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