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 _retained_survivor_gc_alloc_region(NULL) {
46 }
47
48 void G1Allocator::init_mutator_alloc_region() {
49 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
50 _mutator_alloc_region.init();
51
52 reuse_retained_survivor_region(&_retained_survivor_gc_alloc_region);
53 }
54
55 void G1Allocator::reuse_retained_survivor_region(HeapRegion** retained_survivor) {
56 HeapRegion* retained_region = *retained_survivor;
57 *retained_survivor = NULL;
58
59 if (retained_region != NULL) {
60 mutator_alloc_region()->set(retained_region);
61 _g1h->reuse_retained_survivor_region(retained_region);
62 }
63 }
64
65 void G1Allocator::release_mutator_alloc_region() {
66 _mutator_alloc_region.release();
67 assert(_mutator_alloc_region.get() == NULL, "post-condition");
68 }
69
70 bool G1Allocator::is_retained_old_region(HeapRegion* hr) {
71 return _retained_old_gc_alloc_region == hr;
72 }
73
74 void G1Allocator::reuse_retained_old_region(G1EvacuationInfo& evacuation_info,
75 OldGCAllocRegion* old,
76 HeapRegion** retained_old) {
77 HeapRegion* retained_region = *retained_old;
78 *retained_old = NULL;
79 assert(retained_region == NULL || !retained_region->is_archive(),
80 "Archive region should not be alloc region (index %u)", retained_region->hrm_index());
81
82 // We will discard the current GC alloc region if:
83 // a) it's in the collection set (it can happen!),
84 // b) it's already full (no point in using it),
85 // c) it's empty (this means that it was emptied during
86 // a cleanup and it should be on the free list now), or
87 // d) it's humongous (this means that it was emptied
88 // during a cleanup and was added to the free list, but
89 // has been subsequently used to allocate a humongous
90 // object that may be less than the region size).
91 if (retained_region != NULL &&
92 !retained_region->in_collection_set() &&
93 !(retained_region->top() == retained_region->end()) &&
94 !retained_region->is_empty() &&
95 !retained_region->is_humongous()) {
96 // The retained region was added to the old region set when it was
97 // retired. We have to remove it now, since we don't allow regions
98 // we allocate to in the region sets. We'll re-add it later, when
99 // it's retired again.
100 _g1h->old_set_remove(retained_region);
101 old->set(retained_region);
102 _g1h->hr_printer()->reuse(retained_region);
103 evacuation_info.set_alloc_regions_used_before(retained_region->used());
104 }
105 }
106
107 void G1Allocator::init_gc_alloc_regions(G1EvacuationInfo& evacuation_info) {
108 assert_at_safepoint_on_vm_thread();
109
110 _survivor_is_full = false;
111 _old_is_full = false;
112
113 _survivor_gc_alloc_region.init();
114 _old_gc_alloc_region.init();
115 reuse_retained_old_region(evacuation_info,
116 &_old_gc_alloc_region,
117 &_retained_old_gc_alloc_region);
118 }
119
120 void G1Allocator::release_gc_alloc_regions(G1EvacuationInfo& evacuation_info) {
121 evacuation_info.set_allocation_regions(survivor_gc_alloc_region()->count() +
122 old_gc_alloc_region()->count());
123 HeapRegion* reuse_candidate = survivor_gc_alloc_region()->release();
124 if (reuse_candidate != NULL && SurvivorGCAllocRegion::should_retain(reuse_candidate)) {
125 _g1h->update_retained_survivor_gc_alloc_region(reuse_candidate);
126 _retained_survivor_gc_alloc_region = reuse_candidate;
127 }
128
129 // If we have an old GC alloc region to release, we'll save it in
130 // _retained_old_gc_alloc_region. If we don't
131 // _retained_old_gc_alloc_region will become NULL. This is what we
132 // want either way so no reason to check explicitly for either
133 // condition.
134 _retained_old_gc_alloc_region = old_gc_alloc_region()->release();
135 }
136
137 void G1Allocator::abandon_gc_alloc_regions() {
138 assert(survivor_gc_alloc_region()->get() == NULL, "pre-condition");
139 assert(old_gc_alloc_region()->get() == NULL, "pre-condition");
140 _retained_old_gc_alloc_region = NULL;
141 }
142
143 bool G1Allocator::survivor_is_full() const {
144 return _survivor_is_full;
145 }
146
147 bool G1Allocator::old_is_full() const {
148 return _old_is_full;
149 }
150
151 void G1Allocator::set_survivor_full() {
152 _survivor_is_full = true;
153 }
154
155 void G1Allocator::set_old_full() {
156 _old_is_full = true;
157 }
158
159 size_t G1Allocator::unsafe_max_tlab_alloc() {
160 // Return the remaining space in the cur alloc region, but not less than
161 // the min TLAB size.
162
163 // Also, this value can be at most the humongous object threshold,
164 // since we can't allow tlabs to grow big enough to accommodate
165 // humongous objects.
166
167 HeapRegion* hr = mutator_alloc_region()->get();
168 size_t max_tlab = _g1h->max_tlab_size() * wordSize;
169 if (hr == NULL) {
170 return max_tlab;
171 } else {
172 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
173 }
174 }
175
176 size_t G1Allocator::used_in_alloc_regions() {
177 assert(Heap_lock->owner() != NULL, "Should be owned on this thread's behalf.");
178 return mutator_alloc_region()->used_in_alloc_regions();
179 }
180
181
182 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest,
183 size_t word_size) {
184 size_t temp = 0;
185 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp);
186 assert(result == NULL || temp == word_size,
187 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
188 word_size, temp, p2i(result));
189 return result;
190 }
191
192 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest,
193 size_t min_word_size,
194 size_t desired_word_size,
195 size_t* actual_word_size) {
196 switch (dest.type()) {
197 case G1HeapRegionAttr::Young:
198 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
199 case G1HeapRegionAttr::Old:
200 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
201 default:
202 ShouldNotReachHere();
203 return NULL; // Keep some compilers happy
204 }
205 }
206
207 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
208 size_t desired_word_size,
209 size_t* actual_word_size) {
210 assert(!_g1h->is_humongous(desired_word_size),
211 "we should not be seeing humongous-size allocations in this path");
212
213 HeapWord* result = survivor_gc_alloc_region()->attempt_allocation(min_word_size,
214 desired_word_size,
215 actual_word_size);
216 if (result == NULL && !survivor_is_full()) {
217 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
218 result = survivor_gc_alloc_region()->attempt_allocation_locked(min_word_size,
219 desired_word_size,
220 actual_word_size);
221 if (result == NULL) {
222 set_survivor_full();
223 }
224 }
225 if (result != NULL) {
226 _g1h->dirty_young_block(result, *actual_word_size);
227 }
228 return result;
229 }
230
231 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
232 size_t desired_word_size,
233 size_t* actual_word_size) {
234 assert(!_g1h->is_humongous(desired_word_size),
235 "we should not be seeing humongous-size allocations in this path");
236
237 HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size,
238 desired_word_size,
239 actual_word_size);
240 if (result == NULL && !old_is_full()) {
241 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
242 result = old_gc_alloc_region()->attempt_allocation_locked(min_word_size,
243 desired_word_size,
244 actual_word_size);
245 if (result == NULL) {
246 set_old_full();
247 }
248 }
249 return result;
250 }
251
252 uint G1PLABAllocator::calc_survivor_alignment_bytes() {
253 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
254 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
255 // No need to align objects in the survivors differently, return 0
256 // which means "survivor alignment is not used".
257 return 0;
258 } else {
259 assert(SurvivorAlignmentInBytes > 0, "sanity");
260 return SurvivorAlignmentInBytes;
261 }
262 }
263
264 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
265 _g1h(G1CollectedHeap::heap()),
266 _allocator(allocator),
267 _surviving_alloc_buffer(_g1h->desired_plab_sz(G1HeapRegionAttr::Young)),
268 _tenured_alloc_buffer(_g1h->desired_plab_sz(G1HeapRegionAttr::Old)),
269 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
270 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
271 _direct_allocated[state] = 0;
272 _alloc_buffers[state] = NULL;
273 }
274 _alloc_buffers[G1HeapRegionAttr::Young] = &_surviving_alloc_buffer;
275 _alloc_buffers[G1HeapRegionAttr::Old] = &_tenured_alloc_buffer;
276 }
277
278 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
279 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
280 }
281
282 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(G1HeapRegionAttr dest,
283 size_t word_sz,
284 bool* plab_refill_failed) {
285 size_t plab_word_size = _g1h->desired_plab_sz(dest);
286 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
287
288 // Only get a new PLAB if the allocation fits and it would not waste more than
289 // ParallelGCBufferWastePct in the existing buffer.
290 if ((required_in_plab <= plab_word_size) &&
291 may_throw_away_buffer(required_in_plab, plab_word_size)) {
292
293 PLAB* alloc_buf = alloc_buffer(dest);
294 alloc_buf->retire();
295
296 size_t actual_plab_size = 0;
297 HeapWord* buf = _allocator->par_allocate_during_gc(dest,
298 required_in_plab,
299 plab_word_size,
300 &actual_plab_size);
301
302 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
303 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
304 required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
305
306 if (buf != NULL) {
307 alloc_buf->set_buf(buf, actual_plab_size);
308
309 HeapWord* const obj = alloc_buf->allocate(word_sz);
310 assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
311 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
312 word_sz, required_in_plab, plab_word_size);
313 return obj;
314 }
315 // Otherwise.
316 *plab_refill_failed = true;
317 }
318 // Try direct allocation.
319 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz);
320 if (result != NULL) {
321 _direct_allocated[dest.type()] += word_sz;
322 }
323 return result;
324 }
325
326 void G1PLABAllocator::undo_allocation(G1HeapRegionAttr dest, HeapWord* obj, size_t word_sz) {
327 alloc_buffer(dest)->undo_allocation(obj, word_sz);
328 }
329
330 void G1PLABAllocator::flush_and_retire_stats() {
331 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
332 PLAB* const buf = _alloc_buffers[state];
333 if (buf != NULL) {
334 G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
335 buf->flush_and_retire_stats(stats);
336 stats->add_direct_allocated(_direct_allocated[state]);
337 _direct_allocated[state] = 0;
338 }
339 }
340 }
341
342 size_t G1PLABAllocator::waste() const {
343 size_t result = 0;
344 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
345 PLAB * const buf = _alloc_buffers[state];
346 if (buf != NULL) {
347 result += buf->waste();
348 }
349 }
350 return result;
351 }
352
353 size_t G1PLABAllocator::undo_waste() const {
354 size_t result = 0;
355 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
356 PLAB * const buf = _alloc_buffers[state];
357 if (buf != NULL) {
358 result += buf->undo_waste();
359 }
360 }
361 return result;
362 }
363
364 bool G1ArchiveAllocator::_archive_check_enabled = false;
365 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map;
366 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map;
367
368 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) {
369 // Create the archive allocator, and also enable archive object checking
370 // in mark-sweep, since we will be creating archive regions.
371 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h, open);
372 enable_archive_object_check();
373 return result;
374 }
375
376 bool G1ArchiveAllocator::alloc_new_region() {
377 // Allocate the highest free region in the reserved heap,
378 // and add it to our list of allocated regions. It is marked
379 // archive and added to the old set.
380 HeapRegion* hr = _g1h->alloc_highest_free_region();
381 if (hr == NULL) {
382 return false;
383 }
384 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
385 if (_open) {
386 hr->set_open_archive();
387 } else {
388 hr->set_closed_archive();
389 }
390 _g1h->policy()->remset_tracker()->update_at_allocate(hr);
391 _g1h->archive_set_add(hr);
392 _g1h->hr_printer()->alloc(hr);
393 _allocated_regions.append(hr);
394 _allocation_region = hr;
395
396 // Set up _bottom and _max to begin allocating in the lowest
397 // min_region_size'd chunk of the allocated G1 region.
398 _bottom = hr->bottom();
399 _max = _bottom + HeapRegion::min_region_size_in_words();
400
401 // Tell mark-sweep that objects in this region are not to be marked.
402 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open);
403
404 // Since we've modified the old set, call update_sizes.
405 _g1h->g1mm()->update_sizes();
406 return true;
407 }
408
409 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
410 assert(word_size != 0, "size must not be zero");
411 if (_allocation_region == NULL) {
412 if (!alloc_new_region()) {
413 return NULL;
414 }
415 }
416 HeapWord* old_top = _allocation_region->top();
417 assert(_bottom >= _allocation_region->bottom(),
418 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
419 p2i(_bottom), p2i(_allocation_region->bottom()));
420 assert(_max <= _allocation_region->end(),
421 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
422 p2i(_max), p2i(_allocation_region->end()));
423 assert(_bottom <= old_top && old_top <= _max,
424 "inconsistent allocation state: expected "
425 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
426 p2i(_bottom), p2i(old_top), p2i(_max));
427
428 // Allocate the next word_size words in the current allocation chunk.
429 // If allocation would cross the _max boundary, insert a filler and begin
430 // at the base of the next min_region_size'd chunk. Also advance to the next
431 // chunk if we don't yet cross the boundary, but the remainder would be too
432 // small to fill.
433 HeapWord* new_top = old_top + word_size;
434 size_t remainder = pointer_delta(_max, new_top);
435 if ((new_top > _max) ||
436 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
437 if (old_top != _max) {
438 size_t fill_size = pointer_delta(_max, old_top);
439 CollectedHeap::fill_with_object(old_top, fill_size);
440 _summary_bytes_used += fill_size * HeapWordSize;
441 }
442 _allocation_region->set_top(_max);
443 old_top = _bottom = _max;
444
445 // Check if we've just used up the last min_region_size'd chunk
446 // in the current region, and if so, allocate a new one.
447 if (_bottom != _allocation_region->end()) {
448 _max = _bottom + HeapRegion::min_region_size_in_words();
449 } else {
450 if (!alloc_new_region()) {
451 return NULL;
452 }
453 old_top = _allocation_region->bottom();
454 }
455 }
456 _allocation_region->set_top(old_top + word_size);
457 _summary_bytes_used += word_size * HeapWordSize;
458
459 return old_top;
460 }
461
462 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
463 size_t end_alignment_in_bytes) {
464 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
465 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
466 assert(is_aligned(end_alignment_in_bytes, HeapWordSize),
467 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
468
469 // If we've allocated nothing, simply return.
470 if (_allocation_region == NULL) {
471 return;
472 }
473
474 // If an end alignment was requested, insert filler objects.
475 if (end_alignment_in_bytes != 0) {
476 HeapWord* currtop = _allocation_region->top();
477 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes);
478 size_t fill_size = pointer_delta(newtop, currtop);
479 if (fill_size != 0) {
480 if (fill_size < CollectedHeap::min_fill_size()) {
481 // If the required fill is smaller than we can represent,
482 // bump up to the next aligned address. We know we won't exceed the current
483 // region boundary because the max supported alignment is smaller than the min
484 // region size, and because the allocation code never leaves space smaller than
485 // the min_fill_size at the top of the current allocation region.
486 newtop = align_up(currtop + CollectedHeap::min_fill_size(),
487 end_alignment_in_bytes);
488 fill_size = pointer_delta(newtop, currtop);
489 }
490 HeapWord* fill = archive_mem_allocate(fill_size);
491 CollectedHeap::fill_with_objects(fill, fill_size);
492 }
493 }
494
495 // Loop through the allocated regions, and create MemRegions summarizing
496 // the allocated address range, combining contiguous ranges. Add the
497 // MemRegions to the GrowableArray provided by the caller.
498 int index = _allocated_regions.length() - 1;
499 assert(_allocated_regions.at(index) == _allocation_region,
500 "expected region %u at end of array, found %u",
501 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
502 HeapWord* base_address = _allocation_region->bottom();
503 HeapWord* top = base_address;
504
505 while (index >= 0) {
506 HeapRegion* next = _allocated_regions.at(index);
507 HeapWord* new_base = next->bottom();
508 HeapWord* new_top = next->top();
509 if (new_base != top) {
510 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
511 base_address = new_base;
512 }
513 top = new_top;
514 index = index - 1;
515 }
516
517 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
518 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
519 _allocated_regions.clear();
520 _allocation_region = NULL;
521 };