1 /* 2 * Copyright (c) 2014, 2016, 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 if (_retained_old_gc_alloc_region != NULL) { 113 _retained_old_gc_alloc_region->record_retained_region(); 114 } 115 } 116 117 void G1DefaultAllocator::abandon_gc_alloc_regions() { 118 assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition"); 119 assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition"); 120 _retained_old_gc_alloc_region = NULL; 121 } 122 123 bool G1DefaultAllocator::survivor_is_full(AllocationContext_t context) const { 124 return _survivor_is_full; 125 } 126 127 bool G1DefaultAllocator::old_is_full(AllocationContext_t context) const { 128 return _old_is_full; 129 } 130 131 void G1DefaultAllocator::set_survivor_full(AllocationContext_t context) { 132 _survivor_is_full = true; 133 } 134 135 void G1DefaultAllocator::set_old_full(AllocationContext_t context) { 136 _old_is_full = true; 137 } 138 139 G1PLAB::G1PLAB(size_t gclab_word_size) : 140 PLAB(gclab_word_size), _retired(true) { } 141 142 size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) { 143 // Return the remaining space in the cur alloc region, but not less than 144 // the min TLAB size. 145 146 // Also, this value can be at most the humongous object threshold, 147 // since we can't allow tlabs to grow big enough to accommodate 148 // humongous objects. 149 150 HeapRegion* hr = mutator_alloc_region(context)->get(); 151 size_t max_tlab = _g1h->max_tlab_size() * wordSize; 152 if (hr == NULL) { 153 return max_tlab; 154 } else { 155 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 156 } 157 } 158 159 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 160 size_t word_size, 161 AllocationContext_t context) { 162 size_t temp = 0; 163 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp, context); 164 assert(result == NULL || temp == word_size, 165 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 166 word_size, temp, p2i(result)); 167 return result; 168 } 169 170 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 171 size_t min_word_size, 172 size_t desired_word_size, 173 size_t* actual_word_size, 174 AllocationContext_t context) { 175 switch (dest.value()) { 176 case InCSetState::Young: 177 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context); 178 case InCSetState::Old: 179 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context); 180 default: 181 ShouldNotReachHere(); 182 return NULL; // Keep some compilers happy 183 } 184 } 185 186 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size, 187 size_t desired_word_size, 188 size_t* actual_word_size, 189 AllocationContext_t context) { 190 assert(!_g1h->is_humongous(desired_word_size), 191 "we should not be seeing humongous-size allocations in this path"); 192 193 HeapWord* result = survivor_gc_alloc_region(context)->attempt_allocation(min_word_size, 194 desired_word_size, 195 actual_word_size, 196 false /* bot_updates */); 197 if (result == NULL && !survivor_is_full(context)) { 198 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 199 result = survivor_gc_alloc_region(context)->attempt_allocation_locked(min_word_size, 200 desired_word_size, 201 actual_word_size, 202 false /* bot_updates */); 203 if (result == NULL) { 204 set_survivor_full(context); 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 AllocationContext_t context) { 217 assert(!_g1h->is_humongous(desired_word_size), 218 "we should not be seeing humongous-size allocations in this path"); 219 220 HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(min_word_size, 221 desired_word_size, 222 actual_word_size, 223 true /* bot_updates */); 224 if (result == NULL && !old_is_full(context)) { 225 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 226 result = old_gc_alloc_region(context)->attempt_allocation_locked(min_word_size, 227 desired_word_size, 228 actual_word_size, 229 true /* bot_updates */); 230 if (result == NULL) { 231 set_old_full(context); 232 } 233 } 234 return result; 235 } 236 237 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) : 238 _g1h(G1CollectedHeap::heap()), 239 _allocator(allocator), 240 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) { 241 for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) { 242 _direct_allocated[i] = 0; 243 } 244 } 245 246 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const { 247 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct); 248 } 249 250 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest, 251 size_t word_sz, 252 AllocationContext_t context, 253 bool* plab_refill_failed) { 254 size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest); 255 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz); 256 257 // Only get a new PLAB if the allocation fits and it would not waste more than 258 // ParallelGCBufferWastePct in the existing buffer. 259 if ((required_in_plab <= plab_word_size) && 260 may_throw_away_buffer(required_in_plab, plab_word_size)) { 261 262 G1PLAB* alloc_buf = alloc_buffer(dest, context); 263 alloc_buf->retire(); 264 265 size_t actual_plab_size = 0; 266 HeapWord* buf = _allocator->par_allocate_during_gc(dest, 267 required_in_plab, 268 plab_word_size, 269 &actual_plab_size, 270 context); 271 272 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)), 273 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 274 required_in_plab, plab_word_size, actual_plab_size, p2i(buf)); 275 276 if (buf != NULL) { 277 alloc_buf->set_buf(buf, actual_plab_size); 278 279 HeapWord* const obj = alloc_buf->allocate(word_sz); 280 assert(obj != NULL, "PLAB should have been big enough, tried to allocate " 281 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT, 282 word_sz, required_in_plab, plab_word_size); 283 return obj; 284 } 285 // Otherwise. 286 *plab_refill_failed = true; 287 } 288 // Try direct allocation. 289 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context); 290 if (result != NULL) { 291 _direct_allocated[dest.value()] += word_sz; 292 } 293 return result; 294 } 295 296 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) { 297 alloc_buffer(dest, context)->undo_allocation(obj, word_sz); 298 } 299 300 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) : 301 G1PLABAllocator(allocator), 302 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)), 303 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) { 304 for (uint state = 0; state < InCSetState::Num; state++) { 305 _alloc_buffers[state] = NULL; 306 } 307 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer; 308 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer; 309 } 310 311 void G1DefaultPLABAllocator::flush_and_retire_stats() { 312 for (uint state = 0; state < InCSetState::Num; state++) { 313 G1PLAB* 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 G1DefaultPLABAllocator::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 G1PLAB * 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::_archive_region_map; 337 338 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) { 339 // Create the archive allocator, and also enable archive object checking 340 // in mark-sweep, since we will be creating archive regions. 341 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h); 342 enable_archive_object_check(); 343 return result; 344 } 345 346 bool G1ArchiveAllocator::alloc_new_region() { 347 // Allocate the highest free region in the reserved heap, 348 // and add it to our list of allocated regions. It is marked 349 // archive and added to the old set. 350 HeapRegion* hr = _g1h->alloc_highest_free_region(); 351 if (hr == NULL) { 352 return false; 353 } 354 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index()); 355 hr->set_archive(); 356 _g1h->old_set_add(hr); 357 _g1h->hr_printer()->alloc(hr); 358 _allocated_regions.append(hr); 359 _allocation_region = hr; 360 361 // Set up _bottom and _max to begin allocating in the lowest 362 // min_region_size'd chunk of the allocated G1 region. 363 _bottom = hr->bottom(); 364 _max = _bottom + HeapRegion::min_region_size_in_words(); 365 366 // Tell mark-sweep that objects in this region are not to be marked. 367 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), true); 368 369 // Since we've modified the old set, call update_sizes. 370 _g1h->g1mm()->update_sizes(); 371 return true; 372 } 373 374 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) { 375 assert(word_size != 0, "size must not be zero"); 376 if (_allocation_region == NULL) { 377 if (!alloc_new_region()) { 378 return NULL; 379 } 380 } 381 HeapWord* old_top = _allocation_region->top(); 382 assert(_bottom >= _allocation_region->bottom(), 383 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT, 384 p2i(_bottom), p2i(_allocation_region->bottom())); 385 assert(_max <= _allocation_region->end(), 386 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT, 387 p2i(_max), p2i(_allocation_region->end())); 388 assert(_bottom <= old_top && old_top <= _max, 389 "inconsistent allocation state: expected " 390 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT, 391 p2i(_bottom), p2i(old_top), p2i(_max)); 392 393 // Allocate the next word_size words in the current allocation chunk. 394 // If allocation would cross the _max boundary, insert a filler and begin 395 // at the base of the next min_region_size'd chunk. Also advance to the next 396 // chunk if we don't yet cross the boundary, but the remainder would be too 397 // small to fill. 398 HeapWord* new_top = old_top + word_size; 399 size_t remainder = pointer_delta(_max, new_top); 400 if ((new_top > _max) || 401 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) { 402 if (old_top != _max) { 403 size_t fill_size = pointer_delta(_max, old_top); 404 CollectedHeap::fill_with_object(old_top, fill_size); 405 _summary_bytes_used += fill_size * HeapWordSize; 406 } 407 _allocation_region->set_top(_max); 408 old_top = _bottom = _max; 409 410 // Check if we've just used up the last min_region_size'd chunk 411 // in the current region, and if so, allocate a new one. 412 if (_bottom != _allocation_region->end()) { 413 _max = _bottom + HeapRegion::min_region_size_in_words(); 414 } else { 415 if (!alloc_new_region()) { 416 return NULL; 417 } 418 old_top = _allocation_region->bottom(); 419 } 420 } 421 _allocation_region->set_top(old_top + word_size); 422 _summary_bytes_used += word_size * HeapWordSize; 423 424 return old_top; 425 } 426 427 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges, 428 size_t end_alignment_in_bytes) { 429 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(), 430 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes); 431 assert(is_size_aligned(end_alignment_in_bytes, HeapWordSize), 432 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize); 433 434 // If we've allocated nothing, simply return. 435 if (_allocation_region == NULL) { 436 return; 437 } 438 439 // If an end alignment was requested, insert filler objects. 440 if (end_alignment_in_bytes != 0) { 441 HeapWord* currtop = _allocation_region->top(); 442 HeapWord* newtop = (HeapWord*)align_ptr_up(currtop, end_alignment_in_bytes); 443 size_t fill_size = pointer_delta(newtop, currtop); 444 if (fill_size != 0) { 445 if (fill_size < CollectedHeap::min_fill_size()) { 446 // If the required fill is smaller than we can represent, 447 // bump up to the next aligned address. We know we won't exceed the current 448 // region boundary because the max supported alignment is smaller than the min 449 // region size, and because the allocation code never leaves space smaller than 450 // the min_fill_size at the top of the current allocation region. 451 newtop = (HeapWord*)align_ptr_up(currtop + CollectedHeap::min_fill_size(), 452 end_alignment_in_bytes); 453 fill_size = pointer_delta(newtop, currtop); 454 } 455 HeapWord* fill = archive_mem_allocate(fill_size); 456 CollectedHeap::fill_with_objects(fill, fill_size); 457 } 458 } 459 460 // Loop through the allocated regions, and create MemRegions summarizing 461 // the allocated address range, combining contiguous ranges. Add the 462 // MemRegions to the GrowableArray provided by the caller. 463 int index = _allocated_regions.length() - 1; 464 assert(_allocated_regions.at(index) == _allocation_region, 465 "expected region %u at end of array, found %u", 466 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index()); 467 HeapWord* base_address = _allocation_region->bottom(); 468 HeapWord* top = base_address; 469 470 while (index >= 0) { 471 HeapRegion* next = _allocated_regions.at(index); 472 HeapWord* new_base = next->bottom(); 473 HeapWord* new_top = next->top(); 474 if (new_base != top) { 475 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 476 base_address = new_base; 477 } 478 top = new_top; 479 index = index - 1; 480 } 481 482 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address)); 483 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 484 _allocated_regions.clear(); 485 _allocation_region = NULL; 486 };