From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-x242.google.com (mail-pg0-x242.google.com [IPv6:2607:f8b0:400e:c05::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id DCEA53B29E for ; Tue, 5 Sep 2017 10:38:05 -0400 (EDT) Received: by mail-pg0-x242.google.com with SMTP id d8so2074148pgt.3 for ; Tue, 05 Sep 2017 07:38:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mounce.com.au; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=javKu6UhAspzAwAyKD/R05frBULL5ximoAnHnMPqnlk=; b=HyI1EdoyJyNAh3VZ49Toc6lkF/1378op8kvDmWrwlp99JzKfccCbQhwOAW6eFwwjjw lYleNNapAybmP3oaudYaGsiSRGUUK5RLCWRtBr1weKs1FPvP3o/Tvr4uqjqYYevWdSyy 0G6PWHf2kU90e7R4nVyiGY6GMhzGmrbtT38JFBdTRflY3/c1JP6y8i58WUE7TDnr3+YC XlITOmkuOwqergi4slA7s2UOOYvFH3HfCqUiQAmRgMK0b54gc46d5Ps/U+7VNLDUiLtK 9QihijjQoONJHxY5Yd+N+R1MeJyMB29us91RNjhFIH78KDpW5dIz0MW7IHzHxOaoDOJN E5DQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=javKu6UhAspzAwAyKD/R05frBULL5ximoAnHnMPqnlk=; b=VIk8A1zwtKg1xJAM4bhjRpGQbJkfqoxXSxPNGhvuATf5y9rkiVZ26j6/FoFFbaWQgI byxQlmaAbXUuAEt4VF/8XVf6CcVDYYZwvddo8UMzYdtCtXGPPMtfZLVQ/33rCtwLygE9 5hJlQORmWSTLYUNy15NDjvTIB04/pMHRq3yzpRE8nfpWHR5ueaqXCP4+QC/LpfgEQwwZ juGwGwjqhMh455/LJM/gU68mjBUtDHFd2SDrtp90CVMS5WZWWumhQgwM8uck1U1ve21L njVdosFtTnSvrp0XyJ2T8jHqsYYLaApKzWbl2s53n3cx9bOvj0GDJACD+y7tn9yOLDvw kF4Q== X-Gm-Message-State: AHPjjUhjSryqlj5nkFAIBl8sm70s1fzKD2OYS+zU4y6CUeEX2jqqW+q6 kcSLdA2yE2tb9BgtYbg5pAX35i+kAtyrHS80wQ== X-Google-Smtp-Source: ADKCNb4qVoL/M/5KH9tJ686otQKxjPTJ15r0YIikJlA6cerTVORY1r/Of7gGMw7zsAdYJZfMK+/+xRqk9d2SS2T5c6o= X-Received: by 10.84.178.129 with SMTP id z1mr4798244plb.100.1504622284934; Tue, 05 Sep 2017 07:38:04 -0700 (PDT) MIME-Version: 1.0 Received: by 10.100.189.72 with HTTP; Tue, 5 Sep 2017 07:37:49 -0700 (PDT) X-Originating-IP: [101.166.225.7] In-Reply-To: <538A474A-8A75-4909-A386-2095817D4D0D@gmx.de> References: <51c4c54f-dc20-739c-3ee8-eb629cddae24@darbyshire-bryant.me.uk> <538A474A-8A75-4909-A386-2095817D4D0D@gmx.de> From: Ryan Mounce Date: Wed, 6 Sep 2017 00:07:49 +0930 Message-ID: To: Sebastian Moeller Cc: Kevin Darbyshire-Bryant , cake@lists.bufferbloat.net Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Cake] overhead and mpu X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 05 Sep 2017 14:38:06 -0000 On 5 September 2017 at 18:28, Sebastian Moeller wrote: > Hi Kevin, > > >> On Sep 5, 2017, at 10:35, Kevin Darbyshire-Bryant wrote: >> >> >> >> On 05/09/17 09:01, Sebastian Moeller wrote: >> >>> I believe this is used internally so cake can deduce the size of t= he automatically added overhead (the linux kernel will add 14 bytes on ethe= rnet interfaces automatically, which while certainly justifiable are not th= e ideal value for an ethernet shaper); with this cake allows the user to sp= ecify absolute overhead (so if you specify overhead 18, cake will give you = 14 - 14 + 18 =3D 18, while tc's stab method will give you 14 + 18 =3D 32).= So cake is doing the right thing here (the only thing it could do even bet= ter is to report the size of the automatically corrected in-kernel hard_hea= der_len, but then the audience for that information is probably to small to= justify this feature). >> >> >> Actually for the sake of a one line change in the tc code it is an extre= mely useful confidence boost and info source as to just what linux thinks t= he overhead actually is: >> >> // This is actually the *amount* of automatic compensation= , but we only report >> // its presence as a boolean for now. >> if (ethernet) >> - fprintf(f, "via-ethernet "); >> + fprintf(f, "via-ethernet(%d) ", ethernet); >> >> I've run that in a local patch to tc on LEDE for AGES. Very useful. > > That sounds like it would be a great addition, since the informat= ion is already collected... For what it is worth I would vote for adding th= is... (to the version that should be upstreamed ;) ) +1 It would also be nice for tc to know whether the overhead has been explicitly configured and report appropriately. In my case I use cake on a VLAN sub-interface that happens to have a hard_header_len of 18 after the 802.1q tag, and then use the docsis keyword to more explicitly configure the overhead in case I move to an untagged interface in the future. tc -s qdisc can't tell the difference and reports 'raw mpu 64' rather than 'overhead 18 mpu 64'. > > Best Regards > Sebastian > > >> >> Kevin >> _______________________________________________ >> Cake mailing list >> Cake@lists.bufferbloat.net >> https://lists.bufferbloat.net/listinfo/cake > > _______________________________________________ > Cake mailing list > Cake@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cake