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[76.102.12.149]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1247d90d13esm21240114c88.2.2026.01.26.22.00.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Jan 2026 22:00:29 -0800 (PST) Date: Mon, 26 Jan 2026 22:00:28 -0800 From: Stanislav Fomichev To: Jakub Kicinski Cc: Bobby Eshleman , Mina Almasry , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Kuniyuki Iwashima , Willem de Bruijn , Neal Cardwell , David Ahern , Arnd Bergmann , Jonathan Corbet , Andrew Lunn , Shuah Khan , Donald Hunter , Stanislav Fomichev , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, asml.silence@gmail.com, matttbe@kernel.org, skhawaja@google.com, Bobby Eshleman Subject: Re: [PATCH net-next v10 0/5] net: devmem: improve cpu cost of RX token management Message-ID: References: <20260115-scratch-bobbyeshleman-devmem-tcp-token-upstream-v10-0-686d0af71978@meta.com> <20260120170749.101e8bcc@kernel.org> <20260126173124.1f0bb98e@kernel.org> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260126173124.1f0bb98e@kernel.org> 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.