rev 8867 : imported patch 8067336-allow-that-plab-allocations-at-end-of-regions-are-flexible
rev 8869 : imported patch tom-review
rev 8870 : [mq]: tom-remove-obsolete-comment

   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/g1CollectedHeap.inline.hpp"
  29 #include "gc/g1/g1CollectorPolicy.hpp"
  30 #include "gc/g1/g1MarkSweep.hpp"
  31 #include "gc/g1/heapRegion.inline.hpp"
  32 #include "gc/g1/heapRegionSet.inline.hpp"
  33 
  34 G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) :
  35   G1Allocator(heap),
  36   _retained_old_gc_alloc_region(NULL),
  37   _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)),
  38   _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) {
  39 }
  40 
  41 void G1DefaultAllocator::init_mutator_alloc_region() {
  42   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
  43   _mutator_alloc_region.init();
  44 }
  45 
  46 void G1DefaultAllocator::release_mutator_alloc_region() {
  47   _mutator_alloc_region.release();
  48   assert(_mutator_alloc_region.get() == NULL, "post-condition");
  49 }
  50 
  51 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,
  52                                             OldGCAllocRegion* old,
  53                                             HeapRegion** retained_old) {
  54   HeapRegion* retained_region = *retained_old;
  55   *retained_old = NULL;
  56   assert(retained_region == NULL || !retained_region->is_archive(),
  57          err_msg("Archive region should not be alloc region (index %u)", retained_region->hrm_index()));
  58 
  59   // We will discard the current GC alloc region if:
  60   // a) it's in the collection set (it can happen!),
  61   // b) it's already full (no point in using it),
  62   // c) it's empty (this means that it was emptied during
  63   // a cleanup and it should be on the free list now), or
  64   // d) it's humongous (this means that it was emptied
  65   // during a cleanup and was added to the free list, but
  66   // has been subsequently used to allocate a humongous
  67   // object that may be less than the region size).
  68   if (retained_region != NULL &&
  69       !retained_region->in_collection_set() &&
  70       !(retained_region->top() == retained_region->end()) &&
  71       !retained_region->is_empty() &&
  72       !retained_region->is_humongous()) {
  73     retained_region->record_timestamp();
  74     // The retained region was added to the old region set when it was
  75     // retired. We have to remove it now, since we don't allow regions
  76     // we allocate to in the region sets. We'll re-add it later, when
  77     // it's retired again.
  78     _g1h->old_set_remove(retained_region);
  79     bool during_im = _g1h->collector_state()->during_initial_mark_pause();
  80     retained_region->note_start_of_copying(during_im);
  81     old->set(retained_region);
  82     _g1h->hr_printer()->reuse(retained_region);
  83     evacuation_info.set_alloc_regions_used_before(retained_region->used());
  84   }
  85 }
  86 
  87 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
  88   assert_at_safepoint(true /* should_be_vm_thread */);
  89 
  90   G1Allocator::init_gc_alloc_regions(evacuation_info);
  91 
  92   _survivor_gc_alloc_region.init();
  93   _old_gc_alloc_region.init();
  94   reuse_retained_old_region(evacuation_info,
  95                             &_old_gc_alloc_region,
  96                             &_retained_old_gc_alloc_region);
  97 }
  98 
  99 void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) {
 100   AllocationContext_t context = AllocationContext::current();
 101   evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() +
 102                                          old_gc_alloc_region(context)->count());
 103   survivor_gc_alloc_region(context)->release();
 104   // If we have an old GC alloc region to release, we'll save it in
 105   // _retained_old_gc_alloc_region. If we don't
 106   // _retained_old_gc_alloc_region will become NULL. This is what we
 107   // want either way so no reason to check explicitly for either
 108   // condition.
 109   _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release();
 110   if (_retained_old_gc_alloc_region != NULL) {
 111     _retained_old_gc_alloc_region->record_retained_region();
 112   }
 113 
 114   _g1h->alloc_buffer_stats(InCSetState::Young)->adjust_desired_plab_sz();
 115   _g1h->alloc_buffer_stats(InCSetState::Old)->adjust_desired_plab_sz();
 116 }
 117 
 118 void G1DefaultAllocator::abandon_gc_alloc_regions() {
 119   assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
 120   assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
 121   _retained_old_gc_alloc_region = NULL;
 122 }
 123 
 124 G1PLAB::G1PLAB(size_t gclab_word_size) :
 125   PLAB(gclab_word_size), _retired(true) { }
 126 
 127 size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) {
 128   // Return the remaining space in the cur alloc region, but not less than
 129   // the min TLAB size.
 130 
 131   // Also, this value can be at most the humongous object threshold,
 132   // since we can't allow tlabs to grow big enough to accommodate
 133   // humongous objects.
 134 
 135   HeapRegion* hr = mutator_alloc_region(context)->get();
 136   size_t max_tlab = _g1h->max_tlab_size() * wordSize;
 137   if (hr == NULL) {
 138     return max_tlab;
 139   } else {
 140     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
 141   }
 142 }
 143 
 144 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
 145                                               size_t word_size,
 146                                               AllocationContext_t context) {
 147   size_t temp;
 148   return par_allocate_during_gc(dest, word_size, word_size, &temp, context);
 149 }
 150 
 151 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
 152                                               size_t min_word_size,
 153                                               size_t desired_word_size,
 154                                               size_t* actual_word_size,
 155                                               AllocationContext_t context) {
 156   switch (dest.value()) {
 157     case InCSetState::Young:
 158       return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
 159     case InCSetState::Old:
 160       return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
 161     default:
 162       ShouldNotReachHere();
 163       return NULL; // Keep some compilers happy
 164   }
 165 }
 166 
 167 bool G1Allocator::survivor_is_full(AllocationContext_t context) const {
 168   return _survivor_is_full;
 169 }
 170 
 171 bool G1Allocator::old_is_full(AllocationContext_t context) const {
 172   return _old_is_full;
 173 }
 174 
 175 void G1Allocator::set_survivor_full(AllocationContext_t context) {
 176   _survivor_is_full = true;
 177 }
 178 
 179 void G1Allocator::set_old_full(AllocationContext_t context) {
 180   _old_is_full = true;
 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 void G1Allocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
 235   _survivor_is_full = false;
 236   _old_is_full = false;
 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;
 268     HeapWord* buf = _allocator->par_allocate_during_gc(dest,
 269                                                        required_in_plab,
 270                                                        plab_word_size,
 271                                                        &actual_plab_size,
 272                                                        context);
 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, err_msg("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 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) {
 333   // Create the archive allocator, and also enable archive object checking
 334   // in mark-sweep, since we will be creating archive regions.
 335   G1ArchiveAllocator* result =  new G1ArchiveAllocator(g1h);
 336   G1MarkSweep::enable_archive_object_check();
 337   return result;
 338 }
 339 
 340 bool G1ArchiveAllocator::alloc_new_region() {
 341   // Allocate the highest free region in the reserved heap,
 342   // and add it to our list of allocated regions. It is marked
 343   // archive and added to the old set.
 344   HeapRegion* hr = _g1h->alloc_highest_free_region();
 345   if (hr == NULL) {
 346     return false;
 347   }
 348   assert(hr->is_empty(), err_msg("expected empty region (index %u)", hr->hrm_index()));
 349   hr->set_archive();
 350   _g1h->old_set_add(hr);
 351   _g1h->hr_printer()->alloc(hr, G1HRPrinter::Archive);
 352   _allocated_regions.append(hr);
 353   _allocation_region = hr;
 354 
 355   // Set up _bottom and _max to begin allocating in the lowest
 356   // min_region_size'd chunk of the allocated G1 region.
 357   _bottom = hr->bottom();
 358   _max = _bottom + HeapRegion::min_region_size_in_words();
 359 
 360   // Tell mark-sweep that objects in this region are not to be marked.
 361   G1MarkSweep::mark_range_archive(MemRegion(_bottom, HeapRegion::GrainWords));
 362 
 363   // Since we've modified the old set, call update_sizes.
 364   _g1h->g1mm()->update_sizes();
 365   return true;
 366 }
 367 
 368 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
 369   assert(word_size != 0, "size must not be zero");
 370   if (_allocation_region == NULL) {
 371     if (!alloc_new_region()) {
 372       return NULL;
 373     }
 374   }
 375   HeapWord* old_top = _allocation_region->top();
 376   assert(_bottom >= _allocation_region->bottom(),
 377          err_msg("inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
 378                  p2i(_bottom), p2i(_allocation_region->bottom())));
 379   assert(_max <= _allocation_region->end(),
 380          err_msg("inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
 381                  p2i(_max), p2i(_allocation_region->end())));
 382   assert(_bottom <= old_top && old_top <= _max,
 383          err_msg("inconsistent allocation state: expected "
 384                  PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
 385                  p2i(_bottom), p2i(old_top), p2i(_max)));
 386 
 387   // Allocate the next word_size words in the current allocation chunk.
 388   // If allocation would cross the _max boundary, insert a filler and begin
 389   // at the base of the next min_region_size'd chunk. Also advance to the next
 390   // chunk if we don't yet cross the boundary, but the remainder would be too
 391   // small to fill.
 392   HeapWord* new_top = old_top + word_size;
 393   size_t remainder = pointer_delta(_max, new_top);
 394   if ((new_top > _max) ||
 395       ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
 396     if (old_top != _max) {
 397       size_t fill_size = pointer_delta(_max, old_top);
 398       CollectedHeap::fill_with_object(old_top, fill_size);
 399       _summary_bytes_used += fill_size * HeapWordSize;
 400     }
 401     _allocation_region->set_top(_max);
 402     old_top = _bottom = _max;
 403 
 404     // Check if we've just used up the last min_region_size'd chunk
 405     // in the current region, and if so, allocate a new one.
 406     if (_bottom != _allocation_region->end()) {
 407       _max = _bottom + HeapRegion::min_region_size_in_words();
 408     } else {
 409       if (!alloc_new_region()) {
 410         return NULL;
 411       }
 412       old_top = _allocation_region->bottom();
 413     }
 414   }
 415   _allocation_region->set_top(old_top + word_size);
 416   _summary_bytes_used += word_size * HeapWordSize;
 417 
 418   return old_top;
 419 }
 420 
 421 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
 422                                           size_t end_alignment_in_bytes) {
 423   assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
 424           err_msg("alignment " SIZE_FORMAT " too large", end_alignment_in_bytes));
 425   assert(is_size_aligned(end_alignment_in_bytes, HeapWordSize),
 426          err_msg("alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize));
 427 
 428   // If we've allocated nothing, simply return.
 429   if (_allocation_region == NULL) {
 430     return;
 431   }
 432 
 433   // If an end alignment was requested, insert filler objects.
 434   if (end_alignment_in_bytes != 0) {
 435     HeapWord* currtop = _allocation_region->top();
 436     HeapWord* newtop = (HeapWord*)align_pointer_up(currtop, end_alignment_in_bytes);
 437     size_t fill_size = pointer_delta(newtop, currtop);
 438     if (fill_size != 0) {
 439       if (fill_size < CollectedHeap::min_fill_size()) {
 440         // If the required fill is smaller than we can represent,
 441         // bump up to the next aligned address. We know we won't exceed the current
 442         // region boundary because the max supported alignment is smaller than the min
 443         // region size, and because the allocation code never leaves space smaller than
 444         // the min_fill_size at the top of the current allocation region.
 445         newtop = (HeapWord*)align_pointer_up(currtop + CollectedHeap::min_fill_size(),
 446                                              end_alignment_in_bytes);
 447         fill_size = pointer_delta(newtop, currtop);
 448       }
 449       HeapWord* fill = archive_mem_allocate(fill_size);
 450       CollectedHeap::fill_with_objects(fill, fill_size);
 451     }
 452   }
 453 
 454   // Loop through the allocated regions, and create MemRegions summarizing
 455   // the allocated address range, combining contiguous ranges. Add the
 456   // MemRegions to the GrowableArray provided by the caller.
 457   int index = _allocated_regions.length() - 1;
 458   assert(_allocated_regions.at(index) == _allocation_region,
 459          err_msg("expected region %u at end of array, found %u",
 460                  _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index()));
 461   HeapWord* base_address = _allocation_region->bottom();
 462   HeapWord* top = base_address;
 463 
 464   while (index >= 0) {
 465     HeapRegion* next = _allocated_regions.at(index);
 466     HeapWord* new_base = next->bottom();
 467     HeapWord* new_top = next->top();
 468     if (new_base != top) {
 469       ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
 470       base_address = new_base;
 471     }
 472     top = new_top;
 473     index = index - 1;
 474   }
 475 
 476   assert(top != base_address, err_msg("zero-sized range, address " PTR_FORMAT, p2i(base_address)));
 477   ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
 478   _allocated_regions.clear();
 479   _allocation_region = NULL;
 480 };
--- EOF ---