From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.227.136 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792519102; b=4IIDn2OyHUvwyJ5cPsNVck6nx8THHr8h0HWZv0dHPFb0w0Ik1t+m+IwIAKdb4Jl6ln1R 0qBdVdMJZ5rFU68pOI66m40skn3HJt2Gy1ivLqCbqBCWKm5Rz3WeUL4k78fen6WhT4Ray 29luMXOcdXOQ0WGZEYDE86Z3WpC1LpACcdjYVRKWu2IQQCgTGCJQxNRlha2f3PfUZlyzw JmCivExghZqD4Pkj+j7eXBxkMPmG3212HYdrrBvonDdTR3z1X3JFjQc6FFAOhffDHr2Fj WUH420LuzaIjEOZJL+wNB6MPMrR9Mzh2pna0QauF1jeGRnM6snsL9JCy5kh8AeNNLhw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792519102; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; bh=lfvzxumMX8GZYmj1PJHBaPnkGMwtjZCWGV30UbLz0Q0=; b=aPT7dM/VT/CYw+7SXac2CDca3WjOwOCrfN5asTN8nlE+Xtvy+J5FIpYB5NJuht6xBqTg tAo/NIGUU3Fo78tJur/UkYW4a8ofBiro9GctEGwknm2mlMHljZAsJWUA7QzCHPCeiBSij o32Eyu1r1UaAq2TiLktDbLzq0l4UsP4ma8XPStiQJZ/a1wSePmY5t35UcSyzEkF7FV10E OTlQXr4XeKIMoTcfDnRyKbPDu/5gNCjc7STkkrdOtyoWpUwWz5/iyfk/QorUmyfT9hSv/ jYfR6q9ESLRYgr/PVuChEeHvvTklatZrub2lNpoczeY72U7dDDjAi1ak/nwRRGZxWCw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b="hk7DKm8/"; arc=none smtp.remote-ip=74.125.227.136 Received: from mail-pj2-f8.google.com (mail-pj2-f8.google.com [74.125.227.136]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 80C2B606A320 for ; Tue, 20 Oct 2026 17:58:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 80C2B606A320 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=hk7DKm8/ Received: by mail-pj2-f8.google.com with SMTP id 98e67ed59e1d1-3ac749e0719so976523a91.0 for ; Tue, 20 Oct 2026 10:58:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1792519102; x=1793123902; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=lfvzxumMX8GZYmj1PJHBaPnkGMwtjZCWGV30UbLz0Q0=; b=hk7DKm8/HVQtDM7SfuNCgwbY6d9oYkVDTzKvh3xFFVJcjWgeTit4nQ3APKC6JcXMvs 5b1sQ076nR/cD60jiZzZnASVUl2A1IZZGCAtZTv89HFO9xMKTFkmD6zhLqjP8L3wg7YT EZ+XvNHUBXYD7s1wo8gn6iYgnI1fN0liSodgV4PIsesSa9bemHyZzT4hLir3wzeKGmpn 2cfYdmBPyJQrErJTZ2N9KyeYzowC/aQbw4VYo0vWXFp7rwMFbz2ltIGvlLTQQcEQD2Dv OdgjfMkoZTll+JU+ZxsujBTKAj8fDZLFfw03WYAg+wLvoNDOd2pzWmEdC15h4Plr2owA 0SZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792519102; x=1793123902; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=lfvzxumMX8GZYmj1PJHBaPnkGMwtjZCWGV30UbLz0Q0=; b=AOj5xOtENotQUUSWbEM10OGxVdWRfVQ0MSnLp17flNrPh68VmDz30jgJZgvmxj5bqI qUeS4D/fe3oO+C/WIIkVposh7Ynp/gCyfjnNVpkYpRAZGIhGHm1hve9vOydUDNxxR3GQ vkdlKjkVnA3kVVLeZS8ppykUM5yd4Yq1lmUfhJiJfRmy6BYl4kEUBq8mWeW+5PQi1QhB 3PT+Zv0YlNHT6DoB80awEFp29qEBw75HhdBJ24Vy96jme7fEONPM9pNwYXWMtoOB6D5v Wpkrc32DKVo1uJMyvzsm/DRicpQ+Ih53MHegeyb75ByMEytf2T3YqYoLqMD+0FRd0vlu uf4g== X-Forwarded-Encrypted: i=1; AKwUvBxzCH/ggZIi4+iO4JGxiY9xvGDiAeDXcHPUyoEhEhrpsnkHxuXsdbOz5aSveOYAIuuem+w=@vger.kernel.org X-Gm-Message-State: AFq9FYKBBT/0E6HRcvBuMMhJt70YHUU3Twnb3zGyWfqIRICbUp1Yc3ko ClB4+ekaal1OiGiv7/wgQu5s+rsGcSiDf1+WTOIu2FvaAnU1Xoi8uUKE X-Gm-Gg: AYBFou2WkEMnuBIVzXS3k4Irec1iAlLGpbrnO1M31w9AmOj5ADPaFz0WkYx4r0SNpHH 8UX0rALcVIqTevn4FnCmbbD87tpFi1bi34KqIUZX5BTorvFlRB+cXzE7zafxpkjXGuL4toMyu7U vaE4CDrPK68PAmL2aNBOBZuI5XVDgg/7gav/2ZGEjTTXIRzOxpHtqYf3rayJi+bXRHkQTakrk1p dX0x2mr3h5hNpYiYbtaYzdzfhKr63tLtDx6Z2VxydFdRDny61aHDJ/frAY7tOlbJ4KAnIVQ764T EwD5UWbjhtOfQk/HAzprGTNCpIptmdqK4yTn3t9gbwEC6q3tkr8N1ZWmdIyPWSUxHTYSp/LJ2Ci Rf24jc4so5UBDS5KHUaRzlMO1L6/rytnwssIzewMcDnJP1aaMRkPW04MTHaqZg/6pQ4C7jlloID t+l474lgKDQVDDDfnirKvDGBYSEEQL2Em7Z1RYARULpOeQ2aRQjXeFqmwt1yif2hLQoBwdPdrsw RGfKhL761EAEY2fG/IPxPVMe9eNb1yYssq4bUrzpT5w7cPU X-Received: by 2002:a17:90b:4b09:b0:3ab:188b:c5bc with SMTP id 98e67ed59e1d1-3aceebb4bb9mr10542274a91.14.1792519101713; Tue, 20 Oct 2026 10:58:21 -0700 (PDT) Received: from localhost ([2a03:2880:2ff:6::]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ad82f0c0b1sm133581a91.0.2026.10.20.10.58.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 10:58:21 -0700 (PDT) Date: Tue, 20 Oct 2026 10:58:13 -0700 From: Stanislav Fomichev To: Jakub Sitnicki Cc: Willem Ferguson , netdev@vger.kernel.org, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, ncardwell@google.com, bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, linux-doc@vger.kernel.org, corbet@lwn.net, linux-kselftest@vger.kernel.org, shuah@kernel.org, linux-kernel@vger.kernel.org, kernel-team@cloudflare.com Subject: Re: [RFC PATCH net-next 0/4] tcp: carry a BPF-chosen identifier in TSval low bits Message-ID: References: <20261013103906.2660384-1-wferguson@cloudflare.com> <87a4oaf3mv.fsf@cloudflare.com> X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87a4oaf3mv.fsf@cloudflare.com> On 10/19, Jakub Sitnicki wrote: > Hey Stan, > > On Thu, Oct 15, 2026 at 02:45 PM -07, Stanislav Fomichev wrote: > > On 10/13, Willem Ferguson wrote: > > [...] > > >> Questions for reviewers: > >> > >> 1. Is encoding an identifier in the low bits of TSval acceptable in > >> principle, given the trade-offs above? > >> 2. If so, what feedback do you have on the implementation? > > > > Don't see any feedback yet, so from the top of my head: looks like you > > control two sides of the communication, so why not a custom (bpf) tcp option? > > Would you need that on every packet and it makes it expensive? > > > > Or any other field you can abuse maybe? IPv6 Flow label? > > Nah, we don't control the client unfortunately. > > Client here is any device that connects to our edge PoP. I see, so you rely on the fact that it gets mirrored back.. Btw, looks like there is already some similar tsoffset/ts_off infra? Have you considered plugging into that?