1 /* 2 * Copyright (c) 2014, 2015, 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/g1CollectorPolicy.hpp" 31 #include "gc/g1/g1MarkSweep.hpp" 32 #include "gc/g1/heapRegion.inline.hpp" 33 #include "gc/g1/heapRegionSet.inline.hpp" 34 35 G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) : 36 G1Allocator(heap), 37 _survivor_is_full(false), 38 _old_is_full(false), 39 _retained_old_gc_alloc_region(NULL), 40 _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)), 41 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) { 42 } 43 44 void G1DefaultAllocator::init_mutator_alloc_region() { 45 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 46 _mutator_alloc_region.init(); 47 } 48 49 void G1DefaultAllocator::release_mutator_alloc_region() { 50 _mutator_alloc_region.release(); 51 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 52 } 53 54 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info, 55 OldGCAllocRegion* old, 56 HeapRegion** retained_old) { 57 HeapRegion* retained_region = *retained_old; 58 *retained_old = NULL; 59 assert(retained_region == NULL || !retained_region->is_archive(), 60 "Archive region should not be alloc region (index %u)", retained_region->hrm_index()); 61 62 // We will discard the current GC alloc region if: 63 // a) it's in the collection set (it can happen!), 64 // b) it's already full (no point in using it), 65 // c) it's empty (this means that it was emptied during 66 // a cleanup and it should be on the free list now), or 67 // d) it's humongous (this means that it was emptied 68 // during a cleanup and was added to the free list, but 69 // has been subsequently used to allocate a humongous 70 // object that may be less than the region size). 71 if (retained_region != NULL && 72 !retained_region->in_collection_set() && 73 !(retained_region->top() == retained_region->end()) && 74 !retained_region->is_empty() && 75 !retained_region->is_humongous()) { 76 retained_region->record_timestamp(); 77 // The retained region was added to the old region set when it was 78 // retired. We have to remove it now, since we don't allow regions 79 // we allocate to in the region sets. We'll re-add it later, when 80 // it's retired again. 81 _g1h->old_set_remove(retained_region); 82 bool during_im = _g1h->collector_state()->during_initial_mark_pause(); 83 retained_region->note_start_of_copying(during_im); 84 old->set(retained_region); 85 _g1h->hr_printer()->reuse(retained_region); 86 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 87 } 88 } 89 90 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 91 assert_at_safepoint(true /* should_be_vm_thread */); 92 93 _survivor_is_full = false; 94 _old_is_full = false; 95 96 _survivor_gc_alloc_region.init(); 97 _old_gc_alloc_region.init(); 98 reuse_retained_old_region(evacuation_info, 99 &_old_gc_alloc_region, 100 &_retained_old_gc_alloc_region); 101 } 102 103 void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) { 104 AllocationContext_t context = AllocationContext::current(); 105 evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() + 106 old_gc_alloc_region(context)->count()); 107 survivor_gc_alloc_region(context)->release(); 108 // If we have an old GC alloc region to release, we'll save it in 109 // _retained_old_gc_alloc_region. If we don't 110 // _retained_old_gc_alloc_region will become NULL. This is what we 111 // want either way so no reason to check explicitly for either 112 // condition. 113 _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release(); 114 if (_retained_old_gc_alloc_region != NULL) { 115 _retained_old_gc_alloc_region->record_retained_region(); 116 } 117 } 118 119 void G1DefaultAllocator::abandon_gc_alloc_regions() { 120 assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition"); 121 assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition"); 122 _retained_old_gc_alloc_region = NULL; 123 } 124 125 bool G1DefaultAllocator::survivor_is_full(AllocationContext_t context) const { 126 return _survivor_is_full; 127 } 128 129 bool G1DefaultAllocator::old_is_full(AllocationContext_t context) const { 130 return _old_is_full; 131 } 132 133 void G1DefaultAllocator::set_survivor_full(AllocationContext_t context) { 134 _survivor_is_full = true; 135 } 136 137 void G1DefaultAllocator::set_old_full(AllocationContext_t context) { 138 _old_is_full = true; 139 } 140 141 G1PLAB::G1PLAB(size_t gclab_word_size) : 142 PLAB(gclab_word_size), _retired(true) { } 143 144 size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) { 145 // Return the remaining space in the cur alloc region, but not less than 146 // the min TLAB size. 147 148 // Also, this value can be at most the humongous object threshold, 149 // since we can't allow tlabs to grow big enough to accommodate 150 // humongous objects. 151 152 HeapRegion* hr = mutator_alloc_region(context)->get(); 153 size_t max_tlab = _g1h->max_tlab_size() * wordSize; 154 if (hr == NULL) { 155 return max_tlab; 156 } else { 157 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 158 } 159 } 160 161 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 162 size_t word_size, 163 AllocationContext_t context) { 164 size_t temp = 0; 165 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp, context); 166 assert(result == NULL || temp == word_size, 167 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 168 word_size, temp, p2i(result)); 169 return result; 170 } 171 172 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 173 size_t min_word_size, 174 size_t desired_word_size, 175 size_t* actual_word_size, 176 AllocationContext_t context) { 177 switch (dest.value()) { 178 case InCSetState::Young: 179 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context); 180 case InCSetState::Old: 181 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context); 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 AllocationContext_t context) { 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(context)->attempt_allocation(min_word_size, 196 desired_word_size, 197 actual_word_size, 198 false /* bot_updates */); 199 if (result == NULL && !survivor_is_full(context)) { 200 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 201 result = survivor_gc_alloc_region(context)->attempt_allocation_locked(min_word_size, 202 desired_word_size, 203 actual_word_size, 204 false /* bot_updates */); 205 if (result == NULL) { 206 set_survivor_full(context); 207 } 208 } 209 if (result != NULL) { 210 _g1h->dirty_young_block(result, *actual_word_size); 211 } 212 return result; 213 } 214 215 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size, 216 size_t desired_word_size, 217 size_t* actual_word_size, 218 AllocationContext_t context) { 219 assert(!_g1h->is_humongous(desired_word_size), 220 "we should not be seeing humongous-size allocations in this path"); 221 222 HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(min_word_size, 223 desired_word_size, 224 actual_word_size, 225 true /* bot_updates */); 226 if (result == NULL && !old_is_full(context)) { 227 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 228 result = old_gc_alloc_region(context)->attempt_allocation_locked(min_word_size, 229 desired_word_size, 230 actual_word_size, 231 true /* bot_updates */); 232 if (result == NULL) { 233 set_old_full(context); 234 } 235 } 236 return result; 237 } 238 239 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) : 240 _g1h(G1CollectedHeap::heap()), 241 _allocator(allocator), 242 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) { 243 for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) { 244 _direct_allocated[i] = 0; 245 } 246 } 247 248 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const { 249 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct); 250 } 251 252 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest, 253 size_t word_sz, 254 AllocationContext_t context, 255 bool* plab_refill_failed) { 256 size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest); 257 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz); 258 259 // Only get a new PLAB if the allocation fits and it would not waste more than 260 // ParallelGCBufferWastePct in the existing buffer. 261 if ((required_in_plab <= plab_word_size) && 262 may_throw_away_buffer(required_in_plab, plab_word_size)) { 263 264 G1PLAB* alloc_buf = alloc_buffer(dest, context); 265 alloc_buf->retire(); 266 267 size_t actual_plab_size = 0; 268 HeapWord* buf = _allocator->par_allocate_during_gc(dest, 269 required_in_plab, 270 plab_word_size, 271 &actual_plab_size, 272 context); 273 274 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)), 275 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT, 276 required_in_plab, plab_word_size, actual_plab_size, p2i(buf)); 277 278 if (buf != NULL) { 279 alloc_buf->set_buf(buf, actual_plab_size); 280 281 HeapWord* const obj = alloc_buf->allocate(word_sz); 282 assert(obj != NULL, "PLAB should have been big enough, tried to allocate " 283 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT, 284 word_sz, required_in_plab, plab_word_size); 285 return obj; 286 } 287 // Otherwise. 288 *plab_refill_failed = true; 289 } 290 // Try direct allocation. 291 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context); 292 if (result != NULL) { 293 _direct_allocated[dest.value()] += word_sz; 294 } 295 return result; 296 } 297 298 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) { 299 alloc_buffer(dest, context)->undo_allocation(obj, word_sz); 300 } 301 302 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) : 303 G1PLABAllocator(allocator), 304 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)), 305 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) { 306 for (uint state = 0; state < InCSetState::Num; state++) { 307 _alloc_buffers[state] = NULL; 308 } 309 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer; 310 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer; 311 } 312 313 void G1DefaultPLABAllocator::flush_and_retire_stats() { 314 for (uint state = 0; state < InCSetState::Num; state++) { 315 G1PLAB* const buf = _alloc_buffers[state]; 316 if (buf != NULL) { 317 G1EvacStats* stats = _g1h->alloc_buffer_stats(state); 318 buf->flush_and_retire_stats(stats); 319 stats->add_direct_allocated(_direct_allocated[state]); 320 _direct_allocated[state] = 0; 321 } 322 } 323 } 324 325 void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) { 326 wasted = 0; 327 undo_wasted = 0; 328 for (uint state = 0; state < InCSetState::Num; state++) { 329 G1PLAB * const buf = _alloc_buffers[state]; 330 if (buf != NULL) { 331 wasted += buf->waste(); 332 undo_wasted += buf->undo_waste(); 333 } 334 } 335 } 336 337 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) { 338 // Create the archive allocator, and also enable archive object checking 339 // in mark-sweep, since we will be creating archive regions. 340 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h); 341 G1MarkSweep::enable_archive_object_check(); 342 return result; 343 } 344 345 bool G1ArchiveAllocator::alloc_new_region() { 346 // Allocate the highest free region in the reserved heap, 347 // and add it to our list of allocated regions. It is marked 348 // archive and added to the old set. 349 HeapRegion* hr = _g1h->alloc_highest_free_region(); 350 if (hr == NULL) { 351 return false; 352 } 353 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index()); 354 hr->set_archive(); 355 _g1h->old_set_add(hr); 356 _g1h->hr_printer()->alloc(hr); 357 _allocated_regions.append(hr); 358 _allocation_region = hr; 359 360 // Set up _bottom and _max to begin allocating in the lowest 361 // min_region_size'd chunk of the allocated G1 region. 362 _bottom = hr->bottom(); 363 _max = _bottom + HeapRegion::min_region_size_in_words(); 364 365 // Tell mark-sweep that objects in this region are not to be marked. 366 G1MarkSweep::set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), true); 367 368 // Since we've modified the old set, call update_sizes. 369 _g1h->g1mm()->update_sizes(); 370 return true; 371 } 372 373 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) { 374 assert(word_size != 0, "size must not be zero"); 375 if (_allocation_region == NULL) { 376 if (!alloc_new_region()) { 377 return NULL; 378 } 379 } 380 HeapWord* old_top = _allocation_region->top(); 381 assert(_bottom >= _allocation_region->bottom(), 382 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT, 383 p2i(_bottom), p2i(_allocation_region->bottom())); 384 assert(_max <= _allocation_region->end(), 385 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT, 386 p2i(_max), p2i(_allocation_region->end())); 387 assert(_bottom <= old_top && old_top <= _max, 388 "inconsistent allocation state: expected " 389 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT, 390 p2i(_bottom), p2i(old_top), p2i(_max)); 391 392 // Allocate the next word_size words in the current allocation chunk. 393 // If allocation would cross the _max boundary, insert a filler and begin 394 // at the base of the next min_region_size'd chunk. Also advance to the next 395 // chunk if we don't yet cross the boundary, but the remainder would be too 396 // small to fill. 397 HeapWord* new_top = old_top + word_size; 398 size_t remainder = pointer_delta(_max, new_top); 399 if ((new_top > _max) || 400 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) { 401 if (old_top != _max) { 402 size_t fill_size = pointer_delta(_max, old_top); 403 CollectedHeap::fill_with_object(old_top, fill_size); 404 _summary_bytes_used += fill_size * HeapWordSize; 405 } 406 _allocation_region->set_top(_max); 407 old_top = _bottom = _max; 408 409 // Check if we've just used up the last min_region_size'd chunk 410 // in the current region, and if so, allocate a new one. 411 if (_bottom != _allocation_region->end()) { 412 _max = _bottom + HeapRegion::min_region_size_in_words(); 413 } else { 414 if (!alloc_new_region()) { 415 return NULL; 416 } 417 old_top = _allocation_region->bottom(); 418 } 419 } 420 _allocation_region->set_top(old_top + word_size); 421 _summary_bytes_used += word_size * HeapWordSize; 422 423 return old_top; 424 } 425 426 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges, 427 size_t end_alignment_in_bytes) { 428 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(), 429 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes); 430 assert(is_size_aligned(end_alignment_in_bytes, HeapWordSize), 431 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize); 432 433 // If we've allocated nothing, simply return. 434 if (_allocation_region == NULL) { 435 return; 436 } 437 438 // If an end alignment was requested, insert filler objects. 439 if (end_alignment_in_bytes != 0) { 440 HeapWord* currtop = _allocation_region->top(); 441 HeapWord* newtop = (HeapWord*)align_pointer_up(currtop, end_alignment_in_bytes); 442 size_t fill_size = pointer_delta(newtop, currtop); 443 if (fill_size != 0) { 444 if (fill_size < CollectedHeap::min_fill_size()) { 445 // If the required fill is smaller than we can represent, 446 // bump up to the next aligned address. We know we won't exceed the current 447 // region boundary because the max supported alignment is smaller than the min 448 // region size, and because the allocation code never leaves space smaller than 449 // the min_fill_size at the top of the current allocation region. 450 newtop = (HeapWord*)align_pointer_up(currtop + CollectedHeap::min_fill_size(), 451 end_alignment_in_bytes); 452 fill_size = pointer_delta(newtop, currtop); 453 } 454 HeapWord* fill = archive_mem_allocate(fill_size); 455 CollectedHeap::fill_with_objects(fill, fill_size); 456 } 457 } 458 459 // Loop through the allocated regions, and create MemRegions summarizing 460 // the allocated address range, combining contiguous ranges. Add the 461 // MemRegions to the GrowableArray provided by the caller. 462 int index = _allocated_regions.length() - 1; 463 assert(_allocated_regions.at(index) == _allocation_region, 464 "expected region %u at end of array, found %u", 465 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index()); 466 HeapWord* base_address = _allocation_region->bottom(); 467 HeapWord* top = base_address; 468 469 while (index >= 0) { 470 HeapRegion* next = _allocated_regions.at(index); 471 HeapWord* new_base = next->bottom(); 472 HeapWord* new_top = next->top(); 473 if (new_base != top) { 474 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 475 base_address = new_base; 476 } 477 top = new_top; 478 index = index - 1; 479 } 480 481 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address)); 482 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 483 _allocated_regions.clear(); 484 _allocation_region = NULL; 485 };