1 /*
2 * Copyright (c) 2002, 2023, 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 "classfile/javaClasses.inline.hpp"
27 #include "gc/parallel/mutableSpace.hpp"
28 #include "gc/parallel/parallelScavengeHeap.hpp"
29 #include "gc/parallel/psOldGen.hpp"
30 #include "gc/parallel/psPromotionManager.inline.hpp"
31 #include "gc/parallel/psScavenge.inline.hpp"
32 #include "gc/shared/continuationGCSupport.inline.hpp"
33 #include "gc/shared/gcTrace.hpp"
34 #include "gc/shared/preservedMarks.inline.hpp"
35 #include "gc/shared/taskqueue.inline.hpp"
36 #include "logging/log.hpp"
37 #include "logging/logStream.hpp"
38 #include "memory/allocation.inline.hpp"
39 #include "memory/iterator.inline.hpp"
40 #include "memory/memRegion.hpp"
41 #include "memory/padded.inline.hpp"
42 #include "memory/resourceArea.hpp"
43 #include "oops/access.inline.hpp"
44 #include "oops/compressedOops.inline.hpp"
45
46 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = nullptr;
47 PSPromotionManager::PSScannerTasksQueueSet* PSPromotionManager::_stack_array_depth = nullptr;
48 PreservedMarksSet* PSPromotionManager::_preserved_marks_set = nullptr;
49 PSOldGen* PSPromotionManager::_old_gen = nullptr;
50 MutableSpace* PSPromotionManager::_young_space = nullptr;
51
52 void PSPromotionManager::initialize() {
53 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
54
55 _old_gen = heap->old_gen();
56 _young_space = heap->young_gen()->to_space();
57
58 const uint promotion_manager_num = ParallelGCThreads;
59
60 // To prevent false sharing, we pad the PSPromotionManagers
61 // and make sure that the first instance starts at a cache line.
62 assert(_manager_array == nullptr, "Attempt to initialize twice");
63 _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
64
65 _stack_array_depth = new PSScannerTasksQueueSet(ParallelGCThreads);
66
67 // Create and register the PSPromotionManager(s) for the worker threads.
68 for(uint i=0; i<ParallelGCThreads; i++) {
69 stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
70 }
71 // The VMThread gets its own PSPromotionManager, which is not available
72 // for work stealing.
73
74 assert(_preserved_marks_set == nullptr, "Attempt to initialize twice");
75 _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
76 _preserved_marks_set->init(promotion_manager_num);
77 for (uint i = 0; i < promotion_manager_num; i += 1) {
78 _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
79 }
80 }
81
82 // Helper functions to get around the circular dependency between
83 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
84 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
85 return PSScavenge::should_scavenge(p, check_to_space);
86 }
87 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
88 return PSScavenge::should_scavenge(p, check_to_space);
89 }
90
91 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
92 assert(index < ParallelGCThreads, "index out of range");
93 assert(_manager_array != nullptr, "Sanity");
94 return &_manager_array[index];
95 }
96
97 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
98 assert(_manager_array != nullptr, "Sanity");
99 return &_manager_array[0];
100 }
101
102 void PSPromotionManager::pre_scavenge() {
103 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
104
105 _preserved_marks_set->assert_empty();
106 _young_space = heap->young_gen()->to_space();
107
108 for(uint i=0; i<ParallelGCThreads; i++) {
109 manager_array(i)->reset();
110 }
111 }
112
113 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
114 bool promotion_failure_occurred = false;
115
116 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
117 for (uint i = 0; i < ParallelGCThreads; i++) {
118 PSPromotionManager* manager = manager_array(i);
119 assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
120 if (manager->_promotion_failed_info.has_failed()) {
121 gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
122 promotion_failure_occurred = true;
123 }
124 manager->flush_labs();
125 manager->flush_string_dedup_requests();
126 }
127 if (!promotion_failure_occurred) {
128 // If there was no promotion failure, the preserved mark stacks
129 // should be empty.
130 _preserved_marks_set->assert_empty();
131 }
132 return promotion_failure_occurred;
133 }
134
135 #if TASKQUEUE_STATS
136 void
137 PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
138 #define FMT " " SIZE_FORMAT_W(10)
139 out->print_cr("%3u" FMT FMT FMT FMT,
140 i, _array_chunk_pushes, _array_chunk_steals,
141 _arrays_chunked, _array_chunks_processed);
142 #undef FMT
143 }
144
145 static const char* const pm_stats_hdr[] = {
146 " ----partial array---- arrays array",
147 "thr push steal chunked chunks",
148 "--- ---------- ---------- ---------- ----------"
149 };
150
151 void PSPromotionManager::print_taskqueue_stats() {
152 if (!log_is_enabled(Trace, gc, task, stats)) {
153 return;
154 }
155 Log(gc, task, stats) log;
156 ResourceMark rm;
157 LogStream ls(log.trace());
158
159 stack_array_depth()->print_taskqueue_stats(&ls, "Oop Queue");
160
161 const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
162 for (uint i = 0; i < hlines; ++i) ls.print_cr("%s", pm_stats_hdr[i]);
163 for (uint i = 0; i < ParallelGCThreads; ++i) {
164 manager_array(i)->print_local_stats(&ls, i);
165 }
166 }
167
168 void PSPromotionManager::reset_stats() {
169 claimed_stack_depth()->stats.reset();
170 _array_chunk_pushes = _array_chunk_steals = 0;
171 _arrays_chunked = _array_chunks_processed = 0;
172 }
173 #endif // TASKQUEUE_STATS
174
175 PSPromotionManager::PSPromotionManager() {
176 // We set the old lab's start array.
177 _old_lab.set_start_array(old_gen()->start_array());
178
179 if (ParallelGCThreads == 1) {
180 _target_stack_size = 0;
181 } else {
182 _target_stack_size = GCDrainStackTargetSize;
183 }
184
185 _array_chunk_size = ParGCArrayScanChunk;
186 // let's choose 1.5x the chunk size
187 _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
188
189 _preserved_marks = nullptr;
190
191 reset();
192 }
193
194 void PSPromotionManager::reset() {
195 assert(stacks_empty(), "reset of non-empty stack");
196
197 // We need to get an assert in here to make sure the labs are always flushed.
198
199 // Do not prefill the LAB's, save heap wastage!
200 HeapWord* lab_base = young_space()->top();
201 _young_lab.initialize(MemRegion(lab_base, (size_t)0));
202 _young_gen_is_full = false;
203
204 lab_base = old_gen()->object_space()->top();
205 _old_lab.initialize(MemRegion(lab_base, (size_t)0));
206 _old_gen_is_full = false;
207
208 _promotion_failed_info.reset();
209
210 TASKQUEUE_STATS_ONLY(reset_stats());
211 }
212
213 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
214 assert(_preserved_marks == nullptr, "do not set it twice");
215 _preserved_marks = preserved_marks;
216 }
217
218 void PSPromotionManager::restore_preserved_marks() {
219 _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
220 }
221
222 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
223 const uint threshold = totally_drain ? 0
224 : _target_stack_size;
225
226 PSScannerTasksQueue* const tq = claimed_stack_depth();
227 do {
228 ScannerTask task;
229
230 // Drain overflow stack first, so other threads can steal from
231 // claimed stack while we work.
232 while (tq->pop_overflow(task)) {
233 if (!tq->try_push_to_taskqueue(task)) {
234 process_popped_location_depth(task);
235 }
236 }
237
238 while (tq->pop_local(task, threshold)) {
239 process_popped_location_depth(task);
240 }
241 } while (!tq->overflow_empty());
242
243 assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
244 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
245 assert(tq->overflow_empty(), "Sanity");
246 }
247
248 void PSPromotionManager::flush_labs() {
249 assert(stacks_empty(), "Attempt to flush lab with live stack");
250
251 // If either promotion lab fills up, we can flush the
252 // lab but not refill it, so check first.
253 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
254 if (!_young_lab.is_flushed())
255 _young_lab.flush();
256
257 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
258 if (!_old_lab.is_flushed())
259 _old_lab.flush();
260
261 // Let PSScavenge know if we overflowed
262 if (_young_gen_is_full) {
263 PSScavenge::set_survivor_overflow(true);
264 }
265 }
266
267 template <class T> void PSPromotionManager::process_array_chunk_work(
268 oop obj,
269 int start, int end) {
270 assert(start <= end, "invariant");
271 T* const base = (T*)objArrayOop(obj)->base();
272 T* p = base + start;
273 T* const chunk_end = base + end;
274 while (p < chunk_end) {
275 claim_or_forward_depth(p);
276 ++p;
277 }
278 }
279
280 void PSPromotionManager::process_array_chunk(PartialArrayScanTask task) {
281 assert(PSChunkLargeArrays, "invariant");
282
283 oop old = task.to_source_array();
284 assert(old->is_objArray(), "invariant");
285 assert(old->is_forwarded(), "invariant");
286
287 TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
288
289 oop const obj = old->forwardee();
290
291 int start;
292 int const end = arrayOop(old)->length();
293 if (end > (int) _min_array_size_for_chunking) {
294 // we'll chunk more
295 start = end - _array_chunk_size;
296 assert(start > 0, "invariant");
297 arrayOop(old)->set_length(start);
298 push_depth(ScannerTask(PartialArrayScanTask(old)));
299 TASKQUEUE_STATS_ONLY(++_array_chunk_pushes);
300 } else {
301 // this is the final chunk for this array
302 start = 0;
303 int const actual_length = arrayOop(obj)->length();
304 arrayOop(old)->set_length(actual_length);
305 }
306
307 if (UseCompressedOops) {
308 process_array_chunk_work<narrowOop>(obj, start, end);
309 } else {
310 process_array_chunk_work<oop>(obj, start, end);
311 }
312 }
313
314 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
315 assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
316
317 // Attempt to CAS in the header.
318 // This tests if the header is still the same as when
319 // this started. If it is the same (i.e., no forwarding
320 // pointer has been installed), then this thread owns
321 // it.
322 if (obj->forward_to_atomic(obj, obj_mark) == nullptr) {
323 // We won any races, we "own" this object.
324 assert(obj == obj->forwardee(), "Sanity");
325
326 _promotion_failed_info.register_copy_failure(obj->size());
327
328 ContinuationGCSupport::transform_stack_chunk(obj);
329
330 push_contents(obj);
331
332 // Save the markWord of promotion-failed objs in _preserved_marks for later
333 // restoration. This way we don't have to walk the young-gen to locate
334 // these promotion-failed objs.
335 _preserved_marks->push_always(obj, obj_mark);
336 } else {
337 // We lost, someone else "owns" this object
338 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
339
340 // No unallocation to worry about.
341 obj = obj->forwardee();
342 }
343
344 return obj;
345 }