1 /* Copyright 2015 The TensorFlow Authors. All Rights Reserved.
2
3 Licensed under the Apache License, Version 2.0 (the "License");
4 you may not use this file except in compliance with the License.
5 You may obtain a copy of the License at
6
7 http://www.apache.org/licenses/LICENSE-2.0
8
9 Unless required by applicable law or agreed to in writing, software
10 distributed under the License is distributed on an "AS IS" BASIS,
11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 See the License for the specific language governing permissions and
13 limitations under the License.
14 ==============================================================================*/
15
16 #ifndef TENSORFLOW_CORE_PLATFORM_PREFETCH_H_
17 #define TENSORFLOW_CORE_PLATFORM_PREFETCH_H_
18
19 #include "tensorflow/core/platform/platform.h"
20
21 namespace tensorflow {
22 namespace port {
23
24 // Prefetching support
25 //
26 // Defined behavior on some of the uarchs:
27 // PREFETCH_HINT_T0:
28 // prefetch to all levels of the hierarchy (except on p4: prefetch to L2)
29 // PREFETCH_HINT_NTA:
30 // p4: fetch to L2, but limit to 1 way (out of the 8 ways)
31 // core: skip L2, go directly to L1
32 // k8 rev E and later: skip L2, can go to either of the 2-ways in L1
33 enum PrefetchHint {
34 PREFETCH_HINT_T0 = 3, // More temporal locality
35 PREFETCH_HINT_T1 = 2,
36 PREFETCH_HINT_T2 = 1, // Less temporal locality
37 PREFETCH_HINT_NTA = 0 // No temporal locality
38 };
39 template <PrefetchHint hint>
40 void prefetch(const void* x);
41
42 // ---------------------------------------------------------------------------
43 // Inline implementation
44 // ---------------------------------------------------------------------------
45 template <PrefetchHint hint>
prefetch(const void * x)46 inline void prefetch(const void* x) {
47 // Check of COMPILER_GCC macro below is kept only for backward-compatibility
48 // reasons. COMPILER_GCC3 is the macro that actually enables prefetch.
49 #if defined(__llvm__) || defined(COMPILER_GCC) || defined(COMPILER_GCC3)
50 __builtin_prefetch(x, 0, hint);
51 #else
52 // You get no effect. Feel free to add more sections above.
53 #endif
54 }
55
56 } // namespace port
57 } // namespace tensorflow
58
59 #endif // TENSORFLOW_CORE_PLATFORM_PREFETCH_H_
60