1 /*
2 * Copyright (c) 2014, 2020, 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/g1/g1Trace.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,
41 G1RedirtyCardsQueueSet* rdcqs,
42 uint worker_id,
43 size_t young_cset_length,
44 size_t optional_cset_length)
45 : _g1h(g1h),
46 _task_queue(g1h->task_queue(worker_id)),
47 _rdcq(rdcqs),
48 _ct(g1h->card_table()),
49 _closures(NULL),
50 _plab_allocator(NULL),
51 _age_table(false),
52 _tenuring_threshold(g1h->policy()->tenuring_threshold()),
53 _scanner(g1h, this),
54 _worker_id(worker_id),
55 _last_enqueued_card(SIZE_MAX),
56 _stack_trim_upper_threshold(GCDrainStackTargetSize * 2 + 1),
57 _stack_trim_lower_threshold(GCDrainStackTargetSize),
58 _trim_ticks(),
59 _surviving_young_words_base(NULL),
60 _surviving_young_words(NULL),
61 _surviving_words_length(young_cset_length + 1),
62 _old_gen_is_full(false),
63 _num_optional_regions(optional_cset_length),
64 _numa(g1h->numa()),
65 _obj_alloc_stat(NULL)
66 {
67 // We allocate number of young gen regions in the collection set plus one
68 // entries, since entry 0 keeps track of surviving bytes for non-young regions.
69 // We also add a few elements at the beginning and at the end in
70 // an attempt to eliminate cache contention
71 size_t array_length = PADDING_ELEM_NUM + _surviving_words_length + PADDING_ELEM_NUM;
72 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
73 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
74 memset(_surviving_young_words, 0, _surviving_words_length * sizeof(size_t));
75
76 _plab_allocator = new G1PLABAllocator(_g1h->allocator());
77
78 // The dest for Young is used when the objects are aged enough to
79 // need to be moved to the next space.
80 _dest[G1HeapRegionAttr::Young] = G1HeapRegionAttr::Old;
81 _dest[G1HeapRegionAttr::Old] = G1HeapRegionAttr::Old;
82
83 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
84
85 _oops_into_optional_regions = new G1OopStarChunkedList[_num_optional_regions];
86
87 initialize_numa_stats();
88 }
89
90 size_t G1ParScanThreadState::flush(size_t* surviving_young_words) {
91 _rdcq.flush();
92 flush_numa_stats();
93 // Update allocation statistics.
94 _plab_allocator->flush_and_retire_stats();
95 _g1h->policy()->record_age_table(&_age_table);
96
97 size_t sum = 0;
98 for (uint i = 0; i < _surviving_words_length; i++) {
99 surviving_young_words[i] += _surviving_young_words[i];
100 sum += _surviving_young_words[i];
101 }
102 return sum;
103 }
104
105 G1ParScanThreadState::~G1ParScanThreadState() {
106 delete _plab_allocator;
107 delete _closures;
108 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
109 delete[] _oops_into_optional_regions;
110 FREE_C_HEAP_ARRAY(size_t, _obj_alloc_stat);
111 }
112
113 size_t G1ParScanThreadState::lab_waste_words() const {
114 return _plab_allocator->waste();
115 }
116
117 size_t G1ParScanThreadState::lab_undo_waste_words() const {
118 return _plab_allocator->undo_waste();
119 }
120
121 #ifdef ASSERT
122 void G1ParScanThreadState::verify_task(narrowOop* task) const {
123 assert(task != NULL, "invariant");
124 assert(UseCompressedOops, "sanity");
125 oop p = RawAccess<>::oop_load(task);
126 assert(_g1h->is_in_g1_reserved(p),
127 "task=" PTR_FORMAT " p=" PTR_FORMAT, p2i(task), p2i(p));
128 }
129
130 void G1ParScanThreadState::verify_task(oop* task) const {
131 assert(task != NULL, "invariant");
132 oop p = RawAccess<>::oop_load(task);
133 assert(_g1h->is_in_g1_reserved(p),
134 "task=" PTR_FORMAT " p=" PTR_FORMAT, p2i(task), p2i(p));
135 }
136
137 void G1ParScanThreadState::verify_task(PartialArrayScanTask task) const {
138 // Must be in the collection set--it's already been copied.
139 oop p = task.to_source_array();
140 assert(_g1h->is_in_cset(p), "p=" PTR_FORMAT, p2i(p));
141 }
142
143 void G1ParScanThreadState::verify_task(ScannerTask task) const {
144 if (task.is_narrow_oop_ptr()) {
145 verify_task(task.to_narrow_oop_ptr());
146 } else if (task.is_oop_ptr()) {
147 verify_task(task.to_oop_ptr());
148 } else if (task.is_partial_array_task()) {
149 verify_task(task.to_partial_array_task());
150 } else {
151 ShouldNotReachHere();
152 }
153 }
154 #endif // ASSERT
155
156 void G1ParScanThreadState::trim_queue() {
157 do {
158 // Fully drain the queue.
159 trim_queue_to_threshold(0);
160 } while (!_task_queue->is_empty());
161 }
162
163 HeapWord* G1ParScanThreadState::allocate_in_next_plab(G1HeapRegionAttr* dest,
164 size_t word_sz,
165 bool previous_plab_refill_failed,
166 uint node_index) {
167
168 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: %s region attr", dest->get_type_str());
169
170 // Right now we only have two types of regions (young / old) so
171 // let's keep the logic here simple. We can generalize it when necessary.
172 if (dest->is_young()) {
173 bool plab_refill_in_old_failed = false;
174 HeapWord* const obj_ptr = _plab_allocator->allocate(G1HeapRegionAttr::Old,
175 word_sz,
176 &plab_refill_in_old_failed,
177 node_index);
178 // Make sure that we won't attempt to copy any other objects out
179 // of a survivor region (given that apparently we cannot allocate
180 // any new ones) to avoid coming into this slow path again and again.
181 // Only consider failed PLAB refill here: failed inline allocations are
182 // typically large, so not indicative of remaining space.
183 if (previous_plab_refill_failed) {
184 _tenuring_threshold = 0;
185 }
186
187 if (obj_ptr != NULL) {
188 dest->set_old();
189 } else {
190 // We just failed to allocate in old gen. The same idea as explained above
191 // for making survivor gen unavailable for allocation applies for old gen.
192 _old_gen_is_full = plab_refill_in_old_failed;
193 }
194 return obj_ptr;
195 } else {
196 _old_gen_is_full = previous_plab_refill_failed;
197 assert(dest->is_old(), "Unexpected dest region attr: %s", dest->get_type_str());
198 // no other space to try.
199 return NULL;
200 }
201 }
202
203 G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markWord const m, uint& age) {
204 if (region_attr.is_young()) {
205 age = !m.has_displaced_mark_helper() ? m.age()
206 : m.displaced_mark_helper().age();
207 if (age < _tenuring_threshold) {
208 return region_attr;
209 }
210 }
211 return dest(region_attr);
212 }
213
214 void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr,
215 oop const old, size_t word_sz, uint age,
216 HeapWord * const obj_ptr, uint node_index) const {
217 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_attr, node_index);
218 if (alloc_buf->contains(obj_ptr)) {
219 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age,
220 dest_attr.type() == G1HeapRegionAttr::Old,
221 alloc_buf->word_sz() * HeapWordSize);
222 } else {
223 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age,
224 dest_attr.type() == G1HeapRegionAttr::Old);
225 }
226 }
227
228 oop G1ParScanThreadState::copy_to_survivor_space(G1HeapRegionAttr const region_attr,
229 oop const old,
230 markWord const old_mark) {
231 const size_t word_sz = old->size();
232
233 uint age = 0;
234 G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age);
235 // The second clause is to prevent premature evacuation failure in case there
236 // is still space in survivor, but old gen is full.
237 if (_old_gen_is_full && dest_attr.is_old()) {
238 return handle_evacuation_failure_par(old, old_mark);
239 }
240 HeapRegion* const from_region = _g1h->heap_region_containing(old);
241 uint node_index = from_region->node_index();
242
243 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_attr, word_sz, node_index);
244
245 // PLAB allocations should succeed most of the time, so we'll
246 // normally check against NULL once and that's it.
247 if (obj_ptr == NULL) {
248 bool plab_refill_failed = false;
249 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_attr, word_sz, &plab_refill_failed, node_index);
250 if (obj_ptr == NULL) {
251 assert(region_attr.is_in_cset(), "Unexpected region attr type: %s", region_attr.get_type_str());
252 obj_ptr = allocate_in_next_plab(&dest_attr, word_sz, plab_refill_failed, node_index);
253 if (obj_ptr == NULL) {
254 // This will either forward-to-self, or detect that someone else has
255 // installed a forwarding pointer.
256 return handle_evacuation_failure_par(old, old_mark);
257 }
258 }
259 update_numa_stats(node_index);
260
261 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
262 // The events are checked individually as part of the actual commit
263 report_promotion_event(dest_attr, old, word_sz, age, obj_ptr, node_index);
264 }
265 }
266
267 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
268 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
269
270 #ifndef PRODUCT
271 // Should this evacuation fail?
272 if (_g1h->evacuation_should_fail()) {
273 // Doing this after all the allocation attempts also tests the
274 // undo_allocation() method too.
275 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
276 return handle_evacuation_failure_par(old, old_mark);
277 }
278 #endif // !PRODUCT
279
280 // We're going to allocate linearly, so might as well prefetch ahead.
281 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
282
283 const oop obj = oop(obj_ptr);
284 const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed);
285 if (forward_ptr == NULL) {
286 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(old), obj_ptr, word_sz);
287
288 const uint young_index = from_region->young_index_in_cset();
289
290 assert((from_region->is_young() && young_index > 0) ||
291 (!from_region->is_young() && young_index == 0), "invariant" );
292
293 if (dest_attr.is_young()) {
294 if (age < markWord::max_age) {
295 age++;
296 }
297 if (old_mark.has_displaced_mark_helper()) {
298 // In this case, we have to install the mark word first,
299 // otherwise obj looks to be forwarded (the old mark word,
300 // which contains the forward pointer, was copied)
301 obj->set_mark_raw(old_mark);
302 markWord new_mark = old_mark.displaced_mark_helper().set_age(age);
303 old_mark.set_displaced_mark_helper(new_mark);
304 } else {
305 obj->set_mark_raw(old_mark.set_age(age));
306 }
307 _age_table.add(age, word_sz);
308 } else {
309 obj->set_mark_raw(old_mark);
310 }
311
312 if (G1StringDedup::is_enabled()) {
313 const bool is_from_young = region_attr.is_young();
314 const bool is_to_young = dest_attr.is_young();
315 assert(is_from_young == from_region->is_young(),
316 "sanity");
317 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
318 "sanity");
319 G1StringDedup::enqueue_from_evacuation(is_from_young,
320 is_to_young,
321 _worker_id,
322 obj);
323 }
324
325 _surviving_young_words[young_index] += word_sz;
326
327 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
328 // We keep track of the next start index in the length field of
329 // the to-space object. The actual length can be found in the
330 // length field of the from-space object.
331 arrayOop(obj)->set_length(0);
332 do_partial_array(PartialArrayScanTask(old));
333 } else {
334 G1ScanInYoungSetter x(&_scanner, dest_attr.is_young());
335 obj->oop_iterate_backwards(&_scanner);
336 }
337 return obj;
338 } else {
339 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index);
340 return forward_ptr;
341 }
342 }
343
344 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
345 assert(worker_id < _n_workers, "out of bounds access");
346 if (_states[worker_id] == NULL) {
347 _states[worker_id] =
348 new G1ParScanThreadState(_g1h, _rdcqs, worker_id, _young_cset_length, _optional_cset_length);
349 }
350 return _states[worker_id];
351 }
352
353 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
354 assert(_flushed, "thread local state from the per thread states should have been flushed");
355 return _surviving_young_words_total;
356 }
357
358 void G1ParScanThreadStateSet::flush() {
359 assert(!_flushed, "thread local state from the per thread states should be flushed once");
360
361 for (uint worker_id = 0; worker_id < _n_workers; ++worker_id) {
362 G1ParScanThreadState* pss = _states[worker_id];
363
364 if (pss == NULL) {
365 continue;
366 }
367
368 G1GCPhaseTimes* p = _g1h->phase_times();
369
370 // Need to get the following two before the call to G1ParThreadScanState::flush()
371 // because it resets the PLAB allocator where we get this info from.
372 size_t lab_waste_bytes = pss->lab_waste_words() * HeapWordSize;
373 size_t lab_undo_waste_bytes = pss->lab_undo_waste_words() * HeapWordSize;
374 size_t copied_bytes = pss->flush(_surviving_young_words_total) * HeapWordSize;
375
376 p->record_or_add_thread_work_item(G1GCPhaseTimes::MergePSS, worker_id, copied_bytes, G1GCPhaseTimes::MergePSSCopiedBytes);
377 p->record_or_add_thread_work_item(G1GCPhaseTimes::MergePSS, worker_id, lab_waste_bytes, G1GCPhaseTimes::MergePSSLABWasteBytes);
378 p->record_or_add_thread_work_item(G1GCPhaseTimes::MergePSS, worker_id, lab_undo_waste_bytes, G1GCPhaseTimes::MergePSSLABUndoWasteBytes);
379
380 delete pss;
381 _states[worker_id] = NULL;
382 }
383 _flushed = true;
384 }
385
386 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) {
387 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
388 G1ParScanThreadState* pss = _states[worker_index];
389
390 if (pss == NULL) {
391 continue;
392 }
393
394 size_t used_memory = pss->oops_into_optional_region(hr)->used_memory();
395 _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanHR, worker_index, used_memory, G1GCPhaseTimes::ScanHRUsedMemory);
396 }
397 }
398
399 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markWord m) {
400 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
401
402 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed);
403 if (forward_ptr == NULL) {
404 // Forward-to-self succeeded. We are the "owner" of the object.
405 HeapRegion* r = _g1h->heap_region_containing(old);
406
407 if (!r->evacuation_failed()) {
408 r->set_evacuation_failed(true);
409 _g1h->hr_printer()->evac_failure(r);
410 }
411
412 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
413
414 G1ScanInYoungSetter x(&_scanner, r->is_young());
415 old->oop_iterate_backwards(&_scanner);
416
417 return old;
418 } else {
419 // Forward-to-self failed. Either someone else managed to allocate
420 // space for this object (old != forward_ptr) or they beat us in
421 // self-forwarding it (old == forward_ptr).
422 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
423 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
424 "should not be in the CSet",
425 p2i(old), p2i(forward_ptr));
426 return forward_ptr;
427 }
428 }
429 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h,
430 G1RedirtyCardsQueueSet* rdcqs,
431 uint n_workers,
432 size_t young_cset_length,
433 size_t optional_cset_length) :
434 _g1h(g1h),
435 _rdcqs(rdcqs),
436 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
437 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length + 1, mtGC)),
438 _young_cset_length(young_cset_length),
439 _optional_cset_length(optional_cset_length),
440 _n_workers(n_workers),
441 _flushed(false) {
442 for (uint i = 0; i < n_workers; ++i) {
443 _states[i] = NULL;
444 }
445 memset(_surviving_young_words_total, 0, (young_cset_length + 1) * sizeof(size_t));
446 }
447
448 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
449 assert(_flushed, "thread local state from the per thread states should have been flushed");
450 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
451 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
452 }