1 /* 2 * Copyright (c) 2015, Red Hat, Inc. and/or its affiliates. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 * or visit www.oracle.com if you need additional information or have any 20 * questions. 21 * 22 */ 23 24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP 25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP 26 27 #include "gc_implementation/shenandoah/brooksPointer.hpp" 28 #include "gc_implementation/shenandoah/shenandoahAsserts.hpp" 29 #include "gc_implementation/shenandoah/shenandoahBarrierSet.inline.hpp" 30 #include "gc_implementation/shenandoah/shenandoahConcurrentMark.hpp" 31 #include "gc_implementation/shenandoah/shenandoahHeap.inline.hpp" 32 #include "gc_implementation/shenandoah/shenandoahTaskqueue.inline.hpp" 33 #include "memory/iterator.inline.hpp" 34 #include "oops/oop.inline.hpp" 35 #include "runtime/prefetch.inline.hpp" 36 37 template <class T, bool COUNT_LIVENESS> 38 void ShenandoahConcurrentMark::do_task(ShenandoahObjToScanQueue* q, T* cl, jushort* live_data, ShenandoahMarkTask* task) { 39 oop obj = task->obj(); 40 41 shenandoah_assert_not_forwarded(NULL, obj); 42 shenandoah_assert_marked_next(NULL, obj); 43 shenandoah_assert_not_in_cset_except(NULL, obj, _heap->cancelled_concgc()); 44 45 if (task->is_not_chunked()) { 46 if (COUNT_LIVENESS) count_liveness(live_data, obj); 47 if (obj->is_instance()) { 48 // Case 1: Normal oop, process as usual. 49 obj->oop_iterate(cl); 50 } else if (obj->is_objArray()) { 51 // Case 2: Object array instance and no chunk is set. Must be the first 52 // time we visit it, start the chunked processing. 53 do_chunked_array_start<T>(q, cl, obj); 54 } else { 55 // Case 3: Primitive array. Do nothing, no oops there. We use the same 56 // performance tweak TypeArrayKlass::oop_oop_iterate_impl is using: 57 // We skip iterating over the klass pointer since we know that 58 // Universe::TypeArrayKlass never moves. 59 assert (obj->is_typeArray(), "should be type array"); 60 } 61 } else { 62 // Case 4: Array chunk, has sensible chunk id. Process it. 63 do_chunked_array<T>(q, cl, obj, task->chunk(), task->pow()); 64 } 65 } 66 67 inline void ShenandoahConcurrentMark::count_liveness(jushort* live_data, oop obj) { 68 size_t region_idx = _heap->heap_region_index_containing(obj); 69 ShenandoahHeapRegion* region = _heap->get_region(region_idx); 70 if (!region->is_humongous_start()) { 71 assert(!region->is_humongous(), "Cannot have continuations here"); 72 jushort cur = live_data[region_idx]; 73 size_t size = obj->size() + BrooksPointer::word_size(); 74 size_t max = (1 << (sizeof(jushort) * 8)) - 1; 75 if (size >= max) { 76 // too big, add to region data directly 77 region->increase_live_data_gc_words(size); 78 } else { 79 size_t new_val = cur + size; 80 if (new_val >= max) { 81 // overflow, flush to region data 82 region->increase_live_data_gc_words(new_val); 83 live_data[region_idx] = 0; 84 } else { 85 // still good, remember in locals 86 live_data[region_idx] = (jushort) new_val; 87 } 88 } 89 } else { 90 count_liveness_humongous(obj); 91 } 92 } 93 94 inline void ShenandoahConcurrentMark::count_liveness_humongous(oop obj) { 95 shenandoah_assert_in_correct_region(NULL, obj); 96 size_t region_idx = _heap->heap_region_index_containing(obj); 97 size_t size = obj->size() + BrooksPointer::word_size(); 98 size_t num_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 99 100 for (size_t i = region_idx; i < region_idx + num_regions; i++) { 101 ShenandoahHeapRegion* chain_reg = _heap->get_region(i); 102 assert(chain_reg->is_humongous(), "Expecting a humongous region"); 103 chain_reg->increase_live_data_gc_words(chain_reg->used() >> LogHeapWordSize); 104 } 105 } 106 107 template <class T> 108 inline void ShenandoahConcurrentMark::do_chunked_array_start(ShenandoahObjToScanQueue* q, T* cl, oop obj) { 109 assert(obj->is_objArray(), "expect object array"); 110 objArrayOop array = objArrayOop(obj); 111 int len = array->length(); 112 113 if (len <= (int) ObjArrayMarkingStride*2) { 114 // A few slices only, process directly 115 array->oop_iterate_range(cl, 0, len); 116 } else { 117 int bits = log2_long(len); 118 // Compensate for non-power-of-two arrays, cover the array in excess: 119 if (len != (1 << bits)) bits++; 120 121 // Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to 122 // boundaries against array->length(), touching the array header on every chunk. 123 // 124 // To do this, we cut the prefix in full-sized chunks, and submit them on the queue. 125 // If the array is not divided in chunk sizes, then there would be an irregular tail, 126 // which we will process separately. 127 128 int last_idx = 0; 129 130 int chunk = 1; 131 int pow = bits; 132 133 // Handle overflow 134 if (pow >= 31) { 135 assert (pow == 31, "sanity"); 136 pow--; 137 chunk = 2; 138 last_idx = (1 << pow); 139 bool pushed = q->push(ShenandoahMarkTask(array, 1, pow)); 140 assert(pushed, "overflow queue should always succeed pushing"); 141 } 142 143 // Split out tasks, as suggested in ObjArrayChunkedTask docs. Record the last 144 // successful right boundary to figure out the irregular tail. 145 while ((1 << pow) > (int)ObjArrayMarkingStride && 146 (chunk*2 < ShenandoahMarkTask::chunk_size())) { 147 pow--; 148 int left_chunk = chunk*2 - 1; 149 int right_chunk = chunk*2; 150 int left_chunk_end = left_chunk * (1 << pow); 151 if (left_chunk_end < len) { 152 bool pushed = q->push(ShenandoahMarkTask(array, left_chunk, pow)); 153 assert(pushed, "overflow queue should always succeed pushing"); 154 chunk = right_chunk; 155 last_idx = left_chunk_end; 156 } else { 157 chunk = left_chunk; 158 } 159 } 160 161 // Process the irregular tail, if present 162 int from = last_idx; 163 if (from < len) { 164 array->oop_iterate_range(cl, from, len); 165 } 166 } 167 } 168 169 template <class T> 170 inline void ShenandoahConcurrentMark::do_chunked_array(ShenandoahObjToScanQueue* q, T* cl, oop obj, int chunk, int pow) { 171 assert(obj->is_objArray(), "expect object array"); 172 objArrayOop array = objArrayOop(obj); 173 174 assert (ObjArrayMarkingStride > 0, "sanity"); 175 176 // Split out tasks, as suggested in ObjArrayChunkedTask docs. Avoid pushing tasks that 177 // are known to start beyond the array. 178 while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < ShenandoahMarkTask::chunk_size())) { 179 pow--; 180 chunk *= 2; 181 bool pushed = q->push(ShenandoahMarkTask(array, chunk - 1, pow)); 182 assert(pushed, "overflow queue should always succeed pushing"); 183 } 184 185 int chunk_size = 1 << pow; 186 187 int from = (chunk - 1) * chunk_size; 188 int to = chunk * chunk_size; 189 190 #ifdef ASSERT 191 int len = array->length(); 192 assert (0 <= from && from < len, err_msg("from is sane: %d/%d", from, len)); 193 assert (0 < to && to <= len, err_msg("to is sane: %d/%d", to, len)); 194 #endif 195 196 array->oop_iterate_range(cl, from, to); 197 } 198 199 inline bool ShenandoahConcurrentMark::try_queue(ShenandoahObjToScanQueue* q, ShenandoahMarkTask &task) { 200 return (q->pop_buffer(task) || 201 q->pop_local(task) || 202 q->pop_overflow(task)); 203 } 204 205 class ShenandoahSATBBufferClosure : public SATBBufferClosure { 206 private: 207 ShenandoahObjToScanQueue* _queue; 208 ShenandoahHeap* _heap; 209 public: 210 ShenandoahSATBBufferClosure(ShenandoahObjToScanQueue* q) : 211 _queue(q), _heap(ShenandoahHeap::heap()) 212 { 213 } 214 215 void do_buffer(void** buffer, size_t size) { 216 for (size_t i = 0; i < size; ++i) { 217 oop* p = (oop*) &buffer[i]; 218 ShenandoahConcurrentMark::mark_through_ref<oop, RESOLVE>(p, _heap, _queue); 219 } 220 } 221 }; 222 223 inline bool ShenandoahConcurrentMark::try_draining_satb_buffer(ShenandoahObjToScanQueue *q, ShenandoahMarkTask &task) { 224 ShenandoahSATBBufferClosure cl(q); 225 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); 226 bool had_refs = satb_mq_set.apply_closure_to_completed_buffer(&cl); 227 return had_refs && try_queue(q, task); 228 } 229 230 template<class T, UpdateRefsMode UPDATE_REFS> 231 inline void ShenandoahConcurrentMark::mark_through_ref(T *p, ShenandoahHeap* heap, ShenandoahObjToScanQueue* q) { 232 T o = oopDesc::load_heap_oop(p); 233 if (! oopDesc::is_null(o)) { 234 oop obj = oopDesc::decode_heap_oop_not_null(o); 235 switch (UPDATE_REFS) { 236 case NONE: 237 break; 238 case RESOLVE: 239 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj); 240 break; 241 case SIMPLE: 242 // We piggy-back reference updating to the marking tasks. 243 obj = heap->update_with_forwarded_not_null(p, obj); 244 break; 245 case CONCURRENT: 246 obj = heap->maybe_update_with_forwarded_not_null(p, obj); 247 break; 248 default: 249 ShouldNotReachHere(); 250 } 251 252 // Note: Only when concurrently updating references can obj become NULL here. 253 // It happens when a mutator thread beats us by writing another value. In that 254 // case we don't need to do anything else. 255 if (UPDATE_REFS != CONCURRENT || !oopDesc::is_null(obj)) { 256 shenandoah_assert_not_forwarded(p, obj); 257 shenandoah_assert_not_in_cset_except(p, obj, heap->cancelled_concgc()); 258 259 if (heap->mark_next(obj)) { 260 bool pushed = q->push(ShenandoahMarkTask(obj)); 261 assert(pushed, "overflow queue should always succeed pushing"); 262 } 263 264 shenandoah_assert_marked_next(p, obj); 265 } 266 } 267 } 268 269 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP