1 /*
2 * Copyright (c) 2014, 2015, 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/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1CollectorPolicy.hpp"
29 #include "gc/g1/g1MarkSweep.hpp"
30 #include "gc/g1/heapRegion.inline.hpp"
31 #include "gc/g1/heapRegionSet.inline.hpp"
32
33 G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) :
34 G1Allocator(heap),
35 _retained_old_gc_alloc_region(NULL),
36 _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)),
37 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) {
38 }
39
40 void G1DefaultAllocator::init_mutator_alloc_region() {
41 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
42 _mutator_alloc_region.init();
43 }
44
45 void G1DefaultAllocator::release_mutator_alloc_region() {
46 _mutator_alloc_region.release();
47 assert(_mutator_alloc_region.get() == NULL, "post-condition");
48 }
49
50 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,
51 OldGCAllocRegion* old,
52 HeapRegion** retained_old) {
53 HeapRegion* retained_region = *retained_old;
54 *retained_old = NULL;
55 assert(retained_region == NULL || !retained_region->is_archive(),
56 err_msg("Archive region should not be alloc region (index %u)", retained_region->hrm_index()));
57
58 // We will discard the current GC alloc region if:
59 // a) it's in the collection set (it can happen!),
60 // b) it's already full (no point in using it),
61 // c) it's empty (this means that it was emptied during
62 // a cleanup and it should be on the free list now), or
63 // d) it's humongous (this means that it was emptied
64 // during a cleanup and was added to the free list, but
65 // has been subsequently used to allocate a humongous
66 // object that may be less than the region size).
67 if (retained_region != NULL &&
68 !retained_region->in_collection_set() &&
69 !(retained_region->top() == retained_region->end()) &&
70 !retained_region->is_empty() &&
71 !retained_region->is_humongous()) {
72 retained_region->record_timestamp();
73 // The retained region was added to the old region set when it was
74 // retired. We have to remove it now, since we don't allow regions
75 // we allocate to in the region sets. We'll re-add it later, when
76 // it's retired again.
77 _g1h->old_set_remove(retained_region);
78 bool during_im = _g1h->collector_state()->during_initial_mark_pause();
79 retained_region->note_start_of_copying(during_im);
80 old->set(retained_region);
81 _g1h->hr_printer()->reuse(retained_region);
82 evacuation_info.set_alloc_regions_used_before(retained_region->used());
83 }
84 }
85
86 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
87 assert_at_safepoint(true /* should_be_vm_thread */);
88
89 G1Allocator::init_gc_alloc_regions(evacuation_info);
90
91 _survivor_gc_alloc_region.init();
92 _old_gc_alloc_region.init();
93 reuse_retained_old_region(evacuation_info,
94 &_old_gc_alloc_region,
95 &_retained_old_gc_alloc_region);
96 }
97
98 void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) {
99 AllocationContext_t context = AllocationContext::current();
100 evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() +
101 old_gc_alloc_region(context)->count());
102 survivor_gc_alloc_region(context)->release();
103 // If we have an old GC alloc region to release, we'll save it in
104 // _retained_old_gc_alloc_region. If we don't
105 // _retained_old_gc_alloc_region will become NULL. This is what we
106 // want either way so no reason to check explicitly for either
107 // condition.
108 _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release();
109 if (_retained_old_gc_alloc_region != NULL) {
110 _retained_old_gc_alloc_region->record_retained_region();
111 }
112
113 _g1h->alloc_buffer_stats(InCSetState::Young)->adjust_desired_plab_sz();
114 _g1h->alloc_buffer_stats(InCSetState::Old)->adjust_desired_plab_sz();
115 }
116
117 void G1DefaultAllocator::abandon_gc_alloc_regions() {
118 assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
119 assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
120 _retained_old_gc_alloc_region = NULL;
121 }
122
123 G1PLAB::G1PLAB(size_t gclab_word_size) :
124 PLAB(gclab_word_size), _retired(true) { }
125
126 size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) {
127 // Return the remaining space in the cur alloc region, but not less than
128 // the min TLAB size.
129
130 // Also, this value can be at most the humongous object threshold,
131 // since we can't allow tlabs to grow big enough to accommodate
132 // humongous objects.
133
134 HeapRegion* hr = mutator_alloc_region(context)->get();
135 size_t max_tlab = _g1h->max_tlab_size() * wordSize;
136 if (hr == NULL) {
137 return max_tlab;
138 } else {
139 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
140 }
141 }
142
143 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
144 size_t word_size,
145 AllocationContext_t context) {
146 switch (dest.value()) {
147 case InCSetState::Young:
148 return survivor_attempt_allocation(word_size, context);
149 case InCSetState::Old:
150 return old_attempt_allocation(word_size, context);
151 default:
152 ShouldNotReachHere();
153 return NULL; // Keep some compilers happy
154 }
155 }
156
157 bool G1Allocator::survivor_is_full(AllocationContext_t context) const {
158 return _survivor_is_full;
159 }
160
161 bool G1Allocator::old_is_full(AllocationContext_t context) const {
162 return _old_is_full;
163 }
164
165 void G1Allocator::set_survivor_full(AllocationContext_t context) {
166 _survivor_is_full = true;
167 }
168
169 void G1Allocator::set_old_full(AllocationContext_t context) {
170 _old_is_full = true;
171 }
172
173 HeapWord* G1Allocator::survivor_attempt_allocation(size_t word_size,
174 AllocationContext_t context) {
175 assert(!_g1h->is_humongous(word_size),
176 "we should not be seeing humongous-size allocations in this path");
177
178 HeapWord* result = survivor_gc_alloc_region(context)->attempt_allocation(word_size,
179 false /* bot_updates */);
180 if (result == NULL && !survivor_is_full(context)) {
181 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
182 result = survivor_gc_alloc_region(context)->attempt_allocation_locked(word_size,
183 false /* bot_updates */);
184 if (result == NULL) {
185 set_survivor_full(context);
186 }
187 }
188 if (result != NULL) {
189 _g1h->dirty_young_block(result, word_size);
190 }
191 return result;
192 }
193
194 HeapWord* G1Allocator::old_attempt_allocation(size_t word_size,
195 AllocationContext_t context) {
196 assert(!_g1h->is_humongous(word_size),
197 "we should not be seeing humongous-size allocations in this path");
198
199 HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(word_size,
200 true /* bot_updates */);
201 if (result == NULL && !old_is_full(context)) {
202 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
203 result = old_gc_alloc_region(context)->attempt_allocation_locked(word_size,
204 true /* bot_updates */);
205 if (result == NULL) {
206 set_old_full(context);
207 }
208 }
209 return result;
210 }
211
212 void G1Allocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
213 _survivor_is_full = false;
214 _old_is_full = false;
215 }
216
217 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
218 _g1h(G1CollectedHeap::heap()),
219 _allocator(allocator),
220 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
221 for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) {
222 _direct_allocated[i] = 0;
223 }
224 }
225
226 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
227 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
228 }
229
230 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest,
231 size_t word_sz,
232 AllocationContext_t context,
233 bool* plab_refill_failed) {
234 size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest);
235 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
236
237 // Only get a new PLAB if the allocation fits and it would not waste more than
238 // ParallelGCBufferWastePct in the existing buffer.
239 if ((required_in_plab <= plab_word_size) &&
240 may_throw_away_buffer(required_in_plab, plab_word_size)) {
241
242 G1PLAB* alloc_buf = alloc_buffer(dest, context);
243 alloc_buf->retire();
244
245 HeapWord* buf = _allocator->par_allocate_during_gc(dest, plab_word_size, context);
246 if (buf != NULL) {
247 // Otherwise.
248 alloc_buf->set_buf(buf, plab_word_size);
249
250 HeapWord* const obj = alloc_buf->allocate(word_sz);
251 assert(obj != NULL, err_msg("PLAB should have been big enough, tried to allocate "
252 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
253 word_sz, required_in_plab, plab_word_size));
254 return obj;
255 }
256 // Otherwise.
257 *plab_refill_failed = true;
258 }
259 // Try direct allocation.
260 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context);
261 if (result != NULL) {
262 _direct_allocated[dest.value()] += word_sz;
263 }
264 return result;
265 }
266
267 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) {
268 alloc_buffer(dest, context)->undo_allocation(obj, word_sz);
269 }
270
271 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) :
272 G1PLABAllocator(allocator),
273 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)),
274 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) {
275 for (uint state = 0; state < InCSetState::Num; state++) {
276 _alloc_buffers[state] = NULL;
277 }
278 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;
279 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer;
280 }
281
282 void G1DefaultPLABAllocator::flush_and_retire_stats() {
283 for (uint state = 0; state < InCSetState::Num; state++) {
284 G1PLAB* const buf = _alloc_buffers[state];
285 if (buf != NULL) {
286 G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
287 buf->flush_and_retire_stats(stats);
288 stats->add_direct_allocated(_direct_allocated[state]);
289 _direct_allocated[state] = 0;
290 }
291 }
292 }
293
294 void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) {
295 wasted = 0;
296 undo_wasted = 0;
297 for (uint state = 0; state < InCSetState::Num; state++) {
298 G1PLAB * const buf = _alloc_buffers[state];
299 if (buf != NULL) {
300 wasted += buf->waste();
301 undo_wasted += buf->undo_waste();
302 }
303 }
304 }
305
306 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) {
307 // Create the archive allocator, and also enable archive object checking
308 // in mark-sweep, since we will be creating archive regions.
309 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h);
310 G1MarkSweep::enable_archive_object_check();
311 return result;
312 }
313
314 bool G1ArchiveAllocator::alloc_new_region() {
315 // Allocate the highest free region in the reserved heap,
316 // and add it to our list of allocated regions. It is marked
317 // archive and added to the old set.
318 HeapRegion* hr = _g1h->alloc_highest_free_region();
319 if (hr == NULL) {
320 return false;
321 }
322 assert(hr->is_empty(), err_msg("expected empty region (index %u)", hr->hrm_index()));
323 hr->set_archive();
324 _g1h->old_set_add(hr);
325 _g1h->hr_printer()->alloc(hr, G1HRPrinter::Archive);
326 _allocated_regions.append(hr);
327 _allocation_region = hr;
328
329 // Set up _bottom and _max to begin allocating in the lowest
330 // min_region_size'd chunk of the allocated G1 region.
331 _bottom = hr->bottom();
332 _max = _bottom + HeapRegion::min_region_size_in_words();
333
334 // Tell mark-sweep that objects in this region are not to be marked.
335 G1MarkSweep::mark_range_archive(MemRegion(_bottom, HeapRegion::GrainWords));
336
337 // Since we've modified the old set, call update_sizes.
338 _g1h->g1mm()->update_sizes();
339 return true;
340 }
341
342 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
343 assert(word_size != 0, "size must not be zero");
344 if (_allocation_region == NULL) {
345 if (!alloc_new_region()) {
346 return NULL;
347 }
348 }
349 HeapWord* old_top = _allocation_region->top();
350 assert(_bottom >= _allocation_region->bottom(),
351 err_msg("inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
352 p2i(_bottom), p2i(_allocation_region->bottom())));
353 assert(_max <= _allocation_region->end(),
354 err_msg("inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
355 p2i(_max), p2i(_allocation_region->end())));
356 assert(_bottom <= old_top && old_top <= _max,
357 err_msg("inconsistent allocation state: expected "
358 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
359 p2i(_bottom), p2i(old_top), p2i(_max)));
360
361 // Allocate the next word_size words in the current allocation chunk.
362 // If allocation would cross the _max boundary, insert a filler and begin
363 // at the base of the next min_region_size'd chunk. Also advance to the next
364 // chunk if we don't yet cross the boundary, but the remainder would be too
365 // small to fill.
366 HeapWord* new_top = old_top + word_size;
367 size_t remainder = pointer_delta(_max, new_top);
368 if ((new_top > _max) ||
369 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
370 if (old_top != _max) {
371 size_t fill_size = pointer_delta(_max, old_top);
372 CollectedHeap::fill_with_object(old_top, fill_size);
373 _summary_bytes_used += fill_size * HeapWordSize;
374 }
375 _allocation_region->set_top(_max);
376 old_top = _bottom = _max;
377
378 // Check if we've just used up the last min_region_size'd chunk
379 // in the current region, and if so, allocate a new one.
380 if (_bottom != _allocation_region->end()) {
381 _max = _bottom + HeapRegion::min_region_size_in_words();
382 } else {
383 if (!alloc_new_region()) {
384 return NULL;
385 }
386 old_top = _allocation_region->bottom();
387 }
388 }
389 _allocation_region->set_top(old_top + word_size);
390 _summary_bytes_used += word_size * HeapWordSize;
391
392 return old_top;
393 }
394
395 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
396 size_t end_alignment_in_bytes) {
397 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
398 err_msg("alignment " SIZE_FORMAT " too large", end_alignment_in_bytes));
399 assert(is_size_aligned(end_alignment_in_bytes, HeapWordSize),
400 err_msg("alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize));
401
402 // If we've allocated nothing, simply return.
403 if (_allocation_region == NULL) {
404 return;
405 }
406
407 // If an end alignment was requested, insert filler objects.
408 if (end_alignment_in_bytes != 0) {
409 HeapWord* currtop = _allocation_region->top();
410 HeapWord* newtop = (HeapWord*)align_pointer_up(currtop, end_alignment_in_bytes);
411 size_t fill_size = pointer_delta(newtop, currtop);
412 if (fill_size != 0) {
413 if (fill_size < CollectedHeap::min_fill_size()) {
414 // If the required fill is smaller than we can represent,
415 // bump up to the next aligned address. We know we won't exceed the current
416 // region boundary because the max supported alignment is smaller than the min
417 // region size, and because the allocation code never leaves space smaller than
418 // the min_fill_size at the top of the current allocation region.
419 newtop = (HeapWord*)align_pointer_up(currtop + CollectedHeap::min_fill_size(),
420 end_alignment_in_bytes);
421 fill_size = pointer_delta(newtop, currtop);
422 }
423 HeapWord* fill = archive_mem_allocate(fill_size);
424 CollectedHeap::fill_with_objects(fill, fill_size);
425 }
426 }
427
428 // Loop through the allocated regions, and create MemRegions summarizing
429 // the allocated address range, combining contiguous ranges. Add the
430 // MemRegions to the GrowableArray provided by the caller.
431 int index = _allocated_regions.length() - 1;
432 assert(_allocated_regions.at(index) == _allocation_region,
433 err_msg("expected region %u at end of array, found %u",
434 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index()));
435 HeapWord* base_address = _allocation_region->bottom();
436 HeapWord* top = base_address;
437
438 while (index >= 0) {
439 HeapRegion* next = _allocated_regions.at(index);
440 HeapWord* new_base = next->bottom();
441 HeapWord* new_top = next->top();
442 if (new_base != top) {
443 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
444 base_address = new_base;
445 }
446 top = new_top;
447 index = index - 1;
448 }
449
450 assert(top != base_address, err_msg("zero-sized range, address " PTR_FORMAT, p2i(base_address)));
451 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
452 _allocated_regions.clear();
453 _allocation_region = NULL;
454 };