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/g1AllocRegion.inline.hpp"
28 #include "gc/g1/g1EvacStats.inline.hpp"
29 #include "gc/g1/g1CollectedHeap.inline.hpp"
30 #include "gc/g1/g1CollectorPolicy.hpp"
31 #include "gc/g1/g1MarkSweep.hpp"
32 #include "gc/g1/heapRegion.inline.hpp"
33 #include "gc/g1/heapRegionSet.inline.hpp"
34
35 G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) :
36 G1Allocator(heap),
37 _retained_old_gc_alloc_region(NULL),
38 _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)),
39 _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) {
40 }
41
42 void G1DefaultAllocator::init_mutator_alloc_region() {
43 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
44 _mutator_alloc_region.init();
45 }
46
47 void G1DefaultAllocator::release_mutator_alloc_region() {
48 _mutator_alloc_region.release();
49 assert(_mutator_alloc_region.get() == NULL, "post-condition");
50 }
51
52 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,
53 OldGCAllocRegion* old,
54 HeapRegion** retained_old) {
55 HeapRegion* retained_region = *retained_old;
56 *retained_old = NULL;
57 assert(retained_region == NULL || !retained_region->is_archive(),
58 "Archive region should not be alloc region (index %u)", retained_region->hrm_index());
59
60 // We will discard the current GC alloc region if:
61 // a) it's in the collection set (it can happen!),
62 // b) it's already full (no point in using it),
63 // c) it's empty (this means that it was emptied during
64 // a cleanup and it should be on the free list now), or
65 // d) it's humongous (this means that it was emptied
66 // during a cleanup and was added to the free list, but
67 // has been subsequently used to allocate a humongous
68 // object that may be less than the region size).
69 if (retained_region != NULL &&
70 !retained_region->in_collection_set() &&
71 !(retained_region->top() == retained_region->end()) &&
72 !retained_region->is_empty() &&
73 !retained_region->is_humongous()) {
74 retained_region->record_timestamp();
75 // The retained region was added to the old region set when it was
76 // retired. We have to remove it now, since we don't allow regions
77 // we allocate to in the region sets. We'll re-add it later, when
78 // it's retired again.
79 _g1h->old_set_remove(retained_region);
80 bool during_im = _g1h->collector_state()->during_initial_mark_pause();
81 retained_region->note_start_of_copying(during_im);
82 old->set(retained_region);
83 _g1h->hr_printer()->reuse(retained_region);
84 evacuation_info.set_alloc_regions_used_before(retained_region->used());
85 }
86 }
87
88 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
89 assert_at_safepoint(true /* should_be_vm_thread */);
90
91 G1Allocator::init_gc_alloc_regions(evacuation_info);
92
93 _survivor_gc_alloc_region.init();
94 _old_gc_alloc_region.init();
95 reuse_retained_old_region(evacuation_info,
96 &_old_gc_alloc_region,
97 &_retained_old_gc_alloc_region);
98 }
99
100 void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) {
101 AllocationContext_t context = AllocationContext::current();
102 evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() +
103 old_gc_alloc_region(context)->count());
104 survivor_gc_alloc_region(context)->release();
105 // If we have an old GC alloc region to release, we'll save it in
106 // _retained_old_gc_alloc_region. If we don't
107 // _retained_old_gc_alloc_region will become NULL. This is what we
108 // want either way so no reason to check explicitly for either
109 // condition.
110 _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release();
111 if (_retained_old_gc_alloc_region != NULL) {
112 _retained_old_gc_alloc_region->record_retained_region();
113 }
114 }
115
116 void G1DefaultAllocator::abandon_gc_alloc_regions() {
117 assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
118 assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
119 _retained_old_gc_alloc_region = NULL;
120 }
121
122 G1PLAB::G1PLAB(size_t gclab_word_size) :
123 PLAB(gclab_word_size), _retired(true) { }
124
125 size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) {
126 // Return the remaining space in the cur alloc region, but not less than
127 // the min TLAB size.
128
129 // Also, this value can be at most the humongous object threshold,
130 // since we can't allow tlabs to grow big enough to accommodate
131 // humongous objects.
132
133 HeapRegion* hr = mutator_alloc_region(context)->get();
134 size_t max_tlab = _g1h->max_tlab_size() * wordSize;
135 if (hr == NULL) {
136 return max_tlab;
137 } else {
138 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
139 }
140 }
141
142 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
143 size_t word_size,
144 AllocationContext_t context) {
145 size_t temp = 0;
146 HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp, context);
147 assert(result == NULL || temp == word_size,
148 "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
149 word_size, temp, p2i(result));
150 return result;
151 }
152
153 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
154 size_t min_word_size,
155 size_t desired_word_size,
156 size_t* actual_word_size,
157 AllocationContext_t context) {
158 switch (dest.value()) {
159 case InCSetState::Young:
160 return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
161 case InCSetState::Old:
162 return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
163 default:
164 ShouldNotReachHere();
165 return NULL; // Keep some compilers happy
166 }
167 }
168
169 bool G1Allocator::survivor_is_full(AllocationContext_t context) const {
170 return _survivor_is_full;
171 }
172
173 bool G1Allocator::old_is_full(AllocationContext_t context) const {
174 return _old_is_full;
175 }
176
177 void G1Allocator::set_survivor_full(AllocationContext_t context) {
178 _survivor_is_full = true;
179 }
180
181 void G1Allocator::set_old_full(AllocationContext_t context) {
182 _old_is_full = true;
183 }
184
185 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
186 size_t desired_word_size,
187 size_t* actual_word_size,
188 AllocationContext_t context) {
189 assert(!_g1h->is_humongous(desired_word_size),
190 "we should not be seeing humongous-size allocations in this path");
191
192 HeapWord* result = survivor_gc_alloc_region(context)->attempt_allocation(min_word_size,
193 desired_word_size,
194 actual_word_size,
195 false /* bot_updates */);
196 if (result == NULL && !survivor_is_full(context)) {
197 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
198 result = survivor_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,
199 desired_word_size,
200 actual_word_size,
201 false /* bot_updates */);
202 if (result == NULL) {
203 set_survivor_full(context);
204 }
205 }
206 if (result != NULL) {
207 _g1h->dirty_young_block(result, *actual_word_size);
208 }
209 return result;
210 }
211
212 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
213 size_t desired_word_size,
214 size_t* actual_word_size,
215 AllocationContext_t context) {
216 assert(!_g1h->is_humongous(desired_word_size),
217 "we should not be seeing humongous-size allocations in this path");
218
219 HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(min_word_size,
220 desired_word_size,
221 actual_word_size,
222 true /* bot_updates */);
223 if (result == NULL && !old_is_full(context)) {
224 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
225 result = old_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,
226 desired_word_size,
227 actual_word_size,
228 true /* bot_updates */);
229 if (result == NULL) {
230 set_old_full(context);
231 }
232 }
233 return result;
234 }
235
236 void G1Allocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
237 _survivor_is_full = false;
238 _old_is_full = false;
239 }
240
241 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
242 _g1h(G1CollectedHeap::heap()),
243 _allocator(allocator),
244 _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
245 for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) {
246 _direct_allocated[i] = 0;
247 }
248 }
249
250 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
251 return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
252 }
253
254 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest,
255 size_t word_sz,
256 AllocationContext_t context,
257 bool* plab_refill_failed) {
258 size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest);
259 size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
260
261 // Only get a new PLAB if the allocation fits and it would not waste more than
262 // ParallelGCBufferWastePct in the existing buffer.
263 if ((required_in_plab <= plab_word_size) &&
264 may_throw_away_buffer(required_in_plab, plab_word_size)) {
265
266 G1PLAB* alloc_buf = alloc_buffer(dest, context);
267 alloc_buf->retire();
268
269 size_t actual_plab_size = 0;
270 HeapWord* buf = _allocator->par_allocate_during_gc(dest,
271 required_in_plab,
272 plab_word_size,
273 &actual_plab_size,
274 context);
275
276 assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
277 "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
278 required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
279
280 if (buf != NULL) {
281 alloc_buf->set_buf(buf, actual_plab_size);
282
283 HeapWord* const obj = alloc_buf->allocate(word_sz);
284 assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
285 SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
286 word_sz, required_in_plab, plab_word_size);
287 return obj;
288 }
289 // Otherwise.
290 *plab_refill_failed = true;
291 }
292 // Try direct allocation.
293 HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context);
294 if (result != NULL) {
295 _direct_allocated[dest.value()] += word_sz;
296 }
297 return result;
298 }
299
300 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) {
301 alloc_buffer(dest, context)->undo_allocation(obj, word_sz);
302 }
303
304 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) :
305 G1PLABAllocator(allocator),
306 _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)),
307 _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) {
308 for (uint state = 0; state < InCSetState::Num; state++) {
309 _alloc_buffers[state] = NULL;
310 }
311 _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;
312 _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer;
313 }
314
315 void G1DefaultPLABAllocator::flush_and_retire_stats() {
316 for (uint state = 0; state < InCSetState::Num; state++) {
317 G1PLAB* const buf = _alloc_buffers[state];
318 if (buf != NULL) {
319 G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
320 buf->flush_and_retire_stats(stats);
321 stats->add_direct_allocated(_direct_allocated[state]);
322 _direct_allocated[state] = 0;
323 }
324 }
325 }
326
327 void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) {
328 wasted = 0;
329 undo_wasted = 0;
330 for (uint state = 0; state < InCSetState::Num; state++) {
331 G1PLAB * const buf = _alloc_buffers[state];
332 if (buf != NULL) {
333 wasted += buf->waste();
334 undo_wasted += buf->undo_waste();
335 }
336 }
337 }
338
339 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h) {
340 // Create the archive allocator, and also enable archive object checking
341 // in mark-sweep, since we will be creating archive regions.
342 G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h);
343 G1MarkSweep::enable_archive_object_check();
344 return result;
345 }
346
347 bool G1ArchiveAllocator::alloc_new_region() {
348 // Allocate the highest free region in the reserved heap,
349 // and add it to our list of allocated regions. It is marked
350 // archive and added to the old set.
351 HeapRegion* hr = _g1h->alloc_highest_free_region();
352 if (hr == NULL) {
353 return false;
354 }
355 assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
356 hr->set_archive();
357 _g1h->old_set_add(hr);
358 _g1h->hr_printer()->alloc(hr, G1HRPrinter::Archive);
359 _allocated_regions.append(hr);
360 _allocation_region = hr;
361
362 // Set up _bottom and _max to begin allocating in the lowest
363 // min_region_size'd chunk of the allocated G1 region.
364 _bottom = hr->bottom();
365 _max = _bottom + HeapRegion::min_region_size_in_words();
366
367 // Tell mark-sweep that objects in this region are not to be marked.
368 G1MarkSweep::set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), true);
369
370 // Since we've modified the old set, call update_sizes.
371 _g1h->g1mm()->update_sizes();
372 return true;
373 }
374
375 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
376 assert(word_size != 0, "size must not be zero");
377 if (_allocation_region == NULL) {
378 if (!alloc_new_region()) {
379 return NULL;
380 }
381 }
382 HeapWord* old_top = _allocation_region->top();
383 assert(_bottom >= _allocation_region->bottom(),
384 "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
385 p2i(_bottom), p2i(_allocation_region->bottom()));
386 assert(_max <= _allocation_region->end(),
387 "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
388 p2i(_max), p2i(_allocation_region->end()));
389 assert(_bottom <= old_top && old_top <= _max,
390 "inconsistent allocation state: expected "
391 PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
392 p2i(_bottom), p2i(old_top), p2i(_max));
393
394 // Allocate the next word_size words in the current allocation chunk.
395 // If allocation would cross the _max boundary, insert a filler and begin
396 // at the base of the next min_region_size'd chunk. Also advance to the next
397 // chunk if we don't yet cross the boundary, but the remainder would be too
398 // small to fill.
399 HeapWord* new_top = old_top + word_size;
400 size_t remainder = pointer_delta(_max, new_top);
401 if ((new_top > _max) ||
402 ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
403 if (old_top != _max) {
404 size_t fill_size = pointer_delta(_max, old_top);
405 CollectedHeap::fill_with_object(old_top, fill_size);
406 _summary_bytes_used += fill_size * HeapWordSize;
407 }
408 _allocation_region->set_top(_max);
409 old_top = _bottom = _max;
410
411 // Check if we've just used up the last min_region_size'd chunk
412 // in the current region, and if so, allocate a new one.
413 if (_bottom != _allocation_region->end()) {
414 _max = _bottom + HeapRegion::min_region_size_in_words();
415 } else {
416 if (!alloc_new_region()) {
417 return NULL;
418 }
419 old_top = _allocation_region->bottom();
420 }
421 }
422 _allocation_region->set_top(old_top + word_size);
423 _summary_bytes_used += word_size * HeapWordSize;
424
425 return old_top;
426 }
427
428 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
429 size_t end_alignment_in_bytes) {
430 assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
431 "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
432 assert(is_size_aligned(end_alignment_in_bytes, HeapWordSize),
433 "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
434
435 // If we've allocated nothing, simply return.
436 if (_allocation_region == NULL) {
437 return;
438 }
439
440 // If an end alignment was requested, insert filler objects.
441 if (end_alignment_in_bytes != 0) {
442 HeapWord* currtop = _allocation_region->top();
443 HeapWord* newtop = (HeapWord*)align_pointer_up(currtop, end_alignment_in_bytes);
444 size_t fill_size = pointer_delta(newtop, currtop);
445 if (fill_size != 0) {
446 if (fill_size < CollectedHeap::min_fill_size()) {
447 // If the required fill is smaller than we can represent,
448 // bump up to the next aligned address. We know we won't exceed the current
449 // region boundary because the max supported alignment is smaller than the min
450 // region size, and because the allocation code never leaves space smaller than
451 // the min_fill_size at the top of the current allocation region.
452 newtop = (HeapWord*)align_pointer_up(currtop + CollectedHeap::min_fill_size(),
453 end_alignment_in_bytes);
454 fill_size = pointer_delta(newtop, currtop);
455 }
456 HeapWord* fill = archive_mem_allocate(fill_size);
457 CollectedHeap::fill_with_objects(fill, fill_size);
458 }
459 }
460
461 // Loop through the allocated regions, and create MemRegions summarizing
462 // the allocated address range, combining contiguous ranges. Add the
463 // MemRegions to the GrowableArray provided by the caller.
464 int index = _allocated_regions.length() - 1;
465 assert(_allocated_regions.at(index) == _allocation_region,
466 "expected region %u at end of array, found %u",
467 _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
468 HeapWord* base_address = _allocation_region->bottom();
469 HeapWord* top = base_address;
470
471 while (index >= 0) {
472 HeapRegion* next = _allocated_regions.at(index);
473 HeapWord* new_base = next->bottom();
474 HeapWord* new_top = next->top();
475 if (new_base != top) {
476 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
477 base_address = new_base;
478 }
479 top = new_top;
480 index = index - 1;
481 }
482
483 assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
484 ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
485 _allocated_regions.clear();
486 _allocation_region = NULL;
487 };