Download the input data ondemand (#1734)
Summary:
Instead of always downloading all `.tar.gz` files, only download them when the model explicitly ask for them.
Fixes https://github.com/pytorch/benchmark/issues/1717
Note that this is a trade-off - some models share the same data set, and we don't want to download the same files multiple times. Here we are only checking the existence of the file and directory. An improvement could be using checksums or completion flag files.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1734
Reviewed By: ezyang
Differential Revision: D46798459
Pulled By: xuzhao9
fbshipit-source-id: efe71d290b7af79bed8f50954bf5b99b103e7f73
