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 };
--- EOF ---