Re: [PATCH net-next] net: use indirect call wrappers for skb_copy_datagram_iter()

[Paolo Abeni <pabeni@redhat.com>]

On Wed, 2020-03-25 at 10:55 -0400, Willem de Bruijn wrote:
> On the UDP front this reminded me of another indirect function call
> without indirect call wrapper: getfrag in __ip_append_data.
> 
> That is called for each datagram once per linear + once per page. That
> said, the noise in my quick RR test was too great to measure any
> benefit from the following. 

Why an RR test ?

I think you should be able to measure some raw tput improvement with
large UDP GSO write towards a blackhole dst/or dropping ingress pkts
with XDP (just to be sure the bottle-neck is on the sender side).

> Paolo, did you happen to also look at that
> when introducing the indirect callers? Seems like it won't hurt to
> add.

Nope, sorry I haven't experimented that.

For the record, I have 2 others item on my list, I hope to have time to
process some day: the ingress dst->input and the default ->enqueue  and
->dequeue

Cheers,

Paolo

p.s. feel free to move this on a different thread, as it fit you better