1 /* 2 * Copyright (c) 2014, 2019, 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/g1EvacuationInfo.hpp" 30 #include "gc/g1/g1CollectedHeap.inline.hpp" 31 #include "gc/g1/g1Policy.hpp" 32 #include "gc/g1/heapRegion.inline.hpp" 33 #include "gc/g1/heapRegionSet.inline.hpp" 34 #include "gc/g1/heapRegionType.hpp" 35 #include "utilities/align.hpp" 36 37 G1Allocator::G1Allocator(G1CollectedHeap* heap) : 38 _g1h(heap), 39 _survivor_is_full(false), 40 _old_is_full(false), 41 _mutator_alloc_region(), 42 _survivor_gc_alloc_region(heap->alloc_buffer_stats(G1HeapRegionAttr::Young)), 43 _old_gc_alloc_region(heap->alloc_buffer_stats(G1HeapRegionAttr::Old)), 44 _retained_old_gc_alloc_region(NULL) { 45 } 46 47 void G1Allocator::init_mutator_alloc_region() { 48 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 49 _mutator_alloc_region.init(); 50 } 51 52 void G1Allocator::release_mutator_alloc_region() { 53 _mutator_alloc_region.release(); 54 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 55 } 56 57 bool G1Allocator::is_retained_old_region(HeapRegion* hr) { 58 return _retained_old_gc_alloc_region == hr; 59 } 60 61 void G1Allocator::reuse_retained_old_region(G1EvacuationInfo& evacuation_info, 62 OldGCAllocRegion* old, 63 HeapRegion** retained_old) { 64 HeapRegion* retained_region = *retained_old; 65 *retained_old = NULL; 66 assert(retained_region == NULL || !retained_region->is_archive(), 67 "Archive region should not be alloc region (index %u)", retained_region->hrm_index()); 68 69 // We will discard the current GC alloc region if: 70 // a) it's in the collection set (it can happen!), 71 // b) it's already full (no point in using it), 72 // c) it's empty (this means that it was emptied during 73 // a cleanup and it should be on the free list now), or 74 // d) it's humongous (this means that it was emptied 75 // during a cleanup and was added to the free list, but 76 // has been subsequently used to allocate a humongous 77 // object that may be less than the region size). 78 if (retained_region != NULL && 79 !retained_region->in_collection_set() && 80 !(retained_region->top() == retained_region->end()) && 81 !retained_region->is_empty() && 82 !retained_region->is_humongous()) { 83 // The retained region was added to the old region set when it was 84 // retired. We have to remove it now, since we don't allow regions 85 // we allocate to in the region sets. We'll re-add it later, when 86 // it's retired again. 87 _g1h->old_set_remove(retained_region); 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(G1EvacuationInfo& 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(G1EvacuationInfo& 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 return mutator_alloc_region()->used_in_alloc_regions(); 161 } 162 163 164 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest, 165 size_t word_size) { 166 size_t temp = 0; 167 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp); 168 assert(result == NULL || temp == word_size, 169 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 170 word_size, temp, p2i(result)); 171 return result; 172 } 173 174 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest, 175 size_t min_word_size, 176 size_t desired_word_size, 177 size_t* actual_word_size) { 178 switch (dest.type()) { 179 case G1HeapRegionAttr::Young: 180 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size); 181 case G1HeapRegionAttr::Old: 182 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size); 183 default: 184 ShouldNotReachHere(); 185 return NULL; // Keep some compilers happy 186 } 187 } 188 189 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size, 190 size_t desired_word_size, 191 size_t* actual_word_size) { 192 assert(!_g1h->is_humongous(desired_word_size), 193 "we should not be seeing humongous-size allocations in this path"); 194 195 HeapWord* result = survivor_gc_alloc_region()->attempt_allocation(min_word_size, 196 desired_word_size, 197 actual_word_size); 198 if (result == NULL && !survivor_is_full()) { 199 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 200 result = survivor_gc_alloc_region()->attempt_allocation_locked(min_word_size, 201 desired_word_size, 202 actual_word_size); 203 if (result == NULL) { 204 set_survivor_full(); 205 } 206 } 207 if (result != NULL) { 208 _g1h->dirty_young_block(result, *actual_word_size); 209 } 210 return result; 211 } 212 213 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size, 214 size_t desired_word_size, 215 size_t* actual_word_size) { 216 assert(!_g1h->is_humongous(desired_word_size), 217 "we should not be seeing humongous-size allocations in this path"); 218 219 HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size, 220 desired_word_size, 221 actual_word_size); 222 if (result == NULL && !old_is_full()) { 223 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 224 result = old_gc_alloc_region()->attempt_allocation_locked(min_word_size, 225 desired_word_size, 226 actual_word_size); 227 if (result == NULL) { 228 set_old_full(); 229 } 230 } 231 return result; 232 } 233 234 uint G1PLABAllocator::calc_survivor_alignment_bytes() { 235 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity"); 236 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) { 237 // No need to align objects in the survivors differently, return 0 238 // which means "survivor alignment is not used". 239 return 0; 240 } else { 241 assert(SurvivorAlignmentInBytes > 0, "sanity"); 242 return SurvivorAlignmentInBytes; 243 } 244 } 245 246 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) : 247 _g1h(G1CollectedHeap::heap()), 248 _allocator(allocator), 249 _surviving_alloc_buffer(_g1h->desired_plab_sz(G1HeapRegionAttr::Young)), 250 _tenured_alloc_buffer(_g1h->desired_plab_sz(G1HeapRegionAttr::Old)), 251 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) { 252 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) { 253 _direct_allocated[state] = 0; 254 _alloc_buffers[state] = NULL; 255 } 256 _alloc_buffers[G1HeapRegionAttr::Young] = &_surviving_alloc_buffer; 257 _alloc_buffers[G1HeapRegionAttr::Old] = &_tenured_alloc_buffer; 258 } 259 260 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const { 261 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct); 262 } 263 264 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(G1HeapRegionAttr dest, 265 size_t word_sz, 266 bool* plab_refill_failed) { 267 size_t plab_word_size = _g1h->desired_plab_sz(dest); 268 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz); 269 270 // Only get a new PLAB if the allocation fits and it would not waste more than 271 // ParallelGCBufferWastePct in the existing buffer. 272 if ((required_in_plab <= plab_word_size) && 273 may_throw_away_buffer(required_in_plab, plab_word_size)) { 274 275 PLAB* alloc_buf = alloc_buffer(dest); 276 alloc_buf->retire(); 277 278 size_t actual_plab_size = 0; 279 HeapWord* buf = _allocator->par_allocate_during_gc(dest, 280 required_in_plab, 281 plab_word_size, 282 &actual_plab_size); 283 284 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)), 285 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 286 required_in_plab, plab_word_size, actual_plab_size, p2i(buf)); 287 288 if (buf != NULL) { 289 alloc_buf->set_buf(buf, actual_plab_size); 290 291 HeapWord* const obj = alloc_buf->allocate(word_sz); 292 assert(obj != NULL, "PLAB should have been big enough, tried to allocate " 293 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT, 294 word_sz, required_in_plab, plab_word_size); 295 return obj; 296 } 297 // Otherwise. 298 *plab_refill_failed = true; 299 } 300 // Try direct allocation. 301 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz); 302 if (result != NULL) { 303 _direct_allocated[dest.type()] += word_sz; 304 } 305 return result; 306 } 307 308 void G1PLABAllocator::undo_allocation(G1HeapRegionAttr dest, HeapWord* obj, size_t word_sz) { 309 alloc_buffer(dest)->undo_allocation(obj, word_sz); 310 } 311 312 void G1PLABAllocator::flush_and_retire_stats() { 313 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) { 314 PLAB* const buf = _alloc_buffers[state]; 315 if (buf != NULL) { 316 G1EvacStats* stats = _g1h->alloc_buffer_stats(state); 317 buf->flush_and_retire_stats(stats); 318 stats->add_direct_allocated(_direct_allocated[state]); 319 _direct_allocated[state] = 0; 320 } 321 } 322 } 323 324 size_t G1PLABAllocator::waste() const { 325 size_t result = 0; 326 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) { 327 PLAB * const buf = _alloc_buffers[state]; 328 if (buf != NULL) { 329 result += buf->waste(); 330 } 331 } 332 return result; 333 } 334 335 size_t G1PLABAllocator::undo_waste() const { 336 size_t result = 0; 337 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) { 338 PLAB * const buf = _alloc_buffers[state]; 339 if (buf != NULL) { 340 result += buf->undo_waste(); 341 } 342 } 343 return result; 344 } 345 346 bool G1ArchiveAllocator::_archive_check_enabled = false; 347 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map; 348 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map; 349 350 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) { 351 // Create the archive allocator, and also enable archive object checking 352 // in mark-sweep, since we will be creating archive regions. 353 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h, open); 354 enable_archive_object_check(); 355 return result; 356 } 357 358 bool G1ArchiveAllocator::alloc_new_region() { 359 // Allocate the highest free region in the reserved heap, 360 // and add it to our list of allocated regions. It is marked 361 // archive and added to the old set. 362 HeapRegion* hr = _g1h->alloc_highest_free_region(); 363 if (hr == NULL) { 364 return false; 365 } 366 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index()); 367 if (_open) { 368 hr->set_open_archive(); 369 } else { 370 hr->set_closed_archive(); 371 } 372 _g1h->policy()->remset_tracker()->update_at_allocate(hr); 373 _g1h->archive_set_add(hr); 374 _g1h->hr_printer()->alloc(hr); 375 _allocated_regions.append(hr); 376 _allocation_region = hr; 377 378 // Set up _bottom and _max to begin allocating in the lowest 379 // min_region_size'd chunk of the allocated G1 region. 380 _bottom = hr->bottom(); 381 _max = _bottom + HeapRegion::min_region_size_in_words(); 382 383 // Tell mark-sweep that objects in this region are not to be marked. 384 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open); 385 386 // Since we've modified the old set, call update_sizes. 387 _g1h->g1mm()->update_sizes(); 388 return true; 389 } 390 391 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) { 392 assert(word_size != 0, "size must not be zero"); 393 if (_allocation_region == NULL) { 394 if (!alloc_new_region()) { 395 return NULL; 396 } 397 } 398 HeapWord* old_top = _allocation_region->top(); 399 assert(_bottom >= _allocation_region->bottom(), 400 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT, 401 p2i(_bottom), p2i(_allocation_region->bottom())); 402 assert(_max <= _allocation_region->end(), 403 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT, 404 p2i(_max), p2i(_allocation_region->end())); 405 assert(_bottom <= old_top && old_top <= _max, 406 "inconsistent allocation state: expected " 407 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT, 408 p2i(_bottom), p2i(old_top), p2i(_max)); 409 410 // Allocate the next word_size words in the current allocation chunk. 411 // If allocation would cross the _max boundary, insert a filler and begin 412 // at the base of the next min_region_size'd chunk. Also advance to the next 413 // chunk if we don't yet cross the boundary, but the remainder would be too 414 // small to fill. 415 HeapWord* new_top = old_top + word_size; 416 size_t remainder = pointer_delta(_max, new_top); 417 if ((new_top > _max) || 418 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) { 419 if (old_top != _max) { 420 size_t fill_size = pointer_delta(_max, old_top); 421 CollectedHeap::fill_with_object(old_top, fill_size); 422 _summary_bytes_used += fill_size * HeapWordSize; 423 } 424 _allocation_region->set_top(_max); 425 old_top = _bottom = _max; 426 427 // Check if we've just used up the last min_region_size'd chunk 428 // in the current region, and if so, allocate a new one. 429 if (_bottom != _allocation_region->end()) { 430 _max = _bottom + HeapRegion::min_region_size_in_words(); 431 } else { 432 if (!alloc_new_region()) { 433 return NULL; 434 } 435 old_top = _allocation_region->bottom(); 436 } 437 } 438 _allocation_region->set_top(old_top + word_size); 439 _summary_bytes_used += word_size * HeapWordSize; 440 441 return old_top; 442 } 443 444 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges, 445 size_t end_alignment_in_bytes) { 446 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(), 447 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes); 448 assert(is_aligned(end_alignment_in_bytes, HeapWordSize), 449 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize); 450 451 // If we've allocated nothing, simply return. 452 if (_allocation_region == NULL) { 453 return; 454 } 455 456 // If an end alignment was requested, insert filler objects. 457 if (end_alignment_in_bytes != 0) { 458 HeapWord* currtop = _allocation_region->top(); 459 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes); 460 size_t fill_size = pointer_delta(newtop, currtop); 461 if (fill_size != 0) { 462 if (fill_size < CollectedHeap::min_fill_size()) { 463 // If the required fill is smaller than we can represent, 464 // bump up to the next aligned address. We know we won't exceed the current 465 // region boundary because the max supported alignment is smaller than the min 466 // region size, and because the allocation code never leaves space smaller than 467 // the min_fill_size at the top of the current allocation region. 468 newtop = align_up(currtop + CollectedHeap::min_fill_size(), 469 end_alignment_in_bytes); 470 fill_size = pointer_delta(newtop, currtop); 471 } 472 HeapWord* fill = archive_mem_allocate(fill_size); 473 CollectedHeap::fill_with_objects(fill, fill_size); 474 } 475 } 476 477 // Loop through the allocated regions, and create MemRegions summarizing 478 // the allocated address range, combining contiguous ranges. Add the 479 // MemRegions to the GrowableArray provided by the caller. 480 int index = _allocated_regions.length() - 1; 481 assert(_allocated_regions.at(index) == _allocation_region, 482 "expected region %u at end of array, found %u", 483 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index()); 484 HeapWord* base_address = _allocation_region->bottom(); 485 HeapWord* top = base_address; 486 487 while (index >= 0) { 488 HeapRegion* next = _allocated_regions.at(index); 489 HeapWord* new_base = next->bottom(); 490 HeapWord* new_top = next->top(); 491 if (new_base != top) { 492 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 493 base_address = new_base; 494 } 495 top = new_top; 496 index = index - 1; 497 } 498 499 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address)); 500 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 501 _allocated_regions.clear(); 502 _allocation_region = NULL; 503 };