linux-kernel - Re: [PATCH] kselftest: dt: Stop relying on dirname to improve performance

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Date:   Fri, 8 Dec 2023 17:29:31 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
Cc:     Rob Herring <robh+dt@...nel.org>, Shuah Khan <shuah@...nel.org>,
        kernel@...labora.com, Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH] kselftest: dt: Stop relying on dirname to improve
 performance

On Fri, Dec 08, 2023 at 10:39:27AM -0300, Nícolas F. R. A. Prado wrote:
> When walking directory trees, instead of looking for specific files and
> running dirname to get the parent folder, traverse all folders and
> ignore the ones not containing the desired files. This avoids the need
> to call dirname inside the loop, which gives a big performance boost,
> approximately halving run time: Running locally on a
> mt8192-asurada-spherion, which reports 160 test cases, has gone from
> 5.5s to 2.9s, while running remotely with an nfsroot has gone from
> 13.5s to 5.5s.

It's hard to be sure exactly since the runtime is a bit variable but it
does look like this is running substantially faster on the test systems
I have that were most affected by the slowdown, looks like approximately
a quarter of the time, and all the tests that were present before seem
to still be present.

Tested-by: Mark Brown <broonie@...nel.org>

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