1 /* 2 * Copyright (c) 2014, 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/g1Allocator.inline.hpp" 27 #include "gc/g1/g1AllocRegion.inline.hpp" 28 #include "gc/g1/g1EvacStats.inline.hpp" 29 #include "gc/g1/g1CollectedHeap.inline.hpp" 30 #include "gc/g1/g1Policy.hpp" 31 #include "gc/g1/heapRegion.inline.hpp" 32 #include "gc/g1/heapRegionSet.inline.hpp" 33 #include "gc/g1/heapRegionType.hpp" 34 #include "utilities/align.hpp" 35 36 G1Allocator::G1Allocator(G1CollectedHeap* heap) : 37 _g1h(heap), 38 _survivor_is_full(false), 39 _old_is_full(false), 40 _mutator_alloc_region(), 41 _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)), 42 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)), 43 _retained_old_gc_alloc_region(NULL) { 44 } 45 46 void G1Allocator::init_mutator_alloc_region() { 47 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 48 _mutator_alloc_region.init(); 49 } 50 51 void G1Allocator::release_mutator_alloc_region() { 52 _mutator_alloc_region.release(); 53 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 54 } 55 56 bool G1Allocator::is_retained_old_region(HeapRegion* hr) { 57 return _retained_old_gc_alloc_region == hr; 58 } 59 60 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info, 61 OldGCAllocRegion* old, 62 HeapRegion** retained_old) { 63 HeapRegion* retained_region = *retained_old; 64 *retained_old = NULL; 65 assert(retained_region == NULL || !retained_region->is_archive(), 66 "Archive region should not be alloc region (index %u)", retained_region->hrm_index()); 67 68 // We will discard the current GC alloc region if: 69 // a) it's in the collection set (it can happen!), 70 // b) it's already full (no point in using it), 71 // c) it's empty (this means that it was emptied during 72 // a cleanup and it should be on the free list now), or 73 // d) it's humongous (this means that it was emptied 74 // during a cleanup and was added to the free list, but 75 // has been subsequently used to allocate a humongous 76 // object that may be less than the region size). 77 if (retained_region != NULL && 78 !retained_region->in_collection_set() && 79 !(retained_region->top() == retained_region->end()) && 80 !retained_region->is_empty() && 81 !retained_region->is_humongous()) { 82 // The retained region was added to the old region set when it was 83 // retired. We have to remove it now, since we don't allow regions 84 // we allocate to in the region sets. We'll re-add it later, when 85 // it's retired again. 86 _g1h->old_set_remove(retained_region); 87 old->set(retained_region); 88 _g1h->hr_printer()->reuse(retained_region); 89 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 90 } 91 } 92 93 void G1Allocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 94 assert_at_safepoint_on_vm_thread(); 95 96 _survivor_is_full = false; 97 _old_is_full = false; 98 99 _survivor_gc_alloc_region.init(); 100 _old_gc_alloc_region.init(); 101 reuse_retained_old_region(evacuation_info, 102 &_old_gc_alloc_region, 103 &_retained_old_gc_alloc_region); 104 } 105 106 void G1Allocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) { 107 evacuation_info.set_allocation_regions(survivor_gc_alloc_region()->count() + 108 old_gc_alloc_region()->count()); 109 survivor_gc_alloc_region()->release(); 110 // If we have an old GC alloc region to release, we'll save it in 111 // _retained_old_gc_alloc_region. If we don't 112 // _retained_old_gc_alloc_region will become NULL. This is what we 113 // want either way so no reason to check explicitly for either 114 // condition. 115 _retained_old_gc_alloc_region = old_gc_alloc_region()->release(); 116 } 117 118 void G1Allocator::abandon_gc_alloc_regions() { 119 assert(survivor_gc_alloc_region()->get() == NULL, "pre-condition"); 120 assert(old_gc_alloc_region()->get() == NULL, "pre-condition"); 121 _retained_old_gc_alloc_region = NULL; 122 } 123 124 bool G1Allocator::survivor_is_full() const { 125 return _survivor_is_full; 126 } 127 128 bool G1Allocator::old_is_full() const { 129 return _old_is_full; 130 } 131 132 void G1Allocator::set_survivor_full() { 133 _survivor_is_full = true; 134 } 135 136 void G1Allocator::set_old_full() { 137 _old_is_full = true; 138 } 139 140 size_t G1Allocator::unsafe_max_tlab_alloc() { 141 // Return the remaining space in the cur alloc region, but not less than 142 // the min TLAB size. 143 144 // Also, this value can be at most the humongous object threshold, 145 // since we can't allow tlabs to grow big enough to accommodate 146 // humongous objects. 147 148 HeapRegion* hr = mutator_alloc_region()->get(); 149 size_t max_tlab = _g1h->max_tlab_size() * wordSize; 150 if (hr == NULL) { 151 return max_tlab; 152 } else { 153 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 154 } 155 } 156 157 size_t G1Allocator::used_in_alloc_regions() { 158 assert(Heap_lock->owner() != NULL, "Should be owned on this thread's behalf."); 159 return mutator_alloc_region()->used_in_alloc_regions(); 160 } 161 162 163 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 164 size_t word_size) { 165 size_t temp = 0; 166 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp); 167 assert(result == NULL || temp == word_size, 168 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 169 word_size, temp, p2i(result)); 170 return result; 171 } 172 173 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 174 size_t min_word_size, 175 size_t desired_word_size, 176 size_t* actual_word_size) { 177 switch (dest.value()) { 178 case InCSetState::Young: 179 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size); 180 case InCSetState::Old: 181 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size); 182 default: 183 ShouldNotReachHere(); 184 return NULL; // Keep some compilers happy 185 } 186 } 187 188 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size, 189 size_t desired_word_size, 190 size_t* actual_word_size) { 191 assert(!_g1h->is_humongous(desired_word_size), 192 "we should not be seeing humongous-size allocations in this path"); 193 194 HeapWord* result = survivor_gc_alloc_region()->attempt_allocation(min_word_size, 195 desired_word_size, 196 actual_word_size); 197 if (result == NULL && !survivor_is_full()) { 198 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 199 result = survivor_gc_alloc_region()->attempt_allocation_locked(min_word_size, 200 desired_word_size, 201 actual_word_size); 202 if (result == NULL) { 203 set_survivor_full(); 204 } 205 } 206 if (result != NULL) { 207 _g1h->dirty_young_block(result, *actual_word_size); 208 } 209 return result; 210 } 211 212 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size, 213 size_t desired_word_size, 214 size_t* actual_word_size) { 215 assert(!_g1h->is_humongous(desired_word_size), 216 "we should not be seeing humongous-size allocations in this path"); 217 218 HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size, 219 desired_word_size, 220 actual_word_size); 221 if (result == NULL && !old_is_full()) { 222 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 223 result = old_gc_alloc_region()->attempt_allocation_locked(min_word_size, 224 desired_word_size, 225 actual_word_size); 226 if (result == NULL) { 227 set_old_full(); 228 } 229 } 230 return result; 231 } 232 233 uint G1PLABAllocator::calc_survivor_alignment_bytes() { 234 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity"); 235 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) { 236 // No need to align objects in the survivors differently, return 0 237 // which means "survivor alignment is not used". 238 return 0; 239 } else { 240 assert(SurvivorAlignmentInBytes > 0, "sanity"); 241 return SurvivorAlignmentInBytes; 242 } 243 } 244 245 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) : 246 _g1h(G1CollectedHeap::heap()), 247 _allocator(allocator), 248 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)), 249 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)), 250 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) { 251 for (uint state = 0; state < InCSetState::Num; state++) { 252 _direct_allocated[state] = 0; 253 _alloc_buffers[state] = NULL; 254 } 255 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer; 256 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer; 257 } 258 259 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const { 260 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct); 261 } 262 263 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest, 264 size_t word_sz, 265 bool* plab_refill_failed) { 266 size_t plab_word_size = _g1h->desired_plab_sz(dest); 267 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz); 268 269 // Only get a new PLAB if the allocation fits and it would not waste more than 270 // ParallelGCBufferWastePct in the existing buffer. 271 if ((required_in_plab <= plab_word_size) && 272 may_throw_away_buffer(required_in_plab, plab_word_size)) { 273 274 PLAB* alloc_buf = alloc_buffer(dest); 275 alloc_buf->retire(); 276 277 size_t actual_plab_size = 0; 278 HeapWord* buf = _allocator->par_allocate_during_gc(dest, 279 required_in_plab, 280 plab_word_size, 281 &actual_plab_size); 282 283 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)), 284 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 285 required_in_plab, plab_word_size, actual_plab_size, p2i(buf)); 286 287 if (buf != NULL) { 288 alloc_buf->set_buf(buf, actual_plab_size); 289 290 HeapWord* const obj = alloc_buf->allocate(word_sz); 291 assert(obj != NULL, "PLAB should have been big enough, tried to allocate " 292 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT, 293 word_sz, required_in_plab, plab_word_size); 294 return obj; 295 } 296 // Otherwise. 297 *plab_refill_failed = true; 298 } 299 // Try direct allocation. 300 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz); 301 if (result != NULL) { 302 _direct_allocated[dest.value()] += word_sz; 303 } 304 return result; 305 } 306 307 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz) { 308 alloc_buffer(dest)->undo_allocation(obj, word_sz); 309 } 310 311 void G1PLABAllocator::flush_and_retire_stats() { 312 for (uint state = 0; state < InCSetState::Num; state++) { 313 PLAB* const buf = _alloc_buffers[state]; 314 if (buf != NULL) { 315 G1EvacStats* stats = _g1h->alloc_buffer_stats(state); 316 buf->flush_and_retire_stats(stats); 317 stats->add_direct_allocated(_direct_allocated[state]); 318 _direct_allocated[state] = 0; 319 } 320 } 321 } 322 323 void G1PLABAllocator::waste(size_t& wasted, size_t& undo_wasted) { 324 wasted = 0; 325 undo_wasted = 0; 326 for (uint state = 0; state < InCSetState::Num; state++) { 327 PLAB * const buf = _alloc_buffers[state]; 328 if (buf != NULL) { 329 wasted += buf->waste(); 330 undo_wasted += buf->undo_waste(); 331 } 332 } 333 } 334 335 bool G1ArchiveAllocator::_archive_check_enabled = false; 336 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map; 337 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map; 338 339 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) { 340 // Create the archive allocator, and also enable archive object checking 341 // in mark-sweep, since we will be creating archive regions. 342 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h, open); 343 enable_archive_object_check(); 344 return result; 345 } 346 347 bool G1ArchiveAllocator::alloc_new_region() { 348 // Allocate the highest free region in the reserved heap, 349 // and add it to our list of allocated regions. It is marked 350 // archive and added to the old set. 351 HeapRegion* hr = _g1h->alloc_highest_free_region(); 352 if (hr == NULL) { 353 return false; 354 } 355 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index()); 356 if (_open) { 357 hr->set_open_archive(); 358 } else { 359 hr->set_closed_archive(); 360 } 361 _g1h->g1_policy()->remset_tracker()->update_at_allocate(hr); 362 _g1h->archive_set_add(hr); 363 _g1h->hr_printer()->alloc(hr); 364 _allocated_regions.append(hr); 365 _allocation_region = hr; 366 367 // Set up _bottom and _max to begin allocating in the lowest 368 // min_region_size'd chunk of the allocated G1 region. 369 _bottom = hr->bottom(); 370 _max = _bottom + HeapRegion::min_region_size_in_words(); 371 372 // Tell mark-sweep that objects in this region are not to be marked. 373 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open); 374 375 // Since we've modified the old set, call update_sizes. 376 _g1h->g1mm()->update_sizes(); 377 return true; 378 } 379 380 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) { 381 assert(word_size != 0, "size must not be zero"); 382 if (_allocation_region == NULL) { 383 if (!alloc_new_region()) { 384 return NULL; 385 } 386 } 387 HeapWord* old_top = _allocation_region->top(); 388 assert(_bottom >= _allocation_region->bottom(), 389 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT, 390 p2i(_bottom), p2i(_allocation_region->bottom())); 391 assert(_max <= _allocation_region->end(), 392 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT, 393 p2i(_max), p2i(_allocation_region->end())); 394 assert(_bottom <= old_top && old_top <= _max, 395 "inconsistent allocation state: expected " 396 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT, 397 p2i(_bottom), p2i(old_top), p2i(_max)); 398 399 // Allocate the next word_size words in the current allocation chunk. 400 // If allocation would cross the _max boundary, insert a filler and begin 401 // at the base of the next min_region_size'd chunk. Also advance to the next 402 // chunk if we don't yet cross the boundary, but the remainder would be too 403 // small to fill. 404 HeapWord* new_top = old_top + word_size; 405 size_t remainder = pointer_delta(_max, new_top); 406 if ((new_top > _max) || 407 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) { 408 if (old_top != _max) { 409 size_t fill_size = pointer_delta(_max, old_top); 410 CollectedHeap::fill_with_object(old_top, fill_size); 411 _summary_bytes_used += fill_size * HeapWordSize; 412 } 413 _allocation_region->set_top(_max); 414 old_top = _bottom = _max; 415 416 // Check if we've just used up the last min_region_size'd chunk 417 // in the current region, and if so, allocate a new one. 418 if (_bottom != _allocation_region->end()) { 419 _max = _bottom + HeapRegion::min_region_size_in_words(); 420 } else { 421 if (!alloc_new_region()) { 422 return NULL; 423 } 424 old_top = _allocation_region->bottom(); 425 } 426 } 427 _allocation_region->set_top(old_top + word_size); 428 _summary_bytes_used += word_size * HeapWordSize; 429 430 return old_top; 431 } 432 433 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges, 434 size_t end_alignment_in_bytes) { 435 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(), 436 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes); 437 assert(is_aligned(end_alignment_in_bytes, HeapWordSize), 438 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize); 439 440 // If we've allocated nothing, simply return. 441 if (_allocation_region == NULL) { 442 return; 443 } 444 445 // If an end alignment was requested, insert filler objects. 446 if (end_alignment_in_bytes != 0) { 447 HeapWord* currtop = _allocation_region->top(); 448 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes); 449 size_t fill_size = pointer_delta(newtop, currtop); 450 if (fill_size != 0) { 451 if (fill_size < CollectedHeap::min_fill_size()) { 452 // If the required fill is smaller than we can represent, 453 // bump up to the next aligned address. We know we won't exceed the current 454 // region boundary because the max supported alignment is smaller than the min 455 // region size, and because the allocation code never leaves space smaller than 456 // the min_fill_size at the top of the current allocation region. 457 newtop = align_up(currtop + CollectedHeap::min_fill_size(), 458 end_alignment_in_bytes); 459 fill_size = pointer_delta(newtop, currtop); 460 } 461 HeapWord* fill = archive_mem_allocate(fill_size); 462 CollectedHeap::fill_with_objects(fill, fill_size); 463 } 464 } 465 466 // Loop through the allocated regions, and create MemRegions summarizing 467 // the allocated address range, combining contiguous ranges. Add the 468 // MemRegions to the GrowableArray provided by the caller. 469 int index = _allocated_regions.length() - 1; 470 assert(_allocated_regions.at(index) == _allocation_region, 471 "expected region %u at end of array, found %u", 472 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index()); 473 HeapWord* base_address = _allocation_region->bottom(); 474 HeapWord* top = base_address; 475 476 while (index >= 0) { 477 HeapRegion* next = _allocated_regions.at(index); 478 HeapWord* new_base = next->bottom(); 479 HeapWord* new_top = next->top(); 480 if (new_base != top) { 481 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 482 base_address = new_base; 483 } 484 top = new_top; 485 index = index - 1; 486 } 487 488 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address)); 489 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 490 _allocated_regions.clear(); 491 _allocation_region = NULL; 492 };