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   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 };