Use shard file if present, improve functions used for sharding (#54210)
Summary:
Step 2 to fixing https://github.com/pytorch/pytorch/issues/53882 :)
This changes TARGET_DET_LIST and sharding automation by checking if there's already cached data from the commit in `.pytorch-test-times`. If not, it pulls data from S3 and updates the file to have the stats. This way, S3 pulling does not need to happen more than once for the same commit.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/54210
Test Plan:
the following methods should run the same set of tests.
First `export CIRCLE_JOB=pytorch_linux_xenial_cuda10_2_cudnn7_py3_gcc7_test2` or your favorite CIRCLE JOB.
1. Pull data first and use it:
Download the data from S3 and write it to the cache file with `python test/run_test.py --export-historic-test-times .pytorch-test-times`
Now run `python test/run_test.py --shard 1 10`
2. Make the sharding job pull data:
Delete the file you just created: `rm .pytorch-test-times`
Now run `python test/run_test.py --shard 1 10`
Reviewed By: walterddr
Differential Revision: D27136849
Pulled By: janeyx99
fbshipit-source-id: 51a42c4e2fa3f8cf15e682679dd3eb6130aad927
