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/g1CollectedHeap.inline.hpp" 28 #include "gc/g1/g1CollectorPolicy.hpp" 29 #include "gc/g1/g1MarkSweep.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 _retained_old_gc_alloc_region(NULL), 36 _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)), 37 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) { 38 } 39 40 void G1DefaultAllocator::init_mutator_alloc_region() { 41 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 42 _mutator_alloc_region.init(); 43 } 44 45 void G1DefaultAllocator::release_mutator_alloc_region() { 46 _mutator_alloc_region.release(); 47 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 48 } 49 50 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info, 51 OldGCAllocRegion* old, 52 HeapRegion** retained_old) { 53 HeapRegion* retained_region = *retained_old; 54 *retained_old = NULL; 55 assert(retained_region == NULL || !retained_region->is_archive(), 56 err_msg("Archive region should not be alloc region (index %u)", retained_region->hrm_index())); 57 58 // We will discard the current GC alloc region if: 59 // a) it's in the collection set (it can happen!), 60 // b) it's already full (no point in using it), 61 // c) it's empty (this means that it was emptied during 62 // a cleanup and it should be on the free list now), or 63 // d) it's humongous (this means that it was emptied 64 // during a cleanup and was added to the free list, but 65 // has been subsequently used to allocate a humongous 66 // object that may be less than the region size). 67 if (retained_region != NULL && 68 !retained_region->in_collection_set() && 69 !(retained_region->top() == retained_region->end()) && 70 !retained_region->is_empty() && 71 !retained_region->is_humongous()) { 72 retained_region->record_timestamp(); 73 // The retained region was added to the old region set when it was 74 // retired. We have to remove it now, since we don't allow regions 75 // we allocate to in the region sets. We'll re-add it later, when 76 // it's retired again. 77 _g1h->old_set_remove(retained_region); 78 bool during_im = _g1h->collector_state()->during_initial_mark_pause(); 79 retained_region->note_start_of_copying(during_im); 80 old->set(retained_region); 81 _g1h->hr_printer()->reuse(retained_region); 82 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 83 } 84 } 85 86 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 87 assert_at_safepoint(true /* should_be_vm_thread */); 88 89 G1Allocator::init_gc_alloc_regions(evacuation_info); 90 91 _survivor_gc_alloc_region.init(); 92 _old_gc_alloc_region.init(); 93 reuse_retained_old_region(evacuation_info, 94 &_old_gc_alloc_region, 95 &_retained_old_gc_alloc_region); 96 } 97 98 void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) { 99 AllocationContext_t context = AllocationContext::current(); 100 evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() + 101 old_gc_alloc_region(context)->count()); 102 survivor_gc_alloc_region(context)->release(); 103 // If we have an old GC alloc region to release, we'll save it in 104 // _retained_old_gc_alloc_region. If we don't 105 // _retained_old_gc_alloc_region will become NULL. This is what we 106 // want either way so no reason to check explicitly for either 107 // condition. 108 _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release(); 109 if (_retained_old_gc_alloc_region != NULL) { 110 _retained_old_gc_alloc_region->record_retained_region(); 111 } 112 113 _g1h->alloc_buffer_stats(InCSetState::Young)->adjust_desired_plab_sz(); 114 _g1h->alloc_buffer_stats(InCSetState::Old)->adjust_desired_plab_sz(); 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 G1PLAB::G1PLAB(size_t gclab_word_size) : 124 PLAB(gclab_word_size), _retired(true) { } 125 126 size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) { 127 // Return the remaining space in the cur alloc region, but not less than 128 // the min TLAB size. 129 130 // Also, this value can be at most the humongous object threshold, 131 // since we can't allow tlabs to grow big enough to accommodate 132 // humongous objects. 133 134 HeapRegion* hr = mutator_alloc_region(context)->get(); 135 size_t max_tlab = _g1h->max_tlab_size() * wordSize; 136 if (hr == NULL) { 137 return max_tlab; 138 } else { 139 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 140 } 141 } 142 143 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest, 144 size_t word_size, 145 AllocationContext_t context) { 146 switch (dest.value()) { 147 case InCSetState::Young: 148 return survivor_attempt_allocation(word_size, context); 149 case InCSetState::Old: 150 return old_attempt_allocation(word_size, context); 151 default: 152 ShouldNotReachHere(); 153 return NULL; // Keep some compilers happy 154 } 155 } 156 157 bool G1Allocator::survivor_is_full(AllocationContext_t context) const { 158 return _survivor_is_full; 159 } 160 161 bool G1Allocator::old_is_full(AllocationContext_t context) const { 162 return _old_is_full; 163 } 164 165 void G1Allocator::set_survivor_full(AllocationContext_t context) { 166 _survivor_is_full = true; 167 } 168 169 void G1Allocator::set_old_full(AllocationContext_t context) { 170 _old_is_full = true; 171 } 172 173 HeapWord* G1Allocator::survivor_attempt_allocation(size_t word_size, 174 AllocationContext_t context) { 175 assert(!_g1h->is_humongous(word_size), 176 "we should not be seeing humongous-size allocations in this path"); 177 178 HeapWord* result = survivor_gc_alloc_region(context)->attempt_allocation(word_size, 179 false /* bot_updates */); 180 if (result == NULL && !survivor_is_full(context)) { 181 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 182 result = survivor_gc_alloc_region(context)->attempt_allocation_locked(word_size, 183 false /* bot_updates */); 184 if (result == NULL) { 185 set_survivor_full(context); 186 } 187 } 188 if (result != NULL) { 189 _g1h->dirty_young_block(result, word_size); 190 } 191 return result; 192 } 193 194 HeapWord* G1Allocator::old_attempt_allocation(size_t word_size, 195 AllocationContext_t context) { 196 assert(!_g1h->is_humongous(word_size), 197 "we should not be seeing humongous-size allocations in this path"); 198 199 HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(word_size, 200 true /* bot_updates */); 201 if (result == NULL && !old_is_full(context)) { 202 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 203 result = old_gc_alloc_region(context)->attempt_allocation_locked(word_size, 204 true /* bot_updates */); 205 if (result == NULL) { 206 set_old_full(context); 207 } 208 } 209 return result; 210 } 211 212 void G1Allocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 213 _survivor_is_full = false; 214 _old_is_full = false; 215 } 216 217 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) : 218 _g1h(G1CollectedHeap::heap()), 219 _allocator(allocator), 220 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) { 221 for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) { 222 _direct_allocated[i] = 0; 223 } 224 } 225 226 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const { 227 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct); 228 } 229 230 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest, 231 size_t word_sz, 232 AllocationContext_t context, 233 bool* plab_refill_failed) { 234 size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest); 235 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz); 236 237 // Only get a new PLAB if the allocation fits and it would not waste more than 238 // ParallelGCBufferWastePct in the existing buffer. 239 if ((required_in_plab <= plab_word_size) && 240 may_throw_away_buffer(required_in_plab, plab_word_size)) { 241 242 G1PLAB* alloc_buf = alloc_buffer(dest, context); 243 alloc_buf->retire(); 244 245 HeapWord* buf = _allocator->par_allocate_during_gc(dest, plab_word_size, context); 246 if (buf != NULL) { 247 // Otherwise. 248 alloc_buf->set_buf(buf, plab_word_size); 249 250 HeapWord* const obj = alloc_buf->allocate(word_sz); 251 assert(obj != NULL, err_msg("PLAB should have been big enough, tried to allocate " 252 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT, 253 word_sz, required_in_plab, plab_word_size)); 254 return obj; 255 } 256 // Otherwise. 257 *plab_refill_failed = true; 258 } 259 // Try direct allocation. 260 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context); 261 if (result != NULL) { 262 _direct_allocated[dest.value()] += word_sz; 263 } 264 return result; 265 } 266 267 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) { 268 alloc_buffer(dest, context)->undo_allocation(obj, word_sz); 269 } 270 271 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) : 272 G1PLABAllocator(allocator), 273 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)), 274 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) { 275 for (uint state = 0; state < InCSetState::Num; state++) { 276 _alloc_buffers[state] = NULL; 277 } 278 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer; 279 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer; 280 } 281 282 void G1DefaultPLABAllocator::flush_and_retire_stats() { 283 for (uint state = 0; state < InCSetState::Num; state++) { 284 G1PLAB* const buf = _alloc_buffers[state]; 285 if (buf != NULL) { 286 G1EvacStats* stats = _g1h->alloc_buffer_stats(state); 287 buf->flush_and_retire_stats(stats); 288 stats->add_direct_allocated(_direct_allocated[state]); 289 _direct_allocated[state] = 0; 290 } 291 } 292 } 293 294 void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) { 295 wasted = 0; 296 undo_wasted = 0; 297 for (uint state = 0; state < InCSetState::Num; state++) { 298 G1PLAB * const buf = _alloc_buffers[state]; 299 if (buf != NULL) { 300 wasted += buf->waste(); 301 undo_wasted += buf->undo_waste(); 302 } 303 } 304 } 305 306 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) { 307 // Create the archive allocator, and also enable archive object checking 308 // in mark-sweep, since we will be creating archive regions. 309 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h); 310 G1MarkSweep::enable_archive_object_check(); 311 return result; 312 } 313 314 bool G1ArchiveAllocator::alloc_new_region() { 315 // Allocate the highest free region in the reserved heap, 316 // and add it to our list of allocated regions. It is marked 317 // archive and added to the old set. 318 HeapRegion* hr = _g1h->alloc_highest_free_region(); 319 if (hr == NULL) { 320 return false; 321 } 322 assert(hr->is_empty(), err_msg("expected empty region (index %u)", hr->hrm_index())); 323 hr->set_archive(); 324 _g1h->old_set_add(hr); 325 _g1h->hr_printer()->alloc(hr, G1HRPrinter::Archive); 326 _allocated_regions.append(hr); 327 _allocation_region = hr; 328 329 // Set up _bottom and _max to begin allocating in the lowest 330 // min_region_size'd chunk of the allocated G1 region. 331 _bottom = hr->bottom(); 332 _max = _bottom + HeapRegion::min_region_size_in_words(); 333 334 // Tell mark-sweep that objects in this region are not to be marked. 335 G1MarkSweep::mark_range_archive(MemRegion(_bottom, HeapRegion::GrainWords)); 336 337 // Since we've modified the old set, call update_sizes. 338 _g1h->g1mm()->update_sizes(); 339 return true; 340 } 341 342 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) { 343 assert(word_size != 0, "size must not be zero"); 344 if (_allocation_region == NULL) { 345 if (!alloc_new_region()) { 346 return NULL; 347 } 348 } 349 HeapWord* old_top = _allocation_region->top(); 350 assert(_bottom >= _allocation_region->bottom(), 351 err_msg("inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT, 352 p2i(_bottom), p2i(_allocation_region->bottom()))); 353 assert(_max <= _allocation_region->end(), 354 err_msg("inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT, 355 p2i(_max), p2i(_allocation_region->end()))); 356 assert(_bottom <= old_top && old_top <= _max, 357 err_msg("inconsistent allocation state: expected " 358 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT, 359 p2i(_bottom), p2i(old_top), p2i(_max))); 360 361 // Allocate the next word_size words in the current allocation chunk. 362 // If allocation would cross the _max boundary, insert a filler and begin 363 // at the base of the next min_region_size'd chunk. Also advance to the next 364 // chunk if we don't yet cross the boundary, but the remainder would be too 365 // small to fill. 366 HeapWord* new_top = old_top + word_size; 367 size_t remainder = pointer_delta(_max, new_top); 368 if ((new_top > _max) || 369 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) { 370 if (old_top != _max) { 371 size_t fill_size = pointer_delta(_max, old_top); 372 CollectedHeap::fill_with_object(old_top, fill_size); 373 _summary_bytes_used += fill_size * HeapWordSize; 374 } 375 _allocation_region->set_top(_max); 376 old_top = _bottom = _max; 377 378 // Check if we've just used up the last min_region_size'd chunk 379 // in the current region, and if so, allocate a new one. 380 if (_bottom != _allocation_region->end()) { 381 _max = _bottom + HeapRegion::min_region_size_in_words(); 382 } else { 383 if (!alloc_new_region()) { 384 return NULL; 385 } 386 old_top = _allocation_region->bottom(); 387 } 388 } 389 _allocation_region->set_top(old_top + word_size); 390 _summary_bytes_used += word_size * HeapWordSize; 391 392 return old_top; 393 } 394 395 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges, 396 size_t end_alignment_in_bytes) { 397 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(), 398 err_msg("alignment " SIZE_FORMAT " too large", end_alignment_in_bytes)); 399 assert(is_size_aligned(end_alignment_in_bytes, HeapWordSize), 400 err_msg("alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize)); 401 402 // If we've allocated nothing, simply return. 403 if (_allocation_region == NULL) { 404 return; 405 } 406 407 // If an end alignment was requested, insert filler objects. 408 if (end_alignment_in_bytes != 0) { 409 HeapWord* currtop = _allocation_region->top(); 410 HeapWord* newtop = (HeapWord*)align_pointer_up(currtop, end_alignment_in_bytes); 411 size_t fill_size = pointer_delta(newtop, currtop); 412 if (fill_size != 0) { 413 if (fill_size < CollectedHeap::min_fill_size()) { 414 // If the required fill is smaller than we can represent, 415 // bump up to the next aligned address. We know we won't exceed the current 416 // region boundary because the max supported alignment is smaller than the min 417 // region size, and because the allocation code never leaves space smaller than 418 // the min_fill_size at the top of the current allocation region. 419 newtop = (HeapWord*)align_pointer_up(currtop + CollectedHeap::min_fill_size(), 420 end_alignment_in_bytes); 421 fill_size = pointer_delta(newtop, currtop); 422 } 423 HeapWord* fill = archive_mem_allocate(fill_size); 424 CollectedHeap::fill_with_objects(fill, fill_size); 425 } 426 } 427 428 // Loop through the allocated regions, and create MemRegions summarizing 429 // the allocated address range, combining contiguous ranges. Add the 430 // MemRegions to the GrowableArray provided by the caller. 431 int index = _allocated_regions.length() - 1; 432 assert(_allocated_regions.at(index) == _allocation_region, 433 err_msg("expected region %u at end of array, found %u", 434 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index())); 435 HeapWord* base_address = _allocation_region->bottom(); 436 HeapWord* top = base_address; 437 438 while (index >= 0) { 439 HeapRegion* next = _allocated_regions.at(index); 440 HeapWord* new_base = next->bottom(); 441 HeapWord* new_top = next->top(); 442 if (new_base != top) { 443 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 444 base_address = new_base; 445 } 446 top = new_top; 447 index = index - 1; 448 } 449 450 assert(top != base_address, err_msg("zero-sized range, address " PTR_FORMAT, p2i(base_address))); 451 ranges->append(MemRegion(base_address, pointer_delta(top, base_address))); 452 _allocated_regions.clear(); 453 _allocation_region = NULL; 454 };