From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by mail.toke.dk (Postfix) with ESMTPS id 913D1A2EC08 for ; Thu, 5 Oct 2023 20:06:47 +0200 (CEST) Authentication-Results: mail.toke.dk; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=H8U/1MOe Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 151A761A36; Thu, 5 Oct 2023 18:06:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 165D8C433C8; Thu, 5 Oct 2023 18:06:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696529197; bh=j3yuvekkRlzjwP+X1S3U4vfcJhX90l/G2jFB+lby8J8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=H8U/1MOeMmkz/fiYJ2qC5kivExGxkQv0jc+YIUGCD2lx/oVojDyCXXJzZzp8GMDMB shzSmWgYDBdDBvuwnGbuQItv1J9OAJVcvSj/0gkxC13lAgmlTESieos2oyzy/J/ZIW hm8HD/c9RMPS1kjYVjS6+h1JIR/rlQv6Z1oN8BgyQUkpa4cxJT9k1LvERFAvBG7SdN VVIkkOPef/5ppA0reFHX8UzRBaitvus71DYsGBtG8ZBO/VTHuj41x+58sc+eqahJET r9rvl6KLYHj/Dm5xDqcFdOQ6qb50vEkeknx/0uUYq7SsxfK1t0gf3vQp0IVKdGpiAr QJeMGU/UR2uZg== Date: Thu, 5 Oct 2023 11:06:35 -0700 From: Jakub Kicinski To: David Ahern Message-ID: <20231005110635.7020d23b@kernel.org> In-Reply-To: <0be2e89e-8a08-e52c-fecd-3064262c2ecb@gmail.com> References: <20230927075124.23941-1-larysa.zaremba@intel.com> <20230927075124.23941-10-larysa.zaremba@intel.com> <20231003053519.74ae8938@kernel.org> <8e9d830b-556b-b8e6-45df-0bf7971b4237@intel.com> <20231004110850.5501cd52@kernel.org> <20231005101604.33b382d8@kernel.org> <0be2e89e-8a08-e52c-fecd-3064262c2ecb@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: QHSEW6TG6Z5HAW75X7BLQL5MXE2MAUJG X-Message-ID-Hash: QHSEW6TG6Z5HAW75X7BLQL5MXE2MAUJG X-MailFrom: kuba@kernel.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Alexander Lobakin , Larysa Zaremba , bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, Willem de Bruijn , Jesper Dangaard Brouer , Anatoly Burakov , Alexander Lobakin , Magnus Karlsson , Maryam Tahhan , xdp-hints@xdp-project.net, netdev@vger.kernel.org, Willem de Bruijn , Alexei Starovoitov , Simon Horman , Tariq Toukan , Saeed Mahameed , Maciej Fijalkowski X-Mailman-Version: 3.3.8 Precedence: list Subject: [xdp-hints] Re: [RFC bpf-next v2 09/24] xdp: Add VLAN tag hint List-Id: XDP hardware hints design discussion Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Thu, 5 Oct 2023 11:20:49 -0600 David Ahern wrote: > > Every time I'm involved in conversations about NIC datapath host > > interfaces I cringe at this stupid VLAN offload. Maybe I'm too > > daft to understand it's amazing value but we just shift 2B from > > the packet to the descriptor and then we have to worry about all > > the corner cases that come from vlan stacking :( > > 4B (vlan tci + protocol). > > VLAN stripping in S/W and pushing the header on Tx is measurable and > does have a noticeable performance impact. > > XDP programs need to co-exist with enabled offloads. If the tag is not > stripped, XDP program needs to handle it. If the tag is stripped, the > XDP program needs to access to the value. Well, I thought I'd ask :) I'm not opposed. But if either of you have the data on how much slower well-implemented Rx stripping in the driver is than putting the info in the descriptor, I'd be very interested. Tx is a different situation.