1 /*
2 * Copyright (c) 2002, 2022, 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 = NULL;
48 PSPromotionManager::PSScannerTasksQueueSet* PSPromotionManager::_stack_array_depth = NULL;
49 PreservedMarksSet* PSPromotionManager::_preserved_marks_set = NULL;
50 PSOldGen* PSPromotionManager::_old_gen = NULL;
51 MutableSpace* PSPromotionManager::_young_space = NULL;
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 == NULL, "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 == NULL, "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 != NULL, "Sanity");
95 return &_manager_array[index];
96 }
97
98 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
99 assert(_manager_array != NULL, "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;
183 queue_size = claimed_stack_depth()->max_elems();
184
185 if (ParallelGCThreads == 1) {
186 _target_stack_size = 0;
187 } else {
188 // don't let the target stack size to be more than 1/4 of the entries
189 _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
190 (uint) (queue_size / 4));
191 }
192
193 _array_chunk_size = ParGCArrayScanChunk;
194 // let's choose 1.5x the chunk size
195 _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
196
197 _preserved_marks = NULL;
198
199 reset();
200 }
201
202 void PSPromotionManager::reset() {
203 assert(stacks_empty(), "reset of non-empty stack");
204
205 // We need to get an assert in here to make sure the labs are always flushed.
206
207 // Do not prefill the LAB's, save heap wastage!
208 HeapWord* lab_base = young_space()->top();
209 _young_lab.initialize(MemRegion(lab_base, (size_t)0));
210 _young_gen_is_full = false;
211
212 lab_base = old_gen()->object_space()->top();
213 _old_lab.initialize(MemRegion(lab_base, (size_t)0));
214 _old_gen_is_full = false;
215
216 _promotion_failed_info.reset();
217
218 TASKQUEUE_STATS_ONLY(reset_stats());
219 }
220
221 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
222 assert(_preserved_marks == NULL, "do not set it twice");
223 _preserved_marks = preserved_marks;
224 }
225
226 void PSPromotionManager::restore_preserved_marks() {
227 _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
228 }
229
230 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
231 totally_drain = totally_drain || (_target_stack_size == 0);
232
233 PSScannerTasksQueue* const tq = claimed_stack_depth();
234 do {
235 ScannerTask task;
236
237 // Drain overflow stack first, so other threads can steal from
238 // claimed stack while we work.
239 while (tq->pop_overflow(task)) {
240 process_popped_location_depth(task);
241 }
242
243 if (totally_drain) {
244 while (tq->pop_local(task)) {
245 process_popped_location_depth(task);
246 }
247 } else {
248 while (tq->size() > _target_stack_size && tq->pop_local(task)) {
249 process_popped_location_depth(task);
250 }
251 }
252 } while ((totally_drain && !tq->taskqueue_empty()) || !tq->overflow_empty());
253
254 assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
255 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
256 assert(tq->overflow_empty(), "Sanity");
257 }
258
259 void PSPromotionManager::flush_labs() {
260 assert(stacks_empty(), "Attempt to flush lab with live stack");
261
262 // If either promotion lab fills up, we can flush the
263 // lab but not refill it, so check first.
264 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
265 if (!_young_lab.is_flushed())
266 _young_lab.flush();
267
268 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
269 if (!_old_lab.is_flushed())
270 _old_lab.flush();
271
272 // Let PSScavenge know if we overflowed
273 if (_young_gen_is_full) {
274 PSScavenge::set_survivor_overflow(true);
275 }
276 }
277
278 template <class T> void PSPromotionManager::process_array_chunk_work(
279 oop obj,
280 int start, int end) {
281 assert(start <= end, "invariant");
282 T* const base = (T*)objArrayOop(obj)->base();
283 T* p = base + start;
284 T* const chunk_end = base + end;
285 while (p < chunk_end) {
286 if (PSScavenge::should_scavenge(p)) {
287 claim_or_forward_depth(p);
288 }
289 ++p;
290 }
291 }
292
293 void PSPromotionManager::process_array_chunk(PartialArrayScanTask task) {
294 assert(PSChunkLargeArrays, "invariant");
295
296 oop old = task.to_source_array();
297 assert(old->is_objArray(), "invariant");
298 assert(old->is_forwarded(), "invariant");
299
300 TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
301
302 oop const obj = old->forwardee();
303
304 int start;
305 int const end = arrayOop(old)->length();
306 if (end > (int) _min_array_size_for_chunking) {
307 // we'll chunk more
308 start = end - _array_chunk_size;
309 assert(start > 0, "invariant");
310 arrayOop(old)->set_length(start);
311 push_depth(ScannerTask(PartialArrayScanTask(old)));
312 TASKQUEUE_STATS_ONLY(++_array_chunk_pushes);
313 } else {
314 // this is the final chunk for this array
315 start = 0;
316 int const actual_length = arrayOop(obj)->length();
317 arrayOop(old)->set_length(actual_length);
318 }
319
320 if (UseCompressedOops) {
321 process_array_chunk_work<narrowOop>(obj, start, end);
322 } else {
323 process_array_chunk_work<oop>(obj, start, end);
324 }
325 }
326
327 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
328 assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
329
330 // Attempt to CAS in the header.
331 // This tests if the header is still the same as when
332 // this started. If it is the same (i.e., no forwarding
333 // pointer has been installed), then this thread owns
334 // it.
335 if (obj->forward_to_atomic(obj, obj_mark) == NULL) {
336 // We won any races, we "own" this object.
337 assert(obj == obj->forwardee(), "Sanity");
338
339 _promotion_failed_info.register_copy_failure(obj->size());
340
341 ContinuationGCSupport::transform_stack_chunk(obj);
342
343 push_contents(obj);
344
345 // Save the markWord of promotion-failed objs in _preserved_marks for later
346 // restoration. This way we don't have to walk the young-gen to locate
347 // these promotion-failed objs.
348 _preserved_marks->push_always(obj, obj_mark);
349 } else {
350 // We lost, someone else "owns" this object
351 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
352
353 // No unallocation to worry about.
354 obj = obj->forwardee();
355 }
356
357 return obj;
358 }