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_PLATFORM_PREFETCH_H_ 17 #define TENSORFLOW_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> 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_PLATFORM_PREFETCH_H_ 60
