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 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 0F3B521F306 for ; Sun, 12 Apr 2015 17:23:17 -0700 (PDT) Received: from hms-beagle.home.lan ([87.164.165.7]) by mail.gmx.com (mrgmx001) with ESMTPSA (Nemesis) id 0MIe0O-1YfFEY0d5s-002GVQ; Mon, 13 Apr 2015 02:23:14 +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: Date: Mon, 13 Apr 2015 02:23:13 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: References: <68E872EE-C0D3-4091-97C9-19596BF98AEB@gmail.com> To: Sebastian Moeller X-Mailer: Apple Mail (2.1878.6) X-Provags-ID: V03:K0:tfmhhOI7K6E9POL6gXfn1ltXFN5S1PiBrm9yFaMUeuem/IOYNZy teJakOi0C6/24TpLbuMsrLwEiSZ3cR1TxPwdm3bP9bsSU9du8TEqpiLSnft6ZJFKN1O4WnE pFcP3CxGNNYnW5KnDSNgnY/rJhWEtR1WQxHmKttL28eOUZ9alykZBws8odJVW+gUSZBjUTA If+9SW9IUmremMxgElSFA== 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 00:23:46 -0000 Hi Jonathan, on a added note below; Note to self "reading actually helps" On Apr 13, 2015, at 02:15 , Sebastian Moeller wrote: > Hi Jonathan, >=20 >=20 > On Apr 13, 2015, at 01:55 , Jonathan Morton = wrote: >=20 >>=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 >=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 >=20 > 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... >=20 >=20 >> If there=92s a better way than manually calculating ceil(len/48)*53, = so much the better. Ignore my gibberish below, that is almost all required: = ceil(len+additional_per_packet_overhead/48)*53 seems the winner ;) = Effectively this is what stab should offer, but its implementation with = a table has issues if packets are larger than the table estimated=85 Best Regards Sebastian >=20 > 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 >=20 > Best Regards > Sebastian >=20 >>=20 >> - Jonathan Morton >>=20 >=20 > _______________________________________________ > Cake mailing list > Cake@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cake