Re: [PATCH/RFC] gitperformance: add new documentation about git performance tuning

From: Eric Wong <e@80x24.org>
Date: Apr 3, 2017, 21:34 UTC
Message-ID: <20170403213440.GA1409@whir>
In-Reply-To: <20170403211644.26814-1-avarab@gmail.com>

Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:

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> Add a new manpage that gives an overview of how to tweak git's
> performance.
> 
> There's currently no good single resource for things a git site
> administrator might want to look into to improve performance for his
> site & his users. This unfinished documentation aims to be the first
> thing someone might want to look at when investigating ways to improve
> git performance.
> 
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
> 
> I've been wanting to get something like this started for a while. It's
> obviously woefully incomplete. Pointers about what to include would be
> great & whether including something like this makes sense.

Thanks for doing this. I hope something like this can give server operators more confidence to host their own git servers.

> Things I have on my TODO list:

<snip>

>  - Should we be covering good practices for your repo going forward to
>    maintain good performance? E.g. don't have some huge tree all in
>    one directory (use subdirs), don't add binary (rather
>    un-delta-able) content if you can help it etc.

Yes, I think so.

I think avoiding ever growing ChangeLog-type files should also be added to things to avoid.

> --- /dev/null
> +++ b/Documentation/gitperformance.txt
> @@ -0,0 +1,107 @@
> +giteveryday(7)

gitperformance(7)

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> +Server options to help clients
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +These features can be enabled on git servers, they won't help the
> +performance of the servers themselves,

Is that true for bitmaps? I thought they reduced CPU usage on the server side...

A sidenote: I wonder if bitmaps should be the default for bare repos, since bare repos are likely used on servers.

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> but will help clients that need
> +to talk to those servers.
> +
> +- config: "repack.writeBitmaps=true" (see
> +  linkgit:git-config[1]). Spend more time during repack to produce
> +  bitmap index, helps clients with "fetch" & "clone" performance.