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 #include "precompiled.hpp"
25 #include "gc/z/zThreadLocalData.hpp"
26 #include "gc/z/zObjArrayAllocator.hpp"
27 #include "gc/z/zUtils.inline.hpp"
28 #include "oops/arrayKlass.hpp"
29 #include "runtime/interfaceSupport.inline.hpp"
30 #include "utilities/debug.hpp"
31
32 ZObjArrayAllocator::ZObjArrayAllocator(Klass* klass, size_t word_size, int length, bool do_zero, Thread* thread)
33 : ObjArrayAllocator(klass, word_size, length, do_zero, thread) {}
34
35 void ZObjArrayAllocator::yield_for_safepoint() const {
36 ThreadBlockInVM tbivm(JavaThread::cast(_thread));
37 }
38
39 oop ZObjArrayAllocator::initialize(HeapWord* mem) const {
40 // ZGC specializes the initialization by performing segmented clearing
41 // to allow shorter time-to-safepoints.
42
43 if (!_do_zero) {
44 // No need for ZGC specialization
45 return ObjArrayAllocator::initialize(mem);
46 }
47
48 // A max segment size of 64K was chosen because microbenchmarking
49 // suggested that it offered a good trade-off between allocation
50 // time and time-to-safepoint
51 const size_t segment_max = ZUtils::bytes_to_words(64 * K);
52 const BasicType element_type = ArrayKlass::cast(_klass)->element_type();
53 const size_t header = arrayOopDesc::header_size(element_type);
54 const size_t payload_size = _word_size - header;
55
56 if (payload_size <= segment_max) {
57 // To small to use segmented clearing
58 return ObjArrayAllocator::initialize(mem);
59 }
60
61 // Segmented clearing
62
63 // The array is going to be exposed before it has been completely
64 // cleared, therefore we can't expose the header at the end of this
65 // function. Instead explicitly initialize it according to our needs.
66
67 // Signal to the ZIterator that this is an invisible root, by setting
68 // the mark word to "marked". Reset to prototype() after the clearing.
69 arrayOopDesc::set_mark(mem, markWord::prototype().set_marked());
70 arrayOopDesc::release_set_klass(mem, _klass);
71 assert(_length >= 0, "length should be non-negative");
72 arrayOopDesc::set_length(mem, _length);
73
74 // Keep the array alive across safepoints through an invisible
75 // root. Invisible roots are not visited by the heap iterator
76 // and the marking logic will not attempt to follow its elements.
77 // Relocation and remembered set code know how to dodge iterating
78 // over such objects.
79 ZThreadLocalData::set_invisible_root(_thread, (zaddress_unsafe*)&mem);
80
81 uint32_t old_seqnum_before = ZGeneration::old()->seqnum();
82 uint32_t young_seqnum_before = ZGeneration::young()->seqnum();
83 uintptr_t color_before = ZPointerStoreGoodMask;
84 auto gc_safepoint_happened = [&]() {
85 return old_seqnum_before != ZGeneration::old()->seqnum() ||
86 young_seqnum_before != ZGeneration::young()->seqnum() ||
87 color_before != ZPointerStoreGoodMask;
88 };
89
118 // Deal with safepoints
119 if (!seen_gc_safepoint && gc_safepoint_happened()) {
120 // The first time we observe a GC safepoint in the yield point,
121 // we have to restart processing with 11 remembered bits.
122 seen_gc_safepoint = true;
123 return false;
124 }
125 }
126 return true;
127 };
128
129 if (!initialize_memory()) {
130 // Re-color with 11 remset bits if we got intercepted by a GC safepoint
131 const bool result = initialize_memory();
132 assert(result, "Array initialization should always succeed the second time");
133 }
134
135 ZThreadLocalData::clear_invisible_root(_thread);
136
137 // Signal to the ZIterator that this is no longer an invisible root
138 oopDesc::release_set_mark(mem, markWord::prototype());
139
140 return cast_to_oop(mem);
141 }
|
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 #include "precompiled.hpp"
25 #include "gc/z/zThreadLocalData.hpp"
26 #include "gc/z/zObjArrayAllocator.hpp"
27 #include "gc/z/zUtils.inline.hpp"
28 #include "oops/arrayKlass.hpp"
29 #include "runtime/interfaceSupport.inline.hpp"
30 #include "utilities/debug.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 ZObjArrayAllocator::ZObjArrayAllocator(Klass* klass, size_t word_size, int length, bool do_zero, Thread* thread)
34 : ObjArrayAllocator(klass, word_size, length, do_zero, thread) {}
35
36 void ZObjArrayAllocator::yield_for_safepoint() const {
37 ThreadBlockInVM tbivm(JavaThread::cast(_thread));
38 }
39
40 oop ZObjArrayAllocator::initialize(HeapWord* mem) const {
41 // ZGC specializes the initialization by performing segmented clearing
42 // to allow shorter time-to-safepoints.
43
44 if (!_do_zero) {
45 // No need for ZGC specialization
46 return ObjArrayAllocator::initialize(mem);
47 }
48
49 // A max segment size of 64K was chosen because microbenchmarking
50 // suggested that it offered a good trade-off between allocation
51 // time and time-to-safepoint
52 const size_t segment_max = ZUtils::bytes_to_words(64 * K);
53 const BasicType element_type = ArrayKlass::cast(_klass)->element_type();
54 const size_t header = arrayOopDesc::header_size(element_type);
55 const size_t payload_size = _word_size - header;
56
57 if (payload_size <= segment_max || ArrayKlass::cast(_klass)->is_flatArray_klass()) {
58 // To small to use segmented clearing
59 return ObjArrayAllocator::initialize(mem);
60 }
61
62 // Segmented clearing
63
64 // The array is going to be exposed before it has been completely
65 // cleared, therefore we can't expose the header at the end of this
66 // function. Instead explicitly initialize it according to our needs.
67
68 // Signal to the ZIterator that this is an invisible root, by setting
69 // the mark word to "marked". Reset to prototype() after the clearing.
70 arrayOopDesc::set_mark(mem, Klass::default_prototype_header(_klass).set_marked());
71 arrayOopDesc::release_set_klass(mem, _klass);
72 assert(_length >= 0, "length should be non-negative");
73 arrayOopDesc::set_length(mem, _length);
74
75 // Keep the array alive across safepoints through an invisible
76 // root. Invisible roots are not visited by the heap iterator
77 // and the marking logic will not attempt to follow its elements.
78 // Relocation and remembered set code know how to dodge iterating
79 // over such objects.
80 ZThreadLocalData::set_invisible_root(_thread, (zaddress_unsafe*)&mem);
81
82 uint32_t old_seqnum_before = ZGeneration::old()->seqnum();
83 uint32_t young_seqnum_before = ZGeneration::young()->seqnum();
84 uintptr_t color_before = ZPointerStoreGoodMask;
85 auto gc_safepoint_happened = [&]() {
86 return old_seqnum_before != ZGeneration::old()->seqnum() ||
87 young_seqnum_before != ZGeneration::young()->seqnum() ||
88 color_before != ZPointerStoreGoodMask;
89 };
90
119 // Deal with safepoints
120 if (!seen_gc_safepoint && gc_safepoint_happened()) {
121 // The first time we observe a GC safepoint in the yield point,
122 // we have to restart processing with 11 remembered bits.
123 seen_gc_safepoint = true;
124 return false;
125 }
126 }
127 return true;
128 };
129
130 if (!initialize_memory()) {
131 // Re-color with 11 remset bits if we got intercepted by a GC safepoint
132 const bool result = initialize_memory();
133 assert(result, "Array initialization should always succeed the second time");
134 }
135
136 ZThreadLocalData::clear_invisible_root(_thread);
137
138 // Signal to the ZIterator that this is no longer an invisible root
139 oopDesc::release_set_mark(mem, Klass::default_prototype_header(_klass));
140
141 return cast_to_oop(mem);
142 }
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