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