1/*
2 * Copyright (c) 2014, 2016, 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/g1MarkSweep.hpp"
31#include "gc/g1/heapRegion.inline.hpp"
32#include "gc/g1/heapRegionSet.inline.hpp"
33
34G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) :
35  G1Allocator(heap),
36  _survivor_is_full(false),
37  _old_is_full(false),
38  _retained_old_gc_alloc_region(NULL),
39  _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)),
40  _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) {
41}
42
43void G1DefaultAllocator::init_mutator_alloc_region() {
44  assert(_mutator_alloc_region.get() == NULL, "pre-condition");
45  _mutator_alloc_region.init();
46}
47
48void G1DefaultAllocator::release_mutator_alloc_region() {
49  _mutator_alloc_region.release();
50  assert(_mutator_alloc_region.get() == NULL, "post-condition");
51}
52
53void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,
54                                            OldGCAllocRegion* old,
55                                            HeapRegion** retained_old) {
56  HeapRegion* retained_region = *retained_old;
57  *retained_old = NULL;
58  assert(retained_region == NULL || !retained_region->is_archive(),
59         "Archive region should not be alloc region (index %u)", retained_region->hrm_index());
60
61  // We will discard the current GC alloc region if:
62  // a) it's in the collection set (it can happen!),
63  // b) it's already full (no point in using it),
64  // c) it's empty (this means that it was emptied during
65  // a cleanup and it should be on the free list now), or
66  // d) it's humongous (this means that it was emptied
67  // during a cleanup and was added to the free list, but
68  // has been subsequently used to allocate a humongous
69  // object that may be less than the region size).
70  if (retained_region != NULL &&
71      !retained_region->in_collection_set() &&
72      !(retained_region->top() == retained_region->end()) &&
73      !retained_region->is_empty() &&
74      !retained_region->is_humongous()) {
75    retained_region->record_timestamp();
76    // The retained region was added to the old region set when it was
77    // retired. We have to remove it now, since we don't allow regions
78    // we allocate to in the region sets. We'll re-add it later, when
79    // it's retired again.
80    _g1h->old_set_remove(retained_region);
81    bool during_im = _g1h->collector_state()->during_initial_mark_pause();
82    retained_region->note_start_of_copying(during_im);
83    old->set(retained_region);
84    _g1h->hr_printer()->reuse(retained_region);
85    evacuation_info.set_alloc_regions_used_before(retained_region->used());
86  }
87}
88
89void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
90  assert_at_safepoint(true /* should_be_vm_thread */);
91
92  _survivor_is_full = false;
93  _old_is_full = false;
94
95  _survivor_gc_alloc_region.init();
96  _old_gc_alloc_region.init();
97  reuse_retained_old_region(evacuation_info,
98                            &_old_gc_alloc_region,
99                            &_retained_old_gc_alloc_region);
100}
101
102void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) {
103  AllocationContext_t context = AllocationContext::current();
104  evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() +
105                                         old_gc_alloc_region(context)->count());
106  survivor_gc_alloc_region(context)->release();
107  // If we have an old GC alloc region to release, we'll save it in
108  // _retained_old_gc_alloc_region. If we don't
109  // _retained_old_gc_alloc_region will become NULL. This is what we
110  // want either way so no reason to check explicitly for either
111  // condition.
112  _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release();
113  if (_retained_old_gc_alloc_region != NULL) {
114    _retained_old_gc_alloc_region->record_retained_region();
115  }
116}
117
118void 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
124bool G1DefaultAllocator::survivor_is_full(AllocationContext_t context) const {
125  return _survivor_is_full;
126}
127
128bool G1DefaultAllocator::old_is_full(AllocationContext_t context) const {
129  return _old_is_full;
130}
131
132void G1DefaultAllocator::set_survivor_full(AllocationContext_t context) {
133  _survivor_is_full = true;
134}
135
136void G1DefaultAllocator::set_old_full(AllocationContext_t context) {
137  _old_is_full = true;
138}
139
140G1PLAB::G1PLAB(size_t gclab_word_size) :
141  PLAB(gclab_word_size), _retired(true) { }
142
143size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) {
144  // Return the remaining space in the cur alloc region, but not less than
145  // the min TLAB size.
146
147  // Also, this value can be at most the humongous object threshold,
148  // since we can't allow tlabs to grow big enough to accommodate
149  // humongous objects.
150
151  HeapRegion* hr = mutator_alloc_region(context)->get();
152  size_t max_tlab = _g1h->max_tlab_size() * wordSize;
153  if (hr == NULL) {
154    return max_tlab;
155  } else {
156    return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
157  }
158}
159
160HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
161                                              size_t word_size,
162                                              AllocationContext_t context) {
163  size_t temp = 0;
164  HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp, context);
165  assert(result == NULL || temp == word_size,
166         "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
167         word_size, temp, p2i(result));
168  return result;
169}
170
171HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
172                                              size_t min_word_size,
173                                              size_t desired_word_size,
174                                              size_t* actual_word_size,
175                                              AllocationContext_t context) {
176  switch (dest.value()) {
177    case InCSetState::Young:
178      return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
179    case InCSetState::Old:
180      return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
181    default:
182      ShouldNotReachHere();
183      return NULL; // Keep some compilers happy
184  }
185}
186
187HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
188                                                   size_t desired_word_size,
189                                                   size_t* actual_word_size,
190                                                   AllocationContext_t context) {
191  assert(!_g1h->is_humongous(desired_word_size),
192         "we should not be seeing humongous-size allocations in this path");
193
194  HeapWord* result = survivor_gc_alloc_region(context)->attempt_allocation(min_word_size,
195                                                                           desired_word_size,
196                                                                           actual_word_size,
197                                                                           false /* bot_updates */);
198  if (result == NULL && !survivor_is_full(context)) {
199    MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
200    result = survivor_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,
201                                                                          desired_word_size,
202                                                                          actual_word_size,
203                                                                          false /* bot_updates */);
204    if (result == NULL) {
205      set_survivor_full(context);
206    }
207  }
208  if (result != NULL) {
209    _g1h->dirty_young_block(result, *actual_word_size);
210  }
211  return result;
212}
213
214HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
215                                              size_t desired_word_size,
216                                              size_t* actual_word_size,
217                                              AllocationContext_t context) {
218  assert(!_g1h->is_humongous(desired_word_size),
219         "we should not be seeing humongous-size allocations in this path");
220
221  HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(min_word_size,
222                                                                      desired_word_size,
223                                                                      actual_word_size,
224                                                                      true /* bot_updates */);
225  if (result == NULL && !old_is_full(context)) {
226    MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
227    result = old_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,
228                                                                     desired_word_size,
229                                                                     actual_word_size,
230                                                                     true /* bot_updates */);
231    if (result == NULL) {
232      set_old_full(context);
233    }
234  }
235  return result;
236}
237
238G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
239  _g1h(G1CollectedHeap::heap()),
240  _allocator(allocator),
241  _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
242  for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) {
243    _direct_allocated[i] = 0;
244  }
245}
246
247bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
248  return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
249}
250
251HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest,
252                                                       size_t word_sz,
253                                                       AllocationContext_t context,
254                                                       bool* plab_refill_failed) {
255  size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest);
256  size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
257
258  // Only get a new PLAB if the allocation fits and it would not waste more than
259  // ParallelGCBufferWastePct in the existing buffer.
260  if ((required_in_plab <= plab_word_size) &&
261    may_throw_away_buffer(required_in_plab, plab_word_size)) {
262
263    G1PLAB* alloc_buf = alloc_buffer(dest, context);
264    alloc_buf->retire();
265
266    size_t actual_plab_size = 0;
267    HeapWord* buf = _allocator->par_allocate_during_gc(dest,
268                                                       required_in_plab,
269                                                       plab_word_size,
270                                                       &actual_plab_size,
271                                                       context);
272
273    assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
274           "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
275           required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
276
277    if (buf != NULL) {
278      alloc_buf->set_buf(buf, actual_plab_size);
279
280      HeapWord* const obj = alloc_buf->allocate(word_sz);
281      assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
282                          SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
283                          word_sz, required_in_plab, plab_word_size);
284      return obj;
285    }
286    // Otherwise.
287    *plab_refill_failed = true;
288  }
289  // Try direct allocation.
290  HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context);
291  if (result != NULL) {
292    _direct_allocated[dest.value()] += word_sz;
293  }
294  return result;
295}
296
297void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) {
298  alloc_buffer(dest, context)->undo_allocation(obj, word_sz);
299}
300
301G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) :
302  G1PLABAllocator(allocator),
303  _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)),
304  _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) {
305  for (uint state = 0; state < InCSetState::Num; state++) {
306    _alloc_buffers[state] = NULL;
307  }
308  _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;
309  _alloc_buffers[InCSetState::Old]  = &_tenured_alloc_buffer;
310}
311
312void G1DefaultPLABAllocator::flush_and_retire_stats() {
313  for (uint state = 0; state < InCSetState::Num; state++) {
314    G1PLAB* 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
324void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) {
325  wasted = 0;
326  undo_wasted = 0;
327  for (uint state = 0; state < InCSetState::Num; state++) {
328    G1PLAB * const buf = _alloc_buffers[state];
329    if (buf != NULL) {
330      wasted += buf->waste();
331      undo_wasted += buf->undo_waste();
332    }
333  }
334}
335
336G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) {
337  // Create the archive allocator, and also enable archive object checking
338  // in mark-sweep, since we will be creating archive regions.
339  G1ArchiveAllocator* result =  new G1ArchiveAllocator(g1h);
340  G1MarkSweep::enable_archive_object_check();
341  return result;
342}
343
344bool G1ArchiveAllocator::alloc_new_region() {
345  // Allocate the highest free region in the reserved heap,
346  // and add it to our list of allocated regions. It is marked
347  // archive and added to the old set.
348  HeapRegion* hr = _g1h->alloc_highest_free_region();
349  if (hr == NULL) {
350    return false;
351  }
352  assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
353  hr->set_archive();
354  _g1h->old_set_add(hr);
355  _g1h->hr_printer()->alloc(hr);
356  _allocated_regions.append(hr);
357  _allocation_region = hr;
358
359  // Set up _bottom and _max to begin allocating in the lowest
360  // min_region_size'd chunk of the allocated G1 region.
361  _bottom = hr->bottom();
362  _max = _bottom + HeapRegion::min_region_size_in_words();
363
364  // Tell mark-sweep that objects in this region are not to be marked.
365  G1MarkSweep::set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), true);
366
367  // Since we've modified the old set, call update_sizes.
368  _g1h->g1mm()->update_sizes();
369  return true;
370}
371
372HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
373  assert(word_size != 0, "size must not be zero");
374  if (_allocation_region == NULL) {
375    if (!alloc_new_region()) {
376      return NULL;
377    }
378  }
379  HeapWord* old_top = _allocation_region->top();
380  assert(_bottom >= _allocation_region->bottom(),
381         "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
382         p2i(_bottom), p2i(_allocation_region->bottom()));
383  assert(_max <= _allocation_region->end(),
384         "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
385         p2i(_max), p2i(_allocation_region->end()));
386  assert(_bottom <= old_top && old_top <= _max,
387         "inconsistent allocation state: expected "
388         PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
389         p2i(_bottom), p2i(old_top), p2i(_max));
390
391  // Allocate the next word_size words in the current allocation chunk.
392  // If allocation would cross the _max boundary, insert a filler and begin
393  // at the base of the next min_region_size'd chunk. Also advance to the next
394  // chunk if we don't yet cross the boundary, but the remainder would be too
395  // small to fill.
396  HeapWord* new_top = old_top + word_size;
397  size_t remainder = pointer_delta(_max, new_top);
398  if ((new_top > _max) ||
399      ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
400    if (old_top != _max) {
401      size_t fill_size = pointer_delta(_max, old_top);
402      CollectedHeap::fill_with_object(old_top, fill_size);
403      _summary_bytes_used += fill_size * HeapWordSize;
404    }
405    _allocation_region->set_top(_max);
406    old_top = _bottom = _max;
407
408    // Check if we've just used up the last min_region_size'd chunk
409    // in the current region, and if so, allocate a new one.
410    if (_bottom != _allocation_region->end()) {
411      _max = _bottom + HeapRegion::min_region_size_in_words();
412    } else {
413      if (!alloc_new_region()) {
414        return NULL;
415      }
416      old_top = _allocation_region->bottom();
417    }
418  }
419  _allocation_region->set_top(old_top + word_size);
420  _summary_bytes_used += word_size * HeapWordSize;
421
422  return old_top;
423}
424
425void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
426                                          size_t end_alignment_in_bytes) {
427  assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
428         "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
429  assert(is_size_aligned(end_alignment_in_bytes, HeapWordSize),
430         "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
431
432  // If we've allocated nothing, simply return.
433  if (_allocation_region == NULL) {
434    return;
435  }
436
437  // If an end alignment was requested, insert filler objects.
438  if (end_alignment_in_bytes != 0) {
439    HeapWord* currtop = _allocation_region->top();
440    HeapWord* newtop = (HeapWord*)align_ptr_up(currtop, end_alignment_in_bytes);
441    size_t fill_size = pointer_delta(newtop, currtop);
442    if (fill_size != 0) {
443      if (fill_size < CollectedHeap::min_fill_size()) {
444        // If the required fill is smaller than we can represent,
445        // bump up to the next aligned address. We know we won't exceed the current
446        // region boundary because the max supported alignment is smaller than the min
447        // region size, and because the allocation code never leaves space smaller than
448        // the min_fill_size at the top of the current allocation region.
449        newtop = (HeapWord*)align_ptr_up(currtop + CollectedHeap::min_fill_size(),
450                                         end_alignment_in_bytes);
451        fill_size = pointer_delta(newtop, currtop);
452      }
453      HeapWord* fill = archive_mem_allocate(fill_size);
454      CollectedHeap::fill_with_objects(fill, fill_size);
455    }
456  }
457
458  // Loop through the allocated regions, and create MemRegions summarizing
459  // the allocated address range, combining contiguous ranges. Add the
460  // MemRegions to the GrowableArray provided by the caller.
461  int index = _allocated_regions.length() - 1;
462  assert(_allocated_regions.at(index) == _allocation_region,
463         "expected region %u at end of array, found %u",
464         _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
465  HeapWord* base_address = _allocation_region->bottom();
466  HeapWord* top = base_address;
467
468  while (index >= 0) {
469    HeapRegion* next = _allocated_regions.at(index);
470    HeapWord* new_base = next->bottom();
471    HeapWord* new_top = next->top();
472    if (new_base != top) {
473      ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
474      base_address = new_base;
475    }
476    top = new_top;
477    index = index - 1;
478  }
479
480  assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
481  ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
482  _allocated_regions.clear();
483  _allocation_region = NULL;
484};
485