1 /* 2 * Copyright (c) 2001, 2017, 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/heapRegionRemSet.hpp" 30 #include "gc/shared/workgroup.hpp" 31 #include "runtime/atomic.hpp" 32 #include "runtime/mutexLocker.hpp" 33 #include "runtime/safepoint.hpp" 34 #include "runtime/thread.inline.hpp" 35 36 // Closure used for updating remembered sets and recording references that 37 // point into the collection set while the mutator is running. 38 // Assumed to be only executed concurrently with the mutator. Yields via 39 // SuspendibleThreadSet after every card. 40 class G1RefineCardConcurrentlyClosure: public CardTableEntryClosure { 41 public: 42 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 43 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i); 44 45 if (SuspendibleThreadSet::should_yield()) { 46 // Caller will actually yield. 47 return false; 48 } 49 // Otherwise, we finished successfully; return true. 50 return true; 51 } 52 }; 53 54 // Represents a set of free small integer ids. 55 class FreeIdSet : public CHeapObj<mtGC> { 56 enum { 57 end_of_list = UINT_MAX, 58 claimed = UINT_MAX - 1 59 }; 60 61 uint _size; 62 Monitor* _mon; 63 64 uint* _ids; 65 uint _hd; 66 uint _waiters; 67 uint _claimed; 68 69 public: 70 FreeIdSet(uint size, Monitor* mon); 71 ~FreeIdSet(); 72 73 // Returns an unclaimed parallel id (waiting for one to be released if 74 // necessary). 75 uint claim_par_id(); 76 77 void release_par_id(uint id); 78 }; 79 80 FreeIdSet::FreeIdSet(uint size, Monitor* mon) : 81 _size(size), _mon(mon), _hd(0), _waiters(0), _claimed(0) 82 { 83 guarantee(size != 0, "must be"); 84 _ids = NEW_C_HEAP_ARRAY(uint, size, mtGC); 85 for (uint i = 0; i < size - 1; i++) { 86 _ids[i] = i+1; 87 } 88 _ids[size-1] = end_of_list; // end of list. 89 } 90 91 FreeIdSet::~FreeIdSet() { 92 FREE_C_HEAP_ARRAY(uint, _ids); 93 } 94 95 uint FreeIdSet::claim_par_id() { 96 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag); 97 while (_hd == end_of_list) { 98 _waiters++; 99 _mon->wait(Mutex::_no_safepoint_check_flag); 100 _waiters--; 101 } 102 uint res = _hd; 103 _hd = _ids[res]; 104 _ids[res] = claimed; // For debugging. 105 _claimed++; 106 return res; 107 } 108 109 void FreeIdSet::release_par_id(uint id) { 110 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag); 111 assert(_ids[id] == claimed, "Precondition."); 112 _ids[id] = _hd; 113 _hd = id; 114 _claimed--; 115 if (_waiters > 0) { 116 _mon->notify_all(); 117 } 118 } 119 120 DirtyCardQueue::DirtyCardQueue(DirtyCardQueueSet* qset, bool permanent) : 121 // Dirty card queues are always active, so we create them with their 122 // active field set to true. 123 PtrQueue(qset, permanent, true /* active */) 124 { } 125 126 DirtyCardQueue::~DirtyCardQueue() { 127 if (!is_permanent()) { 128 flush(); 129 } 130 } 131 132 DirtyCardQueueSet::DirtyCardQueueSet(bool notify_when_complete) : 133 PtrQueueSet(notify_when_complete), 134 _shared_dirty_card_queue(this, true /* permanent */), 135 _free_ids(NULL), 136 _processed_buffers_mut(0), _processed_buffers_rs_thread(0) 137 { 138 _all_active = true; 139 } 140 141 // Determines how many mutator threads can process the buffers in parallel. 142 uint DirtyCardQueueSet::num_par_ids() { 143 return (uint)os::initial_active_processor_count(); 144 } 145 146 void DirtyCardQueueSet::initialize(Monitor* cbl_mon, 147 Mutex* fl_lock, 148 int process_completed_threshold, 149 int max_completed_queue, 150 Mutex* lock, 151 DirtyCardQueueSet* fl_owner, 152 bool init_free_ids) { 153 PtrQueueSet::initialize(cbl_mon, 154 fl_lock, 155 process_completed_threshold, 156 max_completed_queue, 157 fl_owner); 158 set_buffer_size(G1UpdateBufferSize); 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 t->dirty_card_queue().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 BufferNode* nd = NULL; 225 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); 226 227 if (_n_completed_buffers <= stop_at) { 228 _process_completed = false; 229 return NULL; 230 } 231 232 if (_completed_buffers_head != NULL) { 233 nd = _completed_buffers_head; 234 assert(_n_completed_buffers > 0, "Invariant"); 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 } 242 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked()); 243 return nd; 244 } 245 246 bool DirtyCardQueueSet::refine_completed_buffer_concurrently(uint worker_i, size_t stop_at) { 247 G1RefineCardConcurrentlyClosure cl; 248 return apply_closure_to_completed_buffer(&cl, worker_i, stop_at, false); 249 } 250 251 bool DirtyCardQueueSet::apply_closure_during_gc(CardTableEntryClosure* cl, uint worker_i) { 252 assert_at_safepoint(false); 253 return apply_closure_to_completed_buffer(cl, worker_i, 0, true); 254 } 255 256 bool DirtyCardQueueSet::apply_closure_to_completed_buffer(CardTableEntryClosure* cl, 257 uint worker_i, 258 size_t stop_at, 259 bool during_pause) { 260 assert(!during_pause || stop_at == 0, "Should not leave any completed buffers during a pause"); 261 BufferNode* nd = get_completed_buffer(stop_at); 262 if (nd == NULL) { 263 return false; 264 } else { 265 if (apply_closure_to_buffer(cl, nd, true, worker_i)) { 266 assert_fully_consumed(nd, buffer_size()); 267 // Done with fully processed buffer. 268 deallocate_buffer(nd); 269 Atomic::inc(&_processed_buffers_rs_thread); 270 } else { 271 // Return partially processed buffer to the queue. 272 guarantee(!during_pause, "Should never stop early"); 273 enqueue_complete_buffer(nd); 274 } 275 return true; 276 } 277 } 278 279 void DirtyCardQueueSet::par_apply_closure_to_all_completed_buffers(CardTableEntryClosure* cl) { 280 BufferNode* nd = _cur_par_buffer_node; 281 while (nd != NULL) { 282 BufferNode* next = nd->next(); 283 void* actual = Atomic::cmpxchg(next, &_cur_par_buffer_node, nd); 284 if (actual == nd) { 285 bool b = apply_closure_to_buffer(cl, nd, false); 286 guarantee(b, "Should not stop early."); 287 nd = next; 288 } else { 289 nd = static_cast<BufferNode*>(actual); 290 } 291 } 292 } 293 294 // Deallocates any completed log buffers 295 void DirtyCardQueueSet::clear() { 296 BufferNode* buffers_to_delete = NULL; 297 { 298 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); 299 while (_completed_buffers_head != NULL) { 300 BufferNode* nd = _completed_buffers_head; 301 _completed_buffers_head = nd->next(); 302 nd->set_next(buffers_to_delete); 303 buffers_to_delete = nd; 304 } 305 _n_completed_buffers = 0; 306 _completed_buffers_tail = NULL; 307 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked()); 308 } 309 while (buffers_to_delete != NULL) { 310 BufferNode* nd = buffers_to_delete; 311 buffers_to_delete = nd->next(); 312 deallocate_buffer(nd); 313 } 314 315 } 316 317 void DirtyCardQueueSet::abandon_logs() { 318 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint."); 319 clear(); 320 // Since abandon is done only at safepoints, we can safely manipulate 321 // these queues. 322 for (JavaThread* t = Threads::first(); t; t = t->next()) { 323 t->dirty_card_queue().reset(); 324 } 325 shared_dirty_card_queue()->reset(); 326 } 327 328 void DirtyCardQueueSet::concatenate_log(DirtyCardQueue& dcq) { 329 if (!dcq.is_empty()) { 330 dcq.flush(); 331 } 332 } 333 334 void DirtyCardQueueSet::concatenate_logs() { 335 // Iterate over all the threads, if we find a partial log add it to 336 // the global list of logs. Temporarily turn off the limit on the number 337 // of outstanding buffers. 338 int save_max_completed_queue = _max_completed_queue; 339 _max_completed_queue = max_jint; 340 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint."); 341 for (JavaThread* t = Threads::first(); t; t = t->next()) { 342 concatenate_log(t->dirty_card_queue()); 343 } 344 concatenate_log(_shared_dirty_card_queue); 345 // Restore the completed buffer queue limit. 346 _max_completed_queue = save_max_completed_queue; 347 }