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.
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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
37G1Allocator::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
47void G1Allocator::init_mutator_alloc_region() {
48 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
49 _mutator_alloc_region.init();
50}
51
52void G1Allocator::release_mutator_alloc_region() {
53 _mutator_alloc_region.release();
54 assert(_mutator_alloc_region.get() == NULL, "post-condition");
55}
56
57bool G1Allocator::is_retained_old_region(HeapRegion* hr) {
58 return _retained_old_gc_alloc_region == hr;
59}
60
61void 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
94void 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
107void 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
119void 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
125bool G1Allocator::survivor_is_full() const {
126 return _survivor_is_full;
127}
128
129bool G1Allocator::old_is_full() const {
130 return _old_is_full;
131}
132
133void G1Allocator::set_survivor_full() {
134 _survivor_is_full = true;
135}
136
137void G1Allocator::set_old_full() {
138 _old_is_full = true;
139}
140
141size_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
158size_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
164HeapWord* 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
174HeapWord* 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
189HeapWord* 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
213HeapWord* 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
234uint 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
246G1PLABAllocator::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
260bool 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
264HeapWord* 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
308void G1PLABAllocator::undo_allocation(G1HeapRegionAttr dest, HeapWord* obj, size_t word_sz) {
309 alloc_buffer(dest)->undo_allocation(obj, word_sz);
310}
311
312void 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
324size_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
335size_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
346bool G1ArchiveAllocator::_archive_check_enabled = false;
347G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map;
348G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map;
349
350G1ArchiveAllocator* 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
358bool 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
391HeapWord* 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
444void 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};
504