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
53 if (_word_size <= segment_max) {
54 // To small to use segmented clearing
55 return ObjArrayAllocator::initialize(mem);
56 }
57
58 // Segmented clearing
59
60 // The array is going to be exposed before it has been completely
61 // cleared, therefore we can't expose the header at the end of this
62 // function. Instead explicitly initialize it according to our needs.
63
64 // Signal to the ZIterator that this is an invisible root, by setting
65 // the mark word to "marked". Reset to prototype() after the clearing.
66 arrayOopDesc::set_mark(mem, markWord::prototype().set_marked());
67 arrayOopDesc::release_set_klass(mem, _klass);
68 assert(_length >= 0, "length should be non-negative");
69 arrayOopDesc::set_length(mem, _length);
70
71 // Keep the array alive across safepoints through an invisible
72 // root. Invisible roots are not visited by the heap iterator
73 // and the marking logic will not attempt to follow its elements.
74 // Relocation and remembered set code know how to dodge iterating
75 // over such objects.
76 ZThreadLocalData::set_invisible_root(_thread, (zaddress_unsafe*)&mem);
77
78 const BasicType element_type = ArrayKlass::cast(_klass)->element_type();
79 const size_t base_offset_in_bytes = arrayOopDesc::base_offset_in_bytes(element_type);
80 const size_t process_start_offset_in_bytes = align_up(base_offset_in_bytes, BytesPerWord);
81
82 if (process_start_offset_in_bytes != base_offset_in_bytes) {
83 // initialize_memory can only fill word aligned memory,
84 // fill the first 4 bytes here.
85 assert(process_start_offset_in_bytes - base_offset_in_bytes == 4, "Must be 4-byte aligned");
86 assert(!is_reference_type(element_type), "Only TypeArrays can be 4-byte aligned");
133 // The first time we observe a GC safepoint in the yield point,
134 // we have to restart processing with 11 remembered bits.
135 seen_gc_safepoint = true;
136 return false;
137 }
138 }
139 return true;
140 };
141
142 if (!initialize_memory()) {
143 // Re-color with 11 remset bits if we got intercepted by a GC safepoint
144 const bool result = initialize_memory();
145 assert(result, "Array initialization should always succeed the second time");
146 }
147
148 mem_zap_end_padding(mem);
149
150 ZThreadLocalData::clear_invisible_root(_thread);
151
152 // Signal to the ZIterator that this is no longer an invisible root
153 oopDesc::release_set_mark(mem, markWord::prototype());
154
155 return cast_to_oop(mem);
156 }
|
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
54 if (_word_size <= segment_max || ArrayKlass::cast(_klass)->is_flatArray_klass()) {
55 // To small to use segmented clearing
56 return ObjArrayAllocator::initialize(mem);
57 }
58
59 // Segmented clearing
60
61 // The array is going to be exposed before it has been completely
62 // cleared, therefore we can't expose the header at the end of this
63 // function. Instead explicitly initialize it according to our needs.
64
65 // Signal to the ZIterator that this is an invisible root, by setting
66 // the mark word to "marked". Reset to prototype() after the clearing.
67 arrayOopDesc::set_mark(mem, Klass::default_prototype_header(_klass).set_marked());
68 arrayOopDesc::release_set_klass(mem, _klass);
69 assert(_length >= 0, "length should be non-negative");
70 arrayOopDesc::set_length(mem, _length);
71
72 // Keep the array alive across safepoints through an invisible
73 // root. Invisible roots are not visited by the heap iterator
74 // and the marking logic will not attempt to follow its elements.
75 // Relocation and remembered set code know how to dodge iterating
76 // over such objects.
77 ZThreadLocalData::set_invisible_root(_thread, (zaddress_unsafe*)&mem);
78
79 const BasicType element_type = ArrayKlass::cast(_klass)->element_type();
80 const size_t base_offset_in_bytes = arrayOopDesc::base_offset_in_bytes(element_type);
81 const size_t process_start_offset_in_bytes = align_up(base_offset_in_bytes, BytesPerWord);
82
83 if (process_start_offset_in_bytes != base_offset_in_bytes) {
84 // initialize_memory can only fill word aligned memory,
85 // fill the first 4 bytes here.
86 assert(process_start_offset_in_bytes - base_offset_in_bytes == 4, "Must be 4-byte aligned");
87 assert(!is_reference_type(element_type), "Only TypeArrays can be 4-byte aligned");
134 // The first time we observe a GC safepoint in the yield point,
135 // we have to restart processing with 11 remembered bits.
136 seen_gc_safepoint = true;
137 return false;
138 }
139 }
140 return true;
141 };
142
143 if (!initialize_memory()) {
144 // Re-color with 11 remset bits if we got intercepted by a GC safepoint
145 const bool result = initialize_memory();
146 assert(result, "Array initialization should always succeed the second time");
147 }
148
149 mem_zap_end_padding(mem);
150
151 ZThreadLocalData::clear_invisible_root(_thread);
152
153 // Signal to the ZIterator that this is no longer an invisible root
154 oopDesc::release_set_mark(mem, Klass::default_prototype_header(_klass));
155
156 return cast_to_oop(mem);
157 }
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