1 /*
2 * Copyright (c) 2001, 2016, 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/heapRegionRemSet.hpp"
29 #include "gc/shared/workgroup.hpp"
30 #include "runtime/atomic.inline.hpp"
31 #include "runtime/mutexLocker.hpp"
32 #include "runtime/safepoint.hpp"
33 #include "runtime/thread.inline.hpp"
34
35 // Represents a set of free small integer ids.
36 class FreeIdSet : public CHeapObj<mtGC> {
37 enum {
38 end_of_list = UINT_MAX,
39 claimed = UINT_MAX - 1
40 };
41
42 uint _size;
43 Monitor* _mon;
44
45 uint* _ids;
46 uint _hd;
47 uint _waiters;
48 uint _claimed;
49
50 public:
51 FreeIdSet(uint size, Monitor* mon);
52 ~FreeIdSet();
53
54 // Returns an unclaimed parallel id (waiting for one to be released if
55 // necessary).
56 uint claim_par_id();
57
58 void release_par_id(uint id);
59 };
60
61 FreeIdSet::FreeIdSet(uint size, Monitor* mon) :
62 _size(size), _mon(mon), _hd(0), _waiters(0), _claimed(0)
63 {
64 guarantee(size != 0, "must be");
65 _ids = NEW_C_HEAP_ARRAY(uint, size, mtGC);
66 for (uint i = 0; i < size - 1; i++) {
67 _ids[i] = i+1;
68 }
69 _ids[size-1] = end_of_list; // end of list.
70 }
71
72 FreeIdSet::~FreeIdSet() {
73 FREE_C_HEAP_ARRAY(uint, _ids);
74 }
75
76 uint FreeIdSet::claim_par_id() {
77 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
78 while (_hd == end_of_list) {
79 _waiters++;
80 _mon->wait(Mutex::_no_safepoint_check_flag);
81 _waiters--;
82 }
83 uint res = _hd;
84 _hd = _ids[res];
85 _ids[res] = claimed; // For debugging.
86 _claimed++;
87 return res;
88 }
89
90 void FreeIdSet::release_par_id(uint id) {
91 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
92 assert(_ids[id] == claimed, "Precondition.");
93 _ids[id] = _hd;
94 _hd = id;
95 _claimed--;
96 if (_waiters > 0) {
97 _mon->notify_all();
98 }
99 }
100
101 DirtyCardQueue::DirtyCardQueue(DirtyCardQueueSet* qset, bool permanent) :
102 // Dirty card queues are always active, so we create them with their
103 // active field set to true.
104 PtrQueue(qset, permanent, true /* active */)
105 { }
106
107 DirtyCardQueue::~DirtyCardQueue() {
108 if (!is_permanent()) {
109 flush();
110 }
111 }
112
113 DirtyCardQueueSet::DirtyCardQueueSet(bool notify_when_complete) :
114 PtrQueueSet(notify_when_complete),
115 _mut_process_closure(NULL),
116 _shared_dirty_card_queue(this, true /* permanent */),
117 _free_ids(NULL),
118 _processed_buffers_mut(0), _processed_buffers_rs_thread(0)
119 {
120 _all_active = true;
121 }
122
123 // Determines how many mutator threads can process the buffers in parallel.
124 uint DirtyCardQueueSet::num_par_ids() {
125 return (uint)os::processor_count();
126 }
127
128 void DirtyCardQueueSet::initialize(CardTableEntryClosure* cl,
129 Monitor* cbl_mon,
130 Mutex* fl_lock,
131 int process_completed_threshold,
132 int max_completed_queue,
133 Mutex* lock,
134 DirtyCardQueueSet* fl_owner,
135 bool init_free_ids) {
136 _mut_process_closure = cl;
137 PtrQueueSet::initialize(cbl_mon,
138 fl_lock,
139 process_completed_threshold,
140 max_completed_queue,
141 fl_owner);
142 set_buffer_size(G1UpdateBufferSize);
143 _shared_dirty_card_queue.set_lock(lock);
144 if (init_free_ids) {
145 _free_ids = new FreeIdSet(num_par_ids(), _cbl_mon);
146 }
147 }
148
149 void DirtyCardQueueSet::handle_zero_index_for_thread(JavaThread* t) {
150 t->dirty_card_queue().handle_zero_index();
151 }
152
153 bool DirtyCardQueueSet::apply_closure_to_buffer(CardTableEntryClosure* cl,
154 BufferNode* node,
155 bool consume,
156 uint worker_i) {
157 if (cl == NULL) return true;
158 bool result = true;
159 void** buf = BufferNode::make_buffer_from_node(node);
160 size_t limit = DirtyCardQueue::byte_index_to_index(buffer_size());
161 size_t i = DirtyCardQueue::byte_index_to_index(node->index());
162 for ( ; i < limit; ++i) {
163 jbyte* card_ptr = static_cast<jbyte*>(buf[i]);
164 assert(card_ptr != NULL, "invariant");
165 if (!cl->do_card_ptr(card_ptr, worker_i)) {
166 result = false; // Incomplete processing.
167 break;
168 }
169 }
170 if (consume) {
171 size_t new_index = DirtyCardQueue::index_to_byte_index(i);
172 assert(new_index <= buffer_size(), "invariant");
173 node->set_index(new_index);
174 }
175 return result;
176 }
177
178 bool DirtyCardQueueSet::mut_process_buffer(BufferNode* node) {
179 guarantee(_free_ids != NULL, "must be");
180
181 uint worker_i = _free_ids->claim_par_id(); // temporarily claim an id
182 bool result = apply_closure_to_buffer(_mut_process_closure, node, true, worker_i);
183 _free_ids->release_par_id(worker_i); // release the id
184
185 if (result) {
186 assert(node->index() == buffer_size(), "apply said fully consumed");
187 Atomic::inc(&_processed_buffers_mut);
188 }
189 return result;
190 }
191
192
193 BufferNode* DirtyCardQueueSet::get_completed_buffer(size_t stop_at) {
194 BufferNode* nd = NULL;
195 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
196
197 if (_n_completed_buffers <= stop_at) {
198 _process_completed = false;
199 return NULL;
200 }
201
202 if (_completed_buffers_head != NULL) {
203 nd = _completed_buffers_head;
204 assert(_n_completed_buffers > 0, "Invariant");
205 _completed_buffers_head = nd->next();
206 _n_completed_buffers--;
207 if (_completed_buffers_head == NULL) {
208 assert(_n_completed_buffers == 0, "Invariant");
209 _completed_buffers_tail = NULL;
210 }
211 }
212 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
213 return nd;
214 }
215
216 bool DirtyCardQueueSet::apply_closure_to_completed_buffer(CardTableEntryClosure* cl,
217 uint worker_i,
218 size_t stop_at,
219 bool during_pause) {
220 assert(!during_pause || stop_at == 0, "Should not leave any completed buffers during a pause");
221 BufferNode* nd = get_completed_buffer(stop_at);
222 if (nd == NULL) {
223 return false;
224 } else {
225 if (apply_closure_to_buffer(cl, nd, true, worker_i)) {
226 assert(nd->index() == buffer_size(), "apply said fully consumed");
227 // Done with fully processed buffer.
228 deallocate_buffer(nd);
229 Atomic::inc(&_processed_buffers_rs_thread);
230 } else {
231 // Return partially processed buffer to the queue.
232 guarantee(!during_pause, "Should never stop early");
233 enqueue_complete_buffer(nd);
234 }
235 return true;
236 }
237 }
238
239 void DirtyCardQueueSet::par_apply_closure_to_all_completed_buffers(CardTableEntryClosure* cl) {
240 BufferNode* nd = _cur_par_buffer_node;
241 while (nd != NULL) {
242 BufferNode* next = nd->next();
243 void* actual = Atomic::cmpxchg_ptr(next, &_cur_par_buffer_node, nd);
244 if (actual == nd) {
245 bool b = apply_closure_to_buffer(cl, nd, false);
246 guarantee(b, "Should not stop early.");
247 nd = next;
248 } else {
249 nd = static_cast<BufferNode*>(actual);
250 }
251 }
252 }
253
254 // Deallocates any completed log buffers
255 void DirtyCardQueueSet::clear() {
256 BufferNode* buffers_to_delete = NULL;
257 {
258 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
259 while (_completed_buffers_head != NULL) {
260 BufferNode* nd = _completed_buffers_head;
261 _completed_buffers_head = nd->next();
262 nd->set_next(buffers_to_delete);
263 buffers_to_delete = nd;
264 }
265 _n_completed_buffers = 0;
266 _completed_buffers_tail = NULL;
267 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
268 }
269 while (buffers_to_delete != NULL) {
270 BufferNode* nd = buffers_to_delete;
271 buffers_to_delete = nd->next();
272 deallocate_buffer(nd);
273 }
274
275 }
276
277 void DirtyCardQueueSet::abandon_logs() {
278 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
279 clear();
280 // Since abandon is done only at safepoints, we can safely manipulate
281 // these queues.
282 for (JavaThread* t = Threads::first(); t; t = t->next()) {
283 t->dirty_card_queue().reset();
284 }
285 shared_dirty_card_queue()->reset();
286 }
287
288 void DirtyCardQueueSet::concatenate_log(DirtyCardQueue& dcq) {
289 if (!dcq.is_empty()) {
290 enqueue_complete_buffer(
291 BufferNode::make_node_from_buffer(dcq.get_buf(), dcq.get_index()));
292 dcq.reinitialize();
293 }
294 }
295
296 void DirtyCardQueueSet::concatenate_logs() {
297 // Iterate over all the threads, if we find a partial log add it to
298 // the global list of logs. Temporarily turn off the limit on the number
299 // of outstanding buffers.
300 int save_max_completed_queue = _max_completed_queue;
301 _max_completed_queue = max_jint;
302 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
303 for (JavaThread* t = Threads::first(); t; t = t->next()) {
304 concatenate_log(t->dirty_card_queue());
305 }
306 concatenate_log(_shared_dirty_card_queue);
307 // Restore the completed buffer queue limit.
308 _max_completed_queue = save_max_completed_queue;
309 }