netdev - Re: [PATCH net-next v2] xsk: add indirect call for xsk_destruct

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Message-ID: <CAL+tcoANtmLDuAHeW4JynJqiXoeTwNL2cVcGB5Ff0AxJMkR7mw@mail.gmail.com>
Date: Wed, 29 Oct 2025 09:15:01 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, edumazet@...gle.com, 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, joe@...a.to, 
	willemdebruijn.kernel@...il.com, bpf@...r.kernel.org, netdev@...r.kernel.org, 
	Jason Xing <kernelxing@...cent.com>, Alexander Lobakin <aleksander.lobakin@...el.com>
Subject: Re: [PATCH net-next v2] xsk: add indirect call for xsk_destruct_skb

On Wed, Oct 29, 2025 at 8:30 AM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Sun, 26 Oct 2025 22:58:24 +0800 Jason Xing wrote:
> > Since Eric proposed an idea about adding indirect call for UDP and
> > managed to see a huge improvement[1], the same situation can also be
> > applied in xsk scenario.
> >
> > This patch adds an indirect call for xsk and helps current copy mode
> > improve the performance by around 1% stably which was observed with
> > IXGBE at 10Gb/sec loaded. If the throughput grows, the positive effect
> > will be magnified. I applied this patch on top of batch xmit series[2],
> > and was able to see <5% improvement from our internal application
> > which is a little bit unstable though.
> >
> > Use INDIRECT wrappers to keep xsk_destruct_skb static as it used to
> > be when the mitigation config is off.
>
> FTR I don't think this code complication is worth "stable 1%" win
> on the slowpath. But maybe it's just me so I'll let Paolo decide.

For xdp or af_xdp, the best practice is to turn off mitigation since
it has a noticeable impact. But in some cases we still keep this
config on for safety. This patch is one of small optimizations that
mitigate the impact because I'm trying to optimize the af_xdp in every
possible aspect. Besides, adding this one will not disrupt the benefit
which Eric brought in his commit. Please review.

Thanks,
Jason