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