1 /*
2 * Copyright (c) 2001, 2018, 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/dirtyCardQueue.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1RemSet.hpp"
29 #include "gc/g1/g1ThreadLocalData.hpp"
30 #include "gc/g1/heapRegionRemSet.hpp"
31 #include "gc/shared/suspendibleThreadSet.hpp"
32 #include "gc/shared/workgroup.hpp"
33 #include "runtime/atomic.hpp"
34 #include "runtime/flags/flagSetting.hpp"
35 #include "runtime/mutexLocker.hpp"
36 #include "runtime/safepoint.hpp"
37 #include "runtime/thread.inline.hpp"
38 #include "runtime/threadSMR.hpp"
39
40 // Closure used for updating remembered sets and recording references that
41 // point into the collection set while the mutator is running.
42 // Assumed to be only executed concurrently with the mutator. Yields via
43 // SuspendibleThreadSet after every card.
44 class G1RefineCardConcurrentlyClosure: public CardTableEntryClosure {
45 public:
46 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
47 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
48
49 if (SuspendibleThreadSet::should_yield()) {
50 // Caller will actually yield.
51 return false;
52 }
53 // Otherwise, we finished successfully; return true.
54 return true;
55 }
56 };
57
58 // Represents a set of free small integer ids.
59 class FreeIdSet : public CHeapObj<mtGC> {
60 enum {
61 end_of_list = UINT_MAX,
62 claimed = UINT_MAX - 1
63 };
64
65 uint _size;
66 Monitor* _mon;
67
68 uint* _ids;
69 uint _hd;
70 uint _waiters;
71 uint _claimed;
72
73 public:
74 FreeIdSet(uint size, Monitor* mon);
75 ~FreeIdSet();
76
77 // Returns an unclaimed parallel id (waiting for one to be released if
78 // necessary).
79 uint claim_par_id();
80
81 void release_par_id(uint id);
82 };
83
84 FreeIdSet::FreeIdSet(uint size, Monitor* mon) :
85 _size(size), _mon(mon), _hd(0), _waiters(0), _claimed(0)
86 {
87 guarantee(size != 0, "must be");
88 _ids = NEW_C_HEAP_ARRAY(uint, size, mtGC);
89 for (uint i = 0; i < size - 1; i++) {
90 _ids[i] = i+1;
91 }
92 _ids[size-1] = end_of_list; // end of list.
93 }
94
95 FreeIdSet::~FreeIdSet() {
96 FREE_C_HEAP_ARRAY(uint, _ids);
97 }
98
99 uint FreeIdSet::claim_par_id() {
100 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
101 while (_hd == end_of_list) {
102 _waiters++;
103 _mon->wait(Mutex::_no_safepoint_check_flag);
104 _waiters--;
105 }
106 uint res = _hd;
107 _hd = _ids[res];
108 _ids[res] = claimed; // For debugging.
109 _claimed++;
110 return res;
111 }
112
113 void FreeIdSet::release_par_id(uint id) {
114 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
115 assert(_ids[id] == claimed, "Precondition.");
116 _ids[id] = _hd;
117 _hd = id;
118 _claimed--;
119 if (_waiters > 0) {
120 _mon->notify_all();
121 }
122 }
123
124 DirtyCardQueue::DirtyCardQueue(DirtyCardQueueSet* qset, bool permanent) :
125 // Dirty card queues are always active, so we create them with their
126 // active field set to true.
127 PtrQueue(qset, permanent, true /* active */)
128 { }
129
130 DirtyCardQueue::~DirtyCardQueue() {
131 if (!is_permanent()) {
132 flush();
133 }
134 }
135
136 DirtyCardQueueSet::DirtyCardQueueSet(bool notify_when_complete) :
137 PtrQueueSet(notify_when_complete),
138 _shared_dirty_card_queue(this, true /* permanent */),
139 _free_ids(NULL),
140 _processed_buffers_mut(0),
141 _processed_buffers_rs_thread(0),
142 _cur_par_buffer_node(NULL)
143 {
144 _all_active = true;
145 }
146
147 // Determines how many mutator threads can process the buffers in parallel.
148 uint DirtyCardQueueSet::num_par_ids() {
149 return (uint)os::initial_active_processor_count();
150 }
151
152 void DirtyCardQueueSet::initialize(Monitor* cbl_mon,
153 BufferNode::Allocator* allocator,
154 Mutex* lock,
155 bool init_free_ids) {
156 PtrQueueSet::initialize(cbl_mon, allocator);
157 _shared_dirty_card_queue.set_lock(lock);
158 if (init_free_ids) {
159 _free_ids = new FreeIdSet(num_par_ids(), cbl_mon);
160 }
161 }
162
163 void DirtyCardQueueSet::handle_zero_index_for_thread(JavaThread* t) {
164 G1ThreadLocalData::dirty_card_queue(t).handle_zero_index();
165 }
166
167 bool DirtyCardQueueSet::apply_closure_to_buffer(CardTableEntryClosure* cl,
168 BufferNode* node,
169 bool consume,
170 uint worker_i) {
171 if (cl == NULL) return true;
172 bool result = true;
173 void** buf = BufferNode::make_buffer_from_node(node);
174 size_t i = node->index();
175 size_t limit = buffer_size();
176 for ( ; i < limit; ++i) {
177 jbyte* card_ptr = static_cast<jbyte*>(buf[i]);
178 assert(card_ptr != NULL, "invariant");
179 if (!cl->do_card_ptr(card_ptr, worker_i)) {
180 result = false; // Incomplete processing.
181 break;
182 }
183 }
184 if (consume) {
185 assert(i <= buffer_size(), "invariant");
186 node->set_index(i);
187 }
188 return result;
189 }
190
191 #ifndef ASSERT
192 #define assert_fully_consumed(node, buffer_size)
193 #else
194 #define assert_fully_consumed(node, buffer_size) \
195 do { \
196 size_t _afc_index = (node)->index(); \
197 size_t _afc_size = (buffer_size); \
198 assert(_afc_index == _afc_size, \
199 "Buffer was not fully consumed as claimed: index: " \
200 SIZE_FORMAT ", size: " SIZE_FORMAT, \
201 _afc_index, _afc_size); \
202 } while (0)
203 #endif // ASSERT
204
205 bool DirtyCardQueueSet::mut_process_buffer(BufferNode* node) {
206 guarantee(_free_ids != NULL, "must be");
207
208 uint worker_i = _free_ids->claim_par_id(); // temporarily claim an id
209 G1RefineCardConcurrentlyClosure cl;
210 bool result = apply_closure_to_buffer(&cl, node, true, worker_i);
211 _free_ids->release_par_id(worker_i); // release the id
212
213 if (result) {
214 assert_fully_consumed(node, buffer_size());
215 Atomic::inc(&_processed_buffers_mut);
216 }
217 return result;
218 }
219
220 bool DirtyCardQueueSet::refine_completed_buffer_concurrently(uint worker_i, size_t stop_at) {
221 G1RefineCardConcurrentlyClosure cl;
222 return apply_closure_to_completed_buffer(&cl, worker_i, stop_at, false);
223 }
224
225 bool DirtyCardQueueSet::apply_closure_during_gc(CardTableEntryClosure* cl, uint worker_i) {
226 assert_at_safepoint();
227 return apply_closure_to_completed_buffer(cl, worker_i, 0, true);
228 }
229
230 bool DirtyCardQueueSet::apply_closure_to_completed_buffer(CardTableEntryClosure* cl,
231 uint worker_i,
232 size_t stop_at,
233 bool during_pause) {
234 assert(!during_pause || stop_at == 0, "Should not leave any completed buffers during a pause");
235 BufferNode* nd = get_completed_buffer(stop_at);
236 if (nd == NULL) {
237 return false;
238 } else {
239 if (apply_closure_to_buffer(cl, nd, true, worker_i)) {
240 assert_fully_consumed(nd, buffer_size());
241 // Done with fully processed buffer.
242 deallocate_buffer(nd);
243 Atomic::inc(&_processed_buffers_rs_thread);
244 } else {
245 // Return partially processed buffer to the queue.
246 guarantee(!during_pause, "Should never stop early");
247 enqueue_completed_buffer(nd);
248 }
249 return true;
250 }
251 }
252
253 void DirtyCardQueueSet::par_apply_closure_to_all_completed_buffers(CardTableEntryClosure* cl) {
254 BufferNode* nd = _cur_par_buffer_node;
255 while (nd != NULL) {
256 BufferNode* next = nd->next();
257 BufferNode* actual = Atomic::cmpxchg(next, &_cur_par_buffer_node, nd);
258 if (actual == nd) {
259 bool b = apply_closure_to_buffer(cl, nd, false);
260 guarantee(b, "Should not stop early.");
261 nd = next;
262 } else {
263 nd = actual;
264 }
265 }
266 }
267
268 void DirtyCardQueueSet::abandon_logs() {
269 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
270 abandon_completed_buffers();
271 // Since abandon is done only at safepoints, we can safely manipulate
272 // these queues.
273 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
274 G1ThreadLocalData::dirty_card_queue(t).reset();
275 }
276 shared_dirty_card_queue()->reset();
277 }
278
279 void DirtyCardQueueSet::concatenate_log(DirtyCardQueue& dcq) {
280 if (!dcq.is_empty()) {
281 dcq.flush();
282 }
283 }
284
285 void DirtyCardQueueSet::concatenate_logs() {
286 // Iterate over all the threads, if we find a partial log add it to
287 // the global list of logs. Temporarily turn off the limit on the number
288 // of outstanding buffers.
289 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
290 size_t old_limit = max_completed_buffers();
291 set_max_completed_buffers(MaxCompletedBuffersUnlimited);
292 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
293 concatenate_log(G1ThreadLocalData::dirty_card_queue(t));
294 }
295 concatenate_log(_shared_dirty_card_queue);
296 set_max_completed_buffers(old_limit);
297 }