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 #include "oops/flatArrayKlass.inline.hpp"
46
47 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = nullptr;
48 PSPromotionManager::PSScannerTasksQueueSet* PSPromotionManager::_stack_array_depth = nullptr;
49 PreservedMarksSet* PSPromotionManager::_preserved_marks_set = nullptr;
50 PSOldGen* PSPromotionManager::_old_gen = nullptr;
51 MutableSpace* PSPromotionManager::_young_space = nullptr;
52
53 void PSPromotionManager::initialize() {
54 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
55
56 _old_gen = heap->old_gen();
57 _young_space = heap->young_gen()->to_space();
58
59 const uint promotion_manager_num = ParallelGCThreads;
60
61 // To prevent false sharing, we pad the PSPromotionManagers
62 // and make sure that the first instance starts at a cache line.
63 assert(_manager_array == nullptr, "Attempt to initialize twice");
64 _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
65
66 _stack_array_depth = new PSScannerTasksQueueSet(ParallelGCThreads);
67
68 // Create and register the PSPromotionManager(s) for the worker threads.
69 for(uint i=0; i<ParallelGCThreads; i++) {
70 stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
71 }
72 // The VMThread gets its own PSPromotionManager, which is not available
73 // for work stealing.
74
75 assert(_preserved_marks_set == nullptr, "Attempt to initialize twice");
76 _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
77 _preserved_marks_set->init(promotion_manager_num);
78 for (uint i = 0; i < promotion_manager_num; i += 1) {
79 _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
80 }
81 }
82
83 // Helper functions to get around the circular dependency between
84 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
85 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
86 return PSScavenge::should_scavenge(p, check_to_space);
87 }
88 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
89 return PSScavenge::should_scavenge(p, check_to_space);
90 }
91
92 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
93 assert(index < ParallelGCThreads, "index out of range");
94 assert(_manager_array != nullptr, "Sanity");
95 return &_manager_array[index];
96 }
97
98 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
99 assert(_manager_array != nullptr, "Sanity");
100 return &_manager_array[0];
101 }
102
103 void PSPromotionManager::pre_scavenge() {
104 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
105
106 _preserved_marks_set->assert_empty();
107 _young_space = heap->young_gen()->to_space();
108
109 for(uint i=0; i<ParallelGCThreads; i++) {
110 manager_array(i)->reset();
111 }
112 }
113
114 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
115 bool promotion_failure_occurred = false;
116
117 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
118 for (uint i = 0; i < ParallelGCThreads; i++) {
119 PSPromotionManager* manager = manager_array(i);
120 assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
121 if (manager->_promotion_failed_info.has_failed()) {
122 gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
123 promotion_failure_occurred = true;
124 }
125 manager->flush_labs();
126 manager->flush_string_dedup_requests();
127 }
128 if (!promotion_failure_occurred) {
129 // If there was no promotion failure, the preserved mark stacks
130 // should be empty.
131 _preserved_marks_set->assert_empty();
132 }
133 return promotion_failure_occurred;
134 }
135
136 #if TASKQUEUE_STATS
137 void
138 PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
139 #define FMT " " SIZE_FORMAT_W(10)
140 out->print_cr("%3u" FMT FMT FMT FMT,
141 i, _array_chunk_pushes, _array_chunk_steals,
142 _arrays_chunked, _array_chunks_processed);
143 #undef FMT
144 }
145
146 static const char* const pm_stats_hdr[] = {
147 " ----partial array---- arrays array",
148 "thr push steal chunked chunks",
149 "--- ---------- ---------- ---------- ----------"
150 };
151
152 void PSPromotionManager::print_taskqueue_stats() {
153 if (!log_is_enabled(Trace, gc, task, stats)) {
154 return;
155 }
156 Log(gc, task, stats) log;
157 ResourceMark rm;
158 LogStream ls(log.trace());
159
160 stack_array_depth()->print_taskqueue_stats(&ls, "Oop Queue");
161
162 const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
163 for (uint i = 0; i < hlines; ++i) ls.print_cr("%s", pm_stats_hdr[i]);
164 for (uint i = 0; i < ParallelGCThreads; ++i) {
165 manager_array(i)->print_local_stats(&ls, i);
166 }
167 }
168
169 void PSPromotionManager::reset_stats() {
170 claimed_stack_depth()->stats.reset();
171 _array_chunk_pushes = _array_chunk_steals = 0;
172 _arrays_chunked = _array_chunks_processed = 0;
173 }
174 #endif // TASKQUEUE_STATS
175
176 PSPromotionManager::PSPromotionManager() {
177 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
178
179 // We set the old lab's start array.
180 _old_lab.set_start_array(old_gen()->start_array());
181
182 uint queue_size = claimed_stack_depth()->max_elems();
183
184 if (ParallelGCThreads == 1) {
185 _target_stack_size = 0;
186 } else {
187 _target_stack_size = GCDrainStackTargetSize;
188 }
189
190 _array_chunk_size = ParGCArrayScanChunk;
191 // let's choose 1.5x the chunk size
192 _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
193
194 _preserved_marks = nullptr;
195
196 reset();
197 }
198
199 void PSPromotionManager::reset() {
200 assert(stacks_empty(), "reset of non-empty stack");
201
202 // We need to get an assert in here to make sure the labs are always flushed.
203
204 // Do not prefill the LAB's, save heap wastage!
205 HeapWord* lab_base = young_space()->top();
206 _young_lab.initialize(MemRegion(lab_base, (size_t)0));
207 _young_gen_is_full = false;
208
209 lab_base = old_gen()->object_space()->top();
210 _old_lab.initialize(MemRegion(lab_base, (size_t)0));
211 _old_gen_is_full = false;
212
213 _promotion_failed_info.reset();
214
215 TASKQUEUE_STATS_ONLY(reset_stats());
216 }
217
218 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
219 assert(_preserved_marks == nullptr, "do not set it twice");
220 _preserved_marks = preserved_marks;
221 }
222
223 void PSPromotionManager::restore_preserved_marks() {
224 _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
225 }
226
227 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
228 const uint threshold = totally_drain ? 0
229 : _target_stack_size;
230
231 PSScannerTasksQueue* const tq = claimed_stack_depth();
232 do {
233 ScannerTask task;
234
235 // Drain overflow stack first, so other threads can steal from
236 // claimed stack while we work.
237 while (tq->pop_overflow(task)) {
238 if (!tq->try_push_to_taskqueue(task)) {
239 process_popped_location_depth(task);
240 }
241 }
242
243 while (tq->pop_local(task, threshold)) {
244 process_popped_location_depth(task);
245 }
246 } while (!tq->overflow_empty());
247
248 assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
249 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
250 assert(tq->overflow_empty(), "Sanity");
251 }
252
253 void PSPromotionManager::flush_labs() {
254 assert(stacks_empty(), "Attempt to flush lab with live stack");
255
256 // If either promotion lab fills up, we can flush the
257 // lab but not refill it, so check first.
258 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
259 if (!_young_lab.is_flushed())
260 _young_lab.flush();
261
262 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
263 if (!_old_lab.is_flushed())
264 _old_lab.flush();
265
266 // Let PSScavenge know if we overflowed
267 if (_young_gen_is_full) {
268 PSScavenge::set_survivor_overflow(true);
269 }
270 }
271
272 template <class T> void PSPromotionManager::process_array_chunk_work(
273 oop obj,
274 int start, int end) {
275 assert(start <= end, "invariant");
276 T* const base = (T*)objArrayOop(obj)->base();
277 T* p = base + start;
278 T* const chunk_end = base + end;
279 while (p < chunk_end) {
280 if (PSScavenge::should_scavenge(p)) {
281 claim_or_forward_depth(p);
282 }
283 ++p;
284 }
285 }
286
287 void PSPromotionManager::process_array_chunk(PartialArrayScanTask task) {
288 assert(PSChunkLargeArrays, "invariant");
289
290 oop old = task.to_source_array();
291 assert(old->is_objArray(), "invariant");
292 assert(old->is_forwarded(), "invariant");
293
294 TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
295
296 oop const obj = old->forwardee();
297
298 int start;
299 int const end = arrayOop(old)->length();
300 if (end > (int) _min_array_size_for_chunking) {
301 // we'll chunk more
302 start = end - _array_chunk_size;
303 assert(start > 0, "invariant");
304 arrayOop(old)->set_length(start);
305 push_depth(ScannerTask(PartialArrayScanTask(old)));
306 TASKQUEUE_STATS_ONLY(++_array_chunk_pushes);
307 } else {
308 // this is the final chunk for this array
309 start = 0;
310 int const actual_length = arrayOop(obj)->length();
311 arrayOop(old)->set_length(actual_length);
312 }
313
314 if (UseCompressedOops) {
315 process_array_chunk_work<narrowOop>(obj, start, end);
316 } else {
317 process_array_chunk_work<oop>(obj, start, end);
318 }
319 }
320
321 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
322 assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
323
324 // Attempt to CAS in the header.
325 // This tests if the header is still the same as when
326 // this started. If it is the same (i.e., no forwarding
327 // pointer has been installed), then this thread owns
328 // it.
329 if (obj->forward_to_atomic(obj, obj_mark) == nullptr) {
330 // We won any races, we "own" this object.
331 assert(obj == obj->forwardee(), "Sanity");
332
333 _promotion_failed_info.register_copy_failure(obj->size());
334
335 ContinuationGCSupport::transform_stack_chunk(obj);
336
337 push_contents(obj);
338
339 // Save the markWord of promotion-failed objs in _preserved_marks for later
340 // restoration. This way we don't have to walk the young-gen to locate
341 // these promotion-failed objs.
342 _preserved_marks->push_always(obj, obj_mark);
343 } else {
344 // We lost, someone else "owns" this object
345 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
346
347 // No unallocation to worry about.
348 obj = obj->forwardee();
349 }
350
351 return obj;
352 }