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/g1CollectedHeap.inline.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 void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage, 34 G1RegionToSpaceMapper* prev_bitmap, 35 G1RegionToSpaceMapper* next_bitmap, 36 G1RegionToSpaceMapper* bot, 37 G1RegionToSpaceMapper* cardtable, 38 G1RegionToSpaceMapper* card_counts) { 39 _allocated_heapregions_length = 0; 40 41 _heap_mapper = heap_storage; 42 43 _prev_bitmap_mapper = prev_bitmap; 44 _next_bitmap_mapper = next_bitmap; 45 46 _bot_mapper = bot; 47 _cardtable_mapper = cardtable; 48 49 _card_counts_mapper = card_counts; 50 51 MemRegion reserved = heap_storage->reserved(); 52 _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes); 53 54 _available_map.resize(_regions.length(), false); 55 _available_map.clear(); 56 } 57 58 bool HeapRegionManager::is_available(uint region) const { 59 return _available_map.at(region); 60 } 61 62 #ifdef ASSERT 63 bool HeapRegionManager::is_free(HeapRegion* hr) const { 64 return _free_list.contains(hr); 65 } 66 #endif 67 68 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) { 69 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 70 HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index); 71 MemRegion mr(bottom, bottom + HeapRegion::GrainWords); 72 assert(reserved().contains(mr), "invariant"); 73 return g1h->allocator()->new_heap_region(hrm_index, g1h->bot_shared(), mr); 74 } 75 76 void HeapRegionManager::commit_regions(uint index, size_t num_regions) { 77 guarantee(num_regions > 0, "Must commit more than zero regions"); 78 guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions"); 79 80 _num_committed += (uint)num_regions; 81 82 _heap_mapper->commit_regions(index, num_regions); 83 84 // Also commit auxiliary data 85 _prev_bitmap_mapper->commit_regions(index, num_regions); 86 _next_bitmap_mapper->commit_regions(index, num_regions); 87 88 _bot_mapper->commit_regions(index, num_regions); 89 _cardtable_mapper->commit_regions(index, num_regions); 90 91 _card_counts_mapper->commit_regions(index, num_regions); 92 } 93 94 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) { 95 guarantee(num_regions >= 1, err_msg("Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start)); 96 guarantee(_num_committed >= num_regions, "pre-condition"); 97 98 // Print before uncommitting. 99 if (G1CollectedHeap::heap()->hr_printer()->is_active()) { 100 for (uint i = start; i < start + num_regions; i++) { 101 HeapRegion* hr = at(i); 102 G1CollectedHeap::heap()->hr_printer()->uncommit(hr->bottom(), hr->end()); 103 } 104 } 105 106 _num_committed -= (uint)num_regions; 107 108 _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range); 109 _heap_mapper->uncommit_regions(start, num_regions); 110 111 // Also uncommit auxiliary data 112 _prev_bitmap_mapper->uncommit_regions(start, num_regions); 113 _next_bitmap_mapper->uncommit_regions(start, num_regions); 114 115 _bot_mapper->uncommit_regions(start, num_regions); 116 _cardtable_mapper->uncommit_regions(start, num_regions); 117 118 _card_counts_mapper->uncommit_regions(start, num_regions); 119 } 120 121 void HeapRegionManager::make_regions_available(uint start, uint num_regions) { 122 guarantee(num_regions > 0, "No point in calling this for zero regions"); 123 commit_regions(start, num_regions); 124 for (uint i = start; i < start + num_regions; i++) { 125 if (_regions.get_by_index(i) == NULL) { 126 HeapRegion* new_hr = new_heap_region(i); 127 _regions.set_by_index(i, new_hr); 128 _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1); 129 } 130 } 131 132 _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range); 133 134 for (uint i = start; i < start + num_regions; i++) { 135 assert(is_available(i), err_msg("Just made region %u available but is apparently not.", i)); 136 HeapRegion* hr = at(i); 137 if (G1CollectedHeap::heap()->hr_printer()->is_active()) { 138 G1CollectedHeap::heap()->hr_printer()->commit(hr->bottom(), hr->end()); 139 } 140 HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i); 141 MemRegion mr(bottom, bottom + HeapRegion::GrainWords); 142 143 hr->initialize(mr); 144 insert_into_free_list(at(i)); 145 } 146 } 147 148 MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const { 149 size_t used_sz = 150 _prev_bitmap_mapper->committed_size() + 151 _next_bitmap_mapper->committed_size() + 152 _bot_mapper->committed_size() + 153 _cardtable_mapper->committed_size() + 154 _card_counts_mapper->committed_size(); 155 156 size_t committed_sz = 157 _prev_bitmap_mapper->reserved_size() + 158 _next_bitmap_mapper->reserved_size() + 159 _bot_mapper->reserved_size() + 160 _cardtable_mapper->reserved_size() + 161 _card_counts_mapper->reserved_size(); 162 163 return MemoryUsage(0, used_sz, committed_sz, committed_sz); 164 } 165 166 uint HeapRegionManager::expand_by(uint num_regions) { 167 return expand_at(0, num_regions); 168 } 169 170 uint HeapRegionManager::expand_at(uint start, uint num_regions) { 171 if (num_regions == 0) { 172 return 0; 173 } 174 175 uint cur = start; 176 uint idx_last_found = 0; 177 uint num_last_found = 0; 178 179 uint expanded = 0; 180 181 while (expanded < num_regions && 182 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) { 183 uint to_expand = MIN2(num_regions - expanded, num_last_found); 184 make_regions_available(idx_last_found, to_expand); 185 expanded += to_expand; 186 cur = idx_last_found + num_last_found + 1; 187 } 188 189 verify_optional(); 190 return expanded; 191 } 192 193 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) { 194 uint found = 0; 195 size_t length_found = 0; 196 uint cur = 0; 197 198 while (length_found < num && cur < max_length()) { 199 HeapRegion* hr = _regions.get_by_index(cur); 200 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) { 201 // This region is a potential candidate for allocation into. 202 length_found++; 203 } else { 204 // This region is not a candidate. The next region is the next possible one. 205 found = cur + 1; 206 length_found = 0; 207 } 208 cur++; 209 } 210 211 if (length_found == num) { 212 for (uint i = found; i < (found + num); i++) { 213 HeapRegion* hr = _regions.get_by_index(i); 214 // sanity check 215 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()), 216 err_msg("Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT 217 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr))); 218 } 219 return found; 220 } else { 221 return G1_NO_HRM_INDEX; 222 } 223 } 224 225 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const { 226 guarantee(r != NULL, "Start region must be a valid region"); 227 guarantee(is_available(r->hrm_index()), err_msg("Trying to iterate starting from region %u which is not in the heap", r->hrm_index())); 228 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) { 229 HeapRegion* hr = _regions.get_by_index(i); 230 if (is_available(i)) { 231 return hr; 232 } 233 } 234 return NULL; 235 } 236 237 void HeapRegionManager::iterate(HeapRegionClosure* blk) const { 238 uint len = max_length(); 239 240 for (uint i = 0; i < len; i++) { 241 if (!is_available(i)) { 242 continue; 243 } 244 guarantee(at(i) != NULL, err_msg("Tried to access region %u that has a NULL HeapRegion*", i)); 245 bool res = blk->doHeapRegion(at(i)); 246 if (res) { 247 blk->incomplete(); 248 return; 249 } 250 } 251 } 252 253 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const { 254 guarantee(res_idx != NULL, "checking"); 255 guarantee(start_idx <= (max_length() + 1), "checking"); 256 257 uint num_regions = 0; 258 259 uint cur = start_idx; 260 while (cur < max_length() && is_available(cur)) { 261 cur++; 262 } 263 if (cur == max_length()) { 264 return num_regions; 265 } 266 *res_idx = cur; 267 while (cur < max_length() && !is_available(cur)) { 268 cur++; 269 } 270 num_regions = cur - *res_idx; 271 #ifdef ASSERT 272 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) { 273 assert(!is_available(i), "just checking"); 274 } 275 assert(cur == max_length() || num_regions == 0 || is_available(cur), 276 err_msg("The region at the current position %u must be available or at the end of the heap.", cur)); 277 #endif 278 return num_regions; 279 } 280 281 uint HeapRegionManager::find_highest_available(bool* expanded) { 282 // Loop downwards from the highest region index, looking for an 283 // entry which is either free or not yet committed. If not yet 284 // committed, expand_at that index, and set the 'expanded' output 285 // bool result to true. 286 uint curr = max_length() - 1; 287 while (curr != 0) { 288 HeapRegion *hr = _regions.get_by_index(curr); 289 if (hr == NULL) { 290 uint res = expand_at(curr, 1); 291 if (res == 1) { 292 *expanded = true; 293 return curr; 294 } 295 } else { 296 if (hr->is_free()) { 297 *expanded = false; 298 return curr; 299 } 300 } 301 curr--; 302 } 303 return G1_NO_HRM_INDEX; 304 } 305 306 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const { 307 const uint start_index = hrclaimer->start_region_for_worker(worker_id); 308 309 // Every worker will actually look at all regions, skipping over regions that 310 // are currently not committed. 311 // This also (potentially) iterates over regions newly allocated during GC. This 312 // is no problem except for some extra work. 313 const uint n_regions = hrclaimer->n_regions(); 314 for (uint count = 0; count < n_regions; count++) { 315 const uint index = (start_index + count) % n_regions; 316 assert(index < n_regions, "sanity"); 317 // Skip over unavailable regions 318 if (!is_available(index)) { 319 continue; 320 } 321 HeapRegion* r = _regions.get_by_index(index); 322 // We'll ignore "continues humongous" regions (we'll process them 323 // when we come across their corresponding "start humongous" 324 // region) and regions already claimed. 325 // However, if the iteration is specified as concurrent, the values for 326 // is_starts_humongous and is_continues_humongous can not be trusted, 327 // and we should just blindly iterate over regions regardless of their 328 // humongous status. 329 if (hrclaimer->is_region_claimed(index) || (!concurrent && r->is_continues_humongous())) { 330 continue; 331 } 332 // OK, try to claim it 333 if (!hrclaimer->claim_region(index)) { 334 continue; 335 } 336 // Success! 337 // As mentioned above, special treatment of humongous regions can only be 338 // done if we are iterating non-concurrently. 339 if (!concurrent && r->is_starts_humongous()) { 340 // If the region is "starts humongous" we'll iterate over its 341 // "continues humongous" first; in fact we'll do them 342 // first. The order is important. In one case, calling the 343 // closure on the "starts humongous" region might de-allocate 344 // and clear all its "continues humongous" regions and, as a 345 // result, we might end up processing them twice. So, we'll do 346 // them first (note: most closures will ignore them anyway) and 347 // then we'll do the "starts humongous" region. 348 for (uint ch_index = index + 1; ch_index < index + r->region_num(); ch_index++) { 349 HeapRegion* chr = _regions.get_by_index(ch_index); 350 351 assert(chr->is_continues_humongous(), "Must be humongous region"); 352 assert(chr->humongous_start_region() == r, 353 err_msg("Must work on humongous continuation of the original start region " 354 PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr))); 355 assert(!hrclaimer->is_region_claimed(ch_index), 356 "Must not have been claimed yet because claiming of humongous continuation first claims the start region"); 357 358 // Claim the region so no other worker tries to process the region. When a worker processes a 359 // starts_humongous region it may also process the associated continues_humongous regions. 360 // The continues_humongous regions can be changed to free regions. Unless this worker claims 361 // all of these regions, other workers might try claim and process these newly free regions. 362 bool claim_result = hrclaimer->claim_region(ch_index); 363 guarantee(claim_result, "We should always be able to claim the continuesHumongous part of the humongous object"); 364 365 bool res2 = blk->doHeapRegion(chr); 366 if (res2) { 367 return; 368 } 369 370 // Right now, this holds (i.e., no closure that actually 371 // does something with "continues humongous" regions 372 // clears them). We might have to weaken it in the future, 373 // but let's leave these two asserts here for extra safety. 374 assert(chr->is_continues_humongous(), "should still be the case"); 375 assert(chr->humongous_start_region() == r, "sanity"); 376 } 377 } 378 379 bool res = blk->doHeapRegion(r); 380 if (res) { 381 return; 382 } 383 } 384 } 385 386 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) { 387 assert(length() > 0, "the region sequence should not be empty"); 388 assert(length() <= _allocated_heapregions_length, "invariant"); 389 assert(_allocated_heapregions_length > 0, "we should have at least one region committed"); 390 assert(num_regions_to_remove < length(), "We should never remove all regions"); 391 392 if (num_regions_to_remove == 0) { 393 return 0; 394 } 395 396 uint removed = 0; 397 uint cur = _allocated_heapregions_length - 1; 398 uint idx_last_found = 0; 399 uint num_last_found = 0; 400 401 while ((removed < num_regions_to_remove) && 402 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) { 403 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found); 404 405 uncommit_regions(idx_last_found + num_last_found - to_remove, to_remove); 406 407 cur -= num_last_found; 408 removed += to_remove; 409 } 410 411 verify_optional(); 412 413 return removed; 414 } 415 416 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const { 417 guarantee(start_idx < _allocated_heapregions_length, "checking"); 418 guarantee(res_idx != NULL, "checking"); 419 420 uint num_regions_found = 0; 421 422 jlong cur = start_idx; 423 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) { 424 cur--; 425 } 426 if (cur == -1) { 427 return num_regions_found; 428 } 429 jlong old_cur = cur; 430 // cur indexes the first empty region 431 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) { 432 cur--; 433 } 434 *res_idx = cur + 1; 435 num_regions_found = old_cur - cur; 436 437 #ifdef ASSERT 438 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) { 439 assert(at(i)->is_empty(), "just checking"); 440 } 441 #endif 442 return num_regions_found; 443 } 444 445 void HeapRegionManager::verify() { 446 guarantee(length() <= _allocated_heapregions_length, 447 err_msg("invariant: _length: %u _allocated_length: %u", 448 length(), _allocated_heapregions_length)); 449 guarantee(_allocated_heapregions_length <= max_length(), 450 err_msg("invariant: _allocated_length: %u _max_length: %u", 451 _allocated_heapregions_length, max_length())); 452 453 bool prev_committed = true; 454 uint num_committed = 0; 455 HeapWord* prev_end = heap_bottom(); 456 for (uint i = 0; i < _allocated_heapregions_length; i++) { 457 if (!is_available(i)) { 458 prev_committed = false; 459 continue; 460 } 461 num_committed++; 462 HeapRegion* hr = _regions.get_by_index(i); 463 guarantee(hr != NULL, err_msg("invariant: i: %u", i)); 464 guarantee(!prev_committed || hr->bottom() == prev_end || hr->is_archive(), 465 err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT, 466 i, HR_FORMAT_PARAMS(hr), p2i(prev_end))); 467 guarantee(hr->hrm_index() == i, 468 err_msg("invariant: i: %u hrm_index(): %u", i, hr->hrm_index())); 469 // Asserts will fire if i is >= _length 470 HeapWord* addr = hr->bottom(); 471 guarantee(addr_to_region(addr) == hr, "sanity"); 472 // We cannot check whether the region is part of a particular set: at the time 473 // this method may be called, we have only completed allocation of the regions, 474 // but not put into a region set. 475 prev_committed = true; 476 if (hr->is_starts_humongous()) { 477 prev_end = hr->orig_end(); 478 } else { 479 prev_end = hr->end(); 480 } 481 } 482 for (uint i = _allocated_heapregions_length; i < max_length(); i++) { 483 guarantee(_regions.get_by_index(i) == NULL, err_msg("invariant i: %u", i)); 484 } 485 486 guarantee(num_committed == _num_committed, err_msg("Found %u committed regions, but should be %u", num_committed, _num_committed)); 487 _free_list.verify(); 488 } 489 490 #ifndef PRODUCT 491 void HeapRegionManager::verify_optional() { 492 verify(); 493 } 494 #endif // PRODUCT 495 496 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) : 497 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm._allocated_heapregions_length), _claims(NULL) { 498 assert(n_workers > 0, "Need at least one worker."); 499 _claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC); 500 memset(_claims, Unclaimed, sizeof(*_claims) * _n_regions); 501 } 502 503 HeapRegionClaimer::~HeapRegionClaimer() { 504 if (_claims != NULL) { 505 FREE_C_HEAP_ARRAY(uint, _claims); 506 } 507 } 508 509 uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const { 510 assert(worker_id < _n_workers, "Invalid worker_id."); 511 return _n_regions * worker_id / _n_workers; 512 } 513 514 bool HeapRegionClaimer::is_region_claimed(uint region_index) const { 515 assert(region_index < _n_regions, "Invalid index."); 516 return _claims[region_index] == Claimed; 517 } 518 519 bool HeapRegionClaimer::claim_region(uint region_index) { 520 assert(region_index < _n_regions, "Invalid index."); 521 uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed); 522 return old_val == Unclaimed; 523 }