Marge Bot repeatedly failing due to stat decreases

[Ryan Scott]

Hello,

I've been receiving a flurry of e-mails all weekend about Marge Bot
failing to validate a batch on CI. Moreover, the failures appear to be
consistent each time. From the most recent one [1]:

    Unexpected stat failures:
       /builds/ghc/ghc/tmp/ghctest-mel1y5lo/test
spaces/testsuite/tests/perf/compiler/T12150.run  T12150 [stat
decreased from "x86_64-linux-deb9-hadrian" baseline @ HEAD~6] (optasm)
       /builds/ghc/ghc/tmp/ghctest-mel1y5lo/test
spaces/testsuite/tests/perf/compiler/T12234.run  T12234 [stat
decreased from "x86_64-linux-deb9-hadrian" baseline @ HEAD~6] (optasm)

Where

    T12150(optasm)            compile_time/bytes allocated
    75982592.000
                              (baseline @ HEAD~6)
    76945688.000  [decreased, -1.3%]
    T12234(optasm)            compile_time/bytes allocated
    82149240.000
                              (baseline @ HEAD~6)
    83109896.000  [decreased, -1.2%]

Can something be done about this? It's holding one one of my patches.

Ryan S.
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[1] https://gitlab.haskell.org/ghc/ghc/-/jobs/359994