From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13BBAC6379F for ; Fri, 13 Jan 2023 21:08:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230219AbjAMVH6 (ORCPT ); Fri, 13 Jan 2023 16:07:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230093AbjAMVHj (ORCPT ); Fri, 13 Jan 2023 16:07:39 -0500 Received: from mail-ej1-x62c.google.com (mail-ej1-x62c.google.com [IPv6:2a00:1450:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A50FE88A3F; Fri, 13 Jan 2023 13:07:33 -0800 (PST) Received: by mail-ej1-x62c.google.com with SMTP id tz12so55153702ejc.9; Fri, 13 Jan 2023 13:07:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=Y799U3pjQRIaLfXmIj4zBC/UY5a59GVSQHE28cjR+UA=; b=VecmKqX+y5k2hixW6pxEPzr76Apoh9mdcSNHZ0ExzA057R09OBvj2IH7NJ4H36sJlj RooQaRe1ElWCkd1XDbFeczVeRzXz/DlBtU/D6ctcw36lPNEHTLifWM2lNghUyamgDwOI vH8/j+UZpftNRLxxX3Znn6WNN0s9JsAYQBV5uU6xWNqgZ9Cq1XowOWjoj7tiIP8JYla4 RY6SFmTtnQYoVfdw4Jj1iMmF1+SfXFcYEgkrZN/vCBUBzlLqJrQhJbcSRWoPE5DEoP6X V1/WOVY2ZhEspVOLU7ulakpGtu4HVKjOjFSYXe35csxqt1pXCkYA3JCnJXaEE8+AOSji FIQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Y799U3pjQRIaLfXmIj4zBC/UY5a59GVSQHE28cjR+UA=; b=XOrOmpG3sBqgtkPntfD5OaJAeDCSBtJs31maYtupIapNsy6nuhZUdiU/Db7iDaMKUt k0jVu+ZnK7c+rEG5ZsYmRNVTO6PwXWsuzgkqfX3WzKUwPdlLJa0NCZYA570YyMm/DFwv SC8iTFweL+d/efBKSroWcrXYIO50tSKZXmKDIu0sZ2gEd19Bgb46LZwOHxcLmlnrPpjv QJfskR/WfIRr1Zbob9B75t1wPgNMmLNpi06xj9BcGBj9k4aRIQNb0Uv3w3F28f4PQiF1 lw8u+dm414jK3W8IhwbqK47B5U+N5VLmHhj4Cc2ZxmhPe2QcLQSzSNZlprWUeywJ/vHM 3RRQ== X-Gm-Message-State: AFqh2krLlYGpHTUQ5jRaT/gJIDwR5lRgjewFodQIX2V/JXg6reUNJKoS 5KkE54/7G0m6ILety8gCowQqu/seqR7habLD X-Google-Smtp-Source: AMrXdXuleic1gqc2HKopibM/NzCjJpujxbhMsKeNamt9M3KTvADfZceQtmdZgdmZQ6InNgOOcWf/fw== X-Received: by 2002:a17:907:a0cc:b0:78d:f454:37a6 with SMTP id hw12-20020a170907a0cc00b0078df45437a6mr74017652ejc.73.1673644052185; Fri, 13 Jan 2023 13:07:32 -0800 (PST) Received: from [192.168.0.105] ([77.126.1.183]) by smtp.gmail.com with ESMTPSA id j17-20020a17090623f100b00770812e2394sm6786689ejg.160.2023.01.13.13.07.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Jan 2023 13:07:31 -0800 (PST) Message-ID: <4866ab1d-4d3c-577c-c94f-a51d82ca56a7@gmail.com> Date: Fri, 13 Jan 2023 23:07:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH net-next v2] samples/bpf: fixup some tools to be able to support xdp multibuffer Content-Language: en-US To: Maxim Mikityanskiy , Jakub Kicinski , Eelco Chaudron , Tariq Toukan Cc: =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= , Andy Gospodarek , ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, hawk@kernel.org, john.fastabend@gmail.com, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, kpsingh@kernel.org, lorenzo.bianconi@redhat.com, netdev@vger.kernel.org, bpf@vger.kernel.org, Jesper Dangaard Brouer , Ilias Apalodimas , Andy Gospodarek , Lorenzo Bianconi , gal@nvidia.com, Saeed Mahameed References: <20220621175402.35327-1-gospo@broadcom.com> <40fd78fc-2bb1-8eed-0b64-55cb3db71664@gmail.com> <87k0234pd6.fsf@toke.dk> <20230103172153.58f231ba@kernel.org> From: Tariq Toukan In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 10/01/2023 22:59, Maxim Mikityanskiy wrote: > On Tue, Jan 03, 2023 at 05:21:53PM -0800, Jakub Kicinski wrote: >> On Tue, 03 Jan 2023 16:19:49 +0100 Toke Høiland-Jørgensen wrote: >>> Hmm, good question! I don't think we've ever explicitly documented any >>> assumptions one way or the other. My own mental model has certainly >>> always assumed the first frag would continue to be the same size as in >>> non-multi-buf packets. >> >> Interesting! :) My mental model was closer to GRO by frags >> so the linear part would have no data, just headers. >> >> A random datapoint is that bpf_xdp_adjust_head() seems >> to enforce that there is at least ETH_HLEN. > > Also bpf_xdp_frags_increase_tail has the following check: > > if (!rxq->frag_size || rxq->frag_size > xdp->frame_sz) > return -EOPNOTSUPP; > > However, I can't seem to find where the `frag_size > frame_sz` part is > actually used. Maybe this condition can be dropped? Can someone shed > some light? > > BTW, Tariq, we seem to have missed setting frag_size to a non-zero > value. Hey Maxim, Indeed. We use xdp_rxq_info_reg, it passes 0 as frag_size. > Could you check that increasing the tail indeed doesn't work on > fragmented packets on mlx5e? I can send a oneliner to fix that. I can test early next week, and update.