rev 52211 : imported patch 8212753-improve-forward-to-atomic
rev 52212 : imported patch 8212753-kbarrett-review
rev 52217 : [mq]: 8212911-unify-reference-handling-during-gc
rev 52221 : [mq]: 8212766-plab-size-smaller-than-obj-size
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/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1CollectionSet.hpp"
29 #include "gc/g1/g1OopClosures.inline.hpp"
30 #include "gc/g1/g1ParScanThreadState.inline.hpp"
31 #include "gc/g1/g1RootClosures.hpp"
32 #include "gc/g1/g1StringDedup.hpp"
33 #include "gc/shared/gcTrace.hpp"
34 #include "gc/shared/taskqueue.inline.hpp"
35 #include "memory/allocation.inline.hpp"
36 #include "oops/access.inline.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/prefetch.inline.hpp"
39
40 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint worker_id, size_t young_cset_length)
41 : _g1h(g1h),
42 _refs(g1h->task_queue(worker_id)),
43 _dcq(&g1h->dirty_card_queue_set()),
44 _ct(g1h->card_table()),
45 _closures(NULL),
46 _plab_allocator(NULL),
47 _age_table(false),
48 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()),
49 _scanner(g1h, this),
50 _worker_id(worker_id),
51 _stack_trim_upper_threshold(GCDrainStackTargetSize * 2 + 1),
52 _stack_trim_lower_threshold(GCDrainStackTargetSize),
53 _trim_ticks(),
54 _old_gen_is_full(false)
55 {
56 // we allocate G1YoungSurvRateNumRegions plus one entries, since
57 // we "sacrifice" entry 0 to keep track of surviving bytes for
58 // non-young regions (where the age is -1)
59 // We also add a few elements at the beginning and at the end in
60 // an attempt to eliminate cache contention
61 size_t real_length = 1 + young_cset_length;
62 size_t array_length = PADDING_ELEM_NUM +
63 real_length +
64 PADDING_ELEM_NUM;
65 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
66 if (_surviving_young_words_base == NULL)
67 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
68 "Not enough space for young surv histo.");
69 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
70 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
71
72 _plab_allocator = new G1PLABAllocator(_g1h->allocator());
73
74 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet;
75 // The dest for Young is used when the objects are aged enough to
76 // need to be moved to the next space.
77 _dest[InCSetState::Young] = InCSetState::Old;
78 _dest[InCSetState::Old] = InCSetState::Old;
79
80 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
81 }
82
83 // Pass locally gathered statistics to global state.
84 void G1ParScanThreadState::flush(size_t* surviving_young_words) {
85 _dcq.flush();
86 // Update allocation statistics.
87 _plab_allocator->flush_and_retire_stats();
88 _g1h->g1_policy()->record_age_table(&_age_table);
89
90 uint length = _g1h->collection_set()->young_region_length();
91 for (uint region_index = 0; region_index < length; region_index++) {
92 surviving_young_words[region_index] += _surviving_young_words[region_index];
93 }
94 }
95
96 G1ParScanThreadState::~G1ParScanThreadState() {
97 delete _plab_allocator;
98 delete _closures;
99 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
100 }
101
102 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) {
103 _plab_allocator->waste(wasted, undo_wasted);
104 }
105
106 #ifdef ASSERT
107 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
108 assert(ref != NULL, "invariant");
109 assert(UseCompressedOops, "sanity");
110 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));
111 oop p = RawAccess<>::oop_load(ref);
112 assert(_g1h->is_in_g1_reserved(p),
113 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
114 return true;
115 }
116
117 bool G1ParScanThreadState::verify_ref(oop* ref) const {
118 assert(ref != NULL, "invariant");
119 if (has_partial_array_mask(ref)) {
120 // Must be in the collection set--it's already been copied.
121 oop p = clear_partial_array_mask(ref);
122 assert(_g1h->is_in_cset(p),
123 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
124 } else {
125 oop p = RawAccess<>::oop_load(ref);
126 assert(_g1h->is_in_g1_reserved(p),
127 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
128 }
129 return true;
130 }
131
132 bool G1ParScanThreadState::verify_task(StarTask ref) const {
133 if (ref.is_narrow()) {
134 return verify_ref((narrowOop*) ref);
135 } else {
136 return verify_ref((oop*) ref);
137 }
138 }
139 #endif // ASSERT
140
141 void G1ParScanThreadState::trim_queue() {
142 StarTask ref;
143 do {
144 // Fully drain the queue.
145 trim_queue_to_threshold(0);
146 } while (!_refs->is_empty());
147 }
148
149 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
150 InCSetState* dest,
151 size_t word_sz,
152 bool previous_plab_refill_failed) {
153 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value());
154 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
155
156 // Right now we only have two types of regions (young / old) so
157 // let's keep the logic here simple. We can generalize it when necessary.
158 if (dest->is_young()) {
159 bool plab_refill_in_old_failed = false;
160 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old,
161 word_sz,
162 &plab_refill_in_old_failed);
163 // Make sure that we won't attempt to copy any other objects out
164 // of a survivor region (given that apparently we cannot allocate
165 // any new ones) to avoid coming into this slow path again and again.
166 // Only consider failed PLAB refill here: failed inline allocations are
167 // typically large, so not indicative of remaining space.
168 if (previous_plab_refill_failed) {
169 _tenuring_threshold = 0;
170 }
171
172 if (obj_ptr != NULL) {
173 dest->set_old();
174 } else {
175 // We just failed to allocate in old gen. The same idea as explained above
176 // for making survivor gen unavailable for allocation applies for old gen.
177 _old_gen_is_full = plab_refill_in_old_failed;
178 }
179 return obj_ptr;
180 } else {
181 _old_gen_is_full = previous_plab_refill_failed;
182 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
183 // no other space to try.
184 return NULL;
185 }
186 }
187
188 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
189 if (state.is_young()) {
190 age = !m->has_displaced_mark_helper() ? m->age()
191 : m->displaced_mark_helper()->age();
192 if (age < _tenuring_threshold) {
193 return state;
194 }
195 }
196 return dest(state);
197 }
198
199 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state,
200 oop const old, size_t word_sz, uint age,
201 HeapWord * const obj_ptr) const {
202 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state);
203 if (alloc_buf->contains(obj_ptr)) {
204 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age,
205 dest_state.value() == InCSetState::Old,
206 alloc_buf->word_sz() * HeapWordSize);
207 } else {
208 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age,
209 dest_state.value() == InCSetState::Old);
210 }
211 }
212
213 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
214 oop const old,
215 markOop const old_mark) {
216 const size_t word_sz = old->size();
217 HeapRegion* const from_region = _g1h->heap_region_containing(old);
218 // +1 to make the -1 indexes valid...
219 const int young_index = from_region->young_index_in_cset()+1;
220 assert( (from_region->is_young() && young_index > 0) ||
221 (!from_region->is_young() && young_index == 0), "invariant" );
222
223 uint age = 0;
224 InCSetState dest_state = next_state(state, old_mark, age);
225 // The second clause is to prevent premature evacuation failure in case there
226 // is still space in survivor, but old gen is full.
227 if (_old_gen_is_full && dest_state.is_old()) {
228 return handle_evacuation_failure_par(old, old_mark);
229 }
230 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz);
231
232 // PLAB allocations should succeed most of the time, so we'll
233 // normally check against NULL once and that's it.
234 if (obj_ptr == NULL) {
235 bool plab_refill_failed = false;
236 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed);
237 if (obj_ptr == NULL) {
238 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed);
239 if (obj_ptr == NULL) {
240 // This will either forward-to-self, or detect that someone else has
241 // installed a forwarding pointer.
242 return handle_evacuation_failure_par(old, old_mark);
243 }
244 }
245 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
246 // The events are checked individually as part of the actual commit
247 report_promotion_event(dest_state, old, word_sz, age, obj_ptr);
248 }
249 }
250
251 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
252 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
253
254 #ifndef PRODUCT
255 // Should this evacuation fail?
256 if (_g1h->evacuation_should_fail()) {
257 // Doing this after all the allocation attempts also tests the
258 // undo_allocation() method too.
259 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
260 return handle_evacuation_failure_par(old, old_mark);
261 }
262 #endif // !PRODUCT
263
264 // We're going to allocate linearly, so might as well prefetch ahead.
265 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
266
267 const oop obj = oop(obj_ptr);
268 const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed);
269 if (forward_ptr == NULL) {
270 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
271
272 if (dest_state.is_young()) {
273 if (age < markOopDesc::max_age) {
274 age++;
275 }
276 if (old_mark->has_displaced_mark_helper()) {
277 // In this case, we have to install the mark word first,
278 // otherwise obj looks to be forwarded (the old mark word,
279 // which contains the forward pointer, was copied)
280 obj->set_mark_raw(old_mark);
281 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
282 old_mark->set_displaced_mark_helper(new_mark);
283 } else {
284 obj->set_mark_raw(old_mark->set_age(age));
285 }
286 _age_table.add(age, word_sz);
287 } else {
288 obj->set_mark_raw(old_mark);
289 }
290
291 if (G1StringDedup::is_enabled()) {
292 const bool is_from_young = state.is_young();
293 const bool is_to_young = dest_state.is_young();
294 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(),
295 "sanity");
296 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
297 "sanity");
298 G1StringDedup::enqueue_from_evacuation(is_from_young,
299 is_to_young,
300 _worker_id,
301 obj);
302 }
303
304 _surviving_young_words[young_index] += word_sz;
305
306 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
307 // We keep track of the next start index in the length field of
308 // the to-space object. The actual length can be found in the
309 // length field of the from-space object.
310 arrayOop(obj)->set_length(0);
311 oop* old_p = set_partial_array_mask(old);
312 do_oop_partial_array(old_p);
313 } else {
314 _scanner.set_from_is_young(dest_state.is_young());
315 obj->oop_iterate_backwards(&_scanner);
316 }
317 return obj;
318 } else {
319 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
320 return forward_ptr;
321 }
322 }
323
324 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
325 assert(worker_id < _n_workers, "out of bounds access");
326 if (_states[worker_id] == NULL) {
327 _states[worker_id] = new G1ParScanThreadState(_g1h, worker_id, _young_cset_length);
328 }
329 return _states[worker_id];
330 }
331
332 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
333 assert(_flushed, "thread local state from the per thread states should have been flushed");
334 return _surviving_young_words_total;
335 }
336
337 void G1ParScanThreadStateSet::flush() {
338 assert(!_flushed, "thread local state from the per thread states should be flushed once");
339
340 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
341 G1ParScanThreadState* pss = _states[worker_index];
342
343 if (pss == NULL) {
344 continue;
345 }
346
347 pss->flush(_surviving_young_words_total);
348 delete pss;
349 _states[worker_index] = NULL;
350 }
351 _flushed = true;
352 }
353
354 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
355 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
356
357 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed);
358 if (forward_ptr == NULL) {
359 // Forward-to-self succeeded. We are the "owner" of the object.
360 HeapRegion* r = _g1h->heap_region_containing(old);
361
362 if (!r->evacuation_failed()) {
363 r->set_evacuation_failed(true);
364 _g1h->hr_printer()->evac_failure(r);
365 }
366
367 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
368
369 _scanner.set_from_is_young(r->is_young());
370 old->oop_iterate_backwards(&_scanner);
371
372 return old;
373 } else {
374 // Forward-to-self failed. Either someone else managed to allocate
375 // space for this object (old != forward_ptr) or they beat us in
376 // self-forwarding it (old == forward_ptr).
377 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
378 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
379 "should not be in the CSet",
380 p2i(old), p2i(forward_ptr));
381 return forward_ptr;
382 }
383 }
384 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, uint n_workers, size_t young_cset_length) :
385 _g1h(g1h),
386 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
387 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)),
388 _young_cset_length(young_cset_length),
389 _n_workers(n_workers),
390 _flushed(false) {
391 for (uint i = 0; i < n_workers; ++i) {
392 _states[i] = NULL;
393 }
394 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t));
395 }
396
397 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
398 assert(_flushed, "thread local state from the per thread states should have been flushed");
399 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
400 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
401 }
--- EOF ---