Re: [PATCH net-next v3 0/3] make skip_sw actually skip software

[Asbjørn Sloth Tønnesen]

Hi Kuba,

On 3/11/24 8:44 PM, Jakub Kicinski wrote:
> On Wed,  6 Mar 2024 16:58:08 +0000 Asbjørn Sloth Tønnesen wrote:
> > During development of flower-route[1], which I
> > recently presented at FOSDEM[2], I noticed that
> > CPU usage, would increase the more rules I installed
> > into the hardware for IP forwarding offloading.
> >
> > Since we use TC flower offload for the hottest
> > prefixes, and leave the long tail to the normal (non-TC)
> > Linux network stack for slow-path IP forwarding.
> > 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, since 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, by implementing a TC bypass for these
> > cases, where TC is only used as a control plane
> > for the hardware path.
>
> Linus tagged v6.8 and the merge window for v6.9 has started.
> This feels a bit too risky for me to apply last minute,
> could you repost in 2 weeks once the merge window is over?

Sure, I will repost once net-next opens back up again.

--
Best regards
Asbjørn Sloth Tønnesen
Network Engineer
Fiberby - AS42541