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 _retained_old_gc_alloc_region(NULL), 41 _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)), 42 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) { 43 } 44 45 void G1Allocator::init_mutator_alloc_region() { 46 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 47 _mutator_alloc_region.init(); 48 } 49 50 void G1Allocator::release_mutator_alloc_region() { 51 _mutator_alloc_region.release(); 52 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 53 } 54 55 bool G1Allocator::is_retained_old_region(HeapRegion* hr) { 56 return _retained_old_gc_alloc_region == hr; 57 } 58 59 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info, 60 OldGCAllocRegion* old, 61 HeapRegion** retained_old) { 62 HeapRegion* retained_region = *retained_old; 63 *retained_old = NULL; 64 assert(retained_region == NULL || !retained_region->is_archive(), 65 "Archive region should not be alloc region (index %u)", retained_region->hrm_index()); 66 67 // We will discard the current GC alloc region if: 68 // a) it's in the collection set (it can happen!), 69 // b) it's already full (no point in using it), 70 // c) it's empty (this means that it was emptied during 71 // a cleanup and it should be on the free list now), or 72 // d) it's humongous (this means that it was emptied 73 // during a cleanup and was added to the free list, but 74 // has been subsequently used to allocate a humongous 75 // object that may be less than the region size). 76 if (retained_region != NULL && 77 !retained_region->in_collection_set() && 78 !(retained_region->top() == retained_region->end()) && 79 !retained_region->is_empty() && 80 !retained_region->is_humongous()) { 81 // The retained region was added to the old region set when it was 82 // retired. We have to remove it now, since we don't allow regions 83 // we allocate to in the region sets. We'll re-add it later, when 84 // it's retired again. 85 _g1h->old_set_remove(retained_region); 86 bool during_im = _g1h->collector_state()->in_initial_mark_gc(); 87 retained_region->note_start_of_copying(during_im); 88 old->set(retained_region); 89 _g1h->hr_printer()->reuse(retained_region); 90 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 91 } 92 } 93 94 void G1Allocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 95 assert_at_safepoint_on_vm_thread(); 96 97 _survivor_is_full = false; 98 _old_is_full = false; 99 100 _survivor_gc_alloc_region.init(); 101 _old_gc_alloc_region.init(); 102 reuse_retained_old_region(evacuation_info, 103 &_old_gc_alloc_region, 104 &_retained_old_gc_alloc_region); 105 } 106 107 void G1Allocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) { 108 evacuation_info.set_allocation_regions(survivor_gc_alloc_region()->count() + 109 old_gc_alloc_region()->count()); 110 survivor_gc_alloc_region()->release(); 111 // If we have an old GC alloc region to release, we'll save it in 112 // _retained_old_gc_alloc_region. If we don't 113 // _retained_old_gc_alloc_region will become NULL. This is what we 114 // want either way so no reason to check explicitly for either 115 // condition. 116 _retained_old_gc_alloc_region = old_gc_alloc_region()->release(); 117 } 118 119 void G1Allocator::abandon_gc_alloc_regions() { 120 assert(survivor_gc_alloc_region()->get() == NULL, "pre-condition"); 121 assert(old_gc_alloc_region()->get() == NULL, "pre-condition"); 122 _retained_old_gc_alloc_region = NULL; 123 } 124 125 bool G1Allocator::survivor_is_full() const { 126 return _survivor_is_full; 127 } 128 129 bool G1Allocator::old_is_full() const { 130 return _old_is_full; 131 } 132 133 void G1Allocator::set_survivor_full() { 134 _survivor_is_full = true; 135 } 136 137 void G1Allocator::set_old_full() { 138 _old_is_full = true; 139 } 140 141 size_t G1Allocator::unsafe_max_tlab_alloc() { 142 // Return the remaining space in the cur alloc region, but not less than 143 // the min TLAB size. 144 145 // Also, this value can be at most the humongous object threshold, 146 // since we can't allow tlabs to grow big enough to accommodate 147 // humongous objects. 148 149 HeapRegion* hr = mutator_alloc_region()->get(); 150 size_t max_tlab = _g1h->max_tlab_size() * wordSize; 151 if (hr == NULL) { 152 return max_tlab; 153 } else { 154 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 155 } 156 } 157 158 size_t G1Allocator::used_in_alloc_regions() { 159 assert(Heap_lock->owner() != NULL, "Should be owned on this thread's behalf."); 160 size_t result = 0; 161 162 // Read only once in case it is set to NULL concurrently 163 HeapRegion* hr = mutator_alloc_region()->get(); 164 if (hr != NULL) { 165 result += hr->used(); 166 } 167 return result; 168 } 169 170 171 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 172 size_t word_size) { 173 size_t temp = 0; 174 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp); 175 assert(result == NULL || temp == word_size, 176 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 177 word_size, temp, p2i(result)); 178 return result; 179 } 180 181 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 182 size_t min_word_size, 183 size_t desired_word_size, 184 size_t* actual_word_size) { 185 switch (dest.value()) { 186 case InCSetState::Young: 187 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size); 188 case InCSetState::Old: 189 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size); 190 default: 191 ShouldNotReachHere(); 192 return NULL; // Keep some compilers happy 193 } 194 } 195 196 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size, 197 size_t desired_word_size, 198 size_t* actual_word_size) { 199 assert(!_g1h->is_humongous(desired_word_size), 200 "we should not be seeing humongous-size allocations in this path"); 201 202 HeapWord* result = survivor_gc_alloc_region()->attempt_allocation(min_word_size, 203 desired_word_size, 204 actual_word_size); 205 if (result == NULL && !survivor_is_full()) { 206 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 207 result = survivor_gc_alloc_region()->attempt_allocation_locked(min_word_size, 208 desired_word_size, 209 actual_word_size); 210 if (result == NULL) { 211 set_survivor_full(); 212 } 213 } 214 if (result != NULL) { 215 _g1h->dirty_young_block(result, *actual_word_size); 216 } 217 return result; 218 } 219 220 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size, 221 size_t desired_word_size, 222 size_t* actual_word_size) { 223 assert(!_g1h->is_humongous(desired_word_size), 224 "we should not be seeing humongous-size allocations in this path"); 225 226 HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size, 227 desired_word_size, 228 actual_word_size); 229 if (result == NULL && !old_is_full()) { 230 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 231 result = old_gc_alloc_region()->attempt_allocation_locked(min_word_size, 232 desired_word_size, 233 actual_word_size); 234 if (result == NULL) { 235 set_old_full(); 236 } 237 } 238 return result; 239 } 240 241 uint G1PLABAllocator::calc_survivor_alignment_bytes() { 242 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity"); 243 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) { 244 // No need to align objects in the survivors differently, return 0 245 // which means "survivor alignment is not used". 246 return 0; 247 } else { 248 assert(SurvivorAlignmentInBytes > 0, "sanity"); 249 return SurvivorAlignmentInBytes; 250 } 251 } 252 253 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) : 254 _g1h(G1CollectedHeap::heap()), 255 _allocator(allocator), 256 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)), 257 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)), 258 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) { 259 for (uint state = 0; state < InCSetState::Num; state++) { 260 _direct_allocated[state] = 0; 261 _alloc_buffers[state] = NULL; 262 } 263 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer; 264 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer; 265 } 266 267 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const { 268 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct); 269 } 270 271 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest, 272 size_t word_sz, 273 bool* plab_refill_failed) { 274 size_t plab_word_size = _g1h->desired_plab_sz(dest); 275 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz); 276 277 // Only get a new PLAB if the allocation fits and it would not waste more than 278 // ParallelGCBufferWastePct in the existing buffer. 279 if ((required_in_plab <= plab_word_size) && 280 may_throw_away_buffer(required_in_plab, plab_word_size)) { 281 282 PLAB* alloc_buf = alloc_buffer(dest); 283 alloc_buf->retire(); 284 285 size_t actual_plab_size = 0; 286 HeapWord* buf = _allocator->par_allocate_during_gc(dest, 287 required_in_plab, 288 plab_word_size, 289 &actual_plab_size); 290 291 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)), 292 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 293 required_in_plab, plab_word_size, actual_plab_size, p2i(buf)); 294 295 if (buf != NULL) { 296 alloc_buf->set_buf(buf, actual_plab_size); 297 298 HeapWord* const obj = alloc_buf->allocate(word_sz); 299 assert(obj != NULL, "PLAB should have been big enough, tried to allocate " 300 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT, 301 word_sz, required_in_plab, plab_word_size); 302 return obj; 303 } 304 // Otherwise. 305 *plab_refill_failed = true; 306 } 307 // Try direct allocation. 308 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz); 309 if (result != NULL) { 310 _direct_allocated[dest.value()] += word_sz; 311 } 312 return result; 313 } 314 315 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz) { 316 alloc_buffer(dest)->undo_allocation(obj, word_sz); 317 } 318 319 void G1PLABAllocator::flush_and_retire_stats() { 320 for (uint state = 0; state < InCSetState::Num; state++) { 321 PLAB* const buf = _alloc_buffers[state]; 322 if (buf != NULL) { 323 G1EvacStats* stats = _g1h->alloc_buffer_stats(state); 324 buf->flush_and_retire_stats(stats); 325 stats->add_direct_allocated(_direct_allocated[state]); 326 _direct_allocated[state] = 0; 327 } 328 } 329 } 330 331 void G1PLABAllocator::waste(size_t& wasted, size_t& undo_wasted) { 332 wasted = 0; 333 undo_wasted = 0; 334 for (uint state = 0; state < InCSetState::Num; state++) { 335 PLAB * const buf = _alloc_buffers[state]; 336 if (buf != NULL) { 337 wasted += buf->waste(); 338 undo_wasted += buf->undo_waste(); 339 } 340 } 341 } 342 343 bool G1ArchiveAllocator::_archive_check_enabled = false; 344 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map; 345 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map; 346 347 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) { 348 // Create the archive allocator, and also enable archive object checking 349 // in mark-sweep, since we will be creating archive regions. 350 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h, open); 351 enable_archive_object_check(); 352 return result; 353 } 354 355 bool G1ArchiveAllocator::alloc_new_region() { 356 // Allocate the highest free region in the reserved heap, 357 // and add it to our list of allocated regions. It is marked 358 // archive and added to the old set. 359 HeapRegion* hr = _g1h->alloc_highest_free_region(); 360 if (hr == NULL) { 361 return false; 362 } 363 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index()); 364 if (_open) { 365 hr->set_open_archive(); 366 } else { 367 hr->set_closed_archive(); 368 } 369 _g1h->g1_policy()->remset_tracker()->update_at_allocate(hr); 370 _g1h->old_set_add(hr); 371 _g1h->hr_printer()->alloc(hr); 372 _allocated_regions.append(hr); 373 _allocation_region = hr; 374 375 // Set up _bottom and _max to begin allocating in the lowest 376 // min_region_size'd chunk of the allocated G1 region. 377 _bottom = hr->bottom(); 378 _max = _bottom + HeapRegion::min_region_size_in_words(); 379 380 // Tell mark-sweep that objects in this region are not to be marked. 381 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open); 382 383 // Since we've modified the old set, call update_sizes. 384 _g1h->g1mm()->update_sizes(); 385 return true; 386 } 387 388 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) { 389 assert(word_size != 0, "size must not be zero"); 390 if (_allocation_region == NULL) { 391 if (!alloc_new_region()) { 392 return NULL; 393 } 394 } 395 HeapWord* old_top = _allocation_region->top(); 396 assert(_bottom >= _allocation_region->bottom(), 397 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT, 398 p2i(_bottom), p2i(_allocation_region->bottom())); 399 assert(_max <= _allocation_region->end(), 400 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT, 401 p2i(_max), p2i(_allocation_region->end())); 402 assert(_bottom <= old_top && old_top <= _max, 403 "inconsistent allocation state: expected " 404 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT, 405 p2i(_bottom), p2i(old_top), p2i(_max)); 406 407 // Allocate the next word_size words in the current allocation chunk. 408 // If allocation would cross the _max boundary, insert a filler and begin 409 // at the base of the next min_region_size'd chunk. Also advance to the next 410 // chunk if we don't yet cross the boundary, but the remainder would be too 411 // small to fill. 412 HeapWord* new_top = old_top + word_size; 413 size_t remainder = pointer_delta(_max, new_top); 414 if ((new_top > _max) || 415 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) { 416 if (old_top != _max) { 417 size_t fill_size = pointer_delta(_max, old_top); 418 CollectedHeap::fill_with_object(old_top, fill_size); 419 _summary_bytes_used += fill_size * HeapWordSize; 420 } 421 _allocation_region->set_top(_max); 422 old_top = _bottom = _max; 423 424 // Check if we've just used up the last min_region_size'd chunk 425 // in the current region, and if so, allocate a new one. 426 if (_bottom != _allocation_region->end()) { 427 _max = _bottom + HeapRegion::min_region_size_in_words(); 428 } else { 429 if (!alloc_new_region()) { 430 return NULL; 431 } 432 old_top = _allocation_region->bottom(); 433 } 434 } 435 _allocation_region->set_top(old_top + word_size); 436 _summary_bytes_used += word_size * HeapWordSize; 437 438 return old_top; 439 } 440 441 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges, 442 size_t end_alignment_in_bytes) { 443 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(), 444 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes); 445 assert(is_aligned(end_alignment_in_bytes, HeapWordSize), 446 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize); 447 448 // If we've allocated nothing, simply return. 449 if (_allocation_region == NULL) { 450 return; 451 } 452 453 // If an end alignment was requested, insert filler objects. 454 if (end_alignment_in_bytes != 0) { 455 HeapWord* currtop = _allocation_region->top(); 456 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes); 457 size_t fill_size = pointer_delta(newtop, currtop); 458 if (fill_size != 0) { 459 if (fill_size < CollectedHeap::min_fill_size()) { 460 // If the required fill is smaller than we can represent, 461 // bump up to the next aligned address. We know we won't exceed the current 462 // region boundary because the max supported alignment is smaller than the min 463 // region size, and because the allocation code never leaves space smaller than 464 // the min_fill_size at the top of the current allocation region. 465 newtop = align_up(currtop + CollectedHeap::min_fill_size(), 466 end_alignment_in_bytes); 467 fill_size = pointer_delta(newtop, currtop); 468 } 469 HeapWord* fill = archive_mem_allocate(fill_size); 470 CollectedHeap::fill_with_objects(fill, fill_size); 471 } 472 } 473 474 // Loop through the allocated regions, and create MemRegions summarizing 475 // the allocated address range, combining contiguous ranges. Add the 476 // MemRegions to the GrowableArray provided by the caller. 477 int index = _allocated_regions.length() - 1; 478 assert(_allocated_regions.at(index) == _allocation_region, 479 "expected region %u at end of array, found %u", 480 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index()); 481 HeapWord* base_address = _allocation_region->bottom(); 482 HeapWord* top = base_address; 483 484 while (index >= 0) { 485 HeapRegion* next = _allocated_regions.at(index); 486 HeapWord* new_base = next->bottom(); 487 HeapWord* new_top = next->top(); 488 if (new_base != top) { 489 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 490 base_address = new_base; 491 } 492 top = new_top; 493 index = index - 1; 494 } 495 496 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address)); 497 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 498 _allocated_regions.clear(); 499 _allocation_region = NULL; 500 };