Subject: Re: [PATCH net-next v10 0/5] net: devmem: improve cpu cost of RX token management

From: Stanislav Fomichev <[email-masked]>
Date: Mon, 26 Jan 2026 22:00:28 -0800

On 01/26, Jakub Kicinski wrote:
> On Mon, 26 Jan 2026 10:45:22 -0800 Bobby Eshleman wrote:
> > I'm onboard with improving what we have since it helps all of us
> > currently using this API, though I'm not opposed to discussing a
> > redesign in another thread/RFC. I do see the attraction to locating the
> > core logic in one place and possibly reducing some complexity around
> > socket/binding relationships.
> > 
> > FWIW regarding nl, I do see it supports rtnl lock-free operations via
> > '62256f98f244 rtnetlink: add RTNL_FLAG_DOIT_UNLOCKED' and routing was
> > recently made lockless with that. I don't see / know of any fast path
> > precedent. I'm aware there are some things I'm not sure about being
> > relevant performance-wise, like hitting skb alloc an additional time
> > every release batch. I'd want to do some minimal latency comparisons
> > between that path and sockopt before diving head-first.
> 
> FTR I'm not really pushing Netlink specifically, it may work it 
> may not. Perhaps some other ioctl-y thing exists. Just in general
> setsockopt() on a specific socket feels increasingly awkward for 
> buffer flow. Maybe y'all disagree.
> 
> I thought I'd clarify since I may be seen as "Mr Netlink Everywhere" :)

>From my side, if we do a completely new uapi, my preference would be on
an af_xdp like mapped rings (presumably on a netlink socket?) to completely
avoid the user-kernel copies.