[te] Benchmark comparing fused overhead to unfused (#50305)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50305
That's it
ghstack-source-id: 119631533
Test Plan:
```
buck run //caffe2/benchmarks/cpp/tensorexpr:tensorexpr_bench -- --benchmark_filter=Overhead
```
```
Run on (24 X 2394.67 MHz CPU s)
2021-01-08 16:06:17
-------------------------------------------------------
Benchmark Time CPU Iterations
-------------------------------------------------------
FusedOverhead 2157 ns 2157 ns 311314
UnfusedOverhead 2443 ns 2443 ns 311221
```
Reviewed By: ZolotukhinM
Differential Revision: D25856891
fbshipit-source-id: 0e99515ec2e769a04929157d46903759c03182a3
