netdev - Re: [PATCH net-next 0/2] net: xsk: add two sysctl knobs

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Message-ID: <6852fe267553f_3471a129472@willemb.c.googlers.com.notmuch>
Date: Wed, 18 Jun 2025 13:57:58 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Jason Xing <kerneljasonxing@...il.com>, 
 Stanislav Fomichev <stfomichev@...il.com>
Cc: davem@...emloft.net, 
 edumazet@...gle.com, 
 kuba@...nel.org, 
 pabeni@...hat.com, 
 bjorn@...nel.org, 
 magnus.karlsson@...el.com, 
 maciej.fijalkowski@...el.com, 
 jonathan.lemon@...il.com, 
 sdf@...ichev.me, 
 ast@...nel.org, 
 daniel@...earbox.net, 
 hawk@...nel.org, 
 john.fastabend@...il.com, 
 bpf@...r.kernel.org, 
 netdev@...r.kernel.org, 
 Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next 0/2] net: xsk: add two sysctl knobs

Jason Xing wrote:
> Hi Stanislav,
> 
> On Tue, Jun 17, 2025 at 9:11 AM Stanislav Fomichev <stfomichev@...il.com> wrote:
> >
> > On 06/17, Jason Xing wrote:
> > > From: Jason Xing <kernelxing@...cent.com>
> > >
> > > Introduce a control method in the xsk path to let users have the chance
> > > to tune it manually.
> >
> > Can you expand more on why the defaults don't work for you?
> 
> We use a user-level tcp stack with xsk to transmit packets that have
> higher priorities than other normal kernel tcp flows. It turns out
> that enlarging the number can minimize times of triggering sendto
> sysctl, which contributes to faster transmission. it's very easy to
> hit the upper bound (namely, 32) if you log the return value of
> sendto. I mentioned a bit about this in the second patch, saying that
> we can have a similar knob already appearing in the qdisc layer.
> Furthermore, exposing important parameters can help applications
> complete their AI/auto-tuning to judge which one is the best fit in
> their production workload. That is also one of the promising
> tendencies :)

It would be informative to include this in the commit.

Or more broadly: suggestions for when and how to pick good settings
for these new tunables.