davide at well-typed.com
Wed Mar 11 12:10:08 UTC 2020
-------- Forwarded Message --------
Subject: Re: performance testing
Date: Wed, 11 Mar 2020 12:08:52 +0000
From: David Eichmann <davide at well-typed.com>
To: Richard Eisenberg <rae at richarde.dev>
> Ah yes -- very helpful. So the baseline is always (implicitly) the
> parent commit, if that commit has performance info in the set of
> notes. So if I have this situation (time flows down)
> origin/master: blah
> wip/xyz: big cool change (that slows things down)
> attempt1: comment out some of big cool change
> attempt2: comment out more of big cool change
With you so far.
> and I do a perf test on attempt1, it's quite likely that the perf test
> will*pass*, because it's comparing to the previous commit.
Yes, assuming you actually ran performance tests on the previous commit
with a clean working tree (remember we don't record performance metrics
if the git tree has changes, though you'll see a warning in the test
output in that case). I'd suggest outputting a graph as described in the
wiki if you're wondering which commits have recorded performance metrics.
> And then when I do a perf test on attempt2 and see a metric*decrease*,
> that might just be because I've fixed the perf problem... but I
> haven't actually made an improvement.
Right. The decrease is compared to attempt1, but this may not be a
decrease compared to earlier commits. Again I'd suggest graphing the
data if you want to inspect this yourself.
David Eichmann, Haskell Consultant
Well-Typed LLP, http://www.well-typed.com
Registered in England & Wales, OC335890
118 Wymering Mansions, Wymering Road, London W9 2NF, England
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