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/shenandoah/brooksPointer.hpp"
28 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
29 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
30 #include "memory/iterator.inline.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/prefetch.inline.hpp"
33
34 template <class T, bool COUNT_LIVENESS>
35 void ShenandoahConcurrentMark::do_task(SCMObjToScanQueue* q, T* cl, jushort* live_data, SCMTask* task) {
36 oop obj = task->obj();
37
38 assert(obj != NULL, "expect non-null object");
39
40 assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static_not_null(obj)), "expect forwarded obj in queue");
41
42 #ifdef ASSERT
43 if (! oopDesc::bs()->is_safe(obj)) {
44 tty->print_cr("trying to mark obj: "PTR_FORMAT" (%s) in dirty region: ", p2i((HeapWord*) obj), BOOL_TO_STR(_heap->is_marked_next(obj)));
45 // _heap->heap_region_containing(obj)->print();
46 // _heap->print_heap_regions();
47 }
48 #endif
49 assert(_heap->cancelled_concgc()
50 || oopDesc::bs()->is_safe(obj),
51 "we don't want to mark objects in from-space");
52 assert(_heap->is_in(obj), "referenced objects must be in the heap. No?");
53 assert(_heap->is_marked_next(obj), "only marked objects on task queue");
54
55 if (task->is_not_chunked()) {
56 if (COUNT_LIVENESS) count_liveness(live_data, obj);
57 if (obj->is_instance()) {
58 // Case 1: Normal oop, process as usual.
59 obj->oop_iterate(cl);
60 } else if (obj->is_objArray()) {
61 // Case 2: Object array instance and no chunk is set. Must be the first
62 // time we visit it, start the chunked processing.
63 do_chunked_array_start<T>(q, cl, obj);
64 } else {
65 // Case 3: Primitive array. Do nothing, no oops there. We use the same
66 // performance tweak TypeArrayKlass::oop_oop_iterate_impl is using:
67 // We skip iterating over the klass pointer since we know that
68 // Universe::TypeArrayKlass never moves.
69 assert (obj->is_typeArray(), "should be type array");
70 }
71 } else {
72 // Case 4: Array chunk, has sensible chunk id. Process it.
73 do_chunked_array<T>(q, cl, obj, task->chunk(), task->pow());
74 }
75 }
76
77 inline void ShenandoahConcurrentMark::count_liveness(jushort* live_data, oop obj) {
78 uint region_idx = _heap->heap_region_index_containing(obj);
79 jushort cur = live_data[region_idx];
80 int size = obj->size() + BrooksPointer::word_size();
81 int max = (1 << (sizeof(jushort) * 8)) - 1;
82 if (size >= max) {
83 // too big, add to region data directly
84 _heap->regions()->get_fast(region_idx)->increase_live_data_words(size);
85 } else {
86 int new_val = cur + size;
87 if (new_val >= max) {
88 // overflow, flush to region data
89 _heap->regions()->get_fast(region_idx)->increase_live_data_words(new_val);
90 live_data[region_idx] = 0;
91 } else {
92 // still good, remember in locals
93 live_data[region_idx] = (jushort) new_val;
94 }
95 }
96 }
97
98 template <class T>
99 inline void ShenandoahConcurrentMark::do_chunked_array_start(SCMObjToScanQueue* q, T* cl, oop obj) {
100 assert(obj->is_objArray(), "expect object array");
101 objArrayOop array = objArrayOop(obj);
102 int len = array->length();
103
104 if (len <= (int) ObjArrayMarkingStride*2) {
105 // A few slices only, process directly
106 array->oop_iterate_range(cl, 0, len);
107 } else {
108 int bits = log2_long(len);
109 // Compensate for non-power-of-two arrays, cover the array in excess:
110 if (len != (1 << bits)) bits++;
111
112 // Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to
113 // boundaries against array->length(), touching the array header on every chunk.
114 //
115 // To do this, we cut the prefix in full-sized chunks, and submit them on the queue.
116 // If the array is not divided in chunk sizes, then there would be an irregular tail,
117 // which we will process separately.
118
119 int last_idx = 0;
120
121 int chunk = 1;
122 int pow = bits;
123
124 // Handle overflow
125 if (pow >= 31) {
126 assert (pow == 31, "sanity");
127 pow--;
128 chunk = 2;
129 last_idx = (1 << pow);
130 bool pushed = q->push(SCMTask(array, 1, pow));
131 assert(pushed, "overflow queue should always succeed pushing");
132 }
133
134 // Split out tasks, as suggested in ObjArrayChunkedTask docs. Record the last
135 // successful right boundary to figure out the irregular tail.
136 while ((1 << pow) > (int)ObjArrayMarkingStride &&
137 (chunk*2 < SCMTask::chunk_size)) {
138 pow--;
139 int left_chunk = chunk*2 - 1;
140 int right_chunk = chunk*2;
141 int left_chunk_end = left_chunk * (1 << pow);
142 if (left_chunk_end < len) {
143 bool pushed = q->push(SCMTask(array, left_chunk, pow));
144 assert(pushed, "overflow queue should always succeed pushing");
145 chunk = right_chunk;
146 last_idx = left_chunk_end;
147 } else {
148 chunk = left_chunk;
149 }
150 }
151
152 // Process the irregular tail, if present
153 int from = last_idx;
154 if (from < len) {
155 array->oop_iterate_range(cl, from, len);
156 }
157 }
158 }
159
160 template <class T>
161 inline void ShenandoahConcurrentMark::do_chunked_array(SCMObjToScanQueue* q, T* cl, oop obj, int chunk, int pow) {
162 assert(obj->is_objArray(), "expect object array");
163 objArrayOop array = objArrayOop(obj);
164
165 assert (ObjArrayMarkingStride > 0, "sanity");
166
167 // Split out tasks, as suggested in ObjArrayChunkedTask docs. Avoid pushing tasks that
168 // are known to start beyond the array.
169 while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < SCMTask::chunk_size)) {
170 pow--;
171 chunk *= 2;
172 bool pushed = q->push(SCMTask(array, chunk - 1, pow));
173 assert(pushed, "overflow queue should always succeed pushing");
174 }
175
176 int chunk_size = 1 << pow;
177
178 int from = (chunk - 1) * chunk_size;
179 int to = chunk * chunk_size;
180
181 #ifdef ASSERT
182 int len = array->length();
183 assert (0 <= from && from < len, "from is sane: %d/%d", from, len);
184 assert (0 < to && to <= len, "to is sane: %d/%d", to, len);
185 #endif
186
187 array->oop_iterate_range(cl, from, to);
188 }
189
190 inline bool ShenandoahConcurrentMark::try_queue(SCMObjToScanQueue* q, SCMTask &task) {
191 return (q->pop_buffer(task) ||
192 q->pop_local(task) ||
193 q->pop_overflow(task));
194 }
195
196 class ShenandoahSATBBufferClosure : public SATBBufferClosure {
197 private:
198 SCMObjToScanQueue* _queue;
199 ShenandoahHeap* _heap;
200 public:
201 ShenandoahSATBBufferClosure(SCMObjToScanQueue* q) :
202 _queue(q), _heap(ShenandoahHeap::heap())
203 {
204 }
205
206 void do_buffer(void** buffer, size_t size) {
207 for (size_t i = 0; i < size; ++i) {
208 oop* p = (oop*) &buffer[i];
209 ShenandoahConcurrentMark::mark_through_ref<oop, RESOLVE, false>(p, _heap, _queue, NULL);
210 }
211 }
212 };
213
214 inline bool ShenandoahConcurrentMark::try_draining_satb_buffer(SCMObjToScanQueue *q, SCMTask &task) {
215 ShenandoahSATBBufferClosure cl(q);
216 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
217 bool had_refs = satb_mq_set.apply_closure_to_completed_buffer(&cl);
218 return had_refs && try_queue(q, task);
219 }
220
221 template<class T, UpdateRefsMode UPDATE_REFS, bool UPDATE_MATRIX>
222 inline void ShenandoahConcurrentMark::mark_through_ref(T *p, ShenandoahHeap* heap, SCMObjToScanQueue* q, ShenandoahConnectionMatrix* conn_matrix) {
223 T o = oopDesc::load_heap_oop(p);
224 if (! oopDesc::is_null(o)) {
225 oop obj = oopDesc::decode_heap_oop_not_null(o);
226 switch (UPDATE_REFS) {
227 case NONE:
228 break;
229 case RESOLVE:
230 obj = ShenandoahBarrierSet::resolve_oop_static_not_null(obj);
231 break;
232 case SIMPLE:
233 // We piggy-back reference updating to the marking tasks.
234 obj = heap->update_oop_ref_not_null(p, obj);
235 break;
236 case CONCURRENT:
237 obj = heap->maybe_update_oop_ref_not_null(p, obj);
238 break;
239 default:
240 ShouldNotReachHere();
241 }
242 assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static(obj)), "need to-space object here");
243
244 // Note: Only when concurrently updating references can obj become NULL here.
245 // It happens when a mutator thread beats us by writing another value. In that
246 // case we don't need to do anything else.
247 if (UPDATE_REFS != CONCURRENT || !oopDesc::is_null(obj)) {
248 assert(!oopDesc::is_null(obj), "Must not be null here");
249 assert(heap->is_in(obj), "We shouldn't be calling this on objects not in the heap: " PTR_FORMAT, p2i(obj));
250 assert(oopDesc::bs()->is_safe(obj), "Only mark objects in from-space");
251
252 if (UPDATE_MATRIX) {
253 if (heap->is_in_reserved(p)) { // Could also be in CLD, when marking through metadata.
254 uint from_idx = heap->heap_region_index_containing(p);
255 uint to_idx = heap->heap_region_index_containing(obj);
256 conn_matrix->set_connected(from_idx, to_idx, true);
257 }
258 }
259
260 if (heap->mark_next(obj)) {
261 log_develop_trace(gc, marking)("Marked obj: " PTR_FORMAT, p2i((HeapWord*) obj));
262
263 bool pushed = q->push(SCMTask(obj));
264 assert(pushed, "overflow queue should always succeed pushing");
265 } else {
266 log_develop_trace(gc, marking)("Failed to mark obj (already marked): " PTR_FORMAT, p2i((HeapWord*) obj));
267 assert(heap->is_marked_next(obj), "Consistency: should be marked.");
268 }
269 }
270 }
271 }
272
273 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP