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/g1Arguments.hpp" 27 #include "gc/g1/g1CollectedHeap.inline.hpp" 28 #include "gc/g1/g1ConcurrentRefine.hpp" 29 #include "gc/g1/heapRegion.hpp" 30 #include "gc/g1/heapRegionManager.inline.hpp" 31 #include "gc/g1/heapRegionSet.inline.hpp" 32 #include "gc/g1/heterogeneousHeapRegionManager.hpp" 33 #include "memory/allocation.hpp" 34 #include "utilities/bitMap.inline.hpp" 35 36 class MasterFreeRegionListChecker : public HeapRegionSetChecker { 37 public: 38 void check_mt_safety() { 39 // Master Free List MT safety protocol: 40 // (a) If we're at a safepoint, operations on the master free list 41 // should be invoked by either the VM thread (which will serialize 42 // them) or by the GC workers while holding the 43 // FreeList_lock. 44 // (b) If we're not at a safepoint, operations on the master free 45 // list should be invoked while holding the Heap_lock. 46 47 if (SafepointSynchronize::is_at_safepoint()) { 48 guarantee(Thread::current()->is_VM_thread() || 49 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint"); 50 } else { 51 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint"); 52 } 53 } 54 bool is_correct_type(HeapRegion* hr) { return hr->is_free(); } 55 const char* get_description() { return "Free Regions"; } 56 }; 57 58 HeapRegionManager::HeapRegionManager() : 59 _bot_mapper(NULL), 60 _cardtable_mapper(NULL), 61 _card_counts_mapper(NULL), 62 _available_map(mtGC), 63 _num_committed(0), 64 _allocated_heapregions_length(0), 65 _regions(), _heap_mapper(NULL), 66 _prev_bitmap_mapper(NULL), 67 _next_bitmap_mapper(NULL), 68 _free_list("Free list", new MasterFreeRegionListChecker()) 69 { } 70 71 HeapRegionManager* HeapRegionManager::create_manager(G1CollectedHeap* heap) { 72 if (G1Arguments::is_heterogeneous_heap()) { 73 return new HeterogeneousHeapRegionManager((uint)(G1Arguments::heap_max_size_bytes() / HeapRegion::GrainBytes) /*heap size as num of regions*/); 74 } 75 return new HeapRegionManager(); 76 } 77 78 void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage, 79 G1RegionToSpaceMapper* prev_bitmap, 80 G1RegionToSpaceMapper* next_bitmap, 81 G1RegionToSpaceMapper* bot, 82 G1RegionToSpaceMapper* cardtable, 83 G1RegionToSpaceMapper* card_counts) { 84 _allocated_heapregions_length = 0; 85 86 _heap_mapper = heap_storage; 87 88 _prev_bitmap_mapper = prev_bitmap; 89 _next_bitmap_mapper = next_bitmap; 90 91 _bot_mapper = bot; 92 _cardtable_mapper = cardtable; 93 94 _card_counts_mapper = card_counts; 95 96 MemRegion reserved = heap_storage->reserved(); 97 _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes); 98 99 _available_map.initialize(_regions.length()); 100 } 101 102 bool HeapRegionManager::is_available(uint region) const { 103 return _available_map.at(region); 104 } 105 106 #ifdef ASSERT 107 bool HeapRegionManager::is_free(HeapRegion* hr) const { 108 return _free_list.contains(hr); 109 } 110 #endif 111 112 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) { 113 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 114 HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index); 115 MemRegion mr(bottom, bottom + HeapRegion::GrainWords); 116 assert(reserved().contains(mr), "invariant"); 117 return g1h->new_heap_region(hrm_index, mr); 118 } 119 120 void HeapRegionManager::commit_regions(uint index, size_t num_regions, WorkGang* pretouch_gang) { 121 guarantee(num_regions > 0, "Must commit more than zero regions"); 122 guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions"); 123 124 _num_committed += (uint)num_regions; 125 126 _heap_mapper->commit_regions(index, num_regions, pretouch_gang); 127 128 // Also commit auxiliary data 129 _prev_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang); 130 _next_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang); 131 132 _bot_mapper->commit_regions(index, num_regions, pretouch_gang); 133 _cardtable_mapper->commit_regions(index, num_regions, pretouch_gang); 134 135 _card_counts_mapper->commit_regions(index, num_regions, pretouch_gang); 136 } 137 138 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) { 139 guarantee(num_regions >= 1, "Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start); 140 guarantee(_num_committed >= num_regions, "pre-condition"); 141 142 // Print before uncommitting. 143 if (G1CollectedHeap::heap()->hr_printer()->is_active()) { 144 for (uint i = start; i < start + num_regions; i++) { 145 HeapRegion* hr = at(i); 146 G1CollectedHeap::heap()->hr_printer()->uncommit(hr); 147 } 148 } 149 150 _num_committed -= (uint)num_regions; 151 152 _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range); 153 _heap_mapper->uncommit_regions(start, num_regions); 154 155 // Also uncommit auxiliary data 156 _prev_bitmap_mapper->uncommit_regions(start, num_regions); 157 _next_bitmap_mapper->uncommit_regions(start, num_regions); 158 159 _bot_mapper->uncommit_regions(start, num_regions); 160 _cardtable_mapper->uncommit_regions(start, num_regions); 161 162 _card_counts_mapper->uncommit_regions(start, num_regions); 163 } 164 165 void HeapRegionManager::make_regions_available(uint start, uint num_regions, WorkGang* pretouch_gang) { 166 guarantee(num_regions > 0, "No point in calling this for zero regions"); 167 commit_regions(start, num_regions, pretouch_gang); 168 for (uint i = start; i < start + num_regions; i++) { 169 if (_regions.get_by_index(i) == NULL) { 170 HeapRegion* new_hr = new_heap_region(i); 171 OrderAccess::storestore(); 172 _regions.set_by_index(i, new_hr); 173 _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1); 174 } 175 } 176 177 _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range); 178 179 for (uint i = start; i < start + num_regions; i++) { 180 assert(is_available(i), "Just made region %u available but is apparently not.", i); 181 HeapRegion* hr = at(i); 182 if (G1CollectedHeap::heap()->hr_printer()->is_active()) { 183 G1CollectedHeap::heap()->hr_printer()->commit(hr); 184 } 185 HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i); 186 MemRegion mr(bottom, bottom + HeapRegion::GrainWords); 187 188 hr->initialize(mr); 189 insert_into_free_list(at(i)); 190 } 191 } 192 193 MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const { 194 size_t used_sz = 195 _prev_bitmap_mapper->committed_size() + 196 _next_bitmap_mapper->committed_size() + 197 _bot_mapper->committed_size() + 198 _cardtable_mapper->committed_size() + 199 _card_counts_mapper->committed_size(); 200 201 size_t committed_sz = 202 _prev_bitmap_mapper->reserved_size() + 203 _next_bitmap_mapper->reserved_size() + 204 _bot_mapper->reserved_size() + 205 _cardtable_mapper->reserved_size() + 206 _card_counts_mapper->reserved_size(); 207 208 return MemoryUsage(0, used_sz, committed_sz, committed_sz); 209 } 210 211 uint HeapRegionManager::expand_by(uint num_regions, WorkGang* pretouch_workers) { 212 return expand_at(0, num_regions, pretouch_workers); 213 } 214 215 uint HeapRegionManager::expand_at(uint start, uint num_regions, WorkGang* pretouch_workers) { 216 if (num_regions == 0) { 217 return 0; 218 } 219 220 uint cur = start; 221 uint idx_last_found = 0; 222 uint num_last_found = 0; 223 224 uint expanded = 0; 225 226 while (expanded < num_regions && 227 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) { 228 uint to_expand = MIN2(num_regions - expanded, num_last_found); 229 make_regions_available(idx_last_found, to_expand, pretouch_workers); 230 expanded += to_expand; 231 cur = idx_last_found + num_last_found + 1; 232 } 233 234 verify_optional(); 235 return expanded; 236 } 237 238 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) { 239 uint found = 0; 240 size_t length_found = 0; 241 uint cur = 0; 242 243 while (length_found < num && cur < max_length()) { 244 HeapRegion* hr = _regions.get_by_index(cur); 245 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) { 246 // This region is a potential candidate for allocation into. 247 length_found++; 248 } else { 249 // This region is not a candidate. The next region is the next possible one. 250 found = cur + 1; 251 length_found = 0; 252 } 253 cur++; 254 } 255 256 if (length_found == num) { 257 for (uint i = found; i < (found + num); i++) { 258 HeapRegion* hr = _regions.get_by_index(i); 259 // sanity check 260 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()), 261 "Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT 262 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr)); 263 } 264 return found; 265 } else { 266 return G1_NO_HRM_INDEX; 267 } 268 } 269 270 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const { 271 guarantee(r != NULL, "Start region must be a valid region"); 272 guarantee(is_available(r->hrm_index()), "Trying to iterate starting from region %u which is not in the heap", r->hrm_index()); 273 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) { 274 HeapRegion* hr = _regions.get_by_index(i); 275 if (is_available(i)) { 276 return hr; 277 } 278 } 279 return NULL; 280 } 281 282 void HeapRegionManager::iterate(HeapRegionClosure* blk) const { 283 uint len = max_length(); 284 285 for (uint i = 0; i < len; i++) { 286 if (!is_available(i)) { 287 continue; 288 } 289 guarantee(at(i) != NULL, "Tried to access region %u that has a NULL HeapRegion*", i); 290 bool res = blk->do_heap_region(at(i)); 291 if (res) { 292 blk->set_incomplete(); 293 return; 294 } 295 } 296 } 297 298 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const { 299 guarantee(res_idx != NULL, "checking"); 300 guarantee(start_idx <= (max_length() + 1), "checking"); 301 302 uint num_regions = 0; 303 304 uint cur = start_idx; 305 while (cur < max_length() && is_available(cur)) { 306 cur++; 307 } 308 if (cur == max_length()) { 309 return num_regions; 310 } 311 *res_idx = cur; 312 while (cur < max_length() && !is_available(cur)) { 313 cur++; 314 } 315 num_regions = cur - *res_idx; 316 #ifdef ASSERT 317 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) { 318 assert(!is_available(i), "just checking"); 319 } 320 assert(cur == max_length() || num_regions == 0 || is_available(cur), 321 "The region at the current position %u must be available or at the end of the heap.", cur); 322 #endif 323 return num_regions; 324 } 325 326 uint HeapRegionManager::find_highest_free(bool* expanded) { 327 // Loop downwards from the highest region index, looking for an 328 // entry which is either free or not yet committed. If not yet 329 // committed, expand_at that index. 330 uint curr = max_length() - 1; 331 while (true) { 332 HeapRegion *hr = _regions.get_by_index(curr); 333 if (hr == NULL || !is_available(curr)) { 334 uint res = expand_at(curr, 1, NULL); 335 if (res == 1) { 336 *expanded = true; 337 return curr; 338 } 339 } else { 340 if (hr->is_free()) { 341 *expanded = false; 342 return curr; 343 } 344 } 345 if (curr == 0) { 346 return G1_NO_HRM_INDEX; 347 } 348 curr--; 349 } 350 } 351 352 bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers) { 353 size_t commits = 0; 354 uint start_index = (uint)_regions.get_index_by_address(range.start()); 355 uint last_index = (uint)_regions.get_index_by_address(range.last()); 356 357 // Ensure that each G1 region in the range is free, returning false if not. 358 // Commit those that are not yet available, and keep count. 359 for (uint curr_index = start_index; curr_index <= last_index; curr_index++) { 360 if (!is_available(curr_index)) { 361 commits++; 362 expand_at(curr_index, 1, pretouch_workers); 363 } 364 HeapRegion* curr_region = _regions.get_by_index(curr_index); 365 if (!curr_region->is_free()) { 366 return false; 367 } 368 } 369 370 allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1); 371 *commit_count = commits; 372 return true; 373 } 374 375 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const { 376 // Every worker will actually look at all regions, skipping over regions that 377 // are currently not committed. 378 // This also (potentially) iterates over regions newly allocated during GC. This 379 // is no problem except for some extra work. 380 const uint n_regions = hrclaimer->n_regions(); 381 for (uint count = 0; count < n_regions; count++) { 382 const uint index = (start_index + count) % n_regions; 383 assert(index < n_regions, "sanity"); 384 // Skip over unavailable regions 385 if (!is_available(index)) { 386 continue; 387 } 388 HeapRegion* r = _regions.get_by_index(index); 389 // We'll ignore regions already claimed. 390 // However, if the iteration is specified as concurrent, the values for 391 // is_starts_humongous and is_continues_humongous can not be trusted, 392 // and we should just blindly iterate over regions regardless of their 393 // humongous status. 394 if (hrclaimer->is_region_claimed(index)) { 395 continue; 396 } 397 // OK, try to claim it 398 if (!hrclaimer->claim_region(index)) { 399 continue; 400 } 401 bool res = blk->do_heap_region(r); 402 if (res) { 403 return; 404 } 405 } 406 } 407 408 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) { 409 assert(length() > 0, "the region sequence should not be empty"); 410 assert(length() <= _allocated_heapregions_length, "invariant"); 411 assert(_allocated_heapregions_length > 0, "we should have at least one region committed"); 412 assert(num_regions_to_remove < length(), "We should never remove all regions"); 413 414 if (num_regions_to_remove == 0) { 415 return 0; 416 } 417 418 uint removed = 0; 419 uint cur = _allocated_heapregions_length - 1; 420 uint idx_last_found = 0; 421 uint num_last_found = 0; 422 423 while ((removed < num_regions_to_remove) && 424 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) { 425 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found); 426 427 shrink_at(idx_last_found + num_last_found - to_remove, to_remove); 428 429 cur = idx_last_found; 430 removed += to_remove; 431 } 432 433 verify_optional(); 434 435 return removed; 436 } 437 438 void HeapRegionManager::shrink_at(uint index, size_t num_regions) { 439 #ifdef ASSERT 440 for (uint i = index; i < (index + num_regions); i++) { 441 assert(is_available(i), "Expected available region at index %u", i); 442 assert(at(i)->is_empty(), "Expected empty region at index %u", i); 443 assert(at(i)->is_free(), "Expected free region at index %u", i); 444 } 445 #endif 446 uncommit_regions(index, num_regions); 447 } 448 449 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const { 450 guarantee(start_idx < _allocated_heapregions_length, "checking"); 451 guarantee(res_idx != NULL, "checking"); 452 453 uint num_regions_found = 0; 454 455 jlong cur = start_idx; 456 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) { 457 cur--; 458 } 459 if (cur == -1) { 460 return num_regions_found; 461 } 462 jlong old_cur = cur; 463 // cur indexes the first empty region 464 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) { 465 cur--; 466 } 467 *res_idx = cur + 1; 468 num_regions_found = old_cur - cur; 469 470 #ifdef ASSERT 471 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) { 472 assert(at(i)->is_empty(), "just checking"); 473 } 474 #endif 475 return num_regions_found; 476 } 477 478 void HeapRegionManager::verify() { 479 guarantee(length() <= _allocated_heapregions_length, 480 "invariant: _length: %u _allocated_length: %u", 481 length(), _allocated_heapregions_length); 482 guarantee(_allocated_heapregions_length <= max_length(), 483 "invariant: _allocated_length: %u _max_length: %u", 484 _allocated_heapregions_length, max_length()); 485 486 bool prev_committed = true; 487 uint num_committed = 0; 488 HeapWord* prev_end = heap_bottom(); 489 for (uint i = 0; i < _allocated_heapregions_length; i++) { 490 if (!is_available(i)) { 491 prev_committed = false; 492 continue; 493 } 494 num_committed++; 495 HeapRegion* hr = _regions.get_by_index(i); 496 guarantee(hr != NULL, "invariant: i: %u", i); 497 guarantee(!prev_committed || hr->bottom() == prev_end, 498 "invariant i: %u " HR_FORMAT " prev_end: " PTR_FORMAT, 499 i, HR_FORMAT_PARAMS(hr), p2i(prev_end)); 500 guarantee(hr->hrm_index() == i, 501 "invariant: i: %u hrm_index(): %u", i, hr->hrm_index()); 502 // Asserts will fire if i is >= _length 503 HeapWord* addr = hr->bottom(); 504 guarantee(addr_to_region(addr) == hr, "sanity"); 505 // We cannot check whether the region is part of a particular set: at the time 506 // this method may be called, we have only completed allocation of the regions, 507 // but not put into a region set. 508 prev_committed = true; 509 prev_end = hr->end(); 510 } 511 for (uint i = _allocated_heapregions_length; i < max_length(); i++) { 512 guarantee(_regions.get_by_index(i) == NULL, "invariant i: %u", i); 513 } 514 515 guarantee(num_committed == _num_committed, "Found %u committed regions, but should be %u", num_committed, _num_committed); 516 _free_list.verify(); 517 } 518 519 #ifndef PRODUCT 520 void HeapRegionManager::verify_optional() { 521 verify(); 522 } 523 #endif // PRODUCT 524 525 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) : 526 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm->_allocated_heapregions_length), _claims(NULL) { 527 assert(n_workers > 0, "Need at least one worker."); 528 uint* new_claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC); 529 memset(new_claims, Unclaimed, sizeof(*_claims) * _n_regions); 530 _claims = new_claims; 531 } 532 533 HeapRegionClaimer::~HeapRegionClaimer() { 534 FREE_C_HEAP_ARRAY(uint, _claims); 535 } 536 537 uint HeapRegionClaimer::offset_for_worker(uint worker_id) const { 538 assert(worker_id < _n_workers, "Invalid worker_id."); 539 return _n_regions * worker_id / _n_workers; 540 } 541 542 bool HeapRegionClaimer::is_region_claimed(uint region_index) const { 543 assert(region_index < _n_regions, "Invalid index."); 544 return _claims[region_index] == Claimed; 545 } 546 547 bool HeapRegionClaimer::claim_region(uint region_index) { 548 assert(region_index < _n_regions, "Invalid index."); 549 uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed); 550 return old_val == Unclaimed; 551 }