1 /*
   2  * Copyright (c) 2014, 2019, 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/g1EvacuationInfo.hpp"
  30 #include "gc/g1/g1CollectedHeap.inline.hpp"
  31 #include "gc/g1/g1Policy.hpp"
  32 #include "gc/g1/heapRegion.inline.hpp"
  33 #include "gc/g1/heapRegionSet.inline.hpp"
  34 #include "gc/g1/heapRegionType.hpp"
  35 #include "utilities/align.hpp"
  36 
  37 G1Allocator::G1Allocator(G1CollectedHeap* heap) :
  38   _g1h(heap),
  39   _survivor_is_full(false),
  40   _old_is_full(false),
  41   _mutator_alloc_region(),
  42   _survivor_gc_alloc_region(heap->alloc_buffer_stats(G1HeapRegionAttr::Young)),
  43   _old_gc_alloc_region(heap->alloc_buffer_stats(G1HeapRegionAttr::Old)),
  44   _retained_old_gc_alloc_region(NULL) {
  45 }
  46 
  47 void G1Allocator::init_mutator_alloc_region() {
  48   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
  49   _mutator_alloc_region.init();
  50 }
  51 
  52 void G1Allocator::release_mutator_alloc_region() {
  53   _mutator_alloc_region.release();
  54   assert(_mutator_alloc_region.get() == NULL, "post-condition");
  55 }
  56 
  57 bool G1Allocator::is_retained_old_region(HeapRegion* hr) {
  58   return _retained_old_gc_alloc_region == hr;
  59 }
  60 
  61 void G1Allocator::reuse_retained_old_region(G1EvacuationInfo& evacuation_info,
  62                                             OldGCAllocRegion* old,
  63                                             HeapRegion** retained_old) {
  64   HeapRegion* retained_region = *retained_old;
  65   *retained_old = NULL;
  66   assert(retained_region == NULL || !retained_region->is_archive(),
  67          "Archive region should not be alloc region (index %u)", retained_region->hrm_index());
  68 
  69   // We will discard the current GC alloc region if:
  70   // a) it's in the collection set (it can happen!),
  71   // b) it's already full (no point in using it),
  72   // c) it's empty (this means that it was emptied during
  73   // a cleanup and it should be on the free list now), or
  74   // d) it's humongous (this means that it was emptied
  75   // during a cleanup and was added to the free list, but
  76   // has been subsequently used to allocate a humongous
  77   // object that may be less than the region size).
  78   if (retained_region != NULL &&
  79       !retained_region->in_collection_set() &&
  80       !(retained_region->top() == retained_region->end()) &&
  81       !retained_region->is_empty() &&
  82       !retained_region->is_humongous()) {
  83     // The retained region was added to the old region set when it was
  84     // retired. We have to remove it now, since we don't allow regions
  85     // we allocate to in the region sets. We'll re-add it later, when
  86     // it's retired again.
  87     _g1h->old_set_remove(retained_region);
  88     old->set(retained_region);
  89     _g1h->hr_printer()->reuse(retained_region);
  90     evacuation_info.set_alloc_regions_used_before(retained_region->used());
  91   }
  92 }
  93 
  94 void G1Allocator::init_gc_alloc_regions(G1EvacuationInfo& evacuation_info) {
  95   assert_at_safepoint_on_vm_thread();
  96 
  97   _survivor_is_full = false;
  98   _old_is_full = false;
  99 
 100   _survivor_gc_alloc_region.init();
 101   _old_gc_alloc_region.init();
 102   reuse_retained_old_region(evacuation_info,
 103                             &_old_gc_alloc_region,
 104                             &_retained_old_gc_alloc_region);
 105 }
 106 
 107 void G1Allocator::release_gc_alloc_regions(G1EvacuationInfo& evacuation_info) {
 108   evacuation_info.set_allocation_regions(survivor_gc_alloc_region()->count() +
 109                                          old_gc_alloc_region()->count());
 110   survivor_gc_alloc_region()->release();
 111   // If we have an old GC alloc region to release, we'll save it in
 112   // _retained_old_gc_alloc_region. If we don't
 113   // _retained_old_gc_alloc_region will become NULL. This is what we
 114   // want either way so no reason to check explicitly for either
 115   // condition.
 116   _retained_old_gc_alloc_region = old_gc_alloc_region()->release();
 117 }
 118 
 119 void G1Allocator::abandon_gc_alloc_regions() {
 120   assert(survivor_gc_alloc_region()->get() == NULL, "pre-condition");
 121   assert(old_gc_alloc_region()->get() == NULL, "pre-condition");
 122   _retained_old_gc_alloc_region = NULL;
 123 }
 124 
 125 bool G1Allocator::survivor_is_full() const {
 126   return _survivor_is_full;
 127 }
 128 
 129 bool G1Allocator::old_is_full() const {
 130   return _old_is_full;
 131 }
 132 
 133 void G1Allocator::set_survivor_full() {
 134   _survivor_is_full = true;
 135 }
 136 
 137 void G1Allocator::set_old_full() {
 138   _old_is_full = true;
 139 }
 140 
 141 size_t G1Allocator::unsafe_max_tlab_alloc() {
 142   // Return the remaining space in the cur alloc region, but not less than
 143   // the min TLAB size.
 144 
 145   // Also, this value can be at most the humongous object threshold,
 146   // since we can't allow tlabs to grow big enough to accommodate
 147   // humongous objects.
 148 
 149   HeapRegion* hr = mutator_alloc_region()->get();
 150   size_t max_tlab = _g1h->max_tlab_size() * wordSize;
 151   if (hr == NULL) {
 152     return max_tlab;
 153   } else {
 154     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
 155   }
 156 }
 157 
 158 size_t G1Allocator::used_in_alloc_regions() {
 159   assert(Heap_lock->owner() != NULL, "Should be owned on this thread's behalf.");
 160   return mutator_alloc_region()->used_in_alloc_regions();
 161 }
 162 
 163 
 164 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest,
 165                                               size_t word_size) {
 166   size_t temp = 0;
 167   HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp);
 168   assert(result == NULL || temp == word_size,
 169          "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
 170          word_size, temp, p2i(result));
 171   return result;
 172 }
 173 
 174 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest,
 175                                               size_t min_word_size,
 176                                               size_t desired_word_size,
 177                                               size_t* actual_word_size) {
 178   switch (dest.type()) {
 179     case G1HeapRegionAttr::Young:
 180       return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 181     case G1HeapRegionAttr::Old:
 182       return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
 183     default:
 184       ShouldNotReachHere();
 185       return NULL; // Keep some compilers happy
 186   }
 187 }
 188 
 189 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
 190                                                    size_t desired_word_size,
 191                                                    size_t* actual_word_size) {
 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()->attempt_allocation(min_word_size,
 196                                                                     desired_word_size,
 197                                                                     actual_word_size);
 198   if (result == NULL && !survivor_is_full()) {
 199     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
 200     result = survivor_gc_alloc_region()->attempt_allocation_locked(min_word_size,
 201                                                                    desired_word_size,
 202                                                                    actual_word_size);
 203     if (result == NULL) {
 204       set_survivor_full();
 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   assert(!_g1h->is_humongous(desired_word_size),
 217          "we should not be seeing humongous-size allocations in this path");
 218 
 219   HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size,
 220                                                                desired_word_size,
 221                                                                actual_word_size);
 222   if (result == NULL && !old_is_full()) {
 223     MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
 224     result = old_gc_alloc_region()->attempt_allocation_locked(min_word_size,
 225                                                               desired_word_size,
 226                                                               actual_word_size);
 227     if (result == NULL) {
 228       set_old_full();
 229     }
 230   }
 231   return result;
 232 }
 233 
 234 uint G1PLABAllocator::calc_survivor_alignment_bytes() {
 235   assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
 236   if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
 237     // No need to align objects in the survivors differently, return 0
 238     // which means "survivor alignment is not used".
 239     return 0;
 240   } else {
 241     assert(SurvivorAlignmentInBytes > 0, "sanity");
 242     return SurvivorAlignmentInBytes;
 243   }
 244 }
 245 
 246 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
 247   _g1h(G1CollectedHeap::heap()),
 248   _allocator(allocator),
 249   _surviving_alloc_buffer(_g1h->desired_plab_sz(G1HeapRegionAttr::Young)),
 250   _tenured_alloc_buffer(_g1h->desired_plab_sz(G1HeapRegionAttr::Old)),
 251   _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
 252   for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
 253     _direct_allocated[state] = 0;
 254     _alloc_buffers[state] = NULL;
 255   }
 256   _alloc_buffers[G1HeapRegionAttr::Young] = &_surviving_alloc_buffer;
 257   _alloc_buffers[G1HeapRegionAttr::Old]  = &_tenured_alloc_buffer;
 258 }
 259 
 260 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
 261   return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
 262 }
 263 
 264 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(G1HeapRegionAttr dest,
 265                                                        size_t word_sz,
 266                                                        bool* plab_refill_failed) {
 267   size_t plab_word_size = _g1h->desired_plab_sz(dest);
 268   size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
 269 
 270   // Only get a new PLAB if the allocation fits and it would not waste more than
 271   // ParallelGCBufferWastePct in the existing buffer.
 272   if ((required_in_plab <= plab_word_size) &&
 273     may_throw_away_buffer(required_in_plab, plab_word_size)) {
 274 
 275     PLAB* alloc_buf = alloc_buffer(dest);
 276     alloc_buf->retire();
 277 
 278     size_t actual_plab_size = 0;
 279     HeapWord* buf = _allocator->par_allocate_during_gc(dest,
 280                                                        required_in_plab,
 281                                                        plab_word_size,
 282                                                        &actual_plab_size);
 283 
 284     assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
 285            "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
 286            required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
 287 
 288     if (buf != NULL) {
 289       alloc_buf->set_buf(buf, actual_plab_size);
 290 
 291       HeapWord* const obj = alloc_buf->allocate(word_sz);
 292       assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
 293                           SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
 294                           word_sz, required_in_plab, plab_word_size);
 295       return obj;
 296     }
 297     // Otherwise.
 298     *plab_refill_failed = true;
 299   }
 300   // Try direct allocation.
 301   HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz);
 302   if (result != NULL) {
 303     _direct_allocated[dest.type()] += word_sz;
 304   }
 305   return result;
 306 }
 307 
 308 void G1PLABAllocator::undo_allocation(G1HeapRegionAttr dest, HeapWord* obj, size_t word_sz) {
 309   alloc_buffer(dest)->undo_allocation(obj, word_sz);
 310 }
 311 
 312 void G1PLABAllocator::flush_and_retire_stats() {
 313   for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
 314     PLAB* const buf = _alloc_buffers[state];
 315     if (buf != NULL) {
 316       G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
 317       buf->flush_and_retire_stats(stats);
 318       stats->add_direct_allocated(_direct_allocated[state]);
 319       _direct_allocated[state] = 0;
 320     }
 321   }
 322 }
 323 
 324 size_t G1PLABAllocator::waste() const {
 325   size_t result = 0;
 326   for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
 327     PLAB * const buf = _alloc_buffers[state];
 328     if (buf != NULL) {
 329       result += buf->waste();
 330     }
 331   }
 332   return result;
 333 }
 334 
 335 size_t G1PLABAllocator::undo_waste() const {
 336   size_t result = 0;
 337   for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
 338     PLAB * const buf = _alloc_buffers[state];
 339     if (buf != NULL) {
 340       result += buf->undo_waste();
 341     }
 342   }
 343   return result;
 344 }
 345 
 346 bool G1ArchiveAllocator::_archive_check_enabled = false;
 347 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map;
 348 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map;
 349 
 350 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) {
 351   // Create the archive allocator, and also enable archive object checking
 352   // in mark-sweep, since we will be creating archive regions.
 353   G1ArchiveAllocator* result =  new G1ArchiveAllocator(g1h, open);
 354   enable_archive_object_check();
 355   return result;
 356 }
 357 
 358 bool G1ArchiveAllocator::alloc_new_region() {
 359   // Allocate the highest free region in the reserved heap,
 360   // and add it to our list of allocated regions. It is marked
 361   // archive and added to the old set.
 362   HeapRegion* hr = _g1h->alloc_highest_free_region();
 363   if (hr == NULL) {
 364     return false;
 365   }
 366   assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
 367   if (_open) {
 368     hr->set_open_archive();
 369   } else {
 370     hr->set_closed_archive();
 371   }
 372   _g1h->policy()->remset_tracker()->update_at_allocate(hr);
 373   _g1h->archive_set_add(hr);
 374   _g1h->hr_printer()->alloc(hr);
 375   _allocated_regions.append(hr);
 376   _allocation_region = hr;
 377 
 378   // Set up _bottom and _max to begin allocating in the lowest
 379   // min_region_size'd chunk of the allocated G1 region.
 380   _bottom = hr->bottom();
 381   _max = _bottom + HeapRegion::min_region_size_in_words();
 382 
 383   // Tell mark-sweep that objects in this region are not to be marked.
 384   set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open);
 385 
 386   // Since we've modified the old set, call update_sizes.
 387   _g1h->g1mm()->update_sizes();
 388   return true;
 389 }
 390 
 391 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
 392   assert(word_size != 0, "size must not be zero");
 393   if (_allocation_region == NULL) {
 394     if (!alloc_new_region()) {
 395       return NULL;
 396     }
 397   }
 398   HeapWord* old_top = _allocation_region->top();
 399   assert(_bottom >= _allocation_region->bottom(),
 400          "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
 401          p2i(_bottom), p2i(_allocation_region->bottom()));
 402   assert(_max <= _allocation_region->end(),
 403          "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
 404          p2i(_max), p2i(_allocation_region->end()));
 405   assert(_bottom <= old_top && old_top <= _max,
 406          "inconsistent allocation state: expected "
 407          PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
 408          p2i(_bottom), p2i(old_top), p2i(_max));
 409 
 410   // Allocate the next word_size words in the current allocation chunk.
 411   // If allocation would cross the _max boundary, insert a filler and begin
 412   // at the base of the next min_region_size'd chunk. Also advance to the next
 413   // chunk if we don't yet cross the boundary, but the remainder would be too
 414   // small to fill.
 415   HeapWord* new_top = old_top + word_size;
 416   size_t remainder = pointer_delta(_max, new_top);
 417   if ((new_top > _max) ||
 418       ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
 419     if (old_top != _max) {
 420       size_t fill_size = pointer_delta(_max, old_top);
 421       CollectedHeap::fill_with_object(old_top, fill_size);
 422       _summary_bytes_used += fill_size * HeapWordSize;
 423     }
 424     _allocation_region->set_top(_max);
 425     old_top = _bottom = _max;
 426 
 427     // Check if we've just used up the last min_region_size'd chunk
 428     // in the current region, and if so, allocate a new one.
 429     if (_bottom != _allocation_region->end()) {
 430       _max = _bottom + HeapRegion::min_region_size_in_words();
 431     } else {
 432       if (!alloc_new_region()) {
 433         return NULL;
 434       }
 435       old_top = _allocation_region->bottom();
 436     }
 437   }
 438   _allocation_region->set_top(old_top + word_size);
 439   _summary_bytes_used += word_size * HeapWordSize;
 440 
 441   return old_top;
 442 }
 443 
 444 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
 445                                           size_t end_alignment_in_bytes) {
 446   assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
 447          "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
 448   assert(is_aligned(end_alignment_in_bytes, HeapWordSize),
 449          "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
 450 
 451   // If we've allocated nothing, simply return.
 452   if (_allocation_region == NULL) {
 453     return;
 454   }
 455 
 456   // If an end alignment was requested, insert filler objects.
 457   if (end_alignment_in_bytes != 0) {
 458     HeapWord* currtop = _allocation_region->top();
 459     HeapWord* newtop = align_up(currtop, end_alignment_in_bytes);
 460     size_t fill_size = pointer_delta(newtop, currtop);
 461     if (fill_size != 0) {
 462       if (fill_size < CollectedHeap::min_fill_size()) {
 463         // If the required fill is smaller than we can represent,
 464         // bump up to the next aligned address. We know we won't exceed the current
 465         // region boundary because the max supported alignment is smaller than the min
 466         // region size, and because the allocation code never leaves space smaller than
 467         // the min_fill_size at the top of the current allocation region.
 468         newtop = align_up(currtop + CollectedHeap::min_fill_size(),
 469                           end_alignment_in_bytes);
 470         fill_size = pointer_delta(newtop, currtop);
 471       }
 472       HeapWord* fill = archive_mem_allocate(fill_size);
 473       CollectedHeap::fill_with_objects(fill, fill_size);
 474     }
 475   }
 476 
 477   // Loop through the allocated regions, and create MemRegions summarizing
 478   // the allocated address range, combining contiguous ranges. Add the
 479   // MemRegions to the GrowableArray provided by the caller.
 480   int index = _allocated_regions.length() - 1;
 481   assert(_allocated_regions.at(index) == _allocation_region,
 482          "expected region %u at end of array, found %u",
 483          _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
 484   HeapWord* base_address = _allocation_region->bottom();
 485   HeapWord* top = base_address;
 486 
 487   while (index >= 0) {
 488     HeapRegion* next = _allocated_regions.at(index);
 489     HeapWord* new_base = next->bottom();
 490     HeapWord* new_top = next->top();
 491     if (new_base != top) {
 492       ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
 493       base_address = new_base;
 494     }
 495     top = new_top;
 496     index = index - 1;
 497   }
 498 
 499   assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
 500   ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
 501   _allocated_regions.clear();
 502   _allocation_region = NULL;
 503 };