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 _hash_seed(17),
51 _worker_id(worker_id),
52 _stack_drain_upper_threshold(GCDrainStackTargetSize * 2 + 1),
53 _stack_drain_lower_threshold(GCDrainStackTargetSize),
54 _trim_ticks(),
55 _old_gen_is_full(false)
56 {
57 // we allocate G1YoungSurvRateNumRegions plus one entries, since
58 // we "sacrifice" entry 0 to keep track of surviving bytes for
59 // non-young regions (where the age is -1)
60 // We also add a few elements at the beginning and at the end in
61 // an attempt to eliminate cache contention
62 size_t real_length = 1 + young_cset_length;
63 size_t array_length = PADDING_ELEM_NUM +
64 real_length +
65 PADDING_ELEM_NUM;
66 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
67 if (_surviving_young_words_base == NULL)
68 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
69 "Not enough space for young surv histo.");
70 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
71 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
72
73 _plab_allocator = new G1PLABAllocator(_g1h->allocator());
74
75 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet;
76 // The dest for Young is used when the objects are aged enough to
77 // need to be moved to the next space.
78 _dest[InCSetState::Young] = InCSetState::Old;
79 _dest[InCSetState::Old] = InCSetState::Old;
80
81 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
82 }
83
84 // Pass locally gathered statistics to global state.
85 void G1ParScanThreadState::flush(size_t* surviving_young_words) {
86 _dcq.flush();
87 // Update allocation statistics.
88 _plab_allocator->flush_and_retire_stats();
89 _g1h->g1_policy()->record_age_table(&_age_table);
90
91 uint length = _g1h->collection_set()->young_region_length();
92 for (uint region_index = 0; region_index < length; region_index++) {
93 surviving_young_words[region_index] += _surviving_young_words[region_index];
94 }
95 }
96
97 G1ParScanThreadState::~G1ParScanThreadState() {
98 delete _plab_allocator;
99 delete _closures;
100 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
101 }
102
103 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) {
104 _plab_allocator->waste(wasted, undo_wasted);
105 }
106
107 #ifdef ASSERT
108 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
109 assert(ref != NULL, "invariant");
110 assert(UseCompressedOops, "sanity");
111 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));
112 oop p = RawAccess<>::oop_load(ref);
113 assert(_g1h->is_in_g1_reserved(p),
114 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
115 return true;
116 }
117
118 bool G1ParScanThreadState::verify_ref(oop* ref) const {
119 assert(ref != NULL, "invariant");
120 if (has_partial_array_mask(ref)) {
121 // Must be in the collection set--it's already been copied.
122 oop p = clear_partial_array_mask(ref);
123 assert(_g1h->is_in_cset(p),
124 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
125 } else {
126 oop p = RawAccess<>::oop_load(ref);
127 assert(_g1h->is_in_g1_reserved(p),
128 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
129 }
130 return true;
131 }
132
133 bool G1ParScanThreadState::verify_task(StarTask ref) const {
134 if (ref.is_narrow()) {
135 return verify_ref((narrowOop*) ref);
136 } else {
137 return verify_ref((oop*) ref);
138 }
139 }
140 #endif // ASSERT
141
142 void G1ParScanThreadState::trim_queue() {
143 StarTask ref;
144 do {
145 // Fully drain the queue.
146 trim_queue_to_threshold(0);
147 } while (!_refs->is_empty());
148 }
149
150 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
151 InCSetState* dest,
152 size_t word_sz,
153 bool previous_plab_refill_failed) {
154 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value());
155 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
156
157 // Right now we only have two types of regions (young / old) so
158 // let's keep the logic here simple. We can generalize it when necessary.
159 if (dest->is_young()) {
160 bool plab_refill_in_old_failed = false;
161 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old,
162 word_sz,
163 &plab_refill_in_old_failed);
164 // Make sure that we won't attempt to copy any other objects out
165 // of a survivor region (given that apparently we cannot allocate
166 // any new ones) to avoid coming into this slow path again and again.
167 // Only consider failed PLAB refill here: failed inline allocations are
168 // typically large, so not indicative of remaining space.
169 if (previous_plab_refill_failed) {
170 _tenuring_threshold = 0;
171 }
172
173 if (obj_ptr != NULL) {
174 dest->set_old();
175 } else {
176 // We just failed to allocate in old gen. The same idea as explained above
177 // for making survivor gen unavailable for allocation applies for old gen.
178 _old_gen_is_full = plab_refill_in_old_failed;
179 }
180 return obj_ptr;
181 } else {
182 _old_gen_is_full = previous_plab_refill_failed;
183 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
184 // no other space to try.
185 return NULL;
186 }
187 }
188
189 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
190 if (state.is_young()) {
191 age = !m->has_displaced_mark_helper() ? m->age()
192 : m->displaced_mark_helper()->age();
193 if (age < _tenuring_threshold) {
194 return state;
195 }
196 }
197 return dest(state);
198 }
199
200 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state,
201 oop const old, size_t word_sz, uint age,
202 HeapWord * const obj_ptr) const {
203 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state);
204 if (alloc_buf->contains(obj_ptr)) {
205 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz, age,
206 dest_state.value() == InCSetState::Old,
207 alloc_buf->word_sz());
208 } else {
209 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz, age,
210 dest_state.value() == InCSetState::Old);
211 }
212 }
213
214 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
215 oop const old,
216 markOop const old_mark) {
217 const size_t word_sz = old->size();
218 HeapRegion* const from_region = _g1h->heap_region_containing(old);
219 // +1 to make the -1 indexes valid...
220 const int young_index = from_region->young_index_in_cset()+1;
221 assert( (from_region->is_young() && young_index > 0) ||
222 (!from_region->is_young() && young_index == 0), "invariant" );
223
224 uint age = 0;
225 InCSetState dest_state = next_state(state, old_mark, age);
226 // The second clause is to prevent premature evacuation failure in case there
227 // is still space in survivor, but old gen is full.
228 if (_old_gen_is_full && dest_state.is_old()) {
229 return handle_evacuation_failure_par(old, old_mark);
230 }
231 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz);
232
233 // PLAB allocations should succeed most of the time, so we'll
234 // normally check against NULL once and that's it.
235 if (obj_ptr == NULL) {
236 bool plab_refill_failed = false;
237 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed);
238 if (obj_ptr == NULL) {
239 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed);
240 if (obj_ptr == NULL) {
241 // This will either forward-to-self, or detect that someone else has
242 // installed a forwarding pointer.
243 return handle_evacuation_failure_par(old, old_mark);
244 }
245 }
246 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
247 // The events are checked individually as part of the actual commit
248 report_promotion_event(dest_state, old, word_sz, age, obj_ptr);
249 }
250 }
251
252 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
253 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
254
255 #ifndef PRODUCT
256 // Should this evacuation fail?
257 if (_g1h->evacuation_should_fail()) {
258 // Doing this after all the allocation attempts also tests the
259 // undo_allocation() method too.
260 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
261 return handle_evacuation_failure_par(old, old_mark);
262 }
263 #endif // !PRODUCT
264
265 // We're going to allocate linearly, so might as well prefetch ahead.
266 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
267
268 const oop obj = oop(obj_ptr);
269 const oop forward_ptr = old->forward_to_atomic(obj);
270 if (forward_ptr == NULL) {
271 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
272
273 if (dest_state.is_young()) {
274 if (age < markOopDesc::max_age) {
275 age++;
276 }
277 if (old_mark->has_displaced_mark_helper()) {
278 // In this case, we have to install the mark word first,
279 // otherwise obj looks to be forwarded (the old mark word,
280 // which contains the forward pointer, was copied)
281 obj->set_mark_raw(old_mark);
282 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
283 old_mark->set_displaced_mark_helper(new_mark);
284 } else {
285 obj->set_mark_raw(old_mark->set_age(age));
286 }
287 _age_table.add(age, word_sz);
288 } else {
289 obj->set_mark_raw(old_mark);
290 }
291
292 if (G1StringDedup::is_enabled()) {
293 const bool is_from_young = state.is_young();
294 const bool is_to_young = dest_state.is_young();
295 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(),
296 "sanity");
297 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
298 "sanity");
299 G1StringDedup::enqueue_from_evacuation(is_from_young,
300 is_to_young,
301 _worker_id,
302 obj);
303 }
304
305 _surviving_young_words[young_index] += word_sz;
306
307 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
308 // We keep track of the next start index in the length field of
309 // the to-space object. The actual length can be found in the
310 // length field of the from-space object.
311 arrayOop(obj)->set_length(0);
312 oop* old_p = set_partial_array_mask(old);
313 do_oop_partial_array(old_p);
314 } else {
315 HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr);
316 _scanner.set_region(to_region);
317 obj->oop_iterate_backwards(&_scanner);
318 }
319 return obj;
320 } else {
321 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
322 return forward_ptr;
323 }
324 }
325
326 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
327 assert(worker_id < _n_workers, "out of bounds access");
328 if (_states[worker_id] == NULL) {
329 _states[worker_id] = new G1ParScanThreadState(_g1h, worker_id, _young_cset_length);
330 }
331 return _states[worker_id];
332 }
333
334 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
335 assert(_flushed, "thread local state from the per thread states should have been flushed");
336 return _surviving_young_words_total;
337 }
338
339 void G1ParScanThreadStateSet::flush() {
340 assert(!_flushed, "thread local state from the per thread states should be flushed once");
341
342 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
343 G1ParScanThreadState* pss = _states[worker_index];
344
345 if (pss == NULL) {
346 continue;
347 }
348
349 pss->flush(_surviving_young_words_total);
350 delete pss;
351 _states[worker_index] = NULL;
352 }
353 _flushed = true;
354 }
355
356 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
357 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
358
359 oop forward_ptr = old->forward_to_atomic(old);
360 if (forward_ptr == NULL) {
361 // Forward-to-self succeeded. We are the "owner" of the object.
362 HeapRegion* r = _g1h->heap_region_containing(old);
363
364 if (!r->evacuation_failed()) {
365 r->set_evacuation_failed(true);
366 _g1h->hr_printer()->evac_failure(r);
367 }
368
369 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
370
371 _scanner.set_region(r);
372 old->oop_iterate_backwards(&_scanner);
373
374 return old;
375 } else {
376 // Forward-to-self failed. Either someone else managed to allocate
377 // space for this object (old != forward_ptr) or they beat us in
378 // self-forwarding it (old == forward_ptr).
379 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
380 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
381 "should not be in the CSet",
382 p2i(old), p2i(forward_ptr));
383 return forward_ptr;
384 }
385 }
386 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, uint n_workers, size_t young_cset_length) :
387 _g1h(g1h),
388 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
389 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)),
390 _young_cset_length(young_cset_length),
391 _n_workers(n_workers),
392 _flushed(false) {
393 for (uint i = 0; i < n_workers; ++i) {
394 _states[i] = NULL;
395 }
396 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t));
397 }
398
399 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
400 assert(_flushed, "thread local state from the per thread states should have been flushed");
401 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
402 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
403 }