[tf.data] Add prefetch benchmark.

This CL adds a benchmark to test the performance of the prefetch dataset transformation.

PiperOrigin-RevId: 316605096
Change-Id: Iaf5d8f8c3afba6e51a53805afe5bc978916ff01e

tensorflow/python/data/benchmarks/BUILD

@@ -85,6 +85,15 @@ tf_py_test(
     ],
 )
 
+tf_py_test(
+    name = "prefetch_benchmark",
+    srcs = ["prefetch_benchmark.py"],
+    deps = [
+        ":benchmark_base",
+        "//tensorflow/python/data/ops:dataset_ops",
+    ],
+)
+
 tf_py_test(
     name = "range_benchmark",
     srcs = ["range_benchmark.py"],

tensorflow/python/data/benchmarks/prefetch_benchmark.py

@@ -0,0 +1,40 @@
+# Copyright 2020 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.
+# ==============================================================================
+"""Benchmarks for `tf.data.Dataset.prefetch()`."""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+from tensorflow.python.data.benchmarks import benchmark_base
+from tensorflow.python.data.ops import dataset_ops
+
+
+class PrefetchBenchmark(benchmark_base.DatasetBenchmarkBase):
+  """Benchmarks for `tf.data.Dataset.prefetch()`."""
+
+  def benchmark_prefetch(self):
+    num_elements = 1000000
+    for prefetch_buffer in [1, 5, 10, 20, 100]:
+      dataset = dataset_ops.Dataset.range(num_elements)
+      dataset = dataset.prefetch(prefetch_buffer)
+
+      self.run_and_report_benchmark(
+          dataset,
+          num_elements=num_elements,
+          name="prefetch_{}".format(prefetch_buffer))
+
+
+if __name__ == "__main__":
+  benchmark_base.test.main()