1 /*
2 * Copyright (c) 2014, 2018, 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/g1Policy.hpp"
31 #include "gc/g1/heapRegion.inline.hpp"
32 #include "gc/g1/heapRegionSet.inline.hpp"
33 #include "gc/g1/heapRegionType.hpp"
34 #include "utilities/align.hpp"
35
36 G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) :
37 G1Allocator(heap),
38 _survivor_is_full(false),
39 _old_is_full(false),
40 _retained_old_gc_alloc_region(NULL),
41 _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)),
42 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) {
43 }
44
45 void G1DefaultAllocator::init_mutator_alloc_region() {
46 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
47 _mutator_alloc_region.init();
48 }
49
50 void G1DefaultAllocator::release_mutator_alloc_region() {
51 _mutator_alloc_region.release();
52 assert(_mutator_alloc_region.get() == NULL, "post-condition");
53 }
54
55 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,
56 OldGCAllocRegion* old,
57 HeapRegion** retained_old) {
58 HeapRegion* retained_region = *retained_old;
59 *retained_old = NULL;
60 assert(retained_region == NULL || !retained_region->is_archive(),
61 "Archive region should not be alloc region (index %u)", retained_region->hrm_index());
62
63 // We will discard the current GC alloc region if:
64 // a) it's in the collection set (it can happen!),
65 // b) it's already full (no point in using it),
66 // c) it's empty (this means that it was emptied during
67 // a cleanup and it should be on the free list now), or
68 // d) it's humongous (this means that it was emptied
69 // during a cleanup and was added to the free list, but
70 // has been subsequently used to allocate a humongous
71 // object that may be less than the region size).
72 if (retained_region != NULL &&
73 !retained_region->in_collection_set() &&
74 !(retained_region->top() == retained_region->end()) &&
75 !retained_region->is_empty() &&
76 !retained_region->is_humongous()) {
77 // The retained region was added to the old region set when it was
78 // retired. We have to remove it now, since we don't allow regions
79 // we allocate to in the region sets. We'll re-add it later, when
80 // it's retired again.
81 _g1h->old_set_remove(retained_region);
82 bool during_im = _g1h->collector_state()->in_initial_mark_gc();
83 retained_region->note_start_of_copying(during_im);
84 old->set(retained_region);
85 _g1h->hr_printer()->reuse(retained_region);
86 evacuation_info.set_alloc_regions_used_before(retained_region->used());
87 }
88 }
89
90 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
91 assert_at_safepoint_on_vm_thread();
92
93 _survivor_is_full = false;
94 _old_is_full = false;
95
96 _survivor_gc_alloc_region.init();
97 _old_gc_alloc_region.init();
98 reuse_retained_old_region(evacuation_info,
99 &_old_gc_alloc_region,
100 &_retained_old_gc_alloc_region);
101 }
102
103 void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) {
104 evacuation_info.set_allocation_regions(survivor_gc_alloc_region()->count() +
105 old_gc_alloc_region()->count());
106 survivor_gc_alloc_region()->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()->release();
113 }
114
115 void G1DefaultAllocator::abandon_gc_alloc_regions() {
116 assert(survivor_gc_alloc_region()->get() == NULL, "pre-condition");
117 assert(old_gc_alloc_region()->get() == NULL, "pre-condition");
118 _retained_old_gc_alloc_region = NULL;
119 }
120
121 bool G1DefaultAllocator::survivor_is_full() const {
122 return _survivor_is_full;
123 }
124
125 bool G1DefaultAllocator::old_is_full() const {
126 return _old_is_full;
127 }
128
129 void G1DefaultAllocator::set_survivor_full() {
130 _survivor_is_full = true;
131 }
132
133 void G1DefaultAllocator::set_old_full() {
134 _old_is_full = true;
135 }
136
137 size_t G1Allocator::unsafe_max_tlab_alloc() {
138 // Return the remaining space in the cur alloc region, but not less than
139 // the min TLAB size.
140
141 // Also, this value can be at most the humongous object threshold,
142 // since we can't allow tlabs to grow big enough to accommodate
143 // humongous objects.
144
145 HeapRegion* hr = mutator_alloc_region()->get();
146 size_t max_tlab = _g1h->max_tlab_size() * wordSize;
147 if (hr == NULL) {
148 return max_tlab;
149 } else {
150 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
151 }
152 }
153
154 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
155 size_t word_size) {
156 size_t temp = 0;
157 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp);
158 assert(result == NULL || temp == word_size,
159 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
160 word_size, temp, p2i(result));
161 return result;
162 }
163
164 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
165 size_t min_word_size,
166 size_t desired_word_size,
167 size_t* actual_word_size) {
168 switch (dest.value()) {
169 case InCSetState::Young:
170 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
171 case InCSetState::Old:
172 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
173 default:
174 ShouldNotReachHere();
175 return NULL; // Keep some compilers happy
176 }
177 }
178
179 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
180 size_t desired_word_size,
181 size_t* actual_word_size) {
182 assert(!_g1h->is_humongous(desired_word_size),
183 "we should not be seeing humongous-size allocations in this path");
184
185 HeapWord* result = survivor_gc_alloc_region()->attempt_allocation(min_word_size,
186 desired_word_size,
187 actual_word_size);
188 if (result == NULL && !survivor_is_full()) {
189 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
190 result = survivor_gc_alloc_region()->attempt_allocation_locked(min_word_size,
191 desired_word_size,
192 actual_word_size);
193 if (result == NULL) {
194 set_survivor_full();
195 }
196 }
197 if (result != NULL) {
198 _g1h->dirty_young_block(result, *actual_word_size);
199 }
200 return result;
201 }
202
203 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
204 size_t desired_word_size,
205 size_t* actual_word_size) {
206 assert(!_g1h->is_humongous(desired_word_size),
207 "we should not be seeing humongous-size allocations in this path");
208
209 HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size,
210 desired_word_size,
211 actual_word_size);
212 if (result == NULL && !old_is_full()) {
213 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
214 result = old_gc_alloc_region()->attempt_allocation_locked(min_word_size,
215 desired_word_size,
216 actual_word_size);
217 if (result == NULL) {
218 set_old_full();
219 }
220 }
221 return result;
222 }
223
224 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
225 _g1h(G1CollectedHeap::heap()),
226 _allocator(allocator),
227 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
228 for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) {
229 _direct_allocated[i] = 0;
230 }
231 }
232
233 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
234 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
235 }
236
237 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest,
238 size_t word_sz,
239 bool* plab_refill_failed) {
240 size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest);
241 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
242
243 // Only get a new PLAB if the allocation fits and it would not waste more than
244 // ParallelGCBufferWastePct in the existing buffer.
245 if ((required_in_plab <= plab_word_size) &&
246 may_throw_away_buffer(required_in_plab, plab_word_size)) {
247
248 PLAB* alloc_buf = alloc_buffer(dest);
249 alloc_buf->retire();
250
251 size_t actual_plab_size = 0;
252 HeapWord* buf = _allocator->par_allocate_during_gc(dest,
253 required_in_plab,
254 plab_word_size,
255 &actual_plab_size);
256
257 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
258 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
259 required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
260
261 if (buf != NULL) {
262 alloc_buf->set_buf(buf, actual_plab_size);
263
264 HeapWord* const obj = alloc_buf->allocate(word_sz);
265 assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
266 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
267 word_sz, required_in_plab, plab_word_size);
268 return obj;
269 }
270 // Otherwise.
271 *plab_refill_failed = true;
272 }
273 // Try direct allocation.
274 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz);
275 if (result != NULL) {
276 _direct_allocated[dest.value()] += word_sz;
277 }
278 return result;
279 }
280
281 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz) {
282 alloc_buffer(dest)->undo_allocation(obj, word_sz);
283 }
284
285 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) :
286 G1PLABAllocator(allocator),
287 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)),
288 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) {
289 for (uint state = 0; state < InCSetState::Num; state++) {
290 _alloc_buffers[state] = NULL;
291 }
292 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;
293 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer;
294 }
295
296 void G1DefaultPLABAllocator::flush_and_retire_stats() {
297 for (uint state = 0; state < InCSetState::Num; state++) {
298 PLAB* const buf = _alloc_buffers[state];
299 if (buf != NULL) {
300 G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
301 buf->flush_and_retire_stats(stats);
302 stats->add_direct_allocated(_direct_allocated[state]);
303 _direct_allocated[state] = 0;
304 }
305 }
306 }
307
308 void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) {
309 wasted = 0;
310 undo_wasted = 0;
311 for (uint state = 0; state < InCSetState::Num; state++) {
312 PLAB * const buf = _alloc_buffers[state];
313 if (buf != NULL) {
314 wasted += buf->waste();
315 undo_wasted += buf->undo_waste();
316 }
317 }
318 }
319
320 bool G1ArchiveAllocator::_archive_check_enabled = false;
321 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map;
322 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map;
323
324 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) {
325 // Create the archive allocator, and also enable archive object checking
326 // in mark-sweep, since we will be creating archive regions.
327 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h, open);
328 enable_archive_object_check();
329 return result;
330 }
331
332 bool G1ArchiveAllocator::alloc_new_region() {
333 // Allocate the highest free region in the reserved heap,
334 // and add it to our list of allocated regions. It is marked
335 // archive and added to the old set.
336 HeapRegion* hr = _g1h->alloc_highest_free_region();
337 if (hr == NULL) {
338 return false;
339 }
340 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
341 if (_open) {
342 hr->set_open_archive();
343 } else {
344 hr->set_closed_archive();
345 }
346 _g1h->g1_policy()->remset_tracker()->update_at_allocate(hr);
347 _g1h->old_set_add(hr);
348 _g1h->hr_printer()->alloc(hr);
349 _allocated_regions.append(hr);
350 _allocation_region = hr;
351
352 // Set up _bottom and _max to begin allocating in the lowest
353 // min_region_size'd chunk of the allocated G1 region.
354 _bottom = hr->bottom();
355 _max = _bottom + HeapRegion::min_region_size_in_words();
356
357 // Tell mark-sweep that objects in this region are not to be marked.
358 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open);
359
360 // Since we've modified the old set, call update_sizes.
361 _g1h->g1mm()->update_sizes();
362 return true;
363 }
364
365 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
366 assert(word_size != 0, "size must not be zero");
367 if (_allocation_region == NULL) {
368 if (!alloc_new_region()) {
369 return NULL;
370 }
371 }
372 HeapWord* old_top = _allocation_region->top();
373 assert(_bottom >= _allocation_region->bottom(),
374 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
375 p2i(_bottom), p2i(_allocation_region->bottom()));
376 assert(_max <= _allocation_region->end(),
377 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
378 p2i(_max), p2i(_allocation_region->end()));
379 assert(_bottom <= old_top && old_top <= _max,
380 "inconsistent allocation state: expected "
381 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
382 p2i(_bottom), p2i(old_top), p2i(_max));
383
384 // Allocate the next word_size words in the current allocation chunk.
385 // If allocation would cross the _max boundary, insert a filler and begin
386 // at the base of the next min_region_size'd chunk. Also advance to the next
387 // chunk if we don't yet cross the boundary, but the remainder would be too
388 // small to fill.
389 HeapWord* new_top = old_top + word_size;
390 size_t remainder = pointer_delta(_max, new_top);
391 if ((new_top > _max) ||
392 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
393 if (old_top != _max) {
394 size_t fill_size = pointer_delta(_max, old_top);
395 CollectedHeap::fill_with_object(old_top, fill_size);
396 _summary_bytes_used += fill_size * HeapWordSize;
397 }
398 _allocation_region->set_top(_max);
399 old_top = _bottom = _max;
400
401 // Check if we've just used up the last min_region_size'd chunk
402 // in the current region, and if so, allocate a new one.
403 if (_bottom != _allocation_region->end()) {
404 _max = _bottom + HeapRegion::min_region_size_in_words();
405 } else {
406 if (!alloc_new_region()) {
407 return NULL;
408 }
409 old_top = _allocation_region->bottom();
410 }
411 }
412 _allocation_region->set_top(old_top + word_size);
413 _summary_bytes_used += word_size * HeapWordSize;
414
415 return old_top;
416 }
417
418 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
419 size_t end_alignment_in_bytes) {
420 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
421 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
422 assert(is_aligned(end_alignment_in_bytes, HeapWordSize),
423 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
424
425 // If we've allocated nothing, simply return.
426 if (_allocation_region == NULL) {
427 return;
428 }
429
430 // If an end alignment was requested, insert filler objects.
431 if (end_alignment_in_bytes != 0) {
432 HeapWord* currtop = _allocation_region->top();
433 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes);
434 size_t fill_size = pointer_delta(newtop, currtop);
435 if (fill_size != 0) {
436 if (fill_size < CollectedHeap::min_fill_size()) {
437 // If the required fill is smaller than we can represent,
438 // bump up to the next aligned address. We know we won't exceed the current
439 // region boundary because the max supported alignment is smaller than the min
440 // region size, and because the allocation code never leaves space smaller than
441 // the min_fill_size at the top of the current allocation region.
442 newtop = align_up(currtop + CollectedHeap::min_fill_size(),
443 end_alignment_in_bytes);
444 fill_size = pointer_delta(newtop, currtop);
445 }
446 HeapWord* fill = archive_mem_allocate(fill_size);
447 CollectedHeap::fill_with_objects(fill, fill_size);
448 }
449 }
450
451 // Loop through the allocated regions, and create MemRegions summarizing
452 // the allocated address range, combining contiguous ranges. Add the
453 // MemRegions to the GrowableArray provided by the caller.
454 int index = _allocated_regions.length() - 1;
455 assert(_allocated_regions.at(index) == _allocation_region,
456 "expected region %u at end of array, found %u",
457 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
458 HeapWord* base_address = _allocation_region->bottom();
459 HeapWord* top = base_address;
460
461 while (index >= 0) {
462 HeapRegion* next = _allocated_regions.at(index);
463 HeapWord* new_base = next->bottom();
464 HeapWord* new_top = next->top();
465 if (new_base != top) {
466 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
467 base_address = new_base;
468 }
469 top = new_top;
470 index = index - 1;
471 }
472
473 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
474 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
475 _allocated_regions.clear();
476 _allocation_region = NULL;
477 };