pytorch

2fbc0fab - Setup sccache for linux test (#84916)

Setup sccache for linux test (#84916) The TTS alarm in HUD is quite noisy because of `pull / linux-focal-py3.7-gcc7 / test (backwards_compat)`. Some runs take up to 50m, i.e. [4893945786](https://github.com/pytorch/pytorch/actions/runs/3038960118/jobs/4893945786) while others take only 10m, i.e. [4893781147](https://github.com/pytorch/pytorch/actions/runs/3038943635/jobs/4893781147). Looking closer into their logs, it turns out that the longer runs have a much higher rate of cache miss. For example, [4893945786](https://github.com/pytorch/pytorch/actions/runs/3038960118/jobs/4893945786) ``` Compile requests 6487 Compile requests executed 6224 Cache hits 4975 Cache hits (C/C++) 4975 Cache misses 1227 Cache misses (C/C++) 1227 Cache timeouts 0 Cache read errors 0 Forced recaches 0 Cache write errors 0 Compilation failures 9 Cache errors 13 Cache errors (C/C++) 13 Non-cacheable compilations 0 Non-cacheable calls 16 Non-compilation calls 247 Unsupported compiler calls 0 Average cache write 0.096 s Average cache read miss 11.681 s Average cache read hit 0.040 s Failed distributed compilations 0 Non-cacheable reasons: multiple input files 15 unknown source language 1 Cache location S3, bucket: Bucket(name=ossci-compiler-cache-circleci-v2, base_url=http://ossci-compiler-cache-circleci-v2.s3.amazonaws.com/) ``` In https://github.com/pytorch/pytorch/pull/82103, we didn't setup `SCCACHE_S3_KEY_PREFIX` for `_linux-test`, which could explain the high rate of cache miss here. `backwards_compat` is a bit different than other tests in which it compiles PyTorch and gets the benefit from caching. Pull Request resolved: https://github.com/pytorch/pytorch/pull/84916 Approved by: https://github.com/seemethere