Re: [PATCH net-next,RFC 00/13] New fast forwarding path

Hi Daniel,

On Fri, Jun 15, 2018 at 03:22:24PM +0200, Daniel Borkmann wrote:

Hi Steffen,

On 06/15/2018 08:17 AM, Steffen Klassert wrote:

quoted

I started with this last year because I wanted to improve
the IPsec (and UDP) forwarding path. Batching packets
at layer2  and send them directly to the output path
seemed to be a good method to improve this.

In particular, we need to do only one IPsec lookup
for the whole packet chain. So it relaxes the pain
from reomoving the IPsec flowcache a bit. It can be
only a first step, but we need some improvements here
as people start to complain about that.

But did you also experiment with XDP on this? 

I've already tried to figure out what I have to to
do to get XDP with forwarding, but still don't realy
know how to set this up.

Maybe it is time to have a deeper look into BPF/XDP,
but for now I feel a bit lost with this.

Would be curious about
the numbers. You'd get implicit batching for the forwarding via devmap
as well if you're required to flush it out via different device with
XDP_REDIRECT; otherwise XDP_TX of course. Given we have recently
integrated helpers for XDP to do a FIB and neighbor lookup from the
kernel tables, where it's thus shared and integrated with the rest of
the stack and tooling, it would be awesome to get to the same point
with xfrm as well. Eyal recently did a start on that for xfrm for tc
progs; would be nice to have integration on XDP as well, potentially
it might also result in a bigger plus on the forwarding numbers.

It might make sense to intrgrate XDP with xfrm to
be able to compare numbers etc. But I need a working
XDP setup and some understanding about it first, what
could take some time.