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 "gc/shared/fill.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(InCSetState::Young)),
43 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)),
44 _retained_old_gc_alloc_region(NULL) {
45 }
46
47 void G1Allocator::init_mutator_alloc_region() {
48 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
49 _mutator_alloc_region.init();
50 }
51
52 void G1Allocator::release_mutator_alloc_region() {
53 _mutator_alloc_region.release();
54 assert(_mutator_alloc_region.get() == NULL, "post-condition");
55 }
56
57 bool G1Allocator::is_retained_old_region(HeapRegion* hr) {
58 return _retained_old_gc_alloc_region == hr;
59 }
60
61 void G1Allocator::reuse_retained_old_region(EvacuationInfo& 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 bool during_im = _g1h->collector_state()->in_initial_mark_gc();
89 retained_region->note_start_of_copying(during_im);
90 old->set(retained_region);
91 _g1h->hr_printer()->reuse(retained_region);
92 evacuation_info.set_alloc_regions_used_before(retained_region->used());
93 }
94 }
95
96 void G1Allocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
97 assert_at_safepoint_on_vm_thread();
98
99 _survivor_is_full = false;
100 _old_is_full = false;
101
102 _survivor_gc_alloc_region.init();
103 _old_gc_alloc_region.init();
104 reuse_retained_old_region(evacuation_info,
105 &_old_gc_alloc_region,
106 &_retained_old_gc_alloc_region);
107 }
108
109 void G1Allocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) {
110 evacuation_info.set_allocation_regions(survivor_gc_alloc_region()->count() +
111 old_gc_alloc_region()->count());
112 survivor_gc_alloc_region()->release();
113 // If we have an old GC alloc region to release, we'll save it in
114 // _retained_old_gc_alloc_region. If we don't
115 // _retained_old_gc_alloc_region will become NULL. This is what we
116 // want either way so no reason to check explicitly for either
117 // condition.
118 _retained_old_gc_alloc_region = old_gc_alloc_region()->release();
119 }
120
121 void G1Allocator::abandon_gc_alloc_regions() {
122 assert(survivor_gc_alloc_region()->get() == NULL, "pre-condition");
123 assert(old_gc_alloc_region()->get() == NULL, "pre-condition");
124 _retained_old_gc_alloc_region = NULL;
125 }
126
127 bool G1Allocator::survivor_is_full() const {
128 return _survivor_is_full;
129 }
130
131 bool G1Allocator::old_is_full() const {
132 return _old_is_full;
133 }
134
135 void G1Allocator::set_survivor_full() {
136 _survivor_is_full = true;
137 }
138
139 void G1Allocator::set_old_full() {
140 _old_is_full = true;
141 }
142
143 size_t G1Allocator::unsafe_max_tlab_alloc() {
144 // Return the remaining space in the cur alloc region, but not less than
145 // the min TLAB size.
146
147 // Also, this value can be at most the humongous object threshold,
148 // since we can't allow tlabs to grow big enough to accommodate
149 // humongous objects.
150
151 HeapRegion* hr = mutator_alloc_region()->get();
152 size_t max_tlab = _g1h->max_tlab_size() * wordSize;
153 if (hr == NULL) {
154 return max_tlab;
155 } else {
156 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
157 }
158 }
159
160 size_t G1Allocator::used_in_alloc_regions() {
161 assert(Heap_lock->owner() != NULL, "Should be owned on this thread's behalf.");
162 return mutator_alloc_region()->used_in_alloc_regions();
163 }
164
165
166 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
167 size_t word_size) {
168 size_t temp = 0;
169 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp);
170 assert(result == NULL || temp == word_size,
171 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
172 word_size, temp, p2i(result));
173 return result;
174 }
175
176 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
177 size_t min_word_size,
178 size_t desired_word_size,
179 size_t* actual_word_size) {
180 switch (dest.value()) {
181 case InCSetState::Young:
182 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
183 case InCSetState::Old:
184 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size);
185 default:
186 ShouldNotReachHere();
187 return NULL; // Keep some compilers happy
188 }
189 }
190
191 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
192 size_t desired_word_size,
193 size_t* actual_word_size) {
194 assert(!_g1h->is_humongous(desired_word_size),
195 "we should not be seeing humongous-size allocations in this path");
196
197 HeapWord* result = survivor_gc_alloc_region()->attempt_allocation(min_word_size,
198 desired_word_size,
199 actual_word_size);
200 if (result == NULL && !survivor_is_full()) {
201 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
202 result = survivor_gc_alloc_region()->attempt_allocation_locked(min_word_size,
203 desired_word_size,
204 actual_word_size);
205 if (result == NULL) {
206 set_survivor_full();
207 }
208 }
209 if (result != NULL) {
210 _g1h->dirty_young_block(result, *actual_word_size);
211 }
212 return result;
213 }
214
215 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
216 size_t desired_word_size,
217 size_t* actual_word_size) {
218 assert(!_g1h->is_humongous(desired_word_size),
219 "we should not be seeing humongous-size allocations in this path");
220
221 HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size,
222 desired_word_size,
223 actual_word_size);
224 if (result == NULL && !old_is_full()) {
225 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
226 result = old_gc_alloc_region()->attempt_allocation_locked(min_word_size,
227 desired_word_size,
228 actual_word_size);
229 if (result == NULL) {
230 set_old_full();
231 }
232 }
233 return result;
234 }
235
236 uint G1PLABAllocator::calc_survivor_alignment_bytes() {
237 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
238 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
239 // No need to align objects in the survivors differently, return 0
240 // which means "survivor alignment is not used".
241 return 0;
242 } else {
243 assert(SurvivorAlignmentInBytes > 0, "sanity");
244 return SurvivorAlignmentInBytes;
245 }
246 }
247
248 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
249 _g1h(G1CollectedHeap::heap()),
250 _allocator(allocator),
251 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)),
252 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)),
253 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
254 for (uint state = 0; state < InCSetState::Num; state++) {
255 _direct_allocated[state] = 0;
256 _alloc_buffers[state] = NULL;
257 }
258 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;
259 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer;
260 }
261
262 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
263 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
264 }
265
266 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest,
267 size_t word_sz,
268 bool* plab_refill_failed) {
269 size_t plab_word_size = _g1h->desired_plab_sz(dest);
270 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
271
272 // Only get a new PLAB if the allocation fits and it would not waste more than
273 // ParallelGCBufferWastePct in the existing buffer.
274 if ((required_in_plab <= plab_word_size) &&
275 may_throw_away_buffer(required_in_plab, plab_word_size)) {
276
277 PLAB* alloc_buf = alloc_buffer(dest);
278 alloc_buf->retire();
279
280 size_t actual_plab_size = 0;
281 HeapWord* buf = _allocator->par_allocate_during_gc(dest,
282 required_in_plab,
283 plab_word_size,
284 &actual_plab_size);
285
286 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
287 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
288 required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
289
290 if (buf != NULL) {
291 alloc_buf->set_buf(buf, actual_plab_size);
292
293 HeapWord* const obj = alloc_buf->allocate(word_sz);
294 assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
295 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
296 word_sz, required_in_plab, plab_word_size);
297 return obj;
298 }
299 // Otherwise.
300 *plab_refill_failed = true;
301 }
302 // Try direct allocation.
303 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz);
304 if (result != NULL) {
305 _direct_allocated[dest.value()] += word_sz;
306 }
307 return result;
308 }
309
310 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz) {
311 alloc_buffer(dest)->undo_allocation(obj, word_sz);
312 }
313
314 void G1PLABAllocator::flush_and_retire_stats() {
315 for (uint state = 0; state < InCSetState::Num; state++) {
316 PLAB* const buf = _alloc_buffers[state];
317 if (buf != NULL) {
318 G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
319 buf->flush_and_retire_stats(stats);
320 stats->add_direct_allocated(_direct_allocated[state]);
321 _direct_allocated[state] = 0;
322 }
323 }
324 }
325
326 void G1PLABAllocator::waste(size_t& wasted, size_t& undo_wasted) {
327 wasted = 0;
328 undo_wasted = 0;
329 for (uint state = 0; state < InCSetState::Num; state++) {
330 PLAB * const buf = _alloc_buffers[state];
331 if (buf != NULL) {
332 wasted += buf->waste();
333 undo_wasted += buf->undo_waste();
334 }
335 }
336 }
337
338 bool G1ArchiveAllocator::_archive_check_enabled = false;
339 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map;
340 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map;
341
342 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) {
343 // Create the archive allocator, and also enable archive object checking
344 // in mark-sweep, since we will be creating archive regions.
345 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h, open);
346 enable_archive_object_check();
347 return result;
348 }
349
350 bool G1ArchiveAllocator::alloc_new_region() {
351 // Allocate the highest free region in the reserved heap,
352 // and add it to our list of allocated regions. It is marked
353 // archive and added to the old set.
354 HeapRegion* hr = _g1h->alloc_highest_free_region();
355 if (hr == NULL) {
356 return false;
357 }
358 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
359 if (_open) {
360 hr->set_open_archive();
361 } else {
362 hr->set_closed_archive();
363 }
364 _g1h->g1_policy()->remset_tracker()->update_at_allocate(hr);
365 _g1h->archive_set_add(hr);
366 _g1h->hr_printer()->alloc(hr);
367 _allocated_regions.append(hr);
368 _allocation_region = hr;
369
370 // Set up _bottom and _max to begin allocating in the lowest
371 // min_region_size'd chunk of the allocated G1 region.
372 _bottom = hr->bottom();
373 _max = _bottom + HeapRegion::min_region_size_in_words();
374
375 // Tell mark-sweep that objects in this region are not to be marked.
376 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open);
377
378 // Since we've modified the old set, call update_sizes.
379 _g1h->g1mm()->update_sizes();
380 return true;
381 }
382
383 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
384 assert(word_size != 0, "size must not be zero");
385 if (_allocation_region == NULL) {
386 if (!alloc_new_region()) {
387 return NULL;
388 }
389 }
390 HeapWord* old_top = _allocation_region->top();
391 assert(_bottom >= _allocation_region->bottom(),
392 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
393 p2i(_bottom), p2i(_allocation_region->bottom()));
394 assert(_max <= _allocation_region->end(),
395 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
396 p2i(_max), p2i(_allocation_region->end()));
397 assert(_bottom <= old_top && old_top <= _max,
398 "inconsistent allocation state: expected "
399 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
400 p2i(_bottom), p2i(old_top), p2i(_max));
401
402 // Allocate the next word_size words in the current allocation chunk.
403 // If allocation would cross the _max boundary, insert a filler and begin
404 // at the base of the next min_region_size'd chunk. Also advance to the next
405 // chunk if we don't yet cross the boundary, but the remainder would be too
406 // small to fill.
407 HeapWord* new_top = old_top + word_size;
408 size_t remainder = pointer_delta(_max, new_top);
409 if ((new_top > _max) ||
410 ((new_top < _max) && (remainder < Fill::min_size()))) {
411 if (old_top != _max) {
412 size_t fill_size = pointer_delta(_max, old_top);
413 Fill::range(old_top, fill_size);
414 _summary_bytes_used += fill_size * HeapWordSize;
415 }
416 _allocation_region->set_top(_max);
417 old_top = _bottom = _max;
418
419 // Check if we've just used up the last min_region_size'd chunk
420 // in the current region, and if so, allocate a new one.
421 if (_bottom != _allocation_region->end()) {
422 _max = _bottom + HeapRegion::min_region_size_in_words();
423 } else {
424 if (!alloc_new_region()) {
425 return NULL;
426 }
427 old_top = _allocation_region->bottom();
428 }
429 }
430 _allocation_region->set_top(old_top + word_size);
431 _summary_bytes_used += word_size * HeapWordSize;
432
433 return old_top;
434 }
435
436 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
437 size_t end_alignment_in_bytes) {
438 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
439 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
440 assert(is_aligned(end_alignment_in_bytes, HeapWordSize),
441 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
442
443 // If we've allocated nothing, simply return.
444 if (_allocation_region == NULL) {
445 return;
446 }
447
448 // If an end alignment was requested, insert filler objects.
449 if (end_alignment_in_bytes != 0) {
450 HeapWord* currtop = _allocation_region->top();
451 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes);
452 size_t fill_size = pointer_delta(newtop, currtop);
453 if (fill_size != 0) {
454 if (fill_size < Fill::min_size()) {
455 // If the required fill is smaller than we can represent,
456 // bump up to the next aligned address. We know we won't exceed the current
457 // region boundary because the max supported alignment is smaller than the min
458 // region size, and because the allocation code never leaves space smaller than
459 // the Fill::min_size() at the top of the current allocation region.
460 newtop = align_up(currtop + Fill::min_size(), end_alignment_in_bytes);
461 fill_size = pointer_delta(newtop, currtop);
462 }
463 HeapWord* fill = archive_mem_allocate(fill_size);
464 Fill::range(fill, fill_size);
465 }
466 }
467
468 // Loop through the allocated regions, and create MemRegions summarizing
469 // the allocated address range, combining contiguous ranges. Add the
470 // MemRegions to the GrowableArray provided by the caller.
471 int index = _allocated_regions.length() - 1;
472 assert(_allocated_regions.at(index) == _allocation_region,
473 "expected region %u at end of array, found %u",
474 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
475 HeapWord* base_address = _allocation_region->bottom();
476 HeapWord* top = base_address;
477
478 while (index >= 0) {
479 HeapRegion* next = _allocated_regions.at(index);
480 HeapWord* new_base = next->bottom();
481 HeapWord* new_top = next->top();
482 if (new_base != top) {
483 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
484 base_address = new_base;
485 }
486 top = new_top;
487 index = index - 1;
488 }
489
490 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
491 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
492 _allocated_regions.clear();
493 _allocation_region = NULL;
494 };