1 /*
2 * Copyright (c) 2014, 2017, 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/heapRegion.inline.hpp"
31 #include "gc/g1/heapRegionSet.inline.hpp"
32 #include "utilities/align.hpp"
33
34 G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) :
35 G1Allocator(heap),
36 _survivor_is_full(false),
37 _old_is_full(false),
38 _retained_old_gc_alloc_region(NULL),
39 _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)),
40 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) {
41 }
42
43 void G1DefaultAllocator::init_mutator_alloc_region() {
44 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
45 _mutator_alloc_region.init();
46 }
47
48 void G1DefaultAllocator::release_mutator_alloc_region() {
49 _mutator_alloc_region.release();
50 assert(_mutator_alloc_region.get() == NULL, "post-condition");
51 }
52
53 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,
54 OldGCAllocRegion* old,
55 HeapRegion** retained_old) {
56 HeapRegion* retained_region = *retained_old;
57 *retained_old = NULL;
58 assert(retained_region == NULL || !retained_region->is_archive(),
59 "Archive region should not be alloc region (index %u)", retained_region->hrm_index());
60
61 // We will discard the current GC alloc region if:
62 // a) it's in the collection set (it can happen!),
63 // b) it's already full (no point in using it),
64 // c) it's empty (this means that it was emptied during
65 // a cleanup and it should be on the free list now), or
66 // d) it's humongous (this means that it was emptied
67 // during a cleanup and was added to the free list, but
68 // has been subsequently used to allocate a humongous
69 // object that may be less than the region size).
70 if (retained_region != NULL &&
71 !retained_region->in_collection_set() &&
72 !(retained_region->top() == retained_region->end()) &&
73 !retained_region->is_empty() &&
74 !retained_region->is_humongous()) {
75 retained_region->record_timestamp();
76 // The retained region was added to the old region set when it was
77 // retired. We have to remove it now, since we don't allow regions
78 // we allocate to in the region sets. We'll re-add it later, when
79 // it's retired again.
80 _g1h->old_set_remove(retained_region);
81 bool during_im = _g1h->collector_state()->during_initial_mark_pause();
82 retained_region->note_start_of_copying(during_im);
83 old->set(retained_region);
84 _g1h->hr_printer()->reuse(retained_region);
85 evacuation_info.set_alloc_regions_used_before(retained_region->used());
86 }
87 }
88
89 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
90 assert_at_safepoint(true /* should_be_vm_thread */);
91
92 _survivor_is_full = false;
93 _old_is_full = false;
94
95 _survivor_gc_alloc_region.init();
96 _old_gc_alloc_region.init();
97 reuse_retained_old_region(evacuation_info,
98 &_old_gc_alloc_region,
99 &_retained_old_gc_alloc_region);
100 }
101
102 void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) {
103 AllocationContext_t context = AllocationContext::current();
104 evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() +
105 old_gc_alloc_region(context)->count());
106 survivor_gc_alloc_region(context)->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(context)->release();
113 }
114
115 void G1DefaultAllocator::abandon_gc_alloc_regions() {
116 assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
117 assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
118 _retained_old_gc_alloc_region = NULL;
119 }
120
121 bool G1DefaultAllocator::survivor_is_full(AllocationContext_t context) const {
122 return _survivor_is_full;
123 }
124
125 bool G1DefaultAllocator::old_is_full(AllocationContext_t context) const {
126 return _old_is_full;
127 }
128
129 void G1DefaultAllocator::set_survivor_full(AllocationContext_t context) {
130 _survivor_is_full = true;
131 }
132
133 void G1DefaultAllocator::set_old_full(AllocationContext_t context) {
134 _old_is_full = true;
135 }
136
137 G1PLAB::G1PLAB(size_t gclab_word_size) :
138 PLAB(gclab_word_size), _retired(true) { }
139
140 size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) {
141 // Return the remaining space in the cur alloc region, but not less than
142 // the min TLAB size.
143
144 // Also, this value can be at most the humongous object threshold,
145 // since we can't allow tlabs to grow big enough to accommodate
146 // humongous objects.
147
148 HeapRegion* hr = mutator_alloc_region(context)->get();
149 size_t max_tlab = _g1h->max_tlab_size() * wordSize;
150 if (hr == NULL) {
151 return max_tlab;
152 } else {
153 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
154 }
155 }
156
157 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
158 size_t word_size,
159 AllocationContext_t context) {
160 size_t temp = 0;
161 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp, context);
162 assert(result == NULL || temp == word_size,
163 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
164 word_size, temp, p2i(result));
165 return result;
166 }
167
168 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
169 size_t min_word_size,
170 size_t desired_word_size,
171 size_t* actual_word_size,
172 AllocationContext_t context) {
173 switch (dest.value()) {
174 case InCSetState::Young:
175 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
176 case InCSetState::Old:
177 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
178 default:
179 ShouldNotReachHere();
180 return NULL; // Keep some compilers happy
181 }
182 }
183
184 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
185 size_t desired_word_size,
186 size_t* actual_word_size,
187 AllocationContext_t context) {
188 assert(!_g1h->is_humongous(desired_word_size),
189 "we should not be seeing humongous-size allocations in this path");
190
191 HeapWord* result = survivor_gc_alloc_region(context)->attempt_allocation(min_word_size,
192 desired_word_size,
193 actual_word_size,
194 false /* bot_updates */);
195 if (result == NULL && !survivor_is_full(context)) {
196 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
197 result = survivor_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,
198 desired_word_size,
199 actual_word_size,
200 false /* bot_updates */);
201 if (result == NULL) {
202 set_survivor_full(context);
203 }
204 }
205 if (result != NULL) {
206 _g1h->dirty_young_block(result, *actual_word_size);
207 }
208 return result;
209 }
210
211 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
212 size_t desired_word_size,
213 size_t* actual_word_size,
214 AllocationContext_t context) {
215 assert(!_g1h->is_humongous(desired_word_size),
216 "we should not be seeing humongous-size allocations in this path");
217
218 HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(min_word_size,
219 desired_word_size,
220 actual_word_size,
221 true /* bot_updates */);
222 if (result == NULL && !old_is_full(context)) {
223 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
224 result = old_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,
225 desired_word_size,
226 actual_word_size,
227 true /* bot_updates */);
228 if (result == NULL) {
229 set_old_full(context);
230 }
231 }
232 return result;
233 }
234
235 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
236 _g1h(G1CollectedHeap::heap()),
237 _allocator(allocator),
238 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
239 for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) {
240 _direct_allocated[i] = 0;
241 }
242 }
243
244 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
245 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
246 }
247
248 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest,
249 size_t word_sz,
250 AllocationContext_t context,
251 bool* plab_refill_failed) {
252 size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest);
253 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
254
255 // Only get a new PLAB if the allocation fits and it would not waste more than
256 // ParallelGCBufferWastePct in the existing buffer.
257 if ((required_in_plab <= plab_word_size) &&
258 may_throw_away_buffer(required_in_plab, plab_word_size)) {
259
260 G1PLAB* alloc_buf = alloc_buffer(dest, context);
261 alloc_buf->retire();
262
263 size_t actual_plab_size = 0;
264 HeapWord* buf = _allocator->par_allocate_during_gc(dest,
265 required_in_plab,
266 plab_word_size,
267 &actual_plab_size,
268 context);
269
270 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
271 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
272 required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
273
274 if (buf != NULL) {
275 alloc_buf->set_buf(buf, actual_plab_size);
276
277 HeapWord* const obj = alloc_buf->allocate(word_sz);
278 assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
279 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
280 word_sz, required_in_plab, plab_word_size);
281 return obj;
282 }
283 // Otherwise.
284 *plab_refill_failed = true;
285 }
286 // Try direct allocation.
287 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context);
288 if (result != NULL) {
289 _direct_allocated[dest.value()] += word_sz;
290 }
291 return result;
292 }
293
294 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) {
295 alloc_buffer(dest, context)->undo_allocation(obj, word_sz);
296 }
297
298 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) :
299 G1PLABAllocator(allocator),
300 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)),
301 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) {
302 for (uint state = 0; state < InCSetState::Num; state++) {
303 _alloc_buffers[state] = NULL;
304 }
305 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;
306 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer;
307 }
308
309 void G1DefaultPLABAllocator::flush_and_retire_stats() {
310 for (uint state = 0; state < InCSetState::Num; state++) {
311 G1PLAB* const buf = _alloc_buffers[state];
312 if (buf != NULL) {
313 G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
314 buf->flush_and_retire_stats(stats);
315 stats->add_direct_allocated(_direct_allocated[state]);
316 _direct_allocated[state] = 0;
317 }
318 }
319 }
320
321 void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) {
322 wasted = 0;
323 undo_wasted = 0;
324 for (uint state = 0; state < InCSetState::Num; state++) {
325 G1PLAB * const buf = _alloc_buffers[state];
326 if (buf != NULL) {
327 wasted += buf->waste();
328 undo_wasted += buf->undo_waste();
329 }
330 }
331 }
332
333 bool G1ArchiveAllocator::_archive_check_enabled = false;
334 G1ArchiveRegionMap G1ArchiveAllocator::_archive_region_map;
335
336 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) {
337 // Create the archive allocator, and also enable archive object checking
338 // in mark-sweep, since we will be creating archive regions.
339 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h);
340 enable_archive_object_check();
341 return result;
342 }
343
344 bool G1ArchiveAllocator::alloc_new_region() {
345 // Allocate the highest free region in the reserved heap,
346 // and add it to our list of allocated regions. It is marked
347 // archive and added to the old set.
348 HeapRegion* hr = _g1h->alloc_highest_free_region();
349 if (hr == NULL) {
350 return false;
351 }
352 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
353 hr->set_archive();
354 _g1h->old_set_add(hr);
355 _g1h->hr_printer()->alloc(hr);
356 _allocated_regions.append(hr);
357 _allocation_region = hr;
358
359 // Set up _bottom and _max to begin allocating in the lowest
360 // min_region_size'd chunk of the allocated G1 region.
361 _bottom = hr->bottom();
362 _max = _bottom + HeapRegion::min_region_size_in_words();
363
364 // Tell mark-sweep that objects in this region are not to be marked.
365 set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), true);
366
367 // Since we've modified the old set, call update_sizes.
368 _g1h->g1mm()->update_sizes();
369 return true;
370 }
371
372 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
373 assert(word_size != 0, "size must not be zero");
374 if (_allocation_region == NULL) {
375 if (!alloc_new_region()) {
376 return NULL;
377 }
378 }
379 HeapWord* old_top = _allocation_region->top();
380 assert(_bottom >= _allocation_region->bottom(),
381 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
382 p2i(_bottom), p2i(_allocation_region->bottom()));
383 assert(_max <= _allocation_region->end(),
384 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
385 p2i(_max), p2i(_allocation_region->end()));
386 assert(_bottom <= old_top && old_top <= _max,
387 "inconsistent allocation state: expected "
388 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
389 p2i(_bottom), p2i(old_top), p2i(_max));
390
391 // Allocate the next word_size words in the current allocation chunk.
392 // If allocation would cross the _max boundary, insert a filler and begin
393 // at the base of the next min_region_size'd chunk. Also advance to the next
394 // chunk if we don't yet cross the boundary, but the remainder would be too
395 // small to fill.
396 HeapWord* new_top = old_top + word_size;
397 size_t remainder = pointer_delta(_max, new_top);
398 if ((new_top > _max) ||
399 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
400 if (old_top != _max) {
401 size_t fill_size = pointer_delta(_max, old_top);
402 CollectedHeap::fill_with_object(old_top, fill_size);
403 _summary_bytes_used += fill_size * HeapWordSize;
404 }
405 _allocation_region->set_top(_max);
406 old_top = _bottom = _max;
407
408 // Check if we've just used up the last min_region_size'd chunk
409 // in the current region, and if so, allocate a new one.
410 if (_bottom != _allocation_region->end()) {
411 _max = _bottom + HeapRegion::min_region_size_in_words();
412 } else {
413 if (!alloc_new_region()) {
414 return NULL;
415 }
416 old_top = _allocation_region->bottom();
417 }
418 }
419 _allocation_region->set_top(old_top + word_size);
420 _summary_bytes_used += word_size * HeapWordSize;
421
422 return old_top;
423 }
424
425 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
426 size_t end_alignment_in_bytes) {
427 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
428 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
429 assert(is_aligned(end_alignment_in_bytes, HeapWordSize),
430 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
431
432 // If we've allocated nothing, simply return.
433 if (_allocation_region == NULL) {
434 return;
435 }
436
437 // If an end alignment was requested, insert filler objects.
438 if (end_alignment_in_bytes != 0) {
439 HeapWord* currtop = _allocation_region->top();
440 HeapWord* newtop = align_up(currtop, end_alignment_in_bytes);
441 size_t fill_size = pointer_delta(newtop, currtop);
442 if (fill_size != 0) {
443 if (fill_size < CollectedHeap::min_fill_size()) {
444 // If the required fill is smaller than we can represent,
445 // bump up to the next aligned address. We know we won't exceed the current
446 // region boundary because the max supported alignment is smaller than the min
447 // region size, and because the allocation code never leaves space smaller than
448 // the min_fill_size at the top of the current allocation region.
449 newtop = align_up(currtop + CollectedHeap::min_fill_size(),
450 end_alignment_in_bytes);
451 fill_size = pointer_delta(newtop, currtop);
452 }
453 HeapWord* fill = archive_mem_allocate(fill_size);
454 CollectedHeap::fill_with_objects(fill, fill_size);
455 }
456 }
457
458 // Loop through the allocated regions, and create MemRegions summarizing
459 // the allocated address range, combining contiguous ranges. Add the
460 // MemRegions to the GrowableArray provided by the caller.
461 int index = _allocated_regions.length() - 1;
462 assert(_allocated_regions.at(index) == _allocation_region,
463 "expected region %u at end of array, found %u",
464 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
465 HeapWord* base_address = _allocation_region->bottom();
466 HeapWord* top = base_address;
467
468 while (index >= 0) {
469 HeapRegion* next = _allocated_regions.at(index);
470 HeapWord* new_base = next->bottom();
471 HeapWord* new_top = next->top();
472 if (new_base != top) {
473 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
474 base_address = new_base;
475 }
476 top = new_top;
477 index = index - 1;
478 }
479
480 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
481 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
482 _allocated_regions.clear();
483 _allocation_region = NULL;
484 };