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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 0B78BC4740A for ; Mon, 9 Sep 2019 22:52:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA43A21479 for ; Mon, 9 Sep 2019 22:52:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="EsqgUMto" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728578AbfIIWwe (ORCPT ); Mon, 9 Sep 2019 18:52:34 -0400 Received: from mail-pl1-f171.google.com ([209.85.214.171]:45698 "EHLO mail-pl1-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726231AbfIIWwd (ORCPT ); Mon, 9 Sep 2019 18:52:33 -0400 Received: by mail-pl1-f171.google.com with SMTP id x3so7365190plr.12 for ; Mon, 09 Sep 2019 15:52:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=tY0RP+vo8Hd+sEG6i8r+0SyzMMWsYOOp2olh3OhgPTE=; b=EsqgUMtobgYWCJZCPY7Z5zce+Y7Q2KgTfLfyAVFY+3mfZur7OhJlYn5ofQZFi/xLou hOjmveh2iLTAKBPAYUL5H4lgpuXpWPXtm8QbgrFO2+Gm/wd8oFsTTyubiro0x1KmP8GW 1+x/DoxWa9RFRhxDa+z5Xl2WjB3RUo7z6h56VatDMeg8wcpxnQDjx3zQSBfMDdMwQops WRX+np44bt2suEq1eEFv5pM9NKDFauuA1SnQmbt+TybkrqcORvc8mceHAJbceZ/od8UI sABiktmHYyXsC281csCWV82U37Wa6xIXilbBDuP+fD6vtumKNUZwdDe7XcJvQWkkpD/X V6fg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=tY0RP+vo8Hd+sEG6i8r+0SyzMMWsYOOp2olh3OhgPTE=; b=ojqJn8qIWaIYd3JoYruiYcad6IzeWH1BX1RvkkdwCEded55Dgip04MafSCU4rwHM8s I6Uw4o2xh82ub1UMjAl4o9fEcL47Gj4MVITtqECm+XecujPzYwtchHGr5BcoGtGyB4Cv Ugmcdvr1HEWGvG8jPiPFDEdd4Yjqh6S28ZSsfF8ltt9CI8tlO1+DWjDbaympXNr9E2jg 2QMFInH+nFOYmXcj13nb4qoZxTzPDI+veQV5D7HDpGGnAwhX4OCp2c9Q05KweBjOojy0 n1TzCiYmmOcEvUKMyRYEh78Xx5oPzKq+r/Rg9Lolb14DOp6j96MagUlWtzWyMtrW8kxy m0NA== X-Gm-Message-State: APjAAAU5sw7Y8tmDHdvny4XwBKLViIsVi2OZBDbRMc6ghyAZ1QI5vIyQ 3VBy0VDNJqpI3FUDG+YzbKgJ0PAGt8jEC5vM54qlOaUz X-Google-Smtp-Source: APXvYqzBarsgbTRpxH6uTBV4ekchHQpUGhwr4f8gluJHNgvKC9VfDM6pMQE5mzpxTl8Oxvo5J9VQFAu88c3V0BcmIX0= X-Received: by 2002:a17:902:a5c5:: with SMTP id t5mr25931480plq.316.1568069552784; Mon, 09 Sep 2019 15:52:32 -0700 (PDT) MIME-Version: 1.0 References: <211c7151-7500-f895-7fd7-2c868dd48579@applied-asynchrony.com> In-Reply-To: <211c7151-7500-f895-7fd7-2c868dd48579@applied-asynchrony.com> From: Cong Wang Date: Mon, 9 Sep 2019 15:52:21 -0700 Message-ID: Subject: Re: Default qdisc not correctly initialized with custom MTU To: =?UTF-8?Q?Holger_Hoffst=C3=A4tte?= Cc: Netdev 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 On Mon, Sep 9, 2019 at 5:44 AM Holger Hoffst=C3=A4tte wrote: > I can't help but feel this is a slight bug in terms of initialization ord= er, > and that the default qdisc should only be created when it's first being > used/attached to a link, not when the sysctls are configured. Yeah, this is because the fq_codel qdisc is initialized once and doesn't get any notification when the netdev's MTU get changed. We can "fix" this by adding a NETDEV_CHANGEMTU notifier to qdisc's, but I don't know if it is really worth the effort. Is there any reason you can't change that order? Thanks.