linux-kernel - Re: [PATCH net-next 0/3] make skip

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Date: Thu, 15 Feb 2024 10:00:23 -0800
From: Marcelo Ricardo Leitner <mleitner@...hat.com>
To: Asbjørn Sloth Tønnesen <ast@...erby.net>
Cc: Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>, 
	Jiri Pirko <jiri@...nulli.us>, Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, llu@...erby.dk
Subject: Re: [PATCH net-next 0/3] make skip_sw actually skip software

Hi,

On Thu, Feb 15, 2024 at 04:04:41PM +0000, Asbjørn Sloth Tønnesen wrote:
..
> Since we use TC flower offload for the hottest
> prefixes, and leave the long tail to Linux / the CPU.
> we therefore need both the hardware and software
> datapath to perform well.
>
> I found that skip_sw rules, are quite expensive
> in the kernel datapath, sice they must be evaluated
> and matched upon, before the kernel checks the
> skip_sw flag.
>
> This patchset optimizes the case where all rules
> are skip_sw.

The talk is interesting. Yet, I don't get how it is set up.
How do you use a dedicated block for skip_sw, and then have a
catch-all on sw again please?

I'm missing which traffic is being matched against the sw datapath. In
theory, you have all the heavy duty filters offloaded, so the sw
datapath should be seeing only a few packets, right?

  Marcelo