On 1/30/26 4:13 AM, Pavel Begunkov wrote: > On 1/27/26 06:48, Bobby Eshleman wrote: >> On Mon, Jan 26, 2026 at 10:00?PM Stanislav Fomichev >> <[email protected]> wrote: >>> >>> 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. >> >> I second liking that approach. No put_cmsg() and or token alloc >> overhead (both jump up in my profiling). > > Hmm, makes me wonder why not use zcrx instead of reinventing it? It
Was thinking the same throughout most of this later discussion... We already have an API for this. -- Jens Axboe
