| /* Copyright 2018 The TensorFlow Authors. All Rights Reserved. |
| |
| Licensed under the Apache License, Version 2.0 (the "License"); |
| you may not use this file except in compliance with the License. |
| You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| ==============================================================================*/ |
| |
| #ifndef TENSORFLOW_CORE_KERNELS_DATA_SINGLE_THREADED_EXECUTOR_H_ |
| #define TENSORFLOW_CORE_KERNELS_DATA_SINGLE_THREADED_EXECUTOR_H_ |
| |
| #include "tensorflow/core/common_runtime/executor.h" |
| |
| namespace tensorflow { |
| namespace data { |
| |
| // Creates a new `Executor` for executing `graph` synchronously on the caller |
| // thread. |
| // |
| // NOTE(mrry): The returned executor is optimized to impose low overhead on |
| // graphs that perform a small amount of work (e.g. <15us of work per graph on |
| // present architectures). It eschews concurrency, because issuing work to |
| // multiple threads can dominate the cost of executing small ops synchronously, |
| // and because contention in the executor data structures can reduce throughput |
| // (in terms of ops executed per unit time). |
| // |
| // However, the current implementation has the following limitations: |
| // |
| // 1. Reference-typed tensors are not supported and will not be supported in |
| // future. |
| // 2. Graphs with control flow (containing "Switch" and "Merge" nodes) are not |
| // currently supported. The current plan is to extend support to "functional" |
| // control flow after the TensorFlow APIs transition to building graphs in |
| // that form (e.g. `tf.cond_v2()`). |
| // 3. Partitioned graphs (containing "_Recv" nodes) are not currently supported. |
| // The present implementation executes kernels one at a time in topological |
| // order, and cannot currently distinguish between disconnected subgraphs |
| // that are logically connected by subgraphs on a different device. |
| // 4. Memory logging is not currently supported. |
| // 5. Allocation forwarding is not currently supported. |
| // 6. Non-default device contexts are not currently supported. In effect, this |
| // limits the executor to CPU devices. |
| // 7. Ops that rely on `OpKernelContext::slice_reader_cache()` being non-null |
| // are not currently supported. |
| // |
| // The single-threaded executor is primarily suitable for executing simple |
| // TensorFlow functions, such as one might find in a `tf.data` pipeline. |
| Status NewSingleThreadedExecutor(const LocalExecutorParams& params, |
| std::unique_ptr<const Graph> graph, |
| Executor** executor); |
| |
| } // namespace data |
| } // namespace tensorflow |
| |
| #endif // TENSORFLOW_CORE_KERNELS_DATA_SINGLE_THREADED_EXECUTOR_H_ |