add metrics support for CPU GPU peak memory usage (#1274)
Summary:
Add --metrics [cpu_peak_mem,gpu_peak_mem,flops_dcgm] to run.py. Users could specify different combinations of those three metrics such as --metrics cpu_peak_mem,gpu_peak_mem to obtain the peak memory usage for CPU and GPU. The output is like the following.
```
GPU Peak Memory: 2.4268 GB
CPU Peak Memory: 4.1475 GB
```
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1274
Reviewed By: xuzhao9
Differential Revision: D40897170
Pulled By: FindHao
fbshipit-source-id: cbd47f13234cda004d18c87f04c1149a9474bf8f
