1 /* 2 * Copyright (c) 2014, 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 #ifndef SHARE_VM_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP 26 #define SHARE_VM_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP 27 28 #include "gc/g1/g1ParScanThreadState.hpp" 29 #include "gc/g1/g1RemSet.hpp" 30 #include "oops/access.inline.hpp" 31 #include "oops/oop.inline.hpp" 32 33 template <class T> void G1ParScanThreadState::do_oop_evac(T* p) { 34 // Reference should not be NULL here as such are never pushed to the task queue. 35 oop obj = RawAccess<IS_NOT_NULL>::oop_load(p); 36 37 // Although we never intentionally push references outside of the collection 38 // set, due to (benign) races in the claim mechanism during RSet scanning more 39 // than one thread might claim the same card. So the same card may be 40 // processed multiple times, and so we might get references into old gen here. 41 // So we need to redo this check. 42 const InCSetState in_cset_state = _g1h->in_cset_state(obj); 43 if (in_cset_state.is_in_cset()) { 44 markOop m = obj->mark_raw(); 45 if (m->is_marked()) { 46 obj = (oop) m->decode_pointer(); 47 } else { 48 obj = copy_to_survivor_space(in_cset_state, obj, m); 49 } 50 RawAccess<IS_NOT_NULL>::oop_store(p, obj); 51 } else if (in_cset_state.is_humongous()) { 52 _g1h->set_humongous_is_live(obj); 53 } else { 54 assert(in_cset_state.is_default(), 55 "In_cset_state must be NotInCSet here, but is " CSETSTATE_FORMAT, in_cset_state.value()); 56 } 57 58 assert(obj != NULL, "Must be"); 59 if (!HeapRegion::is_in_same_region(p, obj)) { 60 HeapRegion* from = _g1h->heap_region_containing(p); 61 update_rs(from, p, obj); 62 } 63 } 64 65 template <class T> inline void G1ParScanThreadState::push_on_queue(T* ref) { 66 assert(verify_ref(ref), "sanity"); 67 _refs->push(ref); 68 } 69 70 inline void G1ParScanThreadState::do_oop_partial_array(oop* p) { 71 assert(has_partial_array_mask(p), "invariant"); 72 oop from_obj = clear_partial_array_mask(p); 73 74 assert(_g1h->is_in_reserved(from_obj), "must be in heap."); 75 assert(from_obj->is_objArray(), "must be obj array"); 76 objArrayOop from_obj_array = objArrayOop(from_obj); 77 // The from-space object contains the real length. 78 int length = from_obj_array->length(); 79 80 assert(from_obj->is_forwarded(), "must be forwarded"); 81 oop to_obj = from_obj->forwardee(); 82 assert(from_obj != to_obj, "should not be chunking self-forwarded objects"); 83 objArrayOop to_obj_array = objArrayOop(to_obj); 84 // We keep track of the next start index in the length field of the 85 // to-space object. 86 int next_index = to_obj_array->length(); 87 assert(0 <= next_index && next_index < length, 88 "invariant, next index: %d, length: %d", next_index, length); 89 90 int start = next_index; 91 int end = length; 92 int remainder = end - start; 93 // We'll try not to push a range that's smaller than ParGCArrayScanChunk. 94 if (remainder > 2 * ParGCArrayScanChunk) { 95 end = start + ParGCArrayScanChunk; 96 to_obj_array->set_length(end); 97 // Push the remainder before we process the range in case another 98 // worker has run out of things to do and can steal it. 99 oop* from_obj_p = set_partial_array_mask(from_obj); 100 push_on_queue(from_obj_p); 101 } else { 102 assert(length == end, "sanity"); 103 // We'll process the final range for this object. Restore the length 104 // so that the heap remains parsable in case of evacuation failure. 105 to_obj_array->set_length(end); 106 } 107 _scanner.set_region(_g1h->heap_region_containing(to_obj)); 108 // Process indexes [start,end). It will also process the header 109 // along with the first chunk (i.e., the chunk with start == 0). 110 // Note that at this point the length field of to_obj_array is not 111 // correct given that we are using it to keep track of the next 112 // start index. oop_iterate_range() (thankfully!) ignores the length 113 // field and only relies on the start / end parameters. It does 114 // however return the size of the object which will be incorrect. So 115 // we have to ignore it even if we wanted to use it. 116 to_obj_array->oop_iterate_range(&_scanner, start, end); 117 } 118 119 inline void G1ParScanThreadState::deal_with_reference(oop* ref_to_scan) { 120 if (!has_partial_array_mask(ref_to_scan)) { 121 do_oop_evac(ref_to_scan); 122 } else { 123 do_oop_partial_array(ref_to_scan); 124 } 125 } 126 127 inline void G1ParScanThreadState::deal_with_reference(narrowOop* ref_to_scan) { 128 assert(!has_partial_array_mask(ref_to_scan), "NarrowOop* elements should never be partial arrays."); 129 do_oop_evac(ref_to_scan); 130 } 131 132 inline void G1ParScanThreadState::dispatch_reference(StarTask ref) { 133 assert(verify_task(ref), "sanity"); 134 if (ref.is_narrow()) { 135 deal_with_reference((narrowOop*)ref); 136 } else { 137 deal_with_reference((oop*)ref); 138 } 139 } 140 141 void G1ParScanThreadState::steal_and_trim_queue(RefToScanQueueSet *task_queues) { 142 StarTask stolen_task; 143 while (task_queues->steal(_worker_id, stolen_task)) { 144 assert(verify_task(stolen_task), "sanity"); 145 dispatch_reference(stolen_task); 146 147 // We've just processed a reference and we might have made 148 // available new entries on the queues. So we have to make sure 149 // we drain the queues as necessary. 150 trim_queue(); 151 } 152 } 153 154 inline bool G1ParScanThreadState::needs_partial_trimming() const { 155 return !_refs->overflow_empty() || _refs->size() > _stack_trim_upper_threshold; 156 } 157 158 inline bool G1ParScanThreadState::is_partially_trimmed() const { 159 return _refs->overflow_empty() && _refs->size() <= _stack_trim_lower_threshold; 160 } 161 162 inline void G1ParScanThreadState::trim_queue_to_threshold(uint threshold) { 163 StarTask ref; 164 // Drain the overflow stack first, so other threads can potentially steal. 165 while (_refs->pop_overflow(ref)) { 166 if (!_refs->try_push_to_taskqueue(ref)) { 167 dispatch_reference(ref); 168 } 169 } 170 171 while (_refs->pop_local(ref, threshold)) { 172 dispatch_reference(ref); 173 } 174 } 175 176 inline void G1ParScanThreadState::trim_queue_partially() { 177 if (!needs_partial_trimming()) { 178 return; 179 } 180 181 const Ticks start = Ticks::now(); 182 do { 183 trim_queue_to_threshold(_stack_trim_lower_threshold); 184 } while (!is_partially_trimmed()); 185 _trim_ticks += Ticks::now() - start; 186 } 187 188 inline Tickspan G1ParScanThreadState::trim_ticks() const { 189 return _trim_ticks; 190 } 191 192 inline void G1ParScanThreadState::reset_trim_ticks() { 193 _trim_ticks = Tickspan(); 194 } 195 196 #endif // SHARE_VM_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP