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 75773C4332F for ; Wed, 4 Jan 2023 12:29:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239181AbjADM3x (ORCPT ); Wed, 4 Jan 2023 07:29:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52076 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239089AbjADM3t (ORCPT ); Wed, 4 Jan 2023 07:29:49 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 59FBE1A233 for ; Wed, 4 Jan 2023 04:29:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1672835341; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=D83ggwJK4ngkFfN/2WNdiEe8asazEJXPWDhn2wflgWs=; b=Tn+Pea4WtSYxCpTwYtgysdPwDVBK0BZViHVpk/Ar6PJVGpx3494WR/RLl4idoWBnJ38yLZ RUUfUq7308iTQBKRbbU70yvRys5DkeflKMZKtjSWdaBBvuSDciPHT0mDc9gfrPbMXeRhFr zmZexxpXbncip0dBzcP1s9S4BOFsrAM= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-581--dg5yuaZM1eD4QXBFJ-OwA-1; Wed, 04 Jan 2023 07:29:00 -0500 X-MC-Unique: -dg5yuaZM1eD4QXBFJ-OwA-1 Received: by mail-ed1-f69.google.com with SMTP id z8-20020a056402274800b0048a31c1746aso9145694edd.0 for ; Wed, 04 Jan 2023 04:29:00 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:references :in-reply-to:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=D83ggwJK4ngkFfN/2WNdiEe8asazEJXPWDhn2wflgWs=; b=ISJVbWFbh8cMEK1f26q3H18gu4aK8wGdlg2rumHgpEQQJeflrtjHs/xAtQmFtlgKJh PtnvGAED+1k1MC3atOsHLMO3Uy5MI6qsgOZDMCfVLO2QSWxvyfVPRYn7lBWlCP5Z+YDx Do9rXqrYs5OkDUPZeGdpPzQKDPHauvmT4vaDS2RexidYOAqrPiA9zj3akr/gW894rEtp z0hipR4IzpOPpXR2noYxgTlvQMqmoAYQ1cv7i1rUNX1s+sIR3feg7SlykLaIXMIu8/y0 /1qRTjqEnFfRUxGpqqtrFKsHfIbRxjmXsizgfr8YyWwpbO6Hmx57VA7zyd8A+LR9t3Yv PhzA== X-Gm-Message-State: AFqh2krsycZokBIx/RJ8tUwIVGt+wvtVvc9WgBpZKozQdQDvi71QfXYS shhVWexxL80QFWHyqUQqhdABlRZAY35Wj0RevVqy/eNhoKhzioEhPuc6aoMIkf+O9Frlqoy1XLu MS+s6vNPmXE4y X-Received: by 2002:aa7:c659:0:b0:48c:7e42:844c with SMTP id z25-20020aa7c659000000b0048c7e42844cmr11649452edr.10.1672835339056; Wed, 04 Jan 2023 04:28:59 -0800 (PST) X-Google-Smtp-Source: AMrXdXv3D10jrlC5WnU/hlTFXGNbMH9aBiPcxBGaYmUhTGAyAXaetE2FdzSJ7TbI2gYyDdewD6T+ng== X-Received: by 2002:aa7:c659:0:b0:48c:7e42:844c with SMTP id z25-20020aa7c659000000b0048c7e42844cmr11649443edr.10.1672835338765; Wed, 04 Jan 2023 04:28:58 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id s22-20020aa7cb16000000b00457b5ba968csm14644608edt.27.2023.01.04.04.28.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Jan 2023 04:28:58 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 7A4388A2934; Wed, 4 Jan 2023 13:28:57 +0100 (CET) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Lorenzo Bianconi , Jakub Kicinski Cc: Tariq Toukan , 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 , gal@nvidia.com, Saeed Mahameed , tariqt@nvidia.com Subject: Re: [PATCH net-next v2] samples/bpf: fixup some tools to be able to support xdp multibuffer In-Reply-To: References: <20220621175402.35327-1-gospo@broadcom.com> <40fd78fc-2bb1-8eed-0b64-55cb3db71664@gmail.com> <87k0234pd6.fsf@toke.dk> <20230103172153.58f231ba@kernel.org> X-Clacks-Overhead: GNU Terry Pratchett Date: Wed, 04 Jan 2023 13:28:57 +0100 Message-ID: <87bkne32ly.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Lorenzo Bianconi writes: >> On Tue, 03 Jan 2023 16:19:49 +0100 Toke H=C3=B8iland-J=C3=B8rgensen wrot= e: >> > 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. >>=20 >> Interesting! :) My mental model was closer to GRO by frags=20 >> so the linear part would have no data, just headers. > > That is assumption as well. Right, okay, so how many headers? Only Ethernet, or all the way up to L4 (TCP/UDP)? I do seem to recall a discussion around the header/data split for TCP specifically, but I think I mentally put that down as "something people may way to do at some point in the future", which is why it hasn't made it into my own mental model (yet?) :) -Toke