1 /* 2 * Copyright (c) 2001, 2018, 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/g1CollectedHeap.inline.hpp" 27 #include "gc/g1/g1ConcurrentRefine.hpp" 28 #include "gc/g1/heapRegion.hpp" 29 #include "gc/g1/heapRegionManager.inline.hpp" 30 #include "gc/g1/heapRegionSet.inline.hpp" 31 #include "memory/allocation.hpp" 32 33 class MasterFreeRegionListChecker : public HeapRegionSetChecker { 34 public: 35 void check_mt_safety() { 36 // Master Free List MT safety protocol: 37 // (a) If we're at a safepoint, operations on the master free list 38 // should be invoked by either the VM thread (which will serialize 39 // them) or by the GC workers while holding the 40 // FreeList_lock. 41 // (b) If we're not at a safepoint, operations on the master free 42 // list should be invoked while holding the Heap_lock. 43 44 if (SafepointSynchronize::is_at_safepoint()) { 45 guarantee(Thread::current()->is_VM_thread() || 46 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint"); 47 } else { 48 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint"); 49 } 50 } 51 bool is_correct_type(HeapRegion* hr) { return hr->is_free(); } 52 const char* get_description() { return "Free Regions"; } 53 }; 54 55 HeapRegionManager::HeapRegionManager() : 56 _regions(), _heap_mapper(NULL), 57 _prev_bitmap_mapper(NULL), 58 _next_bitmap_mapper(NULL), 59 _bot_mapper(NULL), 60 _cardtable_mapper(NULL), 61 _card_counts_mapper(NULL), 62 _free_list("Free list", new MasterFreeRegionListChecker()), 63 _available_map(mtGC), 64 _num_committed(0), 65 _allocated_heapregions_length(0) 66 { } 67 68 void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage, 69 G1RegionToSpaceMapper* prev_bitmap, 70 G1RegionToSpaceMapper* next_bitmap, 71 G1RegionToSpaceMapper* bot, 72 G1RegionToSpaceMapper* cardtable, 73 G1RegionToSpaceMapper* card_counts) { 74 _allocated_heapregions_length = 0; 75 76 _heap_mapper = heap_storage; 77 78 _prev_bitmap_mapper = prev_bitmap; 79 _next_bitmap_mapper = next_bitmap; 80 81 _bot_mapper = bot; 82 _cardtable_mapper = cardtable; 83 84 _card_counts_mapper = card_counts; 85 86 MemRegion reserved = heap_storage->reserved(); 87 _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes); 88 89 _available_map.initialize(_regions.length()); 90 } 91 92 bool HeapRegionManager::is_available(uint region) const { 93 return _available_map.at(region); 94 } 95 96 #ifdef ASSERT 97 bool HeapRegionManager::is_free(HeapRegion* hr) const { 98 return _free_list.contains(hr); 99 } 100 #endif 101 102 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) { 103 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 104 HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index); 105 MemRegion mr(bottom, bottom + HeapRegion::GrainWords); 106 assert(reserved().contains(mr), "invariant"); 107 return g1h->new_heap_region(hrm_index, mr); 108 } 109 110 void HeapRegionManager::commit_regions(uint index, size_t num_regions, WorkGang* pretouch_gang) { 111 guarantee(num_regions > 0, "Must commit more than zero regions"); 112 guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions"); 113 114 _num_committed += (uint)num_regions; 115 116 _heap_mapper->commit_regions(index, num_regions, pretouch_gang); 117 118 // Also commit auxiliary data 119 _prev_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang); 120 _next_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang); 121 122 _bot_mapper->commit_regions(index, num_regions, pretouch_gang); 123 _cardtable_mapper->commit_regions(index, num_regions, pretouch_gang); 124 125 _card_counts_mapper->commit_regions(index, num_regions, pretouch_gang); 126 } 127 128 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) { 129 guarantee(num_regions >= 1, "Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start); 130 guarantee(_num_committed >= num_regions, "pre-condition"); 131 132 // Print before uncommitting. 133 if (G1CollectedHeap::heap()->hr_printer()->is_active()) { 134 for (uint i = start; i < start + num_regions; i++) { 135 HeapRegion* hr = at(i); 136 G1CollectedHeap::heap()->hr_printer()->uncommit(hr); 137 } 138 } 139 140 _num_committed -= (uint)num_regions; 141 142 _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range); 143 _heap_mapper->uncommit_regions(start, num_regions); 144 145 // Also uncommit auxiliary data 146 _prev_bitmap_mapper->uncommit_regions(start, num_regions); 147 _next_bitmap_mapper->uncommit_regions(start, num_regions); 148 149 _bot_mapper->uncommit_regions(start, num_regions); 150 _cardtable_mapper->uncommit_regions(start, num_regions); 151 152 _card_counts_mapper->uncommit_regions(start, num_regions); 153 } 154 155 void HeapRegionManager::make_regions_available(uint start, uint num_regions, WorkGang* pretouch_gang) { 156 guarantee(num_regions > 0, "No point in calling this for zero regions"); 157 commit_regions(start, num_regions, pretouch_gang); 158 for (uint i = start; i < start + num_regions; i++) { 159 if (_regions.get_by_index(i) == NULL) { 160 HeapRegion* new_hr = new_heap_region(i); 161 OrderAccess::storestore(); 162 _regions.set_by_index(i, new_hr); 163 _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1); 164 } 165 } 166 167 _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range); 168 169 for (uint i = start; i < start + num_regions; i++) { 170 assert(is_available(i), "Just made region %u available but is apparently not.", i); 171 HeapRegion* hr = at(i); 172 if (G1CollectedHeap::heap()->hr_printer()->is_active()) { 173 G1CollectedHeap::heap()->hr_printer()->commit(hr); 174 } 175 HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i); 176 MemRegion mr(bottom, bottom + HeapRegion::GrainWords); 177 178 hr->initialize(mr); 179 insert_into_free_list(at(i)); 180 } 181 } 182 183 MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const { 184 size_t used_sz = 185 _prev_bitmap_mapper->committed_size() + 186 _next_bitmap_mapper->committed_size() + 187 _bot_mapper->committed_size() + 188 _cardtable_mapper->committed_size() + 189 _card_counts_mapper->committed_size(); 190 191 size_t committed_sz = 192 _prev_bitmap_mapper->reserved_size() + 193 _next_bitmap_mapper->reserved_size() + 194 _bot_mapper->reserved_size() + 195 _cardtable_mapper->reserved_size() + 196 _card_counts_mapper->reserved_size(); 197 198 return MemoryUsage(0, used_sz, committed_sz, committed_sz); 199 } 200 201 uint HeapRegionManager::expand_by(uint num_regions, WorkGang* pretouch_workers) { 202 return expand_at(0, num_regions, pretouch_workers); 203 } 204 205 uint HeapRegionManager::expand_at(uint start, uint num_regions, WorkGang* pretouch_workers) { 206 if (num_regions == 0) { 207 return 0; 208 } 209 210 uint cur = start; 211 uint idx_last_found = 0; 212 uint num_last_found = 0; 213 214 uint expanded = 0; 215 216 while (expanded < num_regions && 217 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) { 218 uint to_expand = MIN2(num_regions - expanded, num_last_found); 219 make_regions_available(idx_last_found, to_expand, pretouch_workers); 220 expanded += to_expand; 221 cur = idx_last_found + num_last_found + 1; 222 } 223 224 verify_optional(); 225 return expanded; 226 } 227 228 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) { 229 uint found = 0; 230 size_t length_found = 0; 231 uint cur = 0; 232 233 while (length_found < num && cur < max_length()) { 234 HeapRegion* hr = _regions.get_by_index(cur); 235 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) { 236 // This region is a potential candidate for allocation into. 237 length_found++; 238 } else { 239 // This region is not a candidate. The next region is the next possible one. 240 found = cur + 1; 241 length_found = 0; 242 } 243 cur++; 244 } 245 246 if (length_found == num) { 247 for (uint i = found; i < (found + num); i++) { 248 HeapRegion* hr = _regions.get_by_index(i); 249 // sanity check 250 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()), 251 "Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT 252 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr)); 253 } 254 return found; 255 } else { 256 return G1_NO_HRM_INDEX; 257 } 258 } 259 260 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const { 261 guarantee(r != NULL, "Start region must be a valid region"); 262 guarantee(is_available(r->hrm_index()), "Trying to iterate starting from region %u which is not in the heap", r->hrm_index()); 263 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) { 264 HeapRegion* hr = _regions.get_by_index(i); 265 if (is_available(i)) { 266 return hr; 267 } 268 } 269 return NULL; 270 } 271 272 void HeapRegionManager::iterate(HeapRegionClosure* blk) const { 273 uint len = max_length(); 274 275 for (uint i = 0; i < len; i++) { 276 if (!is_available(i)) { 277 continue; 278 } 279 guarantee(at(i) != NULL, "Tried to access region %u that has a NULL HeapRegion*", i); 280 bool res = blk->do_heap_region(at(i)); 281 if (res) { 282 blk->set_incomplete(); 283 return; 284 } 285 } 286 } 287 288 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const { 289 guarantee(res_idx != NULL, "checking"); 290 guarantee(start_idx <= (max_length() + 1), "checking"); 291 292 uint num_regions = 0; 293 294 uint cur = start_idx; 295 while (cur < max_length() && is_available(cur)) { 296 cur++; 297 } 298 if (cur == max_length()) { 299 return num_regions; 300 } 301 *res_idx = cur; 302 while (cur < max_length() && !is_available(cur)) { 303 cur++; 304 } 305 num_regions = cur - *res_idx; 306 #ifdef ASSERT 307 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) { 308 assert(!is_available(i), "just checking"); 309 } 310 assert(cur == max_length() || num_regions == 0 || is_available(cur), 311 "The region at the current position %u must be available or at the end of the heap.", cur); 312 #endif 313 return num_regions; 314 } 315 316 uint HeapRegionManager::find_highest_free(bool* expanded) { 317 // Loop downwards from the highest region index, looking for an 318 // entry which is either free or not yet committed. If not yet 319 // committed, expand_at that index. 320 uint curr = max_length() - 1; 321 while (true) { 322 HeapRegion *hr = _regions.get_by_index(curr); 323 if (hr == NULL) { 324 uint res = expand_at(curr, 1, NULL); 325 if (res == 1) { 326 *expanded = true; 327 return curr; 328 } 329 } else { 330 if (hr->is_free()) { 331 *expanded = false; 332 return curr; 333 } 334 } 335 if (curr == 0) { 336 return G1_NO_HRM_INDEX; 337 } 338 curr--; 339 } 340 } 341 342 bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers) { 343 size_t commits = 0; 344 uint start_index = (uint)_regions.get_index_by_address(range.start()); 345 uint last_index = (uint)_regions.get_index_by_address(range.last()); 346 347 // Ensure that each G1 region in the range is free, returning false if not. 348 // Commit those that are not yet available, and keep count. 349 for (uint curr_index = start_index; curr_index <= last_index; curr_index++) { 350 if (!is_available(curr_index)) { 351 commits++; 352 expand_at(curr_index, 1, pretouch_workers); 353 } 354 HeapRegion* curr_region = _regions.get_by_index(curr_index); 355 if (!curr_region->is_free()) { 356 return false; 357 } 358 } 359 360 allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1); 361 *commit_count = commits; 362 return true; 363 } 364 365 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const { 366 // Every worker will actually look at all regions, skipping over regions that 367 // are currently not committed. 368 // This also (potentially) iterates over regions newly allocated during GC. This 369 // is no problem except for some extra work. 370 const uint n_regions = hrclaimer->n_regions(); 371 for (uint count = 0; count < n_regions; count++) { 372 const uint index = (start_index + count) % n_regions; 373 assert(index < n_regions, "sanity"); 374 // Skip over unavailable regions 375 if (!is_available(index)) { 376 continue; 377 } 378 HeapRegion* r = _regions.get_by_index(index); 379 // We'll ignore regions already claimed. 380 // However, if the iteration is specified as concurrent, the values for 381 // is_starts_humongous and is_continues_humongous can not be trusted, 382 // and we should just blindly iterate over regions regardless of their 383 // humongous status. 384 if (hrclaimer->is_region_claimed(index)) { 385 continue; 386 } 387 // OK, try to claim it 388 if (!hrclaimer->claim_region(index)) { 389 continue; 390 } 391 bool res = blk->do_heap_region(r); 392 if (res) { 393 return; 394 } 395 } 396 } 397 398 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) { 399 assert(length() > 0, "the region sequence should not be empty"); 400 assert(length() <= _allocated_heapregions_length, "invariant"); 401 assert(_allocated_heapregions_length > 0, "we should have at least one region committed"); 402 assert(num_regions_to_remove < length(), "We should never remove all regions"); 403 404 if (num_regions_to_remove == 0) { 405 return 0; 406 } 407 408 uint removed = 0; 409 uint cur = _allocated_heapregions_length - 1; 410 uint idx_last_found = 0; 411 uint num_last_found = 0; 412 413 while ((removed < num_regions_to_remove) && 414 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) { 415 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found); 416 417 shrink_at(idx_last_found + num_last_found - to_remove, to_remove); 418 419 cur = idx_last_found; 420 removed += to_remove; 421 } 422 423 verify_optional(); 424 425 return removed; 426 } 427 428 void HeapRegionManager::shrink_at(uint index, size_t num_regions) { 429 #ifdef ASSERT 430 for (uint i = index; i < (index + num_regions); i++) { 431 assert(is_available(i), "Expected available region at index %u", i); 432 assert(at(i)->is_empty(), "Expected empty region at index %u", i); 433 assert(at(i)->is_free(), "Expected free region at index %u", i); 434 } 435 #endif 436 uncommit_regions(index, num_regions); 437 } 438 439 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const { 440 guarantee(start_idx < _allocated_heapregions_length, "checking"); 441 guarantee(res_idx != NULL, "checking"); 442 443 uint num_regions_found = 0; 444 445 jlong cur = start_idx; 446 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) { 447 cur--; 448 } 449 if (cur == -1) { 450 return num_regions_found; 451 } 452 jlong old_cur = cur; 453 // cur indexes the first empty region 454 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) { 455 cur--; 456 } 457 *res_idx = cur + 1; 458 num_regions_found = old_cur - cur; 459 460 #ifdef ASSERT 461 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) { 462 assert(at(i)->is_empty(), "just checking"); 463 } 464 #endif 465 return num_regions_found; 466 } 467 468 void HeapRegionManager::verify() { 469 guarantee(length() <= _allocated_heapregions_length, 470 "invariant: _length: %u _allocated_length: %u", 471 length(), _allocated_heapregions_length); 472 guarantee(_allocated_heapregions_length <= max_length(), 473 "invariant: _allocated_length: %u _max_length: %u", 474 _allocated_heapregions_length, max_length()); 475 476 bool prev_committed = true; 477 uint num_committed = 0; 478 HeapWord* prev_end = heap_bottom(); 479 for (uint i = 0; i < _allocated_heapregions_length; i++) { 480 if (!is_available(i)) { 481 prev_committed = false; 482 continue; 483 } 484 num_committed++; 485 HeapRegion* hr = _regions.get_by_index(i); 486 guarantee(hr != NULL, "invariant: i: %u", i); 487 guarantee(!prev_committed || hr->bottom() == prev_end, 488 "invariant i: %u " HR_FORMAT " prev_end: " PTR_FORMAT, 489 i, HR_FORMAT_PARAMS(hr), p2i(prev_end)); 490 guarantee(hr->hrm_index() == i, 491 "invariant: i: %u hrm_index(): %u", i, hr->hrm_index()); 492 // Asserts will fire if i is >= _length 493 HeapWord* addr = hr->bottom(); 494 guarantee(addr_to_region(addr) == hr, "sanity"); 495 // We cannot check whether the region is part of a particular set: at the time 496 // this method may be called, we have only completed allocation of the regions, 497 // but not put into a region set. 498 prev_committed = true; 499 prev_end = hr->end(); 500 } 501 for (uint i = _allocated_heapregions_length; i < max_length(); i++) { 502 guarantee(_regions.get_by_index(i) == NULL, "invariant i: %u", i); 503 } 504 505 guarantee(num_committed == _num_committed, "Found %u committed regions, but should be %u", num_committed, _num_committed); 506 _free_list.verify(); 507 } 508 509 #ifndef PRODUCT 510 void HeapRegionManager::verify_optional() { 511 verify(); 512 } 513 #endif // PRODUCT 514 515 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) : 516 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm->_allocated_heapregions_length), _claims(NULL) { 517 assert(n_workers > 0, "Need at least one worker."); 518 uint* new_claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC); 519 memset(new_claims, Unclaimed, sizeof(*_claims) * _n_regions); 520 _claims = new_claims; 521 } 522 523 HeapRegionClaimer::~HeapRegionClaimer() { 524 if (_claims != NULL) { 525 FREE_C_HEAP_ARRAY(uint, _claims); 526 } 527 } 528 529 uint HeapRegionClaimer::offset_for_worker(uint worker_id) const { 530 assert(worker_id < _n_workers, "Invalid worker_id."); 531 return _n_regions * worker_id / _n_workers; 532 } 533 534 bool HeapRegionClaimer::is_region_claimed(uint region_index) const { 535 assert(region_index < _n_regions, "Invalid index."); 536 return _claims[region_index] == Claimed; 537 } 538 539 bool HeapRegionClaimer::claim_region(uint region_index) { 540 assert(region_index < _n_regions, "Invalid index."); 541 uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed); 542 return old_val == Unclaimed; 543 }