gitlab contact?

Thu Apr 7 20:42:59 UTC 2022

On Thu, Apr 7, 2022 at 9:57 AM Dave Taht <dave.taht at gmail.com> wrote:

> Most cloud operations websites are kept internal. gitlab's is not,
> which is pretty cool. In looking over this issue, today:
>
> https://gitlab.com/gitlab-com/gl-infra/production/-/issues/6768
>
> They are tracking tcp syn retransmits, but not drops or other
> congestion control related info. And
> also using:
>
> sysctl net.ipv4.tcp_notsent_lowat=4294967295;
>
> where we've been getting good results with that set as low as 32k.
> Anyone know anyone at gitlab?
>

It looks like that's their current setting, but the test they're
running will be to drop it to 16K:
sysctl net.ipv4.tcp_notsent_lowat=16384;

It'll be interesting to see what the results of the
test are, and whether 16K becomes the new "normal"
for them.   :)
(cool to see this--I spent a certain amount of my time at
my previous job doing kernel parameter tuning for large
scale services, so seeing what values others are testing
with is good validation.   :)

Matt
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