1 /* 2 * Copyright (c) 2014, 2017, 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/heapRegion.inline.hpp" 31 #include "gc/g1/heapRegionSet.inline.hpp" 32 33 G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) : 34 G1Allocator(heap), 35 _survivor_is_full(false), 36 _old_is_full(false), 37 _retained_old_gc_alloc_region(NULL), 38 _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)), 39 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) { 40 } 41 42 void G1DefaultAllocator::init_mutator_alloc_region() { 43 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 44 _mutator_alloc_region.init(); 45 } 46 47 void G1DefaultAllocator::release_mutator_alloc_region() { 48 _mutator_alloc_region.release(); 49 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 50 } 51 52 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info, 53 OldGCAllocRegion* old, 54 HeapRegion** retained_old) { 55 HeapRegion* retained_region = *retained_old; 56 *retained_old = NULL; 57 assert(retained_region == NULL || !retained_region->is_archive(), 58 "Archive region should not be alloc region (index %u)", retained_region->hrm_index()); 59 60 // We will discard the current GC alloc region if: 61 // a) it's in the collection set (it can happen!), 62 // b) it's already full (no point in using it), 63 // c) it's empty (this means that it was emptied during 64 // a cleanup and it should be on the free list now), or 65 // d) it's humongous (this means that it was emptied 66 // during a cleanup and was added to the free list, but 67 // has been subsequently used to allocate a humongous 68 // object that may be less than the region size). 69 if (retained_region != NULL && 70 !retained_region->in_collection_set() && 71 !(retained_region->top() == retained_region->end()) && 72 !retained_region->is_empty() && 73 !retained_region->is_humongous()) { 74 retained_region->record_timestamp(); 75 // The retained region was added to the old region set when it was 76 // retired. We have to remove it now, since we don't allow regions 77 // we allocate to in the region sets. We'll re-add it later, when 78 // it's retired again. 79 _g1h->old_set_remove(retained_region); 80 bool during_im = _g1h->collector_state()->during_initial_mark_pause(); 81 retained_region->note_start_of_copying(during_im); 82 old->set(retained_region); 83 _g1h->hr_printer()->reuse(retained_region); 84 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 85 } 86 } 87 88 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 89 assert_at_safepoint(true /* should_be_vm_thread */); 90 91 _survivor_is_full = false; 92 _old_is_full = false; 93 94 _survivor_gc_alloc_region.init(); 95 _old_gc_alloc_region.init(); 96 reuse_retained_old_region(evacuation_info, 97 &_old_gc_alloc_region, 98 &_retained_old_gc_alloc_region); 99 } 100 101 void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) { 102 AllocationContext_t context = AllocationContext::current(); 103 evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() + 104 old_gc_alloc_region(context)->count()); 105 survivor_gc_alloc_region(context)->release(); 106 // If we have an old GC alloc region to release, we'll save it in 107 // _retained_old_gc_alloc_region. If we don't 108 // _retained_old_gc_alloc_region will become NULL. This is what we 109 // want either way so no reason to check explicitly for either 110 // condition. 111 _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release(); 112 } 113 114 void G1DefaultAllocator::abandon_gc_alloc_regions() { 115 assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition"); 116 assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition"); 117 _retained_old_gc_alloc_region = NULL; 118 } 119 120 bool G1DefaultAllocator::survivor_is_full(AllocationContext_t context) const { 121 return _survivor_is_full; 122 } 123 124 bool G1DefaultAllocator::old_is_full(AllocationContext_t context) const { 125 return _old_is_full; 126 } 127 128 void G1DefaultAllocator::set_survivor_full(AllocationContext_t context) { 129 _survivor_is_full = true; 130 } 131 132 void G1DefaultAllocator::set_old_full(AllocationContext_t context) { 133 _old_is_full = true; 134 } 135 136 G1PLAB::G1PLAB(size_t gclab_word_size) : 137 PLAB(gclab_word_size), _retired(true) { } 138 139 size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) { 140 // Return the remaining space in the cur alloc region, but not less than 141 // the min TLAB size. 142 143 // Also, this value can be at most the humongous object threshold, 144 // since we can't allow tlabs to grow big enough to accommodate 145 // humongous objects. 146 147 HeapRegion* hr = mutator_alloc_region(context)->get(); 148 size_t max_tlab = _g1h->max_tlab_size() * wordSize; 149 if (hr == NULL) { 150 return max_tlab; 151 } else { 152 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 153 } 154 } 155 156 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 157 size_t word_size, 158 AllocationContext_t context) { 159 size_t temp = 0; 160 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp, context); 161 assert(result == NULL || temp == word_size, 162 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 163 word_size, temp, p2i(result)); 164 return result; 165 } 166 167 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 168 size_t min_word_size, 169 size_t desired_word_size, 170 size_t* actual_word_size, 171 AllocationContext_t context) { 172 switch (dest.value()) { 173 case InCSetState::Young: 174 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context); 175 case InCSetState::Old: 176 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context); 177 default: 178 ShouldNotReachHere(); 179 return NULL; // Keep some compilers happy 180 } 181 } 182 183 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size, 184 size_t desired_word_size, 185 size_t* actual_word_size, 186 AllocationContext_t context) { 187 assert(!_g1h->is_humongous(desired_word_size), 188 "we should not be seeing humongous-size allocations in this path"); 189 190 HeapWord* result = survivor_gc_alloc_region(context)->attempt_allocation(min_word_size, 191 desired_word_size, 192 actual_word_size, 193 false /* bot_updates */); 194 if (result == NULL && !survivor_is_full(context)) { 195 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 196 result = survivor_gc_alloc_region(context)->attempt_allocation_locked(min_word_size, 197 desired_word_size, 198 actual_word_size, 199 false /* bot_updates */); 200 if (result == NULL) { 201 set_survivor_full(context); 202 } 203 } 204 if (result != NULL) { 205 _g1h->dirty_young_block(result, *actual_word_size); 206 } 207 return result; 208 } 209 210 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size, 211 size_t desired_word_size, 212 size_t* actual_word_size, 213 AllocationContext_t context) { 214 assert(!_g1h->is_humongous(desired_word_size), 215 "we should not be seeing humongous-size allocations in this path"); 216 217 HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(min_word_size, 218 desired_word_size, 219 actual_word_size, 220 true /* bot_updates */); 221 if (result == NULL && !old_is_full(context)) { 222 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 223 result = old_gc_alloc_region(context)->attempt_allocation_locked(min_word_size, 224 desired_word_size, 225 actual_word_size, 226 true /* bot_updates */); 227 if (result == NULL) { 228 set_old_full(context); 229 } 230 } 231 return result; 232 } 233 234 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) : 235 _g1h(G1CollectedHeap::heap()), 236 _allocator(allocator), 237 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) { 238 for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) { 239 _direct_allocated[i] = 0; 240 } 241 } 242 243 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const { 244 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct); 245 } 246 247 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest, 248 size_t word_sz, 249 AllocationContext_t context, 250 bool* plab_refill_failed) { 251 size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest); 252 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz); 253 254 // Only get a new PLAB if the allocation fits and it would not waste more than 255 // ParallelGCBufferWastePct in the existing buffer. 256 if ((required_in_plab <= plab_word_size) && 257 may_throw_away_buffer(required_in_plab, plab_word_size)) { 258 259 G1PLAB* alloc_buf = alloc_buffer(dest, context); 260 alloc_buf->retire(); 261 262 size_t actual_plab_size = 0; 263 HeapWord* buf = _allocator->par_allocate_during_gc(dest, 264 required_in_plab, 265 plab_word_size, 266 &actual_plab_size, 267 context); 268 269 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)), 270 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 271 required_in_plab, plab_word_size, actual_plab_size, p2i(buf)); 272 273 if (buf != NULL) { 274 alloc_buf->set_buf(buf, actual_plab_size); 275 276 HeapWord* const obj = alloc_buf->allocate(word_sz); 277 assert(obj != NULL, "PLAB should have been big enough, tried to allocate " 278 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT, 279 word_sz, required_in_plab, plab_word_size); 280 return obj; 281 } 282 // Otherwise. 283 *plab_refill_failed = true; 284 } 285 // Try direct allocation. 286 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context); 287 if (result != NULL) { 288 _direct_allocated[dest.value()] += word_sz; 289 } 290 return result; 291 } 292 293 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) { 294 alloc_buffer(dest, context)->undo_allocation(obj, word_sz); 295 } 296 297 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) : 298 G1PLABAllocator(allocator), 299 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)), 300 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) { 301 for (uint state = 0; state < InCSetState::Num; state++) { 302 _alloc_buffers[state] = NULL; 303 } 304 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer; 305 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer; 306 } 307 308 void G1DefaultPLABAllocator::flush_and_retire_stats() { 309 for (uint state = 0; state < InCSetState::Num; state++) { 310 G1PLAB* const buf = _alloc_buffers[state]; 311 if (buf != NULL) { 312 G1EvacStats* stats = _g1h->alloc_buffer_stats(state); 313 buf->flush_and_retire_stats(stats); 314 stats->add_direct_allocated(_direct_allocated[state]); 315 _direct_allocated[state] = 0; 316 } 317 } 318 } 319 320 void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) { 321 wasted = 0; 322 undo_wasted = 0; 323 for (uint state = 0; state < InCSetState::Num; state++) { 324 G1PLAB * const buf = _alloc_buffers[state]; 325 if (buf != NULL) { 326 wasted += buf->waste(); 327 undo_wasted += buf->undo_waste(); 328 } 329 } 330 } 331 332 bool G1ArchiveAllocator::_archive_check_enabled = false; 333 G1ArchiveRegionMap G1ArchiveAllocator::_archive_region_map; 334 335 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) { 336 // Create the archive allocator, and also enable archive object checking 337 // in mark-sweep, since we will be creating archive regions. 338 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h); 339 enable_archive_object_check(); 340 return result; 341 } 342 343 bool G1ArchiveAllocator::alloc_new_region() { 344 // Allocate the highest free region in the reserved heap, 345 // and add it to our list of allocated regions. It is marked 346 // archive and added to the old set. 347 HeapRegion* hr = _g1h->alloc_highest_free_region(); 348 if (hr == NULL) { 349 return false; 350 } 351 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index()); 352 hr->set_archive(); 353 _g1h->old_set_add(hr); 354 _g1h->hr_printer()->alloc(hr); 355 _allocated_regions.append(hr); 356 _allocation_region = hr; 357 358 // Set up _bottom and _max to begin allocating in the lowest 359 // min_region_size'd chunk of the allocated G1 region. 360 _bottom = hr->bottom(); 361 _max = _bottom + HeapRegion::min_region_size_in_words(); 362 363 // Tell mark-sweep that objects in this region are not to be marked. 364 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), true); 365 366 // Since we've modified the old set, call update_sizes. 367 _g1h->g1mm()->update_sizes(); 368 return true; 369 } 370 371 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) { 372 assert(word_size != 0, "size must not be zero"); 373 if (_allocation_region == NULL) { 374 if (!alloc_new_region()) { 375 return NULL; 376 } 377 } 378 HeapWord* old_top = _allocation_region->top(); 379 assert(_bottom >= _allocation_region->bottom(), 380 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT, 381 p2i(_bottom), p2i(_allocation_region->bottom())); 382 assert(_max <= _allocation_region->end(), 383 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT, 384 p2i(_max), p2i(_allocation_region->end())); 385 assert(_bottom <= old_top && old_top <= _max, 386 "inconsistent allocation state: expected " 387 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT, 388 p2i(_bottom), p2i(old_top), p2i(_max)); 389 390 // Allocate the next word_size words in the current allocation chunk. 391 // If allocation would cross the _max boundary, insert a filler and begin 392 // at the base of the next min_region_size'd chunk. Also advance to the next 393 // chunk if we don't yet cross the boundary, but the remainder would be too 394 // small to fill. 395 HeapWord* new_top = old_top + word_size; 396 size_t remainder = pointer_delta(_max, new_top); 397 if ((new_top > _max) || 398 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) { 399 if (old_top != _max) { 400 size_t fill_size = pointer_delta(_max, old_top); 401 CollectedHeap::fill_with_object(old_top, fill_size); 402 _summary_bytes_used += fill_size * HeapWordSize; 403 } 404 _allocation_region->set_top(_max); 405 old_top = _bottom = _max; 406 407 // Check if we've just used up the last min_region_size'd chunk 408 // in the current region, and if so, allocate a new one. 409 if (_bottom != _allocation_region->end()) { 410 _max = _bottom + HeapRegion::min_region_size_in_words(); 411 } else { 412 if (!alloc_new_region()) { 413 return NULL; 414 } 415 old_top = _allocation_region->bottom(); 416 } 417 } 418 _allocation_region->set_top(old_top + word_size); 419 _summary_bytes_used += word_size * HeapWordSize; 420 421 return old_top; 422 } 423 424 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges, 425 size_t end_alignment_in_bytes) { 426 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(), 427 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes); 428 assert(is_aligned(end_alignment_in_bytes, HeapWordSize), 429 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize); 430 431 // If we've allocated nothing, simply return. 432 if (_allocation_region == NULL) { 433 return; 434 } 435 436 // If an end alignment was requested, insert filler objects. 437 if (end_alignment_in_bytes != 0) { 438 HeapWord* currtop = _allocation_region->top(); 439 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes); 440 size_t fill_size = pointer_delta(newtop, currtop); 441 if (fill_size != 0) { 442 if (fill_size < CollectedHeap::min_fill_size()) { 443 // If the required fill is smaller than we can represent, 444 // bump up to the next aligned address. We know we won't exceed the current 445 // region boundary because the max supported alignment is smaller than the min 446 // region size, and because the allocation code never leaves space smaller than 447 // the min_fill_size at the top of the current allocation region. 448 newtop = align_up(currtop + CollectedHeap::min_fill_size(), 449 end_alignment_in_bytes); 450 fill_size = pointer_delta(newtop, currtop); 451 } 452 HeapWord* fill = archive_mem_allocate(fill_size); 453 CollectedHeap::fill_with_objects(fill, fill_size); 454 } 455 } 456 457 // Loop through the allocated regions, and create MemRegions summarizing 458 // the allocated address range, combining contiguous ranges. Add the 459 // MemRegions to the GrowableArray provided by the caller. 460 int index = _allocated_regions.length() - 1; 461 assert(_allocated_regions.at(index) == _allocation_region, 462 "expected region %u at end of array, found %u", 463 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index()); 464 HeapWord* base_address = _allocation_region->bottom(); 465 HeapWord* top = base_address; 466 467 while (index >= 0) { 468 HeapRegion* next = _allocated_regions.at(index); 469 HeapWord* new_base = next->bottom(); 470 HeapWord* new_top = next->top(); 471 if (new_base != top) { 472 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 473 base_address = new_base; 474 } 475 top = new_top; 476 index = index - 1; 477 } 478 479 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address)); 480 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 481 _allocated_regions.clear(); 482 _allocation_region = NULL; 483 };