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/mutexLocker.hpp"
35 #include "runtime/safepoint.hpp"
36 #include "runtime/thread.inline.hpp"
37 #include "runtime/threadSMR.hpp"
38
39 // Closure used for updating remembered sets and recording references that
40 // point into the collection set while the mutator is running.
41 // Assumed to be only executed concurrently with the mutator. Yields via
42 // SuspendibleThreadSet after every card.
43 class G1RefineCardConcurrentlyClosure: public CardTableEntryClosure {
44 public:
45 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
46 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
47
48 if (SuspendibleThreadSet::should_yield()) {
49 // Caller will actually yield.
50 return false;
51 }
52 // Otherwise, we finished successfully; return true.
53 return true;
54 }
55 };
56
57 // Represents a set of free small integer ids.
58 class FreeIdSet : public CHeapObj<mtGC> {
59 enum {
60 end_of_list = UINT_MAX,
61 claimed = UINT_MAX - 1
62 };
63
64 uint _size;
65 Monitor* _mon;
66
67 uint* _ids;
68 uint _hd;
69 uint _waiters;
70 uint _claimed;
71
72 public:
73 FreeIdSet(uint size, Monitor* mon);
74 ~FreeIdSet();
75
76 // Returns an unclaimed parallel id (waiting for one to be released if
77 // necessary).
78 uint claim_par_id();
79
80 void release_par_id(uint id);
81 };
82
83 FreeIdSet::FreeIdSet(uint size, Monitor* mon) :
84 _size(size), _mon(mon), _hd(0), _waiters(0), _claimed(0)
85 {
86 guarantee(size != 0, "must be");
87 _ids = NEW_C_HEAP_ARRAY(uint, size, mtGC);
88 for (uint i = 0; i < size - 1; i++) {
89 _ids[i] = i+1;
90 }
91 _ids[size-1] = end_of_list; // end of list.
92 }
93
94 FreeIdSet::~FreeIdSet() {
95 FREE_C_HEAP_ARRAY(uint, _ids);
96 }
97
98 uint FreeIdSet::claim_par_id() {
99 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
100 while (_hd == end_of_list) {
101 _waiters++;
102 _mon->wait(Mutex::_no_safepoint_check_flag);
103 _waiters--;
104 }
105 uint res = _hd;
106 _hd = _ids[res];
107 _ids[res] = claimed; // For debugging.
108 _claimed++;
109 return res;
110 }
111
112 void FreeIdSet::release_par_id(uint id) {
113 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
114 assert(_ids[id] == claimed, "Precondition.");
115 _ids[id] = _hd;
116 _hd = id;
117 _claimed--;
118 if (_waiters > 0) {
119 _mon->notify_all();
120 }
121 }
122
123 DirtyCardQueue::DirtyCardQueue(DirtyCardQueueSet* qset, bool permanent) :
124 // Dirty card queues are always active, so we create them with their
125 // active field set to true.
126 PtrQueue(qset, permanent, true /* active */)
127 { }
128
129 DirtyCardQueue::~DirtyCardQueue() {
130 if (!is_permanent()) {
131 flush();
132 }
133 }
134
135 DirtyCardQueueSet::DirtyCardQueueSet(bool notify_when_complete) :
136 PtrQueueSet(notify_when_complete),
137 _shared_dirty_card_queue(this, true /* permanent */),
138 _free_ids(NULL),
139 _processed_buffers_mut(0), _processed_buffers_rs_thread(0)
140 {
141 _all_active = true;
142 }
143
144 // Determines how many mutator threads can process the buffers in parallel.
145 uint DirtyCardQueueSet::num_par_ids() {
146 return (uint)os::initial_active_processor_count();
147 }
148
149 void DirtyCardQueueSet::initialize(Monitor* cbl_mon,
150 BufferNode::Allocator* allocator,
151 int process_completed_threshold,
152 int max_completed_queue,
153 Mutex* lock,
154 bool init_free_ids) {
155 PtrQueueSet::initialize(cbl_mon,
156 allocator,
157 process_completed_threshold,
158 max_completed_queue);
159 _shared_dirty_card_queue.set_lock(lock);
160 if (init_free_ids) {
161 _free_ids = new FreeIdSet(num_par_ids(), _cbl_mon);
162 }
163 }
164
165 void DirtyCardQueueSet::handle_zero_index_for_thread(JavaThread* t) {
166 G1ThreadLocalData::dirty_card_queue(t).handle_zero_index();
167 }
168
169 bool DirtyCardQueueSet::apply_closure_to_buffer(CardTableEntryClosure* cl,
170 BufferNode* node,
171 bool consume,
172 uint worker_i) {
173 if (cl == NULL) return true;
174 bool result = true;
175 void** buf = BufferNode::make_buffer_from_node(node);
176 size_t i = node->index();
177 size_t limit = buffer_size();
178 for ( ; i < limit; ++i) {
179 jbyte* card_ptr = static_cast<jbyte*>(buf[i]);
180 assert(card_ptr != NULL, "invariant");
181 if (!cl->do_card_ptr(card_ptr, worker_i)) {
182 result = false; // Incomplete processing.
183 break;
184 }
185 }
186 if (consume) {
187 assert(i <= buffer_size(), "invariant");
188 node->set_index(i);
189 }
190 return result;
191 }
192
193 #ifndef ASSERT
194 #define assert_fully_consumed(node, buffer_size)
195 #else
196 #define assert_fully_consumed(node, buffer_size) \
197 do { \
198 size_t _afc_index = (node)->index(); \
199 size_t _afc_size = (buffer_size); \
200 assert(_afc_index == _afc_size, \
201 "Buffer was not fully consumed as claimed: index: " \
202 SIZE_FORMAT ", size: " SIZE_FORMAT, \
203 _afc_index, _afc_size); \
204 } while (0)
205 #endif // ASSERT
206
207 bool DirtyCardQueueSet::mut_process_buffer(BufferNode* node) {
208 guarantee(_free_ids != NULL, "must be");
209
210 uint worker_i = _free_ids->claim_par_id(); // temporarily claim an id
211 G1RefineCardConcurrentlyClosure cl;
212 bool result = apply_closure_to_buffer(&cl, node, true, worker_i);
213 _free_ids->release_par_id(worker_i); // release the id
214
215 if (result) {
216 assert_fully_consumed(node, buffer_size());
217 Atomic::inc(&_processed_buffers_mut);
218 }
219 return result;
220 }
221
222
223 BufferNode* DirtyCardQueueSet::get_completed_buffer(size_t stop_at) {
224 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
225
226 if (_n_completed_buffers <= stop_at) {
227 return NULL;
228 }
229
230 assert(_n_completed_buffers > 0, "invariant");
231 assert(_completed_buffers_head != NULL, "invariant");
232 assert(_completed_buffers_tail != NULL, "invariant");
233
234 BufferNode* nd = _completed_buffers_head;
235 _completed_buffers_head = nd->next();
236 _n_completed_buffers--;
237 if (_completed_buffers_head == NULL) {
238 assert(_n_completed_buffers == 0, "Invariant");
239 _completed_buffers_tail = NULL;
240 }
241 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
242 return nd;
243 }
244
245 bool DirtyCardQueueSet::refine_completed_buffer_concurrently(uint worker_i, size_t stop_at) {
246 G1RefineCardConcurrentlyClosure cl;
247 return apply_closure_to_completed_buffer(&cl, worker_i, stop_at, false);
248 }
249
250 bool DirtyCardQueueSet::apply_closure_during_gc(CardTableEntryClosure* cl, uint worker_i) {
251 assert_at_safepoint();
252 return apply_closure_to_completed_buffer(cl, worker_i, 0, true);
253 }
254
255 bool DirtyCardQueueSet::apply_closure_to_completed_buffer(CardTableEntryClosure* cl,
256 uint worker_i,
257 size_t stop_at,
258 bool during_pause) {
259 assert(!during_pause || stop_at == 0, "Should not leave any completed buffers during a pause");
260 BufferNode* nd = get_completed_buffer(stop_at);
261 if (nd == NULL) {
262 return false;
263 } else {
264 if (apply_closure_to_buffer(cl, nd, true, worker_i)) {
265 assert_fully_consumed(nd, buffer_size());
266 // Done with fully processed buffer.
267 deallocate_buffer(nd);
268 Atomic::inc(&_processed_buffers_rs_thread);
269 } else {
270 // Return partially processed buffer to the queue.
271 guarantee(!during_pause, "Should never stop early");
272 enqueue_complete_buffer(nd);
273 }
274 return true;
275 }
276 }
277
278 void DirtyCardQueueSet::par_apply_closure_to_all_completed_buffers(CardTableEntryClosure* cl) {
279 BufferNode* nd = _cur_par_buffer_node;
280 while (nd != NULL) {
281 BufferNode* next = nd->next();
282 BufferNode* actual = Atomic::cmpxchg(next, &_cur_par_buffer_node, nd);
283 if (actual == nd) {
284 bool b = apply_closure_to_buffer(cl, nd, false);
285 guarantee(b, "Should not stop early.");
286 nd = next;
287 } else {
288 nd = actual;
289 }
290 }
291 }
292
293 // Deallocates any completed log buffers
294 void DirtyCardQueueSet::clear() {
295 BufferNode* buffers_to_delete = NULL;
296 {
297 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
298 while (_completed_buffers_head != NULL) {
299 BufferNode* nd = _completed_buffers_head;
300 _completed_buffers_head = nd->next();
301 nd->set_next(buffers_to_delete);
302 buffers_to_delete = nd;
303 }
304 _n_completed_buffers = 0;
305 _completed_buffers_tail = NULL;
306 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
307 }
308 while (buffers_to_delete != NULL) {
309 BufferNode* nd = buffers_to_delete;
310 buffers_to_delete = nd->next();
311 deallocate_buffer(nd);
312 }
313
314 }
315
316 void DirtyCardQueueSet::abandon_logs() {
317 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
318 clear();
319 // Since abandon is done only at safepoints, we can safely manipulate
320 // these queues.
321 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
322 G1ThreadLocalData::dirty_card_queue(t).reset();
323 }
324 shared_dirty_card_queue()->reset();
325 }
326
327 void DirtyCardQueueSet::concatenate_log(DirtyCardQueue& dcq) {
328 if (!dcq.is_empty()) {
329 dcq.flush();
330 }
331 }
332
333 void DirtyCardQueueSet::concatenate_logs() {
334 // Iterate over all the threads, if we find a partial log add it to
335 // the global list of logs. Temporarily turn off the limit on the number
336 // of outstanding buffers.
337 int save_max_completed_queue = _max_completed_queue;
338 _max_completed_queue = max_jint;
339 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
340 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
341 concatenate_log(G1ThreadLocalData::dirty_card_queue(t));
342 }
343 concatenate_log(_shared_dirty_card_queue);
344 // Restore the completed buffer queue limit.
345 _max_completed_queue = save_max_completed_queue;
346 }