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 #ifndef SHARE_VM_GC_G1_G1CONCURRENTMARK_INLINE_HPP 26 #define SHARE_VM_GC_G1_G1CONCURRENTMARK_INLINE_HPP 27 28 #include "gc/g1/g1CollectedHeap.inline.hpp" 29 #include "gc/g1/g1ConcurrentMark.hpp" 30 #include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp" 31 #include "gc/g1/g1ConcurrentMarkObjArrayProcessor.inline.hpp" 32 #include "gc/g1/suspendibleThreadSet.hpp" 33 #include "gc/shared/taskqueue.inline.hpp" 34 #include "utilities/bitMap.inline.hpp" 35 36 inline bool G1ConcurrentMark::mark_in_next_bitmap(oop const obj) { 37 HeapRegion* const hr = _g1h->heap_region_containing(obj); 38 return mark_in_next_bitmap(hr, obj); 39 } 40 41 inline bool G1ConcurrentMark::mark_in_next_bitmap(HeapRegion* const hr, oop const obj) { 42 assert(hr != NULL, "just checking"); 43 assert(hr->is_in_reserved(obj), "Attempting to mark object at " PTR_FORMAT " that is not contained in the given region %u", p2i(obj), hr->hrm_index()); 44 45 if (hr->obj_allocated_since_next_marking(obj)) { 46 return false; 47 } 48 49 // Some callers may have stale objects to mark above nTAMS after humongous reclaim. 50 // Can't assert that this is a valid object at this point, since it might be in the process of being copied by another thread. 51 assert(!hr->is_continues_humongous(), "Should not try to mark object " PTR_FORMAT " in Humongous continues region %u above nTAMS " PTR_FORMAT, p2i(obj), hr->hrm_index(), p2i(hr->next_top_at_mark_start())); 52 53 HeapWord* const obj_addr = (HeapWord*)obj; 54 // Dirty read to avoid CAS. 55 if (_nextMarkBitMap->is_marked(obj_addr)) { 56 return false; 57 } 58 59 return _nextMarkBitMap->par_mark(obj_addr); 60 } 61 62 #ifndef PRODUCT 63 template<typename Fn> 64 inline void G1CMMarkStack::iterate(Fn fn) const { 65 assert_at_safepoint(true); 66 67 size_t num_chunks = 0; 68 69 TaskQueueEntryChunk* cur = _chunk_list; 70 while (cur != NULL) { 71 guarantee(num_chunks <= _chunks_in_chunk_list, "Found " SIZE_FORMAT " oop chunks which is more than there should be", num_chunks); 72 73 for (size_t i = 0; i < EntriesPerChunk; ++i) { 74 if (cur->data[i].is_null()) { 75 break; 76 } 77 fn(cur->data[i]); 78 } 79 cur = cur->next; 80 num_chunks++; 81 } 82 } 83 #endif 84 85 // It scans an object and visits its children. 86 inline void G1CMTask::scan_task_entry(G1TaskQueueEntry task_entry) { process_grey_task_entry<true>(task_entry); } 87 88 inline void G1CMTask::push(G1TaskQueueEntry task_entry) { 89 assert(task_entry.is_array_slice() || _g1h->is_in_g1_reserved(task_entry.obj()), "invariant"); 90 assert(task_entry.is_array_slice() || !_g1h->is_on_master_free_list( 91 _g1h->heap_region_containing(task_entry.obj())), "invariant"); 92 assert(task_entry.is_array_slice() || !_g1h->is_obj_ill(task_entry.obj()), "invariant"); // FIXME!!! 93 assert(task_entry.is_array_slice() || _nextMarkBitMap->is_marked((HeapWord*)task_entry.obj()), "invariant"); 94 95 if (!_task_queue->push(task_entry)) { 96 // The local task queue looks full. We need to push some entries 97 // to the global stack. 98 move_entries_to_global_stack(); 99 100 // this should succeed since, even if we overflow the global 101 // stack, we should have definitely removed some entries from the 102 // local queue. So, there must be space on it. 103 bool success = _task_queue->push(task_entry); 104 assert(success, "invariant"); 105 } 106 } 107 108 inline bool G1CMTask::is_below_finger(oop obj, HeapWord* global_finger) const { 109 // If obj is above the global finger, then the mark bitmap scan 110 // will find it later, and no push is needed. Similarly, if we have 111 // a current region and obj is between the local finger and the 112 // end of the current region, then no push is needed. The tradeoff 113 // of checking both vs only checking the global finger is that the 114 // local check will be more accurate and so result in fewer pushes, 115 // but may also be a little slower. 116 HeapWord* objAddr = (HeapWord*)obj; 117 if (_finger != NULL) { 118 // We have a current region. 119 120 // Finger and region values are all NULL or all non-NULL. We 121 // use _finger to check since we immediately use its value. 122 assert(_curr_region != NULL, "invariant"); 123 assert(_region_limit != NULL, "invariant"); 124 assert(_region_limit <= global_finger, "invariant"); 125 126 // True if obj is less than the local finger, or is between 127 // the region limit and the global finger. 128 if (objAddr < _finger) { 129 return true; 130 } else if (objAddr < _region_limit) { 131 return false; 132 } // Else check global finger. 133 } 134 // Check global finger. 135 return objAddr < global_finger; 136 } 137 138 template<bool scan> 139 inline void G1CMTask::process_grey_task_entry(G1TaskQueueEntry task_entry) { 140 assert(scan || (task_entry.is_oop() && task_entry.obj()->is_typeArray()), "Skipping scan of grey non-typeArray"); 141 assert(task_entry.is_array_slice() || _nextMarkBitMap->is_marked((HeapWord*)task_entry.obj()), 142 "Any stolen object should be a slice or marked"); 143 144 if (scan) { 145 if (task_entry.is_array_slice()) { 146 _words_scanned += _objArray_processor.process_slice(task_entry.slice()); 147 } else { 148 oop obj = task_entry.obj(); 149 if (G1CMObjArrayProcessor::should_be_sliced(obj)) { 150 _words_scanned += _objArray_processor.process_obj(obj); 151 } else { 152 _words_scanned += obj->oop_iterate_size(_cm_oop_closure);; 153 } 154 } 155 } 156 check_limits(); 157 } 158 159 inline size_t G1CMTask::scan_objArray(objArrayOop obj, MemRegion mr) { 160 obj->oop_iterate(_cm_oop_closure, mr); 161 return mr.word_size(); 162 } 163 164 inline void G1CMTask::make_reference_grey(oop obj) { 165 if (!_cm->mark_in_next_bitmap(obj)) { 166 return; 167 } 168 169 // No OrderAccess:store_load() is needed. It is implicit in the 170 // CAS done in G1CMBitMap::parMark() call in the routine above. 171 HeapWord* global_finger = _cm->finger(); 172 173 // We only need to push a newly grey object on the mark 174 // stack if it is in a section of memory the mark bitmap 175 // scan has already examined. Mark bitmap scanning 176 // maintains progress "fingers" for determining that. 177 // 178 // Notice that the global finger might be moving forward 179 // concurrently. This is not a problem. In the worst case, we 180 // mark the object while it is above the global finger and, by 181 // the time we read the global finger, it has moved forward 182 // past this object. In this case, the object will probably 183 // be visited when a task is scanning the region and will also 184 // be pushed on the stack. So, some duplicate work, but no 185 // correctness problems. 186 if (is_below_finger(obj, global_finger)) { 187 G1TaskQueueEntry entry = G1TaskQueueEntry::from_oop(obj); 188 if (obj->is_typeArray()) { 189 // Immediately process arrays of primitive types, rather 190 // than pushing on the mark stack. This keeps us from 191 // adding humongous objects to the mark stack that might 192 // be reclaimed before the entry is processed - see 193 // selection of candidates for eager reclaim of humongous 194 // objects. The cost of the additional type test is 195 // mitigated by avoiding a trip through the mark stack, 196 // by only doing a bookkeeping update and avoiding the 197 // actual scan of the object - a typeArray contains no 198 // references, and the metadata is built-in. 199 process_grey_task_entry<false>(entry); 200 } else { 201 push(entry); 202 } 203 } 204 } 205 206 inline void G1CMTask::deal_with_reference(oop obj) { 207 increment_refs_reached(); 208 if (obj == NULL) { 209 return; 210 } 211 make_reference_grey(obj); 212 } 213 214 inline void G1ConcurrentMark::markPrev(oop p) { 215 assert(!_prevMarkBitMap->is_marked((HeapWord*) p), "sanity"); 216 _prevMarkBitMap->mark((HeapWord*) p); 217 } 218 219 bool G1ConcurrentMark::isPrevMarked(oop p) const { 220 assert(p != NULL && p->is_oop(), "expected an oop"); 221 return _prevMarkBitMap->is_marked((HeapWord*)p); 222 } 223 224 inline bool G1ConcurrentMark::do_yield_check() { 225 if (SuspendibleThreadSet::should_yield()) { 226 SuspendibleThreadSet::yield(); 227 return true; 228 } else { 229 return false; 230 } 231 } 232 233 #endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_INLINE_HPP