netdev - Re: [PATCH net-next v3] net: xsk: introduce XDP_MAX_TX

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Message-ID: <CAL+tcoCz6bK+NHs21QvC+vtZfir6s=k_qLAi+hu0+vw-7bc-2w@mail.gmail.com>
Date: Sun, 22 Jun 2025 08:05:25 +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>
Subject: Re: [PATCH net-next v3] net: xsk: introduce XDP_MAX_TX_BUDGET set/getsockopt

On Sat, Jun 21, 2025 at 10:43 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Fri, 20 Jun 2025 08:17:48 +0800 Jason Xing wrote:
> > > Jason, I think some additions to Documentation/ and quantification of
> > > the benefits would be needed as well.
> >
> > Got it.
> >
> > #1 Documentation. I would add one small section 'XDP_MAX_TX_BUDGET
> > setsockopt' in Documentation/networking/af_xdp.rst.
> >
> > #2 quantification
> > It's really hard to do so mainly because of various stacks implemented
> > in the user-space. AF_XDP is providing a fundamental mechanism only
> > and its upper layer is prosperous.
>
> Sorry for the awkward phrase. By "quantification of the benefits"
> I meant what performance improvement you have seen from increasing
> this "budget".

I see. A week ago, I saw a stable improvement of around 4% for both
PPS and throughput. Special notice: not all the cases, just one of
them I traced...

Less resources consumption was found to be observed by strace -c -p xxx:
1) %time is decreased by 7.8%
2) error counter is decreased from 18367 to 572

I will add the numbers into the commit next time.

Thanks,
Jason