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 B67BFC54EBD for ; Thu, 5 Jan 2023 16:22:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234988AbjAEQWK (ORCPT ); Thu, 5 Jan 2023 11:22:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57694 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234830AbjAEQWI (ORCPT ); Thu, 5 Jan 2023 11:22:08 -0500 Received: from mail-qt1-x834.google.com (mail-qt1-x834.google.com [IPv6:2607:f8b0:4864:20::834]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3832E4E42F for ; Thu, 5 Jan 2023 08:22:07 -0800 (PST) Received: by mail-qt1-x834.google.com with SMTP id jr11so30296417qtb.7 for ; Thu, 05 Jan 2023 08:22:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:date:from:from:to :cc:subject:date:message-id:reply-to; bh=ffFs6MhOEallo9JreaDhoMujgaZC+42IQ6jp+96uB8w=; b=chfT8y0msZkaskvuV7/8nOEOPp9zd2IJZ4h+Bqm8yFlbbArirbxKxYrl8ahe7tCwqM xZwOKo2o8v6FEGoIEExZcLq9r8MPTgZn+tH/KgVEcpyH8lggaDWB7DRTv1Q5gblrayKs AaSgUBsBeikTN2AwblmVBUGW1NCfL9gkpqStY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:date:from :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=ffFs6MhOEallo9JreaDhoMujgaZC+42IQ6jp+96uB8w=; b=ZiH4wbRj7sdvu6IBAyG4Jp5FPZM7f06jQ22fJEL2NofIpApVXwykTaMPYZoe4/DbR+ X4f2zPnwUTmlyWACyD19ziorEsg4KKR0l9M0fKTl2sq771Q5Eax/ci+/pXn1DeCrUji6 7WmpZZ1r5o3BiPrOHhIdkZBV3IiyzXr33JusD7zjLgmnjQR7o60k2XDzKYL8H+IjvsJu qlzj6lYK++oKzUUK4xszutQhGVvhFLsyL9xBJcYAalI94kBXJuEXOB7CzGhEQA9zhhr0 nOkcWwy8L2pPCspbuKeH7hNdRfDAojkpaiSJGT06MWHy1ouPvt4TPqd5LoSbPNX7vO3X 6LDQ== X-Gm-Message-State: AFqh2kpuHRABp2JgudXcY6hzKFPBtB1FfcT7MP5BzL3y1mPJGeTzi6jE ACtmFPES1X4riyFfiym9JwbC9w== X-Google-Smtp-Source: AMrXdXtDytKaVmtg0efflOyXfymcBKXt5koF+tMQJ6ARq++uJEKl8yn91O4CftNKJAXeTMUNP38wpA== X-Received: by 2002:ac8:7551:0:b0:3a7:f46b:7a82 with SMTP id b17-20020ac87551000000b003a7f46b7a82mr68271708qtr.21.1672935726225; Thu, 05 Jan 2023 08:22:06 -0800 (PST) Received: from C02YVCJELVCG.dhcp.broadcom.net ([192.19.144.250]) by smtp.gmail.com with ESMTPSA id v15-20020a05620a440f00b0070495934152sm25987506qkp.48.2023.01.05.08.22.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Jan 2023 08:22:05 -0800 (PST) From: Andy Gospodarek X-Google-Original-From: Andy Gospodarek Date: Thu, 5 Jan 2023 11:22:03 -0500 To: Jakub Kicinski Cc: Toke =?iso-8859-1?Q?H=F8iland-J=F8rgensen?= , 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 , Lorenzo Bianconi , 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 Message-ID: References: <20220621175402.35327-1-gospo@broadcom.com> <40fd78fc-2bb1-8eed-0b64-55cb3db71664@gmail.com> <87k0234pd6.fsf@toke.dk> <20230103172153.58f231ba@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230103172153.58f231ba@kernel.org> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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. As I mentioned in my mail just a few mins ago, I think this would be a good model to consider. All headers (including potentially tunnel headers) could be in the linear area with the actual packet data in frags. > A random datapoint is that bpf_xdp_adjust_head() seems > to enforce that there is at least ETH_HLEN.