From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.15]) (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 37D5C3B2A4 for ; Tue, 5 Sep 2017 04:58:09 -0400 (EDT) Received: from [192.168.250.101] ([134.76.241.253]) by mail.gmx.com (mrgmx001 [212.227.17.190]) with ESMTPSA (Nemesis) id 0MfmWy-1e9zwn2I8i-00NBNV; Tue, 05 Sep 2017 10:58:05 +0200 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) From: Sebastian Moeller In-Reply-To: <51c4c54f-dc20-739c-3ee8-eb629cddae24@darbyshire-bryant.me.uk> Date: Tue, 5 Sep 2017 10:58:04 +0200 Cc: cake@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <538A474A-8A75-4909-A386-2095817D4D0D@gmx.de> References: <51c4c54f-dc20-739c-3ee8-eb629cddae24@darbyshire-bryant.me.uk> To: Kevin Darbyshire-Bryant X-Mailer: Apple Mail (2.3273) X-Provags-ID: V03:K0:XWl7gPmw1onJ+zNuUzAN4QJThMW7G+lO6ttyCdibbT78dSt6vDD C8dLiyFMxWudym+csb93fkYdk4MA8+OYJVi9QgXjgoYTJ1BUpvsYfMDPYfhLlpt/zqAEBOJ p9VFDFHPNsyaOi2jGGVZRbFqHJGLDwGoLYVNgKdoRhzc62uZaWAvRNwy94deOfmD2cr3+Wn 3wrfN40TYSmttsCFPMH9w== X-UI-Out-Filterresults: notjunk:1;V01:K0:EA6q+12Gd6w=:jZoKc+qDWsoCrTyJNWV1ts yFGtase2aw/LmjJEJoLe468vm4PoHWVnlA2Lzj38Qx1zvIC6yx+cDh8JuKHmAvZSllda1pzSh w8jTTr5v2GGQw0Up4Y0unEYBrAf12trgVH2jBzeIf8Th30lqZ8xJZpx5UPXHjswqAkU53Id0k EV2w4rQlHPz3tvf5H7kQW08o2F+/Fd6LGoVKBm1FuLAnoSYrutvANyD4188/Co2eFkh+pRxvA 0DpxyE3jTHV9jVDppFx2ft47/AqH7w2uqRDuUTlD7XXKs5auUEHVkU6zAxVRI+u8SECfVrwAC DZR6v0abV2R+K0S79NZJuusUVNCEUmyQE1FyHamXqtbdrKQnMcilL/tP+6TfHAHftR0MHH+0c 7dGmje4xKWf4rlHoyg8K4dRQ7eH6dMaU/N4rF9JWqmsO/q+acMUsLndGwtu+VyQaGhiS8T8mO mHWEuTEojeipcnrzCUVC7MfdP16A9Ije4EfcTR8+kVpbmfi6QJTSinTuQqH/XAryFmwIMND/O RJ5CBDboEjRzsZ3S3dAJBHnsKBZrueSol5h/jUolW3VJu5F3Kv4dFhv4xE4tEB7C6dTkq7WxY QtrzEvge36taX1T103IJ2CTs8w4LvsFhMmFt03iAqazJo4Sl+OVwK7HY+oQ0rOo8hF6/A8YnN wtialYn7L4rQG60QWfA6JX4z8R+J2juPIsR2BSXTH+Ntak6Jok+c8p7OlQysaNNijLaQN04w9 wq35RTkOfltW2dS0iZQLu+Di9vJTN9LUksp2BUaYzoniZ76HHFm4PvLGVGEdEZlR5iMMeh58V XnfvxpyJOEDl5hRPka39vmfI1vK829WOf2WT0515apLl++FRi7euDqebhCauuQifH0ytxHm7u Vi32f7crXxAEOLgEju0jCMkXbDCDcwqNIU7rEEclbiPKIuNhKhjP+tjeA0UyRM 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 08:58:09 -0000 Hi Kevin, > On Sep 5, 2017, at 10:35, Kevin Darbyshire-Bryant = wrote: >=20 >=20 >=20 > On 05/09/17 09:01, Sebastian Moeller wrote: > >> I believe this is used internally so cake can deduce the size of = the automatically added overhead (the linux kernel will add 14 bytes on = ethernet interfaces automatically, which while certainly justifiable are = not the ideal value for an ethernet shaper); with this cake allows the = user to specify 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 better is to report the size of the automatically = corrected in-kernel hard_header_len, but then the audience for that = information is probably to small to justify this feature). >=20 >=20 > Actually for the sake of a one line change in the tc code it is an = extremely useful confidence boost and info source as to just what linux = thinks the overhead actually is: >=20 > // 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); >=20 > 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 = information is already collected... For what it is worth I would vote = for adding this... (to the version that should be upstreamed ;) ) Best Regards Sebastian >=20 > Kevin > _______________________________________________ > Cake mailing list > Cake@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cake