From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.17.22]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id E44B921F306 for ; Sun, 12 Apr 2015 17:15:04 -0700 (PDT) Received: from hms-beagle.home.lan ([87.164.165.7]) by mail.gmx.com (mrgmx103) with ESMTPSA (Nemesis) id 0MXZNq-1YvK5o1vEs-00WVxi; Mon, 13 Apr 2015 02:15:02 +0200 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) From: Sebastian Moeller In-Reply-To: <68E872EE-C0D3-4091-97C9-19596BF98AEB@gmail.com> Date: Mon, 13 Apr 2015 02:15:01 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: References: <68E872EE-C0D3-4091-97C9-19596BF98AEB@gmail.com> To: Jonathan Morton X-Mailer: Apple Mail (2.1878.6) X-Provags-ID: V03:K0:bnLqo3I+OUl30I7BFYNhlt82izQJipREjiMmLo2VmlXL8zs9NGi lV9WOMeRjYEM5jVhWu0h0BNGyxx6LXaIvO3fOB27HHVTcBiblU0YGzBCzScgZj2XQfIjjLq BJn8z1gzzfhabwnZZC9ARyznFFN/CTJx4M/ncBDVEdhnqLbFMVLhn5dwEHNyLquGpMyEMhX AYY0H3Sj50nLZmvDR4S8A== X-UI-Out-Filterresults: notjunk:1; Cc: cake@lists.bufferbloat.net Subject: Re: [Cake] #17 X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Apr 2015 00:15:33 -0000 Hi Jonathan, On Apr 13, 2015, at 01:55 , Jonathan Morton = wrote: >=20 >> On 13 Apr, 2015, at 02:50, Sebastian Moeller wrote: >>=20 >> As mentioned above, as long as cake can work with tc=92s stab option = all framing and overhead handling should be available to whoever needs = it. >=20 > Remind me to look into how to use that, then. =20 basically you add: stab mtu 2047 tsize 512 mpu 0 overhead 40 linklayer atm to the top level qdisc invocation, it fudges the size variable in the = SKB? just as the kernels internal accounting for the ethernet header = does, and all qdisc will see the fudged value, this is unlike HTB = private implementation of basically the same (TB=92s version has some = advantages with GRO though). e.g.: $TC qdisc add dev $DEV root handle 1: stab mtu 2047 tsize 512 mpu 0 = overhead 40 linklayer atm htb default 12 Note: mtu in the stab context only defines the upper bound for which the = size table gets created (this is the limit up to which stab works = reliable), tsize gives the number of entries in the table, for ATM all = increases are at multiples of 16, so 2048/512 =3D 4bits is enough, and = mpu allows to specify a minimum packet size. All in all stab gives more = freedom than strictly needed for atm ,link layer accounting... > If there=92s a better way than manually calculating ceil(len/48)*53, = so much the better. Well, =93stab=94 is so much better than statically accounting = for the ~9% ATM cell overhead tax that it is just not funny anymore. Due = to the AAL5=92s? weird idea that each payload package has to fill an = integer number of ATM cells, small packets can get an obscene amount of = additional overhead: worst case is something like 1 ATM cell with of = data + 1 byte, which will drag in another ATM cell with 47 bytes = padding=85 increasing the overhead by 100% on top of the 9% cell tax and = the normal per packet overhead gunk ISPs force unto the unlucky ATM = users=85 Best Regards Sebastian >=20 > - Jonathan Morton >=20