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 X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66098C35247 for ; Wed, 5 Feb 2020 15:55:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3C701217BA for ; Wed, 5 Feb 2020 15:55:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="RPN1E12a" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727493AbgBEPzv (ORCPT ); Wed, 5 Feb 2020 10:55:51 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:31950 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726678AbgBEPzv (ORCPT ); Wed, 5 Feb 2020 10:55:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580918150; 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=JbXnDG/6nNKeQdTAz2d1XZx/5OAa043KSPnkNaGe/nM=; b=RPN1E12aOgN1eYpA6bnWPJKd6jijnQA7DTK16+K0tLx+GfR0lGhxiPN/42wPQS2rY+9Qlz sJAdmlwF92ElAQ6GUR9OzZ/wKH2OnsoEEV7QK+k3v/Dff7v9pxoO0kJLPcnicH8XxSPCBy NI0kygDlvw+NRmcxZJ1G5E91irxdbJk= Received: from mail-lf1-f72.google.com (mail-lf1-f72.google.com [209.85.167.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-327-mVkB4wfSN1i86NdE0zPOmg-1; Wed, 05 Feb 2020 10:55:48 -0500 X-MC-Unique: mVkB4wfSN1i86NdE0zPOmg-1 Received: by mail-lf1-f72.google.com with SMTP id k26so709561lfm.0 for ; Wed, 05 Feb 2020 07:55:48 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version:content-transfer-encoding; bh=JbXnDG/6nNKeQdTAz2d1XZx/5OAa043KSPnkNaGe/nM=; b=Q2HzENOSc+Q1SdA7ZIfyxMT95zpQ14AImIhTZHwusTMPb/zzxsmNOmei9bzf7PVU2o Lg9g6Z1y/HKnpTJ5jAgS3GR/qhgSrQooB1XNBDB5G6BJtMYqC38YVE6EkmJLN9S6lkBu SxTiyB88gVFFTTKozKpy8ylyx+jMk0fu9BO3+hm1WWvUZysYF4TqMAalYf6ACFrcCa7C s2g3oebp5OL6LFS4cdHtBuKTUjisJmL7fDdjPzg9c1z4+g3Gn2a5KhET+yt5mQS4zDrs tgx/OWMEaCMrTZtOe8kJDsvobFXIIvlUJfmAZTgMrxiufO6LDrdJj09zDfiQHW/SRGw1 XyqQ== X-Gm-Message-State: APjAAAV1+d48wnU2Apy/z7zLdKY3uqrcFfQENFxUBIE7rtzXut9c8Utj xzzNCRm39jZB+ziYfHZcBkRjUdqiTw1kFsGS4s8KxZ/MthmcvCsFsmU8FphqszJs3Zo/JElABOJ R2yQ1dqnlgWvLbo59 X-Received: by 2002:a2e:b017:: with SMTP id y23mr20634669ljk.229.1580918146912; Wed, 05 Feb 2020 07:55:46 -0800 (PST) X-Google-Smtp-Source: APXvYqyOnCfiBNRR4QuFU2V7Ts67R/IlY+A16BxHP7Ss6R58TOm3JL1VxqoQIXJKZxa6qgD81gDhuQ== X-Received: by 2002:a2e:b017:: with SMTP id y23mr20634655ljk.229.1580918146701; Wed, 05 Feb 2020 07:55:46 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id f5sm12458582lfh.32.2020.02.05.07.55.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Feb 2020 07:55:46 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 5DE171802D4; Wed, 5 Feb 2020 16:55:45 +0100 (CET) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Luigi Rizzo Cc: Luigi Rizzo , Daniel Borkmann , netdev , Jesper Dangaard Brouer , "David S. Miller" , "Jubran\, Samih" Subject: Re: [PATCH] net-xdp: netdev attribute to control xdpgeneric skb linearization In-Reply-To: References: <20200122203253.20652-1-lrizzo@google.com> <875zh2bis0.fsf@toke.dk> <953c8fee-91f0-85e7-6c7b-b9a2f8df5aa6@iogearbox.net> <87blqui1zu.fsf@toke.dk> <875zh2hx20.fsf@toke.dk> <87r1zpgosp.fsf@toke.dk> <87r1zog9cj.fsf@toke.dk> <87a76cfstd.fsf@toke.dk> X-Clacks-Overhead: GNU Terry Pratchett Date: Wed, 05 Feb 2020 16:55:45 +0100 Message-ID: <874kw5do5a.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Luigi Rizzo writes: > On Fri, Jan 24, 2020 at 1:28 PM Toke H=C3=B8iland-J=C3=B8rgensen > wrote: > >> Luigi Rizzo writes: >> >> > On Fri, Jan 24, 2020 at 7:31 AM Toke H=C3=B8iland-J=C3=B8rgensen >> wrote: >> >> >> >> Luigi Rizzo writes: >> >> >> > ... >> >> > My motivation for this change is that enforcing those guarantees has >> >> > significant cost (even for native xdp in the cases I mentioned - mt= u > >> >> > 1 page, hw LRO, header split), and this is an interim solution to m= ake >> >> > generic skb usable without too much penalty. >> >> >> >> Sure, that part I understand; I just don't like that this "interim" >> >> solution makes generic and native XDP diverge further in their >> >> semantics... >> > >> > As a matter of fact I think it would make full sense to use the same >> approach >> > to control whether native xdp should pay the price converting to linear >> buffers >> > when the hw cannot guarantee that. >> > >> > To me this seems to be a case of "perfect is enemy of good":.. >> >> Hmm, I can kinda see your point (now that I've actually grok'ed how the >> length works with skbs and generic XDP :)). I would still worry that >> only having the header there would lead some XDP programs to just >> silently fail. But on the other hand, this is opt-in... so IDK - maybe >> this is fine to merge as-is, and leave improvements for later? >> > > Sorry I let this slip, any consensus on this patch? Dunno if there's a consensus, but I certainly ran out of objections ;) -Toke