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 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest,
227 size_t word_sz,
228 AllocationContext_t context,
229 bool* plab_refill_failed) {
230 size_t gclab_word_size = _g1h->desired_plab_sz(dest);
231 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
232 G1PLAB* alloc_buf = alloc_buffer(dest, context);
233 alloc_buf->retire();
234
235 HeapWord* buf = _allocator->par_allocate_during_gc(dest, gclab_word_size, context);
236 if (buf != NULL) {
237 // Otherwise.
238 alloc_buf->set_word_size(gclab_word_size);
239 alloc_buf->set_buf(buf);
240
241 HeapWord* const obj = alloc_buf->allocate(word_sz);
242 assert(obj != NULL, "buffer was definitely big enough...");
243 return obj;
244 }
245 // Otherwise.
246 *plab_refill_failed = true;
247 }
248 // Try direct allocation.
249 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context);
250 if (result != NULL) {
251 _direct_allocated[dest.value()] += word_sz;
252 }
253 return result;
254 }
255
256 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) {
257 alloc_buffer(dest, context)->undo_allocation(obj, word_sz);
258 }
259
260 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) :
261 G1PLABAllocator(allocator),
262 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)),
263 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) {
264 for (uint state = 0; state < InCSetState::Num; state++) {
265 _alloc_buffers[state] = NULL;
266 }
267 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;
268 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer;
269 }
270
271 void G1DefaultPLABAllocator::flush_and_retire_stats() {
272 for (uint state = 0; state < InCSetState::Num; state++) {
273 G1PLAB* const buf = _alloc_buffers[state];
274 if (buf != NULL) {
275 G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
276 buf->flush_and_retire_stats(stats);
277 stats->add_direct_allocated(_direct_allocated[state]);
278 _direct_allocated[state] = 0;
279 }
280 }
281 }
282
283 void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) {
284 wasted = 0;
285 undo_wasted = 0;
286 for (uint state = 0; state < InCSetState::Num; state++) {
287 G1PLAB * const buf = _alloc_buffers[state];
288 if (buf != NULL) {
289 wasted += buf->waste();
290 undo_wasted += buf->undo_waste();
291 }
292 }
293 }
294
295 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) {
296 // Create the archive allocator, and also enable archive object checking
297 // in mark-sweep, since we will be creating archive regions.
298 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h);
299 G1MarkSweep::enable_archive_object_check();
300 return result;
301 }
302
303 bool G1ArchiveAllocator::alloc_new_region() {
304 // Allocate the highest free region in the reserved heap,
305 // and add it to our list of allocated regions. It is marked
306 // archive and added to the old set.
307 HeapRegion* hr = _g1h->alloc_highest_free_region();
308 if (hr == NULL) {
309 return false;
310 }
311 assert(hr->is_empty(), err_msg("expected empty region (index %u)", hr->hrm_index()));
312 hr->set_archive();
313 _g1h->old_set_add(hr);
314 _g1h->hr_printer()->alloc(hr, G1HRPrinter::Archive);
315 _allocated_regions.append(hr);
316 _allocation_region = hr;
317
318 // Set up _bottom and _max to begin allocating in the lowest
319 // min_region_size'd chunk of the allocated G1 region.
320 _bottom = hr->bottom();
321 _max = _bottom + HeapRegion::min_region_size_in_words();
322
323 // Tell mark-sweep that objects in this region are not to be marked.
324 G1MarkSweep::mark_range_archive(MemRegion(_bottom, HeapRegion::GrainWords));
325
326 // Since we've modified the old set, call update_sizes.
327 _g1h->g1mm()->update_sizes();
328 return true;
329 }
330
331 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
332 assert(word_size != 0, "size must not be zero");
333 if (_allocation_region == NULL) {
334 if (!alloc_new_region()) {
335 return NULL;
336 }
337 }
338 HeapWord* old_top = _allocation_region->top();
339 assert(_bottom >= _allocation_region->bottom(),
340 err_msg("inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
341 p2i(_bottom), p2i(_allocation_region->bottom())));
342 assert(_max <= _allocation_region->end(),
343 err_msg("inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
344 p2i(_max), p2i(_allocation_region->end())));
345 assert(_bottom <= old_top && old_top <= _max,
346 err_msg("inconsistent allocation state: expected "
347 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
348 p2i(_bottom), p2i(old_top), p2i(_max)));
349
350 // Allocate the next word_size words in the current allocation chunk.
351 // If allocation would cross the _max boundary, insert a filler and begin
352 // at the base of the next min_region_size'd chunk. Also advance to the next
353 // chunk if we don't yet cross the boundary, but the remainder would be too
354 // small to fill.
355 HeapWord* new_top = old_top + word_size;
356 size_t remainder = pointer_delta(_max, new_top);
357 if ((new_top > _max) ||
358 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
359 if (old_top != _max) {
360 size_t fill_size = pointer_delta(_max, old_top);
361 CollectedHeap::fill_with_object(old_top, fill_size);
362 _summary_bytes_used += fill_size * HeapWordSize;
363 }
364 _allocation_region->set_top(_max);
365 old_top = _bottom = _max;
366
367 // Check if we've just used up the last min_region_size'd chunk
368 // in the current region, and if so, allocate a new one.
369 if (_bottom != _allocation_region->end()) {
370 _max = _bottom + HeapRegion::min_region_size_in_words();
371 } else {
372 if (!alloc_new_region()) {
373 return NULL;
374 }
375 old_top = _allocation_region->bottom();
376 }
377 }
378 _allocation_region->set_top(old_top + word_size);
379 _summary_bytes_used += word_size * HeapWordSize;
380
381 return old_top;
382 }
383
384 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
385 size_t end_alignment_in_bytes) {
386 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
387 err_msg("alignment " SIZE_FORMAT " too large", end_alignment_in_bytes));
388 assert(is_size_aligned(end_alignment_in_bytes, HeapWordSize),
389 err_msg("alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize));
390
391 // If we've allocated nothing, simply return.
392 if (_allocation_region == NULL) {
393 return;
394 }
395
396 // If an end alignment was requested, insert filler objects.
397 if (end_alignment_in_bytes != 0) {
398 HeapWord* currtop = _allocation_region->top();
399 HeapWord* newtop = (HeapWord*)align_pointer_up(currtop, end_alignment_in_bytes);
400 size_t fill_size = pointer_delta(newtop, currtop);
401 if (fill_size != 0) {
402 if (fill_size < CollectedHeap::min_fill_size()) {
403 // If the required fill is smaller than we can represent,
404 // bump up to the next aligned address. We know we won't exceed the current
405 // region boundary because the max supported alignment is smaller than the min
406 // region size, and because the allocation code never leaves space smaller than
407 // the min_fill_size at the top of the current allocation region.
408 newtop = (HeapWord*)align_pointer_up(currtop + CollectedHeap::min_fill_size(),
409 end_alignment_in_bytes);
410 fill_size = pointer_delta(newtop, currtop);
411 }
412 HeapWord* fill = archive_mem_allocate(fill_size);
413 CollectedHeap::fill_with_objects(fill, fill_size);
414 }
415 }
416
417 // Loop through the allocated regions, and create MemRegions summarizing
418 // the allocated address range, combining contiguous ranges. Add the
419 // MemRegions to the GrowableArray provided by the caller.
420 int index = _allocated_regions.length() - 1;
421 assert(_allocated_regions.at(index) == _allocation_region,
422 err_msg("expected region %u at end of array, found %u",
423 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index()));
424 HeapWord* base_address = _allocation_region->bottom();
425 HeapWord* top = base_address;
426
427 while (index >= 0) {
428 HeapRegion* next = _allocated_regions.at(index);
429 HeapWord* new_base = next->bottom();
430 HeapWord* new_top = next->top();
431 if (new_base != top) {
432 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
433 base_address = new_base;
434 }
435 top = new_top;
436 index = index - 1;
437 }
438
439 assert(top != base_address, err_msg("zero-sized range, address " PTR_FORMAT, p2i(base_address)));
440 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
441 _allocated_regions.clear();
442 _allocation_region = NULL;
443 };