable* max = NULL; 529 jint max_occ = 0; 530 PerRegionTable** max_prev = NULL; 531 size_t max_ind; 532 533 size_t i = _fine_eviction_start; 534 for (size_t k = 0; k < _fine_eviction_sample_size; k++) { 535 size_t ii = i; 536 // Make sure we get a non-NULL sample. 537 while (_fine_grain_regions[ii] == NULL) { 538 ii++; 539 if (ii == _max_fine_entries) ii = 0; 540 guarantee(ii != i, "We must find one."); 541 } 542 PerRegionTable** prev = &_fine_grain_regions[ii]; 543 PerRegionTable* cur = *prev; 544 while (cur != NULL) { 545 jint cur_occ = cur->occupied(); 546 if (max == NULL || cur_occ > max_occ) { 547 max = cur; 548 max_prev = prev; 549 max_ind = i; 550 max_occ = cur_occ; 551 } 552 prev = cur->collision_list_next_addr(); 553 cur = cur->collision_list_next(); 554 } 555 i = i + _fine_eviction_stride; 556 if (i >= _n_fine_entries) i = i - _n_fine_entries; 557 } 558 559 _fine_eviction_start++; 560 561 if (_fine_eviction_start >= _n_fine_entries) { 562 _fine_eviction_start -= _n_fine_entries; 563 } 564 565 guarantee(max != NULL, "Since _n_fine_entries > 0"); 566 guarantee(max_prev != NULL, "Since max != NULL."); 567 568 // Set the corresponding coarse bit. 569 size_t max_hrm_index = (size_t) max->hr()->hrm_index(); 570 if (!_coarse_map.at(max_hrm_index)) { 571 _coarse_map.at_put(max_hrm_index, true); 572 _n_coarse_entries++; 573 log_develop(gc, remset)("Coarsened entry in region [" PTR_FORMAT "...] for region [" PTR_FORMAT "...] (" SIZE_FORMAT " coarse entries)", 574 p2i(_hr->bottom()), p2i(max->hr()->bottom()), _n_coarse_entries); 575 } 576 577 // Unsplice. 578 *max_prev = max->collision_list_next(); 579 Atomic::inc(&_n_coarsenings); 580 _n_fine_entries--; 581 return max; 582 } 583 584 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs, 585 BitMap* region_bm, BitMap* card_bm) { 586 // First eliminated garbage regions from the coarse map. 587 log_develop(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index()); 588 589 assert(_coarse_map.size() == region_bm->size(), "Precondition"); 590 log_develop(gc, remset, scrub)(" Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries); 591 _coarse_map.set_intersection(*region_bm); 592 _n_coarse_entries = _coarse_map.count_one_bits(); 593 log_develop(gc, remset, scrub)(" after = " SIZE_FORMAT ".", _n_coarse_entries); 594 595 // Now do the fine-grained maps. 596 for (size_t i = 0; i < _max_fine_entries; i++) { 597 PerRegionTable* cur = _fine_grain_regions[i]; 598 PerRegionTable** prev = &_fine_grain_regions[i]; 599 while (cur != NULL) { 600 PerRegionTable* nxt = cur->collision_list_next(); 601 // If the entire region is dead, eliminate. 602 log_develop(gc, remset, scrub)(" For other region %u:", cur->hr()->hrm_index()); 603 if (!region_bm->at((size_t) cur->hr()->hrm_index())) { 604 *prev = nxt; 605 cur->set_collision_list_next(NULL); 606 _n_fine_entries--; 607 log_develop(gc, remset, scrub)(" deleted via region map."); 608 unlink_from_all(cur); 609 PerRegionTable::free(cur); 610 } else { 611 // Do fine-grain elimination. 612 log_develop(gc, remset, scrub)(" occ: before = %4d.", cur->occupied()); 613 cur->scrub(ctbs, card_bm); 614 log_develop(gc, remset, scrub)(" after = %4d.", cur->occupied()); 615 // Did that empty the table completely? 616 if (cur->occupied() == 0) { 617 *prev = nxt; 618 cur->set_collision_list_next(NULL); 619 _n_fine_entries--; 620 unlink_from_all(cur); 621 PerRegionTable::free(cur); 622 } else { 623 prev = cur->collision_list_next_addr(); 624 } 625 } 626 cur = nxt; 627 } 628 } 629 // Since we may have deleted a from_card_cache entry from the RS, clear 630 // the FCC. 631 clear_fcc(); 632 } 633 634 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const { 635 if (limit <= (size_t)G1RSetSparseRegionEntries) { 636 return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit; 637 } else { 638 // Current uses of this method may only use values less than G1RSetSparseRegionEntries 639 // for the limit. The solution, comparing against occupied() would be too slow 640 // at this time. 641 Unimplemented(); 642 return false; 643 } 644 } 645 646 bool OtherRegionsTable::is_empty() const { 647 return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL; 648 } 649 650 size_t OtherRegionsTable::occupied() const { 651 size_t sum = occ_fine(); 652 sum += occ_sparse(); 653 sum += occ_coarse(); 654 return sum; 655 } 656 657 size_t OtherRegionsTable::occ_fine() const { 658 size_t sum = 0; 659 660 size_t num = 0; 661 PerRegionTable * cur = _first_all_fine_prts; 662 while (cur != NULL) { 663 sum += cur->occupied(); 664 cur = cur->next(); 665 num++; 666 } 667 guarantee(num == _n_fine_entries, "just checking"); 668 return sum; 669 } 670 671 size_t OtherRegionsTable::occ_coarse() const { 672 return (_n_coarse_entries * HeapRegion::CardsPerRegion); 673 } 674 675 size_t OtherRegionsTable::occ_sparse() const { 676 return _sparse_table.occupied(); 677 } 678 679 size_t OtherRegionsTable::mem_size() const { 680 size_t sum = 0; 681 // all PRTs are of the same size so it is sufficient to query only one of them. 682 if (_first_all_fine_prts != NULL) { 683 assert(_last_all_fine_prts != NULL && 684 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant"); 685 sum += _first_all_fine_prts->mem_size() * _n_fine_entries; 686 } 687 sum += (sizeof(PerRegionTable*) * _max_fine_entries); 688 sum += (_coarse_map.size_in_words() * HeapWordSize); 689 sum += (_sparse_table.mem_size()); 690 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above. 691 return sum; 692 } 693 694 size_t OtherRegionsTable::static_mem_size() { 695 return FromCardCache::static_mem_size(); 696 } 697 698 size_t OtherRegionsTable::fl_mem_size() { 699 return PerRegionTable::fl_mem_size(); 700 } 701 702 void OtherRegionsTable::clear_fcc() { 703 FromCardCache::clear(_hr->hrm_index()); 704 } 705 706 void OtherRegionsTable::clear() { 707 // if there are no entries, skip this step 708 if (_first_all_fine_prts != NULL) { 709 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking"); 710 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts); 711 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0])); 712 } else { 713 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking"); 714 } 715 716 _first_all_fine_prts = _last_all_fine_prts = NULL; 717 _sparse_table.clear(); 718 _coarse_map.clear(); 719 _n_fine_entries = 0; 720 _n_coarse_entries = 0; 721 722 clear_fcc(); 723 } 724 725 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const { 726 // Cast away const in this case. 727 MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag); 728 return contains_reference_locked(from); 729 } 730 731 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const { 732 HeapRegion* hr = _g1h->heap_region_containing_raw(from); 733 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index(); 734 // Is this region in the coarse map? 735 if (_coarse_map.at(hr_ind)) return true; 736 737 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask, 738 hr); 739 if (prt != NULL) { 740 return prt->contains_reference(from); 741 742 } else { 743 uintptr_t from_card = 744 (uintptr_t(from) >> CardTableModRefBS::card_shift); 745 uintptr_t hr_bot_card_index = 746 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift; 747 assert(from_card >= hr_bot_card_index, "Inv"); 748 CardIdx_t card_index = from_card - hr_bot_card_index; 749 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion, 750 "Must be in range."); 751 return _sparse_table.contains_card(hr_ind, card_index); 752 } 753 } 754 755 void 756 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) { 757 _sparse_table.do_cleanup_work(hrrs_cleanup_task); 758 } 759 760 // Determines how many threads can add records to an rset in parallel. 761 // This can be done by either mutator threads together with the 762 // concurrent refinement threads or GC threads. 763 uint HeapRegionRemSet::num_par_rem_sets() { 764 return MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), ParallelGCThreads); 765 } 766 767 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, 768 HeapRegion* hr) 769 : _bosa(bosa), 770 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never), 771 _code_roots(), _other_regions(hr, &_m), _iter_state(Unclaimed), _iter_claimed(0) { 772 reset_for_par_iteration(); 773 } 774 775 void HeapRegionRemSet::setup_remset_size() { 776 // Setup sparse and fine-grain tables sizes. 777 // table_size = base * (log(region_size / 1M) + 1) 778 const int LOG_M = 20; 779 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0); 780 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) { 781 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1); 782 } 783 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) { 784 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1); 785 } 786 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity"); 787 } 788 789 bool HeapRegionRemSet::claim_iter() { 790 if (_iter_state != Unclaimed) return false; 791 jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed); 792 return (res == Unclaimed); 793 } 794 795 void HeapRegionRemSet::set_iter_complete() { 796 _iter_state = Complete; 797 } 798 799 bool HeapRegionRemSet::iter_is_complete() { 800 return _iter_state == Complete; 801 } 802 803 #ifndef PRODUCT 804 void HeapRegionRemSet::print() { 805 HeapRegionRemSetIterator iter(this); 806 size_t card_index; 807 while (iter.has_next(card_index)) { 808 HeapWord* card_start = 809 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index); 810 tty->print_cr(" Card " PTR_FORMAT, p2i(card_start)); 811 } 812 if (iter.n_yielded() != occupied()) { 813 tty->print_cr("Yielded disagrees with occupied:"); 814 tty->print_cr(" " SIZE_FORMAT_W(6) " yielded (" SIZE_FORMAT_W(6) 815 " coarse, " SIZE_FORMAT_W(6) " fine).", 816 iter.n_yielded(), 817 iter.n_yielded_coarse(), iter.n_yielded_fine()); 818 tty->print_cr(" " SIZE_FORMAT_W(6) " occ (" SIZE_FORMAT_W(6) 819 " coarse, " SIZE_FORMAT_W(6) " fine).", 820 occupied(), occ_coarse(), occ_fine()); 821 } 822 guarantee(iter.n_yielded() == occupied(), 823 "We should have yielded all the represented cards."); 824 } 825 #endif 826 827 void HeapRegionRemSet::cleanup() { 828 SparsePRT::cleanup_all(); 829 } 830 831 void HeapRegionRemSet::clear() { 832 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); 833 clear_locked(); 834 } 835 836 void HeapRegionRemSet::clear_locked() { 837 _code_roots.clear(); 838 _other_regions.clear(); 839 assert(occupied_locked() == 0, "Should be clear."); 840 reset_for_par_iteration(); 841 } 842 843 void HeapRegionRemSet::reset_for_par_iteration() { 844 _iter_state = Unclaimed; 845 _iter_claimed = 0; 846 // It's good to check this to make sure that the two methods are in sync. 847 assert(verify_ready_for_par_iteration(), "post-condition"); 848 } 849 850 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs, 851 BitMap* region_bm, BitMap* card_bm) { 852 _other_regions.scrub(ctbs, region_bm, card_bm); 853 } 854 855 // Code roots support 856 // 857 // The code root set is protected by two separate locking schemes 858 // When at safepoint the per-hrrs lock must be held during modifications 859 // except when doing a full gc. 860 // When not at safepoint the CodeCache_lock must be held during modifications. 861 // When concurrent readers access the contains() function 862 // (during the evacuation phase) no removals are allowed. 863 864 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) { 865 assert(nm != NULL, "sanity"); 866 // Optimistic unlocked contains-check 867 if (!_code_roots.contains(nm)) { 868 MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag); 869 add_strong_code_root_locked(nm); 870 } 871 } 872 873 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) { 874 assert(nm != NULL, "sanity"); 875 _code_roots.add(nm); 876 } 877 878 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) { 879 assert(nm != NULL, "sanity"); 880 assert_locked_or_safepoint(CodeCache_lock); 881 882 MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag); 883 _code_roots.remove(nm); 884 885 // Check that there were no duplicates 886 guarantee(!_code_roots.contains(nm), "duplicate entry found"); 887 } 888 889 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const { 890 _code_roots.nmethods_do(blk); 891 } 892 893 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) { 894 _code_roots.clean(hr); 895 } 896 897 size_t HeapRegionRemSet::strong_code_roots_mem_size() { 898 return _code_roots.mem_size(); 899 } 900 901 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) : 902 _hrrs(hrrs), 903 _g1h(G1CollectedHeap::heap()), 904 _coarse_map(&hrrs->_other_regions._coarse_map), 905 _bosa(hrrs->_bosa), 906 _is(Sparse), 907 // Set these values so that we increment to the first region. 908 _coarse_cur_region_index(-1), 909 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1), 910 _cur_card_in_prt(HeapRegion::CardsPerRegion), 911 _fine_cur_prt(NULL), 912 _n_yielded_coarse(0), 913 _n_yielded_fine(0), 914 _n_yielded_sparse(0), 915 _sparse_iter(&hrrs->_other_regions._sparse_table) {} 916 917 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) { 918 if (_hrrs->_other_regions._n_coarse_entries == 0) return false; 919 // Go to the next card. 920 _coarse_cur_region_cur_card++; 921 // Was the last the last card in the current region? 922 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) { 923 // Yes: find the next region. This may leave _coarse_cur_region_index 924 // Set to the last index, in which case there are no more coarse 925 // regions. 926 _coarse_cur_region_index = 927 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1); 928 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) { 929 _coarse_cur_region_cur_card = 0; 930 HeapWord* r_bot = 931 _g1h->region_at((uint) _coarse_cur_region_index)->bottom(); 932 _cur_region_card_offset = _bosa->index_for(r_bot); 933 } else { 934 return false; 935 } 936 } 937 // If we didn't return false above, then we can yield a card. 938 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card; 939 return true; 940 } 941 942 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) { 943 if (fine_has_next()) { 944 _cur_card_in_prt = 945 _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1); 946 } 947 if (_cur_card_in_prt == HeapRegion::CardsPerRegion) { 948 // _fine_cur_prt may still be NULL in case if there are not PRTs at all for 949 // the remembered set. 950 if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) { 951 return false; 952 } 953 PerRegionTable* next_prt = _fine_cur_prt->next(); 954 switch_to_prt(next_prt); 955 _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1); 956 } 957 958 card_index = _cur_region_card_offset + _cur_card_in_prt; 959 guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion, 960 "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt); 961 return true; 962 } 963 964 bool HeapRegionRemSetIterator::fine_has_next() { 965 return _cur_card_in_prt != HeapRegion::CardsPerRegion; 966 } 967 968 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) { 969 assert(prt != NULL, "Cannot switch to NULL prt"); 970 _fine_cur_prt = prt; 971 972 HeapWord* r_bot = _fine_cur_prt->hr()->bottom(); 973 _cur_region_card_offset = _bosa->index_for(r_bot); 974 975 // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1. 976 // To avoid special-casing this start case, and not miss the first bitmap 977 // entry, initialize _cur_region_cur_card with -1 instead of 0. 978 _cur_card_in_prt = (size_t)-1; 979 } 980 981 bool HeapRegionRemSetIterator::has_next(size_t& card_index) { 982 switch (_is) { 983 case Sparse: { 984 if (_sparse_iter.has_next(card_index)) { 985 _n_yielded_sparse++; 986 return true; 987 } 988 // Otherwise, deliberate fall-through 989 _is = Fine; 990 PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts; 991 if (initial_fine_prt != NULL) { 992 switch_to_prt(_hrrs->_other_regions._first_all_fine_prts); 993 } 994 } 995 case Fine: 996 if (fine_has_next(card_index)) { 997 _n_yielded_fine++; 998 return true; 999 } 1000 // Otherwise, deliberate fall-through 1001 _is = Coarse; 1002 case Coarse: 1003 if (coarse_has_next(card_index)) { 1004 _n_yielded_coarse++; 1005 return true; 1006 } 1007 // Otherwise... 1008 break; 1009 } 1010 assert(ParallelGCThreads > 1 || 1011 n_yielded() == _hrrs->occupied(), 1012 "Should have yielded all the cards in the rem set " 1013 "(in the non-par case)."); 1014 return false; 1015 } 1016 1017 void HeapRegionRemSet::reset_for_cleanup_tasks() { 1018 SparsePRT::reset_for_cleanup_tasks(); 1019 } 1020 1021 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) { 1022 _other_regions.do_cleanup_work(hrrs_cleanup_task); 1023 } 1024 1025 void 1026 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) { 1027 SparsePRT::finish_cleanup_task(hrrs_cleanup_task); 1028 } 1029 1030 #ifndef PRODUCT 1031 void PerRegionTable::test_fl_mem_size() { 1032 PerRegionTable* dummy = alloc(NULL); 1033 1034 size_t min_prt_size = sizeof(void*) + dummy->bm()->size_in_words() * HeapWordSize; 1035 assert(dummy->mem_size() > min_prt_size, 1036 "PerRegionTable memory usage is suspiciously small, only has " SIZE_FORMAT " bytes. " 1037 "Should be at least " SIZE_FORMAT " bytes.", dummy->mem_size(), min_prt_size); 1038 free(dummy); 1039 guarantee(dummy->mem_size() == fl_mem_size(), "fl_mem_size() does not return the correct element size"); 1040 // try to reset the state 1041 _free_list = NULL; 1042 delete dummy; 1043 } 1044 1045 void HeapRegionRemSet::test_prt() { 1046 PerRegionTable::test_fl_mem_size(); 1047 } 1048 1049 void HeapRegionRemSet::test() { 1050 os::sleep(Thread::current(), (jlong)5000, false); 1051 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1052 1053 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same 1054 // hash bucket. 1055 HeapRegion* hr0 = g1h->region_at(0); 1056 HeapRegion* hr1 = g1h->region_at(1); 1057 HeapRegion* hr2 = g1h->region_at(5); 1058 HeapRegion* hr3 = g1h->region_at(6); 1059 HeapRegion* hr4 = g1h->region_at(7); 1060 HeapRegion* hr5 = g1h->region_at(8); 1061 1062 HeapWord* hr1_start = hr1->bottom(); 1063 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2; 1064 HeapWord* hr1_last = hr1->end() - 1; 1065 1066 HeapWord* hr2_start = hr2->bottom(); 1067 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2; 1068 HeapWord* hr2_last = hr2->end() - 1; 1069 1070 HeapWord* hr3_start = hr3->bottom(); 1071 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2; 1072 HeapWord* hr3_last = hr3->end() - 1; 1073 1074 HeapRegionRemSet* hrrs = hr0->rem_set(); 1075 1076 // Make three references from region 0x101... 1077 hrrs->add_reference((OopOrNarrowOopStar)hr1_start); 1078 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid); 1079 hrrs->add_reference((OopOrNarrowOopStar)hr1_last); 1080 1081 hrrs->add_reference((OopOrNarrowOopStar)hr2_start); 1082 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid); 1083 hrrs->add_reference((OopOrNarrowOopStar)hr2_last); 1084 1085 hrrs->add_reference((OopOrNarrowOopStar)hr3_start); 1086 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid); 1087 hrrs->add_reference((OopOrNarrowOopStar)hr3_last); 1088 1089 // Now cause a coarsening. 1090 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom()); 1091 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom()); 1092 1093 // Now, does iteration yield these three? 1094 HeapRegionRemSetIterator iter(hrrs); 1095 size_t sum = 0; 1096 size_t card_index; 1097 while (iter.has_next(card_index)) { 1098 HeapWord* card_start = 1099 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index); 1100 tty->print_cr(" Card " PTR_FORMAT ".", p2i(card_start)); 1101 sum++; 1102 } 1103 guarantee(sum == 11 - 3 + 2048, "Failure"); 1104 guarantee(sum == hrrs->occupied(), "Failure"); 1105 } 1106 #endif