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_region(heap->alloc_buffer_stats(G1HeapRegionAttr::Young)),
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 for (uint i = 0; i < _num_alloc_regions; i++) {
51 ::new(_mutator_alloc_regions + i) MutatorAllocRegion(i);
52 }
53 }
54
55 G1Allocator::~G1Allocator() {
56 for (uint i = 0; i < _num_alloc_regions; i++) {
57 _mutator_alloc_regions[i].~MutatorAllocRegion();
58 }
59 FREE_C_HEAP_ARRAY(MutatorAllocRegion, _mutator_alloc_regions);
60 }
61
62 #ifdef ASSERT
63 bool G1Allocator::has_mutator_alloc_region() {
64 uint node_index = current_node_index();
65 return mutator_alloc_region(node_index)->get() != NULL;
66 }
67 #endif
68
69 void G1Allocator::init_mutator_alloc_regions() {
70 for (uint i = 0; i < _num_alloc_regions; i++) {
71 assert(mutator_alloc_region(i)->get() == NULL, "pre-condition");
72 mutator_alloc_region(i)->init();
73 }
74 }
75
76 void G1Allocator::release_mutator_alloc_regions() {
77 for (uint i = 0; i < _num_alloc_regions; i++) {
78 mutator_alloc_region(i)->release();
79 assert(mutator_alloc_region(i)->get() == NULL, "post-condition");
80 }
81 }
82
83 bool G1Allocator::is_retained_old_region(HeapRegion* hr) {
84 return _retained_old_gc_alloc_region == hr;
85 }
86
87 void G1Allocator::reuse_retained_old_region(G1EvacuationInfo& evacuation_info,
88 OldGCAllocRegion* old,
89 HeapRegion** retained_old) {
90 HeapRegion* retained_region = *retained_old;
91 *retained_old = NULL;
92 assert(retained_region == NULL || !retained_region->is_archive(),
93 "Archive region should not be alloc region (index %u)", retained_region->hrm_index());
94
95 // We will discard the current GC alloc region if:
96 // a) it's in the collection set (it can happen!),
97 // b) it's already full (no point in using it),
98 // c) it's empty (this means that it was emptied during
99 // a cleanup and it should be on the free list now), or
100 // d) it's humongous (this means that it was emptied
101 // during a cleanup and was added to the free list, but
102 // has been subsequently used to allocate a humongous
103 // object that may be less than the region size).
104 if (retained_region != NULL &&
105 !retained_region->in_collection_set() &&
106 !(retained_region->top() == retained_region->end()) &&
107 !retained_region->is_empty() &&
108 !retained_region->is_humongous()) {
109 // The retained region was added to the old region set when it was
110 // retired. We have to remove it now, since we don't allow regions
111 // we allocate to in the region sets. We'll re-add it later, when
112 // it's retired again.
113 _g1h->old_set_remove(retained_region);
114 old->set(retained_region);
115 _g1h->hr_printer()->reuse(retained_region);
116 evacuation_info.set_alloc_regions_used_before(retained_region->used());
117 }
118 }
119
120 void G1Allocator::init_gc_alloc_regions(G1EvacuationInfo& evacuation_info) {
121 assert_at_safepoint_on_vm_thread();
122
123 _survivor_is_full = false;
124 _old_is_full = false;
125
126 _survivor_gc_alloc_region.init();
127 _old_gc_alloc_region.init();
128 reuse_retained_old_region(evacuation_info,
129 &_old_gc_alloc_region,
130 &_retained_old_gc_alloc_region);
131 }
132
133 void G1Allocator::release_gc_alloc_regions(G1EvacuationInfo& evacuation_info) {
134 evacuation_info.set_allocation_regions(survivor_gc_alloc_region()->count() +
135 old_gc_alloc_region()->count());
136 survivor_gc_alloc_region()->release();
137 // If we have an old GC alloc region to release, we'll save it in
138 // _retained_old_gc_alloc_region. If we don't
139 // _retained_old_gc_alloc_region will become NULL. This is what we
140 // want either way so no reason to check explicitly for either
141 // condition.
142 _retained_old_gc_alloc_region = old_gc_alloc_region()->release();
143 }
144
145 void G1Allocator::abandon_gc_alloc_regions() {
146 assert(survivor_gc_alloc_region()->get() == NULL, "pre-condition");
147 assert(old_gc_alloc_region()->get() == NULL, "pre-condition");
148 _retained_old_gc_alloc_region = NULL;
149 }
150
151 bool G1Allocator::survivor_is_full() const {
152 return _survivor_is_full;
153 }
154
155 bool G1Allocator::old_is_full() const {
156 return _old_is_full;
157 }
158
159 void G1Allocator::set_survivor_full() {
160 _survivor_is_full = true;
161 }
162
163 void G1Allocator::set_old_full() {
164 _old_is_full = true;
165 }
166
167 size_t G1Allocator::unsafe_max_tlab_alloc() {
168 // Return the remaining space in the cur alloc region, but not less than
169 // the min TLAB size.
170
171 // Also, this value can be at most the humongous object threshold,
172 // since we can't allow tlabs to grow big enough to accommodate
173 // humongous objects.
174
175 uint node_index = current_node_index();
176 HeapRegion* hr = mutator_alloc_region(node_index)->get();
177 size_t max_tlab = _g1h->max_tlab_size() * wordSize;
178 if (hr == NULL) {
179 return max_tlab;
180 } else {
181 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
182 }
183 }
184
185 size_t G1Allocator::used_in_alloc_regions() {
186 assert(Heap_lock->owner() != NULL, "Should be owned on this thread's behalf.");
187 size_t used = 0;
188 for (uint i = 0; i < _num_alloc_regions; i++) {
189 used += mutator_alloc_region(i)->used_in_alloc_regions();
190 }
191 return used;
192 }
193
194
195 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest,
196 size_t word_size) {
197 size_t temp = 0;
198 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp);
199 assert(result == NULL || temp == word_size,
200 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
201 word_size, temp, p2i(result));
202 return result;
203 }
204
205 HeapWord* G1Allocator::par_allocate_during_gc(G1HeapRegionAttr dest,
206 size_t min_word_size,
207 size_t desired_word_size,
208 size_t* actual_word_size) {
209 switch (dest.type()) {
210 case G1HeapRegionAttr::Young:
211 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
212 case G1HeapRegionAttr::Old:
213 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
214 default:
215 ShouldNotReachHere();
216 return NULL; // Keep some compilers happy
217 }
218 }
219
220 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
221 size_t desired_word_size,
222 size_t* actual_word_size) {
223 assert(!_g1h->is_humongous(desired_word_size),
224 "we should not be seeing humongous-size allocations in this path");
225
226 HeapWord* result = survivor_gc_alloc_region()->attempt_allocation(min_word_size,
227 desired_word_size,
228 actual_word_size);
229 if (result == NULL && !survivor_is_full()) {
230 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
231 result = survivor_gc_alloc_region()->attempt_allocation_locked(min_word_size,
232 desired_word_size,
233 actual_word_size);
234 if (result == NULL) {
235 set_survivor_full();
236 }
237 }
238 if (result != NULL) {
239 _g1h->dirty_young_block(result, *actual_word_size);
240 }
241 return result;
242 }
243
244 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
245 size_t desired_word_size,
246 size_t* actual_word_size) {
247 assert(!_g1h->is_humongous(desired_word_size),
248 "we should not be seeing humongous-size allocations in this path");
249
250 HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size,
251 desired_word_size,
252 actual_word_size);
253 if (result == NULL && !old_is_full()) {
254 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
255 result = old_gc_alloc_region()->attempt_allocation_locked(min_word_size,
256 desired_word_size,
257 actual_word_size);
258 if (result == NULL) {
259 set_old_full();
260 }
261 }
262 return result;
263 }
264
265 uint G1PLABAllocator::calc_survivor_alignment_bytes() {
266 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
267 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
268 // No need to align objects in the survivors differently, return 0
269 // which means "survivor alignment is not used".
270 return 0;
271 } else {
272 assert(SurvivorAlignmentInBytes > 0, "sanity");
273 return SurvivorAlignmentInBytes;
274 }
275 }
276
277 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
278 _g1h(G1CollectedHeap::heap()),
279 _allocator(allocator),
280 _surviving_alloc_buffer(_g1h->desired_plab_sz(G1HeapRegionAttr::Young)),
281 _tenured_alloc_buffer(_g1h->desired_plab_sz(G1HeapRegionAttr::Old)),
282 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
283 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
284 _direct_allocated[state] = 0;
285 _alloc_buffers[state] = NULL;
286 }
287 _alloc_buffers[G1HeapRegionAttr::Young] = &_surviving_alloc_buffer;
288 _alloc_buffers[G1HeapRegionAttr::Old] = &_tenured_alloc_buffer;
289 }
290
291 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
292 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
293 }
294
295 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(G1HeapRegionAttr dest,
296 size_t word_sz,
297 bool* plab_refill_failed) {
298 size_t plab_word_size = _g1h->desired_plab_sz(dest);
299 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
300
301 // Only get a new PLAB if the allocation fits and it would not waste more than
302 // ParallelGCBufferWastePct in the existing buffer.
303 if ((required_in_plab <= plab_word_size) &&
304 may_throw_away_buffer(required_in_plab, plab_word_size)) {
305
306 PLAB* alloc_buf = alloc_buffer(dest);
307 alloc_buf->retire();
308
309 size_t actual_plab_size = 0;
310 HeapWord* buf = _allocator->par_allocate_during_gc(dest,
311 required_in_plab,
312 plab_word_size,
313 &actual_plab_size);
314
315 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
316 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
317 required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
318
319 if (buf != NULL) {
320 alloc_buf->set_buf(buf, actual_plab_size);
321
322 HeapWord* const obj = alloc_buf->allocate(word_sz);
323 assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
324 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
325 word_sz, required_in_plab, plab_word_size);
326 return obj;
327 }
328 // Otherwise.
329 *plab_refill_failed = true;
330 }
331 // Try direct allocation.
332 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz);
333 if (result != NULL) {
334 _direct_allocated[dest.type()] += word_sz;
335 }
336 return result;
337 }
338
339 void G1PLABAllocator::undo_allocation(G1HeapRegionAttr dest, HeapWord* obj, size_t word_sz) {
340 alloc_buffer(dest)->undo_allocation(obj, word_sz);
341 }
342
343 void G1PLABAllocator::flush_and_retire_stats() {
344 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
345 PLAB* const buf = _alloc_buffers[state];
346 if (buf != NULL) {
347 G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
348 buf->flush_and_retire_stats(stats);
349 stats->add_direct_allocated(_direct_allocated[state]);
350 _direct_allocated[state] = 0;
351 }
352 }
353 }
354
355 size_t G1PLABAllocator::waste() const {
356 size_t result = 0;
357 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
358 PLAB * const buf = _alloc_buffers[state];
359 if (buf != NULL) {
360 result += buf->waste();
361 }
362 }
363 return result;
364 }
365
366 size_t G1PLABAllocator::undo_waste() const {
367 size_t result = 0;
368 for (uint state = 0; state < G1HeapRegionAttr::Num; state++) {
369 PLAB * const buf = _alloc_buffers[state];
370 if (buf != NULL) {
371 result += buf->undo_waste();
372 }
373 }
374 return result;
375 }
376
377 bool G1ArchiveAllocator::_archive_check_enabled = false;
378 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map;
379 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map;
380
381 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) {
382 // Create the archive allocator, and also enable archive object checking
383 // in mark-sweep, since we will be creating archive regions.
384 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h, open);
385 enable_archive_object_check();
386 return result;
387 }
388
389 bool G1ArchiveAllocator::alloc_new_region() {
390 // Allocate the highest free region in the reserved heap,
391 // and add it to our list of allocated regions. It is marked
392 // archive and added to the old set.
393 HeapRegion* hr = _g1h->alloc_highest_free_region();
394 if (hr == NULL) {
395 return false;
396 }
397 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
398 if (_open) {
399 hr->set_open_archive();
400 } else {
401 hr->set_closed_archive();
402 }
403 _g1h->policy()->remset_tracker()->update_at_allocate(hr);
404 _g1h->archive_set_add(hr);
405 _g1h->hr_printer()->alloc(hr);
406 _allocated_regions.append(hr);
407 _allocation_region = hr;
408
409 // Set up _bottom and _max to begin allocating in the lowest
410 // min_region_size'd chunk of the allocated G1 region.
411 _bottom = hr->bottom();
412 _max = _bottom + HeapRegion::min_region_size_in_words();
413
414 // Tell mark-sweep that objects in this region are not to be marked.
415 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open);
416
417 // Since we've modified the old set, call update_sizes.
418 _g1h->g1mm()->update_sizes();
419 return true;
420 }
421
422 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
423 assert(word_size != 0, "size must not be zero");
424 if (_allocation_region == NULL) {
425 if (!alloc_new_region()) {
426 return NULL;
427 }
428 }
429 HeapWord* old_top = _allocation_region->top();
430 assert(_bottom >= _allocation_region->bottom(),
431 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
432 p2i(_bottom), p2i(_allocation_region->bottom()));
433 assert(_max <= _allocation_region->end(),
434 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
435 p2i(_max), p2i(_allocation_region->end()));
436 assert(_bottom <= old_top && old_top <= _max,
437 "inconsistent allocation state: expected "
438 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
439 p2i(_bottom), p2i(old_top), p2i(_max));
440
441 // Allocate the next word_size words in the current allocation chunk.
442 // If allocation would cross the _max boundary, insert a filler and begin
443 // at the base of the next min_region_size'd chunk. Also advance to the next
444 // chunk if we don't yet cross the boundary, but the remainder would be too
445 // small to fill.
446 HeapWord* new_top = old_top + word_size;
447 size_t remainder = pointer_delta(_max, new_top);
448 if ((new_top > _max) ||
449 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
450 if (old_top != _max) {
451 size_t fill_size = pointer_delta(_max, old_top);
452 CollectedHeap::fill_with_object(old_top, fill_size);
453 _summary_bytes_used += fill_size * HeapWordSize;
454 }
455 _allocation_region->set_top(_max);
456 old_top = _bottom = _max;
457
458 // Check if we've just used up the last min_region_size'd chunk
459 // in the current region, and if so, allocate a new one.
460 if (_bottom != _allocation_region->end()) {
461 _max = _bottom + HeapRegion::min_region_size_in_words();
462 } else {
463 if (!alloc_new_region()) {
464 return NULL;
465 }
466 old_top = _allocation_region->bottom();
467 }
468 }
469 _allocation_region->set_top(old_top + word_size);
470 _summary_bytes_used += word_size * HeapWordSize;
471
472 return old_top;
473 }
474
475 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
476 size_t end_alignment_in_bytes) {
477 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
478 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
479 assert(is_aligned(end_alignment_in_bytes, HeapWordSize),
480 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
481
482 // If we've allocated nothing, simply return.
483 if (_allocation_region == NULL) {
484 return;
485 }
486
487 // If an end alignment was requested, insert filler objects.
488 if (end_alignment_in_bytes != 0) {
489 HeapWord* currtop = _allocation_region->top();
490 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes);
491 size_t fill_size = pointer_delta(newtop, currtop);
492 if (fill_size != 0) {
493 if (fill_size < CollectedHeap::min_fill_size()) {
494 // If the required fill is smaller than we can represent,
495 // bump up to the next aligned address. We know we won't exceed the current
496 // region boundary because the max supported alignment is smaller than the min
497 // region size, and because the allocation code never leaves space smaller than
498 // the min_fill_size at the top of the current allocation region.
499 newtop = align_up(currtop + CollectedHeap::min_fill_size(),
500 end_alignment_in_bytes);
501 fill_size = pointer_delta(newtop, currtop);
502 }
503 HeapWord* fill = archive_mem_allocate(fill_size);
504 CollectedHeap::fill_with_objects(fill, fill_size);
505 }
506 }
507
508 // Loop through the allocated regions, and create MemRegions summarizing
509 // the allocated address range, combining contiguous ranges. Add the
510 // MemRegions to the GrowableArray provided by the caller.
511 int index = _allocated_regions.length() - 1;
512 assert(_allocated_regions.at(index) == _allocation_region,
513 "expected region %u at end of array, found %u",
514 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
515 HeapWord* base_address = _allocation_region->bottom();
516 HeapWord* top = base_address;
517
518 while (index >= 0) {
519 HeapRegion* next = _allocated_regions.at(index);
520 HeapWord* new_base = next->bottom();
521 HeapWord* new_top = next->top();
522 if (new_base != top) {
523 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
524 base_address = new_base;
525 }
526 top = new_top;
527 index = index - 1;
528 }
529
530 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
531 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
532 _allocated_regions.clear();
533 _allocation_region = NULL;
534 };