1 /*
2 * Copyright (c) 2001, 2019, 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/g1BufferNodeList.hpp"
27 #include "gc/g1/g1CardTableEntryClosure.hpp"
28 #include "gc/g1/g1CollectedHeap.inline.hpp"
29 #include "gc/g1/g1DirtyCardQueue.hpp"
30 #include "gc/g1/g1FreeIdSet.hpp"
31 #include "gc/g1/g1RedirtyCardsQueue.hpp"
32 #include "gc/g1/g1RemSet.hpp"
33 #include "gc/g1/g1ThreadLocalData.hpp"
34 #include "gc/g1/heapRegionRemSet.hpp"
35 #include "gc/shared/suspendibleThreadSet.hpp"
36 #include "gc/shared/workgroup.hpp"
37 #include "runtime/atomic.hpp"
38 #include "runtime/flags/flagSetting.hpp"
39 #include "runtime/mutexLocker.hpp"
40 #include "runtime/safepoint.hpp"
41 #include "runtime/thread.inline.hpp"
42 #include "runtime/threadSMR.hpp"
43
44 // Closure used for updating remembered sets and recording references that
45 // point into the collection set while the mutator is running.
46 // Assumed to be only executed concurrently with the mutator. Yields via
47 // SuspendibleThreadSet after every card.
48 class G1RefineCardConcurrentlyClosure: public G1CardTableEntryClosure {
49 public:
50 bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
51 G1CollectedHeap::heap()->rem_set()->refine_card_concurrently(card_ptr, worker_i);
52
53 if (SuspendibleThreadSet::should_yield()) {
54 // Caller will actually yield.
55 return false;
56 }
57 // Otherwise, we finished successfully; return true.
58 return true;
59 }
60 };
61
62 G1DirtyCardQueue::G1DirtyCardQueue(G1DirtyCardQueueSet* qset) :
63 // Dirty card queues are always active, so we create them with their
64 // active field set to true.
65 PtrQueue(qset, true /* active */)
66 { }
67
68 G1DirtyCardQueue::~G1DirtyCardQueue() {
69 flush();
70 }
71
72 void G1DirtyCardQueue::handle_completed_buffer() {
73 assert(_buf != NULL, "precondition");
74 BufferNode* node = BufferNode::make_node_from_buffer(_buf, index());
75 G1DirtyCardQueueSet* dcqs = dirty_card_qset();
76 if (dcqs->process_or_enqueue_completed_buffer(node)) {
77 reset(); // Buffer fully processed, reset index.
78 } else {
79 allocate_buffer(); // Buffer enqueued, get a new one.
80 }
81 }
82
83 G1DirtyCardQueueSet::G1DirtyCardQueueSet(bool notify_when_complete) :
84 PtrQueueSet(),
85 _cbl_mon(NULL),
86 _completed_buffers_head(NULL),
87 _completed_buffers_tail(NULL),
88 _num_entries_in_completed_buffers(0),
89 _process_completed_buffers_threshold(ProcessCompletedBuffersThresholdNever),
90 _process_completed_buffers(false),
91 _notify_when_complete(notify_when_complete),
92 _max_completed_buffers(MaxCompletedBuffersUnlimited),
93 _completed_buffers_padding(0),
94 _free_ids(NULL),
95 _processed_buffers_mut(0),
96 _processed_buffers_rs_thread(0)
97 {
98 _all_active = true;
99 }
100
101 G1DirtyCardQueueSet::~G1DirtyCardQueueSet() {
102 abandon_completed_buffers();
103 delete _free_ids;
104 }
105
106 // Determines how many mutator threads can process the buffers in parallel.
107 uint G1DirtyCardQueueSet::num_par_ids() {
108 return (uint)os::initial_active_processor_count();
109 }
110
111 void G1DirtyCardQueueSet::initialize(Monitor* cbl_mon,
112 BufferNode::Allocator* allocator,
113 bool init_free_ids) {
114 PtrQueueSet::initialize(allocator);
115 assert(_cbl_mon == NULL, "Init order issue?");
116 _cbl_mon = cbl_mon;
117 if (init_free_ids) {
118 _free_ids = new G1FreeIdSet(0, num_par_ids());
119 }
120 }
121
122 void G1DirtyCardQueueSet::handle_zero_index_for_thread(Thread* t) {
123 G1ThreadLocalData::dirty_card_queue(t).handle_zero_index();
124 }
125
126 void G1DirtyCardQueueSet::enqueue_completed_buffer(BufferNode* cbn) {
127 MutexLocker x(_cbl_mon, Mutex::_no_safepoint_check_flag);
128 cbn->set_next(NULL);
129 if (_completed_buffers_tail == NULL) {
130 assert(_completed_buffers_head == NULL, "Well-formedness");
131 _completed_buffers_head = cbn;
132 _completed_buffers_tail = cbn;
133 } else {
134 _completed_buffers_tail->set_next(cbn);
135 _completed_buffers_tail = cbn;
136 }
137 _num_entries_in_completed_buffers += buffer_size() - cbn->index();
138
139 if (!process_completed_buffers() &&
140 (num_completed_buffers() > process_completed_buffers_threshold())) {
141 set_process_completed_buffers(true);
142 if (_notify_when_complete) {
143 _cbl_mon->notify_all();
144 }
145 }
146 verify_num_entries_in_completed_buffers();
147 }
148
149 BufferNode* G1DirtyCardQueueSet::get_completed_buffer(size_t stop_at) {
150 MutexLocker x(_cbl_mon, Mutex::_no_safepoint_check_flag);
151
152 if (num_completed_buffers() <= stop_at) {
153 return NULL;
154 }
155
156 assert(num_completed_buffers() > 0, "invariant");
157 assert(_completed_buffers_head != NULL, "invariant");
158 assert(_completed_buffers_tail != NULL, "invariant");
159
160 BufferNode* bn = _completed_buffers_head;
161 _num_entries_in_completed_buffers -= buffer_size() - bn->index();
162 _completed_buffers_head = bn->next();
163 if (_completed_buffers_head == NULL) {
164 assert(num_completed_buffers() == 0, "invariant");
165 _completed_buffers_tail = NULL;
166 set_process_completed_buffers(false);
167 }
168 verify_num_entries_in_completed_buffers();
169 bn->set_next(NULL);
170 return bn;
171 }
172
173 #ifdef ASSERT
174 void G1DirtyCardQueueSet::verify_num_entries_in_completed_buffers() const {
175 size_t actual = 0;
176 BufferNode* cur = _completed_buffers_head;
177 while (cur != NULL) {
178 actual += buffer_size() - cur->index();
179 cur = cur->next();
180 }
181 assert(actual == _num_entries_in_completed_buffers,
182 "Num entries in completed buffers should be " SIZE_FORMAT " but are " SIZE_FORMAT,
183 _num_entries_in_completed_buffers, actual);
184 }
185 #endif
186
187 void G1DirtyCardQueueSet::abandon_completed_buffers() {
188 BufferNode* buffers_to_delete = NULL;
189 {
190 MutexLocker x(_cbl_mon, Mutex::_no_safepoint_check_flag);
191 buffers_to_delete = _completed_buffers_head;
192 _completed_buffers_head = NULL;
193 _completed_buffers_tail = NULL;
194 _num_entries_in_completed_buffers = 0;
195 set_process_completed_buffers(false);
196 }
197 while (buffers_to_delete != NULL) {
198 BufferNode* bn = buffers_to_delete;
199 buffers_to_delete = bn->next();
200 bn->set_next(NULL);
201 deallocate_buffer(bn);
202 }
203 }
204
205 void G1DirtyCardQueueSet::notify_if_necessary() {
206 MutexLocker x(_cbl_mon, Mutex::_no_safepoint_check_flag);
207 if (num_completed_buffers() > process_completed_buffers_threshold()) {
208 set_process_completed_buffers(true);
209 if (_notify_when_complete)
210 _cbl_mon->notify();
211 }
212 }
213
214 // Merge lists of buffers. Notify the processing threads.
215 // The source queue is emptied as a result. The queues
216 // must share the monitor.
217 void G1DirtyCardQueueSet::merge_bufferlists(G1RedirtyCardsQueueSet* src) {
218 assert(allocator() == src->allocator(), "precondition");
219 const G1BufferNodeList from = src->take_all_completed_buffers();
220 if (from._head == NULL) return;
221
222 MutexLocker x(_cbl_mon, Mutex::_no_safepoint_check_flag);
223 if (_completed_buffers_tail == NULL) {
224 assert(_completed_buffers_head == NULL, "Well-formedness");
225 _completed_buffers_head = from._head;
226 _completed_buffers_tail = from._tail;
227 } else {
228 assert(_completed_buffers_head != NULL, "Well formedness");
229 _completed_buffers_tail->set_next(from._head);
230 _completed_buffers_tail = from._tail;
231 }
232 _num_entries_in_completed_buffers += from._entry_count;
233
234 assert(_completed_buffers_head == NULL && _completed_buffers_tail == NULL ||
235 _completed_buffers_head != NULL && _completed_buffers_tail != NULL,
236 "Sanity");
237 verify_num_entries_in_completed_buffers();
238 }
239
240 bool G1DirtyCardQueueSet::apply_closure_to_buffer(G1CardTableEntryClosure* cl,
241 BufferNode* node,
242 uint worker_i) {
243 if (cl == NULL) return true;
244 bool result = true;
245 void** buf = BufferNode::make_buffer_from_node(node);
246 size_t i = node->index();
247 size_t limit = buffer_size();
248 for ( ; i < limit; ++i) {
249 CardTable::CardValue* card_ptr = static_cast<CardTable::CardValue*>(buf[i]);
250 assert(card_ptr != NULL, "invariant");
251 if (!cl->do_card_ptr(card_ptr, worker_i)) {
252 result = false; // Incomplete processing.
253 break;
254 }
255 }
256 assert(i <= buffer_size(), "invariant");
257 node->set_index(i);
258 return result;
259 }
260
261 #ifndef ASSERT
262 #define assert_fully_consumed(node, buffer_size)
263 #else
264 #define assert_fully_consumed(node, buffer_size) \
265 do { \
266 size_t _afc_index = (node)->index(); \
267 size_t _afc_size = (buffer_size); \
268 assert(_afc_index == _afc_size, \
269 "Buffer was not fully consumed as claimed: index: " \
270 SIZE_FORMAT ", size: " SIZE_FORMAT, \
271 _afc_index, _afc_size); \
272 } while (0)
273 #endif // ASSERT
274
275 bool G1DirtyCardQueueSet::process_or_enqueue_completed_buffer(BufferNode* node) {
276 if (Thread::current()->is_Java_thread()) {
277 // If the number of buffers exceeds the limit, make this Java
278 // thread do the processing itself. We don't lock to access
279 // buffer count or padding; it is fine to be imprecise here. The
280 // add of padding could overflow, which is treated as unlimited.
281 size_t max_buffers = max_completed_buffers();
282 size_t limit = max_buffers + completed_buffers_padding();
283 if ((num_completed_buffers() > limit) && (limit >= max_buffers)) {
284 if (mut_process_buffer(node)) {
285 return true;
286 }
287 }
288 }
289 enqueue_completed_buffer(node);
290 return false;
291 }
292
293 bool G1DirtyCardQueueSet::mut_process_buffer(BufferNode* node) {
294 guarantee(_free_ids != NULL, "must be");
295
296 uint worker_i = _free_ids->claim_par_id(); // temporarily claim an id
297 G1RefineCardConcurrentlyClosure cl;
298 bool result = apply_closure_to_buffer(&cl, node, worker_i);
299 _free_ids->release_par_id(worker_i); // release the id
300
301 if (result) {
302 assert_fully_consumed(node, buffer_size());
303 Atomic::inc(&_processed_buffers_mut);
304 }
305 return result;
306 }
307
308 bool G1DirtyCardQueueSet::refine_completed_buffer_concurrently(uint worker_i, size_t stop_at) {
309 G1RefineCardConcurrentlyClosure cl;
310 return apply_closure_to_completed_buffer(&cl, worker_i, stop_at, false);
311 }
312
313 bool G1DirtyCardQueueSet::apply_closure_during_gc(G1CardTableEntryClosure* cl, uint worker_i) {
314 assert_at_safepoint();
315 return apply_closure_to_completed_buffer(cl, worker_i, 0, true);
316 }
317
318 bool G1DirtyCardQueueSet::apply_closure_to_completed_buffer(G1CardTableEntryClosure* cl,
319 uint worker_i,
320 size_t stop_at,
321 bool during_pause) {
322 assert(!during_pause || stop_at == 0, "Should not leave any completed buffers during a pause");
323 BufferNode* nd = get_completed_buffer(stop_at);
324 if (nd == NULL) {
325 return false;
326 } else {
327 if (apply_closure_to_buffer(cl, nd, worker_i)) {
328 assert_fully_consumed(nd, buffer_size());
329 // Done with fully processed buffer.
330 deallocate_buffer(nd);
331 Atomic::inc(&_processed_buffers_rs_thread);
332 } else {
333 // Return partially processed buffer to the queue.
334 guarantee(!during_pause, "Should never stop early");
335 enqueue_completed_buffer(nd);
336 }
337 return true;
338 }
339 }
340
341 void G1DirtyCardQueueSet::abandon_logs() {
342 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
343 abandon_completed_buffers();
344
345 // Since abandon is done only at safepoints, we can safely manipulate
346 // these queues.
347 struct AbandonThreadLogClosure : public ThreadClosure {
348 virtual void do_thread(Thread* t) {
349 G1ThreadLocalData::dirty_card_queue(t).reset();
350 }
351 } closure;
352 Threads::threads_do(&closure);
353
354 G1BarrierSet::shared_dirty_card_queue().reset();
355 }
356
357 void G1DirtyCardQueueSet::concatenate_logs() {
358 // Iterate over all the threads, if we find a partial log add it to
359 // the global list of logs. Temporarily turn off the limit on the number
360 // of outstanding buffers.
361 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
362 size_t old_limit = max_completed_buffers();
363 set_max_completed_buffers(MaxCompletedBuffersUnlimited);
364
365 struct ConcatenateThreadLogClosure : public ThreadClosure {
366 virtual void do_thread(Thread* t) {
367 G1DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(t);
368 if (!dcq.is_empty()) {
369 dcq.flush();
370 }
371 }
372 } closure;
373 Threads::threads_do(&closure);
374
375 G1BarrierSet::shared_dirty_card_queue().flush();
376 set_max_completed_buffers(old_limit);
377 }