1 /*
2 * Copyright (c) 2014, 2017, 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/oop.inline.hpp"
37 #include "runtime/prefetch.inline.hpp"
38
39 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint worker_id, size_t young_cset_length)
40 : _g1h(g1h),
41 _refs(g1h->task_queue(worker_id)),
42 _dcq(&g1h->dirty_card_queue_set()),
43 _ct_bs(g1h->g1_barrier_set()),
44 _closures(NULL),
45 _hash_seed(17),
46 _worker_id(worker_id),
47 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()),
48 _age_table(false),
49 _scanner(g1h, this),
50 _old_gen_is_full(false)
51 {
52 // we allocate G1YoungSurvRateNumRegions plus one entries, since
53 // we "sacrifice" entry 0 to keep track of surviving bytes for
54 // non-young regions (where the age is -1)
55 // We also add a few elements at the beginning and at the end in
56 // an attempt to eliminate cache contention
57 size_t real_length = 1 + young_cset_length;
58 size_t array_length = PADDING_ELEM_NUM +
59 real_length +
60 PADDING_ELEM_NUM;
61 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
62 if (_surviving_young_words_base == NULL)
63 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
64 "Not enough space for young surv histo.");
65 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
66 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
67
68 _plab_allocator = G1PLABAllocator::create_allocator(_g1h->allocator());
69
70 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet;
71 // The dest for Young is used when the objects are aged enough to
72 // need to be moved to the next space.
73 _dest[InCSetState::Young] = InCSetState::Old;
74 _dest[InCSetState::Old] = InCSetState::Old;
75
76 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
77 }
78
79 // Pass locally gathered statistics to global state.
80 void G1ParScanThreadState::flush(size_t* surviving_young_words) {
81 _dcq.flush();
82 // Update allocation statistics.
83 _plab_allocator->flush_and_retire_stats();
84 _g1h->g1_policy()->record_age_table(&_age_table);
85
86 uint length = _g1h->collection_set()->young_region_length();
87 for (uint region_index = 0; region_index < length; region_index++) {
88 surviving_young_words[region_index] += _surviving_young_words[region_index];
89 }
90 }
91
92 G1ParScanThreadState::~G1ParScanThreadState() {
93 delete _plab_allocator;
94 delete _closures;
95 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
96 }
97
98 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) {
99 _plab_allocator->waste(wasted, undo_wasted);
100 }
101
102 #ifdef ASSERT
103 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
104 assert(ref != NULL, "invariant");
105 assert(UseCompressedOops, "sanity");
106 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));
107 oop p = oopDesc::load_decode_heap_oop(ref);
108 assert(_g1h->is_in_g1_reserved(p),
109 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
110 return true;
111 }
112
113 bool G1ParScanThreadState::verify_ref(oop* ref) const {
114 assert(ref != NULL, "invariant");
115 if (has_partial_array_mask(ref)) {
116 // Must be in the collection set--it's already been copied.
117 oop p = clear_partial_array_mask(ref);
118 assert(_g1h->is_in_cset(p),
119 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
120 } else {
121 oop p = oopDesc::load_decode_heap_oop(ref);
122 assert(_g1h->is_in_g1_reserved(p),
123 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
124 }
125 return true;
126 }
127
128 bool G1ParScanThreadState::verify_task(StarTask ref) const {
129 if (ref.is_narrow()) {
130 return verify_ref((narrowOop*) ref);
131 } else {
132 return verify_ref((oop*) ref);
133 }
134 }
135 #endif // ASSERT
136
137 void G1ParScanThreadState::trim_queue() {
138 StarTask ref;
139 do {
140 // Drain the overflow stack first, so other threads can steal.
141 while (_refs->pop_overflow(ref)) {
142 if (!_refs->try_push_to_taskqueue(ref)) {
143 dispatch_reference(ref);
144 }
145 }
146
147 while (_refs->pop_local(ref)) {
148 dispatch_reference(ref);
149 }
150 } while (!_refs->is_empty());
151 }
152
153 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
154 InCSetState* dest,
155 size_t word_sz,
156 AllocationContext_t const context,
157 bool previous_plab_refill_failed) {
158 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value());
159 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
160
161 // Right now we only have two types of regions (young / old) so
162 // let's keep the logic here simple. We can generalize it when necessary.
163 if (dest->is_young()) {
164 bool plab_refill_in_old_failed = false;
165 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old,
166 word_sz,
167 context,
168 &plab_refill_in_old_failed);
169 // Make sure that we won't attempt to copy any other objects out
170 // of a survivor region (given that apparently we cannot allocate
171 // any new ones) to avoid coming into this slow path again and again.
172 // Only consider failed PLAB refill here: failed inline allocations are
173 // typically large, so not indicative of remaining space.
174 if (previous_plab_refill_failed) {
175 _tenuring_threshold = 0;
176 }
177
178 if (obj_ptr != NULL) {
179 dest->set_old();
180 } else {
181 // We just failed to allocate in old gen. The same idea as explained above
182 // for making survivor gen unavailable for allocation applies for old gen.
183 _old_gen_is_full = plab_refill_in_old_failed;
184 }
185 return obj_ptr;
186 } else {
187 _old_gen_is_full = previous_plab_refill_failed;
188 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
189 // no other space to try.
190 return NULL;
191 }
192 }
193
194 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
195 if (state.is_young()) {
196 age = !m->has_displaced_mark_helper() ? m->age()
197 : m->displaced_mark_helper()->age();
198 if (age < _tenuring_threshold) {
199 return state;
200 }
201 }
202 return dest(state);
203 }
204
205 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state,
206 oop const old, size_t word_sz, uint age,
207 HeapWord * const obj_ptr,
208 const AllocationContext_t context) const {
209 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state, context);
210 if (alloc_buf->contains(obj_ptr)) {
211 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz, age,
212 dest_state.value() == InCSetState::Old,
213 alloc_buf->word_sz());
214 } else {
215 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz, age,
216 dest_state.value() == InCSetState::Old);
217 }
218 }
219
220 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
221 oop const old,
222 markOop const old_mark) {
223 const size_t word_sz = old->size();
224 HeapRegion* const from_region = _g1h->heap_region_containing(old);
225 // +1 to make the -1 indexes valid...
226 const int young_index = from_region->young_index_in_cset()+1;
227 assert( (from_region->is_young() && young_index > 0) ||
228 (!from_region->is_young() && young_index == 0), "invariant" );
229 const AllocationContext_t context = from_region->allocation_context();
230
231 uint age = 0;
232 InCSetState dest_state = next_state(state, old_mark, age);
233 // The second clause is to prevent premature evacuation failure in case there
234 // is still space in survivor, but old gen is full.
235 if (_old_gen_is_full && dest_state.is_old()) {
236 return handle_evacuation_failure_par(old, old_mark);
237 }
238 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz, context);
239
240 // PLAB allocations should succeed most of the time, so we'll
241 // normally check against NULL once and that's it.
242 if (obj_ptr == NULL) {
243 bool plab_refill_failed = false;
244 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, context, &plab_refill_failed);
245 if (obj_ptr == NULL) {
246 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context, plab_refill_failed);
247 if (obj_ptr == NULL) {
248 // This will either forward-to-self, or detect that someone else has
249 // installed a forwarding pointer.
250 return handle_evacuation_failure_par(old, old_mark);
251 }
252 }
253 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
254 // The events are checked individually as part of the actual commit
255 report_promotion_event(dest_state, old, word_sz, age, obj_ptr, context);
256 }
257 }
258
259 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
260 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
261
262 #ifndef PRODUCT
263 // Should this evacuation fail?
264 if (_g1h->evacuation_should_fail()) {
265 // Doing this after all the allocation attempts also tests the
266 // undo_allocation() method too.
267 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
268 return handle_evacuation_failure_par(old, old_mark);
269 }
270 #endif // !PRODUCT
271
272 // We're going to allocate linearly, so might as well prefetch ahead.
273 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
274
275 const oop obj = oop(obj_ptr);
276 const oop forward_ptr = old->forward_to_atomic(obj);
277 if (forward_ptr == NULL) {
278 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
279
280 if (dest_state.is_young()) {
281 if (age < markOopDesc::max_age) {
282 age++;
283 }
284 if (old_mark->has_displaced_mark_helper()) {
285 // In this case, we have to install the mark word first,
286 // otherwise obj looks to be forwarded (the old mark word,
287 // which contains the forward pointer, was copied)
288 obj->set_mark(old_mark);
289 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
290 old_mark->set_displaced_mark_helper(new_mark);
291 } else {
292 obj->set_mark(old_mark->set_age(age));
293 }
294 _age_table.add(age, word_sz);
295 } else {
296 obj->set_mark(old_mark);
297 }
298
299 if (G1StringDedup::is_enabled()) {
300 const bool is_from_young = state.is_young();
301 const bool is_to_young = dest_state.is_young();
302 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(),
303 "sanity");
304 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
305 "sanity");
306 G1StringDedup::enqueue_from_evacuation(is_from_young,
307 is_to_young,
308 _worker_id,
309 obj);
310 }
311
312 _surviving_young_words[young_index] += word_sz;
313
314 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
315 // We keep track of the next start index in the length field of
316 // the to-space object. The actual length can be found in the
317 // length field of the from-space object.
318 arrayOop(obj)->set_length(0);
319 oop* old_p = set_partial_array_mask(old);
320 push_on_queue(old_p);
321 } else {
322 HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr);
323 _scanner.set_region(to_region);
324 obj->oop_iterate_backwards(&_scanner);
325 }
326 return obj;
327 } else {
328 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
329 return forward_ptr;
330 }
331 }
332
333 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
334 assert(worker_id < _n_workers, "out of bounds access");
335 if (_states[worker_id] == NULL) {
336 _states[worker_id] = new_par_scan_state(worker_id, _young_cset_length);
337 }
338 return _states[worker_id];
339 }
340
341 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
342 assert(_flushed, "thread local state from the per thread states should have been flushed");
343 return _surviving_young_words_total;
344 }
345
346 void G1ParScanThreadStateSet::flush() {
347 assert(!_flushed, "thread local state from the per thread states should be flushed once");
348
349 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
350 G1ParScanThreadState* pss = _states[worker_index];
351
352 if (pss == NULL) {
353 continue;
354 }
355
356 pss->flush(_surviving_young_words_total);
357 delete pss;
358 _states[worker_index] = NULL;
359 }
360 _flushed = true;
361 }
362
363 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
364 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
365
366 oop forward_ptr = old->forward_to_atomic(old);
367 if (forward_ptr == NULL) {
368 // Forward-to-self succeeded. We are the "owner" of the object.
369 HeapRegion* r = _g1h->heap_region_containing(old);
370
371 if (!r->evacuation_failed()) {
372 r->set_evacuation_failed(true);
373 _g1h->hr_printer()->evac_failure(r);
374 }
375
376 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
377
378 _scanner.set_region(r);
379 old->oop_iterate_backwards(&_scanner);
380
381 return old;
382 } else {
383 // Forward-to-self failed. Either someone else managed to allocate
384 // space for this object (old != forward_ptr) or they beat us in
385 // self-forwarding it (old == forward_ptr).
386 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
387 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
388 "should not be in the CSet",
389 p2i(old), p2i(forward_ptr));
390 return forward_ptr;
391 }
392 }
393
394 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, uint n_workers, size_t young_cset_length) :
395 _g1h(g1h),
396 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
397 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)),
398 _young_cset_length(young_cset_length),
399 _n_workers(n_workers),
400 _flushed(false) {
401 for (uint i = 0; i < n_workers; ++i) {
402 _states[i] = NULL;
403 }
404 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t));
405 }
406
407 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
408 assert(_flushed, "thread local state from the per thread states should have been flushed");
409 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
410 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
411 }