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 // _dest
49 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()),
50 _scanner(g1h, this),
51 _hash_seed(17),
52 _worker_id(worker_id),
53 _stack_drain_upper_threshold(GCDrainStackTargetSize * 2 + 1),
54 _stack_drain_lower_threshold(GCDrainStackTargetSize),
55 // _surviving_young_words(NULL),
56 // _surviving_young_words_base(NULL),
57 _trim_ticks(),
58 _old_gen_is_full(false)
59 {
60 // we allocate G1YoungSurvRateNumRegions plus one entries, since
61 // we "sacrifice" entry 0 to keep track of surviving bytes for
62 // non-young regions (where the age is -1)
63 // We also add a few elements at the beginning and at the end in
64 // an attempt to eliminate cache contention
65 size_t real_length = 1 + young_cset_length;
66 size_t array_length = PADDING_ELEM_NUM +
67 real_length +
68 PADDING_ELEM_NUM;
69 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
70 if (_surviving_young_words_base == NULL)
71 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
72 "Not enough space for young surv histo.");
73 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
74 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
75
76 _plab_allocator = new G1PLABAllocator(_g1h->allocator());
77
78 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet;
79 // The dest for Young is used when the objects are aged enough to
80 // need to be moved to the next space.
81 _dest[InCSetState::Young] = InCSetState::Old;
82 _dest[InCSetState::Old] = InCSetState::Old;
83
84 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
85 }
86
87 // Pass locally gathered statistics to global state.
88 void G1ParScanThreadState::flush(size_t* surviving_young_words) {
89 _dcq.flush();
90 // Update allocation statistics.
91 _plab_allocator->flush_and_retire_stats();
92 _g1h->g1_policy()->record_age_table(&_age_table);
93
94 uint length = _g1h->collection_set()->young_region_length();
95 for (uint region_index = 0; region_index < length; region_index++) {
96 surviving_young_words[region_index] += _surviving_young_words[region_index];
97 }
98 }
99
100 G1ParScanThreadState::~G1ParScanThreadState() {
101 delete _plab_allocator;
102 delete _closures;
103 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
104 }
105
106 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) {
107 _plab_allocator->waste(wasted, undo_wasted);
108 }
109
110 #ifdef ASSERT
111 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
112 assert(ref != NULL, "invariant");
113 assert(UseCompressedOops, "sanity");
114 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));
115 oop p = RawAccess<>::oop_load(ref);
116 assert(_g1h->is_in_g1_reserved(p),
117 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
118 return true;
119 }
120
121 bool G1ParScanThreadState::verify_ref(oop* ref) const {
122 assert(ref != NULL, "invariant");
123 if (has_partial_array_mask(ref)) {
124 // Must be in the collection set--it's already been copied.
125 oop p = clear_partial_array_mask(ref);
126 assert(_g1h->is_in_cset(p),
127 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
128 } else {
129 oop p = RawAccess<>::oop_load(ref);
130 assert(_g1h->is_in_g1_reserved(p),
131 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
132 }
133 return true;
134 }
135
136 bool G1ParScanThreadState::verify_task(StarTask ref) const {
137 if (ref.is_narrow()) {
138 return verify_ref((narrowOop*) ref);
139 } else {
140 return verify_ref((oop*) ref);
141 }
142 }
143 #endif // ASSERT
144
145 void G1ParScanThreadState::trim_queue() {
146 StarTask ref;
147 do {
148 // Drain the overflow stack first, so other threads can steal.
149 while (_refs->pop_overflow(ref)) {
150 if (!_refs->try_push_to_taskqueue(ref)) {
151 dispatch_reference(ref);
152 }
153 }
154
155 while (_refs->pop_local(ref)) {
156 dispatch_reference(ref);
157 }
158 } while (!_refs->is_empty());
159 }
160
161 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
162 InCSetState* dest,
163 size_t word_sz,
164 bool previous_plab_refill_failed) {
165 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value());
166 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
167
168 // Right now we only have two types of regions (young / old) so
169 // let's keep the logic here simple. We can generalize it when necessary.
170 if (dest->is_young()) {
171 bool plab_refill_in_old_failed = false;
172 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old,
173 word_sz,
174 &plab_refill_in_old_failed);
175 // Make sure that we won't attempt to copy any other objects out
176 // of a survivor region (given that apparently we cannot allocate
177 // any new ones) to avoid coming into this slow path again and again.
178 // Only consider failed PLAB refill here: failed inline allocations are
179 // typically large, so not indicative of remaining space.
180 if (previous_plab_refill_failed) {
181 _tenuring_threshold = 0;
182 }
183
184 if (obj_ptr != NULL) {
185 dest->set_old();
186 } else {
187 // We just failed to allocate in old gen. The same idea as explained above
188 // for making survivor gen unavailable for allocation applies for old gen.
189 _old_gen_is_full = plab_refill_in_old_failed;
190 }
191 return obj_ptr;
192 } else {
193 _old_gen_is_full = previous_plab_refill_failed;
194 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
195 // no other space to try.
196 return NULL;
197 }
198 }
199
200 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
201 if (state.is_young()) {
202 age = !m->has_displaced_mark_helper() ? m->age()
203 : m->displaced_mark_helper()->age();
204 if (age < _tenuring_threshold) {
205 return state;
206 }
207 }
208 return dest(state);
209 }
210
211 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state,
212 oop const old, size_t word_sz, uint age,
213 HeapWord * const obj_ptr) const {
214 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state);
215 if (alloc_buf->contains(obj_ptr)) {
216 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz, age,
217 dest_state.value() == InCSetState::Old,
218 alloc_buf->word_sz());
219 } else {
220 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz, age,
221 dest_state.value() == InCSetState::Old);
222 }
223 }
224
225 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
226 oop const old,
227 markOop const old_mark) {
228 const size_t word_sz = old->size();
229 HeapRegion* const from_region = _g1h->heap_region_containing(old);
230 // +1 to make the -1 indexes valid...
231 const int young_index = from_region->young_index_in_cset()+1;
232 assert( (from_region->is_young() && young_index > 0) ||
233 (!from_region->is_young() && young_index == 0), "invariant" );
234
235 uint age = 0;
236 InCSetState dest_state = next_state(state, old_mark, age);
237 // The second clause is to prevent premature evacuation failure in case there
238 // is still space in survivor, but old gen is full.
239 if (_old_gen_is_full && dest_state.is_old()) {
240 return handle_evacuation_failure_par(old, old_mark);
241 }
242 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz);
243
244 // PLAB allocations should succeed most of the time, so we'll
245 // normally check against NULL once and that's it.
246 if (obj_ptr == NULL) {
247 bool plab_refill_failed = false;
248 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed);
249 if (obj_ptr == NULL) {
250 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed);
251 if (obj_ptr == NULL) {
252 // This will either forward-to-self, or detect that someone else has
253 // installed a forwarding pointer.
254 return handle_evacuation_failure_par(old, old_mark);
255 }
256 }
257 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
258 // The events are checked individually as part of the actual commit
259 report_promotion_event(dest_state, old, word_sz, age, obj_ptr);
260 }
261 }
262
263 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
264 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
265
266 #ifndef PRODUCT
267 // Should this evacuation fail?
268 if (_g1h->evacuation_should_fail()) {
269 // Doing this after all the allocation attempts also tests the
270 // undo_allocation() method too.
271 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
272 return handle_evacuation_failure_par(old, old_mark);
273 }
274 #endif // !PRODUCT
275
276 // We're going to allocate linearly, so might as well prefetch ahead.
277 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
278
279 const oop obj = oop(obj_ptr);
280 const oop forward_ptr = old->forward_to_atomic(obj);
281 if (forward_ptr == NULL) {
282 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
283
284 if (dest_state.is_young()) {
285 if (age < markOopDesc::max_age) {
286 age++;
287 }
288 if (old_mark->has_displaced_mark_helper()) {
289 // In this case, we have to install the mark word first,
290 // otherwise obj looks to be forwarded (the old mark word,
291 // which contains the forward pointer, was copied)
292 obj->set_mark_raw(old_mark);
293 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
294 old_mark->set_displaced_mark_helper(new_mark);
295 } else {
296 obj->set_mark_raw(old_mark->set_age(age));
297 }
298 _age_table.add(age, word_sz);
299 } else {
300 obj->set_mark_raw(old_mark);
301 }
302
303 if (G1StringDedup::is_enabled()) {
304 const bool is_from_young = state.is_young();
305 const bool is_to_young = dest_state.is_young();
306 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(),
307 "sanity");
308 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
309 "sanity");
310 G1StringDedup::enqueue_from_evacuation(is_from_young,
311 is_to_young,
312 _worker_id,
313 obj);
314 }
315
316 _surviving_young_words[young_index] += word_sz;
317
318 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
319 // We keep track of the next start index in the length field of
320 // the to-space object. The actual length can be found in the
321 // length field of the from-space object.
322 arrayOop(obj)->set_length(0);
323 oop* old_p = set_partial_array_mask(old);
324 do_oop_partial_array(old_p);
325 } else {
326 HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr);
327 _scanner.set_region(to_region);
328 obj->oop_iterate_backwards(&_scanner);
329 }
330 return obj;
331 } else {
332 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
333 return forward_ptr;
334 }
335 }
336
337 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
338 assert(worker_id < _n_workers, "out of bounds access");
339 if (_states[worker_id] == NULL) {
340 _states[worker_id] = new G1ParScanThreadState(_g1h, worker_id, _young_cset_length);
341 }
342 return _states[worker_id];
343 }
344
345 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
346 assert(_flushed, "thread local state from the per thread states should have been flushed");
347 return _surviving_young_words_total;
348 }
349
350 void G1ParScanThreadStateSet::flush() {
351 assert(!_flushed, "thread local state from the per thread states should be flushed once");
352
353 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
354 G1ParScanThreadState* pss = _states[worker_index];
355
356 if (pss == NULL) {
357 continue;
358 }
359
360 pss->flush(_surviving_young_words_total);
361 delete pss;
362 _states[worker_index] = NULL;
363 }
364 _flushed = true;
365 }
366
367 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
368 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
369
370 oop forward_ptr = old->forward_to_atomic(old);
371 if (forward_ptr == NULL) {
372 // Forward-to-self succeeded. We are the "owner" of the object.
373 HeapRegion* r = _g1h->heap_region_containing(old);
374
375 if (!r->evacuation_failed()) {
376 r->set_evacuation_failed(true);
377 _g1h->hr_printer()->evac_failure(r);
378 }
379
380 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
381
382 _scanner.set_region(r);
383 old->oop_iterate_backwards(&_scanner);
384
385 return old;
386 } else {
387 // Forward-to-self failed. Either someone else managed to allocate
388 // space for this object (old != forward_ptr) or they beat us in
389 // self-forwarding it (old == forward_ptr).
390 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
391 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
392 "should not be in the CSet",
393 p2i(old), p2i(forward_ptr));
394 return forward_ptr;
395 }
396 }
397 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, uint n_workers, size_t young_cset_length) :
398 _g1h(g1h),
399 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
400 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)),
401 _young_cset_length(young_cset_length),
402 _n_workers(n_workers),
403 _flushed(false) {
404 for (uint i = 0; i < n_workers; ++i) {
405 _states[i] = NULL;
406 }
407 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t));
408 }
409
410 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
411 assert(_flushed, "thread local state from the per thread states should have been flushed");
412 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
413 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
414 }