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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 D4132C43381 for ; Mon, 25 Mar 2019 08:48:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99CE520863 for ; Mon, 25 Mar 2019 08:48:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Dfsb0FvG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730115AbfCYIse (ORCPT ); Mon, 25 Mar 2019 04:48:34 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:55374 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730100AbfCYIsd (ORCPT ); Mon, 25 Mar 2019 04:48:33 -0400 Received: by mail-wm1-f65.google.com with SMTP id o25so7897372wmf.5 for ; Mon, 25 Mar 2019 01:48:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=w/CRUPqKgcgKPnt046HEHkPrHPMMKuYGCq1YVWyiu/Y=; b=Dfsb0FvGOvdWyvmq8u+8MeSunxsaOHyG4pEDWDY7jcy3SpfXItT17lawgKD0JN//N2 S4BXLJEmfXxfstrN1WG0R+w/MLUzSXEpLOoav8Dk5PhlOnyQMcsuAWxRSTPe7XWut6JH 3X+dj2/V0Z+B0I9svRzbnlWRzjgq9TuOvpRW0Q8xYpcV7lPTRK9vyiCsU+Wd2VqwaDeL bkPiP3gh2J8KrEJbqCM+bz0y+SpdwUMm/mVI3mt41VlcRB2Vw6Gp9DGxJNqkGoJ7cWj3 Sv+YT4CdipMcAMwaf/h9b1Kx4RZyss6CCurrZI+BhTJwANXf4OIN482T+CLtsoJMbdkD csmQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=w/CRUPqKgcgKPnt046HEHkPrHPMMKuYGCq1YVWyiu/Y=; b=lXLgnll6GnC53IKObnmPiWl2Lpl0x1YiauCOrk9NJw7a69MM3vuVlvD19LLlZ4CeMq gpczUJ0plOTZ9gXM6nA0nJpnBb6Q0oE61Wme5DjzbE0jlCSxTpfl7y4+Q1/EkqKI8pBJ TKZEYeBe1SyyoTDjMblB6IIv5vd/qm9DBlVd7t4Z328n1pEuO2Fh8kDt0hYkmHw0izvt I5ZZALgIcBaXfz3997Ye36gmZgheOIx1bacR09qFtVKH3D2Q/Xg3whYqkpfIfiCvCFYy FVdsuI3qacwpUyFaMTCeSzYnX8Jvl8mDcEnJ3hVtX/TCSzFJP0OnVDNhewSNgqNzEkGZ U1EA== X-Gm-Message-State: APjAAAV5TIfDdL6WTzvBJn3pOKASY7ZGO3i2toDHFBigVIU1t3H+ncPB LAgYblD91bxbyWUERRIZ0bs= X-Google-Smtp-Source: APXvYqzz0+he79gx6xMAxkjTLPK0sgWwbyt4ZrUuYpqYOLXC9K0wvDfk1+mF+2NwZ3RkYNxtyQNhdA== X-Received: by 2002:a7b:c7d0:: with SMTP id z16mr11119826wmk.136.1553503711497; Mon, 25 Mar 2019 01:48:31 -0700 (PDT) Received: from [192.168.8.147] (126.82.136.77.rev.sfr.net. [77.136.82.126]) by smtp.gmail.com with ESMTPSA id t14sm8452664wmi.16.2019.03.25.01.48.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 25 Mar 2019 01:48:30 -0700 (PDT) Subject: Re: [PATCH bpf-next 0/7] bpf: Propagate cn to TCP To: Eric Dumazet , Alexei Starovoitov Cc: brakmo , netdev , Martin Lau , Alexei Starovoitov , Daniel Borkmann , Kernel Team References: <20190323080542.173569-1-brakmo@fb.com> <704cb63c-13cd-f0ed-d546-18e3596bb63d@gmail.com> <20190323154124.gorqpaqex7ihfs6d@ast-mbp> <0841fe0d-7fcd-bb59-3694-af9969cec5af@gmail.com> <20190324161911.h5eotv2j7f5avcpm@ast-mbp> <5aec97f1-545a-f898-fdd9-c5821d5c6e39@gmail.com> From: Eric Dumazet Message-ID: <27e91d11-b454-924d-58ab-a68a0aade906@gmail.com> Date: Mon, 25 Mar 2019 01:48:27 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <5aec97f1-545a-f898-fdd9-c5821d5c6e39@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 03/25/2019 01:33 AM, Eric Dumazet wrote: > > > On 03/24/2019 09:19 AM, Alexei Starovoitov wrote: >> Cover letter also explains why bpf_skb_ecn_set_ce is not enough. >> Please realize that existing qdiscs already doing this. >> The patchset allows bpf-cgroup to do the same. > > Not the same thing I am afraid. To be clear Alexei : Existing qdisc set CE mark on a packet, exactly like a router would do. Simple and universal. This can be stacked, and done far away from the sender. We do not _call_ back local TCP to propagate cn. We simply rely on the fact that incoming ACK will carry the needed information, and TCP stack already handles the case just fine. Larry cover letter does not really explain why we need to handle a corner case (local drops) with such intrusive changes. TCP Small Queues already should make sure local drops are non existent.