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/g1NUMA.hpp"
32 #include "gc/g1/g1Policy.hpp"
33 #include "gc/g1/heapRegion.inline.hpp"
34 #include "gc/g1/heapRegionSet.inline.hpp"
35 #include "gc/g1/heapRegionType.hpp"
36 #include "utilities/align.hpp"
37
38 G1Allocator::G1Allocator(G1CollectedHeap* heap) :
39 _g1h(heap),
40 _numa(heap->numa()),
41 _survivor_is_full(false),
42 _old_is_full(false),
43 _num_alloc_regions(_numa->num_active_nodes()),
44 _mutator_alloc_regions(NULL),
45 _survivor_gc_alloc_regions(NULL),
46 _old_gc_alloc_region(heap->alloc_buffer_stats(G1HeapRegionAttr::Old)),
47 _retained_old_gc_alloc_region(NULL) {
48
49 _mutator_alloc_regions = NEW_C_HEAP_ARRAY(MutatorAllocRegion, _num_alloc_regions, mtGC);
50 _survivor_gc_alloc_regions = NEW_C_HEAP_ARRAY(SurvivorGCAllocRegion, _num_alloc_regions, mtGC);
51 G1EvacStats* stat = heap->alloc_buffer_stats(G1HeapRegionAttr::Young);
52
53 for (uint i = 0; i < _num_alloc_regions; i++) {
54 ::new(_mutator_alloc_regions + i) MutatorAllocRegion(i);
55 ::new(_survivor_gc_alloc_regions + i) SurvivorGCAllocRegion(stat, i);
56 }
57 }
58
59 G1Allocator::~G1Allocator() {
60 for (uint i = 0; i < _num_alloc_regions; i++) {
61 _mutator_alloc_regions[i].~MutatorAllocRegion();
62 _survivor_gc_alloc_regions[i].~SurvivorGCAllocRegion();
63 }
64 FREE_C_HEAP_ARRAY(MutatorAllocRegion, _mutator_alloc_regions);
65 FREE_C_HEAP_ARRAY(SurvivorGCAllocRegion, _survivor_gc_alloc_regions);
66 }
67
68 #ifdef ASSERT
69 bool G1Allocator::has_mutator_alloc_region() {
70 uint node_index = current_node_index();
71 return mutator_alloc_region(node_index)->get() != NULL;
72 }
73 #endif
74
75 void G1Allocator::init_mutator_alloc_regions() {
76 for (uint i = 0; i < _num_alloc_regions; i++) {
77 assert(mutator_alloc_region(i)->get() == NULL, "pre-condition");
78 mutator_alloc_region(i)->init();
79 }
80 }
81
82 void G1Allocator::release_mutator_alloc_regions() {
83 for (uint i = 0; i < _num_alloc_regions; i++) {
84 mutator_alloc_region(i)->release();
85 assert(mutator_alloc_region(i)->get() == NULL, "post-condition");
86 }
87 }
88
89 bool G1Allocator::is_retained_old_region(HeapRegion* hr) {
90 return _retained_old_gc_alloc_region == hr;
91 }
92
93 void G1Allocator::reuse_retained_old_region(G1EvacuationInfo& evacuation_info,
94 OldGCAllocRegion* old,
95 HeapRegion** retained_old) {
96 HeapRegion* retained_region = *retained_old;
97 *retained_old = NULL;
98 assert(retained_region == NULL || !retained_region->is_archive(),
99 "Archive region should not be alloc region (index %u)", retained_region->hrm_index());
100
101 // We will discard the current GC alloc region if:
102 // a) it's in the collection set (it can happen!),
103 // b) it's already full (no point in using it),
104 // c) it's empty (this means that it was emptied during
105 // a cleanup and it should be on the free list now), or
106 // d) it's humongous (this means that it was emptied
107 // during a cleanup and was added to the free list, but
108 // has been subsequently used to allocate a humongous
109 // object that may be less than the region size).
110 if (retained_region != NULL &&
111 !retained_region->in_collection_set() &&
112 !(retained_region->top() == retained_region->end()) &&
113 !retained_region->is_empty() &&
114 !retained_region->is_humongous()) {
115 // The retained region was added to the old region set when it was
116 // retired. We have to remove it now, since we don't allow regions
117 // we allocate to in the region sets. We'll re-add it later, when
118 // it's retired again.
119 _g1h->old_set_remove(retained_region);
120 old->set(retained_region);
121 _g1h->hr_printer()->reuse(retained_region);
122 evacuation_info.set_alloc_regions_used_before(retained_region->used());
123 }
124 }
125
126 void G1Allocator::init_gc_alloc_regions(G1EvacuationInfo& evacuation_info) {
127 assert_at_safepoint_on_vm_thread();
128
129 _survivor_is_full = false;
130 _old_is_full = false;
131
132 for (uint i = 0; i < _num_alloc_regions; i++) {
133 survivor_gc_alloc_region(i)->init();
134 }
135
136 _old_gc_alloc_region.init();
137 reuse_retained_old_region(evacuation_info,
138 &_old_gc_alloc_region,
139 &_retained_old_gc_alloc_region);
140 }
141
142 void G1Allocator::release_gc_alloc_regions(G1EvacuationInfo& evacuation_info) {
143 uint survivor_region_count = 0;
144 for (uint node_index = 0; node_index < _num_alloc_regions; node_index++) {
145 survivor_region_count += survivor_gc_alloc_region(node_index)->count();
146 survivor_gc_alloc_region(node_index)->release();
147 }
148 evacuation_info.set_allocation_regions(survivor_region_count +
149 old_gc_alloc_region()->count());
150
151 // If we have an old GC alloc region to release, we'll save it in
152 // _retained_old_gc_alloc_region. If we don't
153 // _retained_old_gc_alloc_region will become NULL. This is what we
154 // want either way so no reason to check explicitly for either
155 // condition.
156 _retained_old_gc_alloc_region = old_gc_alloc_region()->release();
157 }
158
159 void G1Allocator::abandon_gc_alloc_regions() {
160 for (uint i = 0; i < _num_alloc_regions; i++) {
161 assert(survivor_gc_alloc_region(i)->get() == NULL, "pre-condition");
162 }
163 assert(old_gc_alloc_region()->get() == NULL, "pre-condition");
164 _retained_old_gc_alloc_region = NULL;
165 }
166
167 bool G1Allocator::survivor_is_full() const {
168 return _survivor_is_full;
169 }
170
171 bool G1Allocator::old_is_full() const {
172 return _old_is_full;
173 }
174
175 void G1Allocator::set_survivor_full() {
176 _survivor_is_full = true;
177 }
178
179 void G1Allocator::set_old_full() {
180 _old_is_full = true;
181 }
182
183 size_t G1Allocator::unsafe_max_tlab_alloc() {
184 // Return the remaining space in the cur alloc region, but not less than
185 // the min TLAB size.
186
187 // Also, this value can be at most the humongous object threshold,
188 // since we can't allow tlabs to grow big enough to accommodate
189 // humongous objects.
190
191 uint node_index = current_node_index();
192 HeapRegion* hr = mutator_alloc_region(node_index)->get();
193 size_t max_tlab = _g1h->max_tlab_size() * wordSize;
194 if (hr == NULL) {
195 return max_tlab;
196 } else {
197 return clamp(hr->free(), MinTLABSize, max_tlab);
198 }
199 }
200
201 size_t G1Allocator::used_in_alloc_regions() {
202 assert(Heap_lock->owner() != NULL, "Should be owned on this thread's behalf.");
203 size_t used = 0;
204 for (uint i = 0; i < _num_alloc_regions; i++) {
205 used += mutator_alloc_region(i)->used_in_alloc_regions();
206 }
207 return used;
208 }
209
210
211 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest,
212 size_t word_size,
213 uint node_index) {
214 size_t temp = 0;
215 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp, node_index);
216 assert(result == NULL || temp == word_size,
217 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
218 word_size, temp, p2i(result));
219 return result;
220 }
221
222 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest,
223 size_t min_word_size,
224 size_t desired_word_size,
225 size_t* actual_word_size,
226 uint node_index) {
227 switch (dest.type()) {
228 case G1HeapRegionAttr::Young:
229 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, node_index);
230 case G1HeapRegionAttr::Old:
231 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
232 default:
233 ShouldNotReachHere();
234 return NULL; // Keep some compilers happy
235 }
236 }
237
238 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
239 size_t desired_word_size,
240 size_t* actual_word_size,
241 uint node_index) {
242 assert(!_g1h->is_humongous(desired_word_size),
243 "we should not be seeing humongous-size allocations in this path");
244
245 HeapWord* result = survivor_gc_alloc_region(node_index)->attempt_allocation(min_word_size,
246 desired_word_size,
247 actual_word_size);
248 if (result == NULL && !survivor_is_full()) {
249 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
250 result = survivor_gc_alloc_region(node_index)->attempt_allocation_locked(min_word_size,
251 desired_word_size,
252 actual_word_size);
253 if (result == NULL) {
254 set_survivor_full();
255 }
256 }
257 if (result != NULL) {
258 _g1h->dirty_young_block(result, *actual_word_size);
259 }
260 return result;
261 }
262
263 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
264 size_t desired_word_size,
265 size_t* actual_word_size) {
266 assert(!_g1h->is_humongous(desired_word_size),
267 "we should not be seeing humongous-size allocations in this path");
268
269 HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size,
270 desired_word_size,
271 actual_word_size);
272 if (result == NULL && !old_is_full()) {
273 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
274 result = old_gc_alloc_region()->attempt_allocation_locked(min_word_size,
275 desired_word_size,
276 actual_word_size);
277 if (result == NULL) {
278 set_old_full();
279 }
280 }
281 return result;
282 }
283
284 uint G1PLABAllocator::calc_survivor_alignment_bytes() {
285 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
286 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
287 // No need to align objects in the survivors differently, return 0
288 // which means "survivor alignment is not used".
289 return 0;
290 } else {
291 assert(SurvivorAlignmentInBytes > 0, "sanity");
292 return SurvivorAlignmentInBytes;
293 }
294 }
295
296 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
297 _g1h(G1CollectedHeap::heap()),
298 _allocator(allocator),
299 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
300 for (region_type_t state = 0; state < G1HeapRegionAttr::Num; state++) {
301 _direct_allocated[state] = 0;
302 uint length = alloc_buffers_length(state);
303 _alloc_buffers[state] = NEW_C_HEAP_ARRAY(PLAB*, length, mtGC);
304 for (uint node_index = 0; node_index < length; node_index++) {
305 _alloc_buffers[state][node_index] = new PLAB(_g1h->desired_plab_sz(state));
306 }
307 }
308 }
309
310 G1PLABAllocator::~G1PLABAllocator() {
311 for (region_type_t state = 0; state < G1HeapRegionAttr::Num; state++) {
312 uint length = alloc_buffers_length(state);
313 for (uint node_index = 0; node_index < length; node_index++) {
314 delete _alloc_buffers[state][node_index];
315 }
316 FREE_C_HEAP_ARRAY(PLAB*, _alloc_buffers[state]);
317 }
318 }
319
320 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
321 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
322 }
323
324 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(G1HeapRegionAttr dest,
325 size_t word_sz,
326 bool* plab_refill_failed,
327 uint node_index) {
328 size_t plab_word_size = _g1h->desired_plab_sz(dest);
329 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
330
331 // Only get a new PLAB if the allocation fits and it would not waste more than
332 // ParallelGCBufferWastePct in the existing buffer.
333 if ((required_in_plab <= plab_word_size) &&
334 may_throw_away_buffer(required_in_plab, plab_word_size)) {
335
336 PLAB* alloc_buf = alloc_buffer(dest, node_index);
337 alloc_buf->retire();
338
339 size_t actual_plab_size = 0;
340 HeapWord* buf = _allocator->par_allocate_during_gc(dest,
341 required_in_plab,
342 plab_word_size,
343 &actual_plab_size,
344 node_index);
345
346 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
347 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
348 required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
349
350 if (buf != NULL) {
351 alloc_buf->set_buf(buf, actual_plab_size);
352
353 HeapWord* const obj = alloc_buf->allocate(word_sz);
354 assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
355 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
356 word_sz, required_in_plab, plab_word_size);
357 return obj;
358 }
359 // Otherwise.
360 *plab_refill_failed = true;
361 }
362 // Try direct allocation.
363 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, node_index);
364 if (result != NULL) {
365 _direct_allocated[dest.type()] += word_sz;
366 }
367 return result;
368 }
369
370 void G1PLABAllocator::undo_allocation(G1HeapRegionAttr dest, HeapWord* obj, size_t word_sz, uint node_index) {
371 alloc_buffer(dest, node_index)->undo_allocation(obj, word_sz);
372 }
373
374 void G1PLABAllocator::flush_and_retire_stats() {
375 for (region_type_t state = 0; state < G1HeapRegionAttr::Num; state++) {
376 G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
377 for (uint node_index = 0; node_index < alloc_buffers_length(state); node_index++) {
378 PLAB* const buf = alloc_buffer(state, node_index);
379 if (buf != NULL) {
380 buf->flush_and_retire_stats(stats);
381 }
382 }
383 stats->add_direct_allocated(_direct_allocated[state]);
384 _direct_allocated[state] = 0;
385 }
386 }
387
388 size_t G1PLABAllocator::waste() const {
389 size_t result = 0;
390 for (region_type_t state = 0; state < G1HeapRegionAttr::Num; state++) {
391 for (uint node_index = 0; node_index < alloc_buffers_length(state); node_index++) {
392 PLAB* const buf = alloc_buffer(state, node_index);
393 if (buf != NULL) {
394 result += buf->waste();
395 }
396 }
397 }
398 return result;
399 }
400
401 size_t G1PLABAllocator::undo_waste() const {
402 size_t result = 0;
403 for (region_type_t state = 0; state < G1HeapRegionAttr::Num; state++) {
404 for (uint node_index = 0; node_index < alloc_buffers_length(state); node_index++) {
405 PLAB* const buf = alloc_buffer(state, node_index);
406 if (buf != NULL) {
407 result += buf->undo_waste();
408 }
409 }
410 }
411 return result;
412 }
413
414 bool G1ArchiveAllocator::_archive_check_enabled = false;
415 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map;
416 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map;
417
418 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) {
419 // Create the archive allocator, and also enable archive object checking
420 // in mark-sweep, since we will be creating archive regions.
421 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h, open);
422 enable_archive_object_check();
423 return result;
424 }
425
426 bool G1ArchiveAllocator::alloc_new_region() {
427 // Allocate the highest free region in the reserved heap,
428 // and add it to our list of allocated regions. It is marked
429 // archive and added to the old set.
430 HeapRegion* hr = _g1h->alloc_highest_free_region();
431 if (hr == NULL) {
432 return false;
433 }
434 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
435 if (_open) {
436 hr->set_open_archive();
437 } else {
438 hr->set_closed_archive();
439 }
440 _g1h->policy()->remset_tracker()->update_at_allocate(hr);
441 _g1h->archive_set_add(hr);
442 _g1h->hr_printer()->alloc(hr);
443 _allocated_regions.append(hr);
444 _allocation_region = hr;
445
446 // Set up _bottom and _max to begin allocating in the lowest
447 // min_region_size'd chunk of the allocated G1 region.
448 _bottom = hr->bottom();
449 _max = _bottom + HeapRegion::min_region_size_in_words();
450
451 // Tell mark-sweep that objects in this region are not to be marked.
452 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open);
453
454 // Since we've modified the old set, call update_sizes.
455 _g1h->g1mm()->update_sizes();
456 return true;
457 }
458
459 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
460 assert(word_size != 0, "size must not be zero");
461 if (_allocation_region == NULL) {
462 if (!alloc_new_region()) {
463 return NULL;
464 }
465 }
466 HeapWord* old_top = _allocation_region->top();
467 assert(_bottom >= _allocation_region->bottom(),
468 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
469 p2i(_bottom), p2i(_allocation_region->bottom()));
470 assert(_max <= _allocation_region->end(),
471 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
472 p2i(_max), p2i(_allocation_region->end()));
473 assert(_bottom <= old_top && old_top <= _max,
474 "inconsistent allocation state: expected "
475 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
476 p2i(_bottom), p2i(old_top), p2i(_max));
477
478 // Allocate the next word_size words in the current allocation chunk.
479 // If allocation would cross the _max boundary, insert a filler and begin
480 // at the base of the next min_region_size'd chunk. Also advance to the next
481 // chunk if we don't yet cross the boundary, but the remainder would be too
482 // small to fill.
483 HeapWord* new_top = old_top + word_size;
484 size_t remainder = pointer_delta(_max, new_top);
485 if ((new_top > _max) ||
486 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
487 if (old_top != _max) {
488 size_t fill_size = pointer_delta(_max, old_top);
489 CollectedHeap::fill_with_object(old_top, fill_size);
490 _summary_bytes_used += fill_size * HeapWordSize;
491 }
492 _allocation_region->set_top(_max);
493 old_top = _bottom = _max;
494
495 // Check if we've just used up the last min_region_size'd chunk
496 // in the current region, and if so, allocate a new one.
497 if (_bottom != _allocation_region->end()) {
498 _max = _bottom + HeapRegion::min_region_size_in_words();
499 } else {
500 if (!alloc_new_region()) {
501 return NULL;
502 }
503 old_top = _allocation_region->bottom();
504 }
505 }
506 _allocation_region->set_top(old_top + word_size);
507 _summary_bytes_used += word_size * HeapWordSize;
508
509 return old_top;
510 }
511
512 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
513 size_t end_alignment_in_bytes) {
514 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
515 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
516 assert(is_aligned(end_alignment_in_bytes, HeapWordSize),
517 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
518
519 // If we've allocated nothing, simply return.
520 if (_allocation_region == NULL) {
521 return;
522 }
523
524 // If an end alignment was requested, insert filler objects.
525 if (end_alignment_in_bytes != 0) {
526 HeapWord* currtop = _allocation_region->top();
527 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes);
528 size_t fill_size = pointer_delta(newtop, currtop);
529 if (fill_size != 0) {
530 if (fill_size < CollectedHeap::min_fill_size()) {
531 // If the required fill is smaller than we can represent,
532 // bump up to the next aligned address. We know we won't exceed the current
533 // region boundary because the max supported alignment is smaller than the min
534 // region size, and because the allocation code never leaves space smaller than
535 // the min_fill_size at the top of the current allocation region.
536 newtop = align_up(currtop + CollectedHeap::min_fill_size(),
537 end_alignment_in_bytes);
538 fill_size = pointer_delta(newtop, currtop);
539 }
540 HeapWord* fill = archive_mem_allocate(fill_size);
541 CollectedHeap::fill_with_objects(fill, fill_size);
542 }
543 }
544
545 // Loop through the allocated regions, and create MemRegions summarizing
546 // the allocated address range, combining contiguous ranges. Add the
547 // MemRegions to the GrowableArray provided by the caller.
548 int index = _allocated_regions.length() - 1;
549 assert(_allocated_regions.at(index) == _allocation_region,
550 "expected region %u at end of array, found %u",
551 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
552 HeapWord* base_address = _allocation_region->bottom();
553 HeapWord* top = base_address;
554
555 while (index >= 0) {
556 HeapRegion* next = _allocated_regions.at(index);
557 HeapWord* new_base = next->bottom();
558 HeapWord* new_top = next->top();
559 if (new_base != top) {
560 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
561 base_address = new_base;
562 }
563 top = new_top;
564 index = index - 1;
565 }
566
567 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
568 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
569 _allocated_regions.clear();
570 _allocation_region = NULL;
571 };