From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) (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 7426C21F2F9 for ; Thu, 11 Jun 2015 04:51:49 -0700 (PDT) Received: from u-081-c022.eap.uni-tuebingen.de ([134.2.81.22]) by mail.gmx.com (mrgmx003) with ESMTPSA (Nemesis) id 0MLujU-1YxVF81MS4-007lr1; Thu, 11 Jun 2015 13:51:46 +0200 User-Agent: K-9 Mail for Android In-Reply-To: <20150611131615.20b1648f@redhat.com> References: <5572F7E0.3060602@darbyshire-bryant.me.uk> <0A0D06AB-CC83-4D99-80C6-8E7822C8707C@gmx.de> <20150611131615.20b1648f@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable From: Sebastian Moeller Date: Thu, 11 Jun 2015 13:51:41 +0200 To: Jesper Dangaard Brouer Message-ID: X-Provags-ID: V03:K0:IY0XcEFRbq0ijuWs/5qJLBSxn0iMot20OOPpTNLJCF8WXtdrHX3 5bJnF2K6JWYVgDMBVmGsHa7fqRqGCITyzouzKsO26bxTfs3Mu/Qm2yEOZG7gCv1t3i7SeuX TaCOO/PiJISAg5eOCJEVOqSWDR4GV2cxKtOo29MZlhS9H0bsNVUOqptg/Z2bEmGAu418dxX ztxcFHFCoAKLpTk4RUAKA== X-UI-Out-Filterresults: notjunk:1; Cc: bloat@lists.bufferbloat.net Subject: Re: [Bloat] ADSL, ATM drivers, bloat, education & confusion X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Jun 2015 11:52:19 -0000 Hi Jesper, On June 11, 2015 1:16:15 PM GMT+02:00, Jesper Dangaard Brouer wrote: > >On Sat, 6 Jun 2015 16:29:15 +0200 Sebastian Moeller >wrote: > >> On Jun 6, 2015, at 15:38 , Kevin Darbyshire-Bryant > wrote: >>=20 >[=2E=2E=2E] >> > The problem I have is setting outbound rate limiting=2E I was hoping >> > that 'cake' without the 'bandwidth' parameter would work on the >> > 'backpressure' from the ATM(?) driver, sadly this wasn't the case >> > and so setting a bandwidth limit (I'm not in a position to test the >> > new keywords for ATM encapsulation etc yet) was the only way >> > forward=2E =20 >>=20 >> This is rather important to get right, ATM=E2=80=99s arcane 48/53 >> encapsulation only leaves 100*48/53 =3D 90=2E5% of the sync rate for >> useable bits, and even those need to contain all the headers specific >> to your line (plus AAL5=E2=80=99s unfortunate choice of fitting each pa= cket >> into an integer number of ATM cells), mean that without AQM taking >> the link layer encapsulation into account you need to aim for roughly >> 80-85% of the sync rates on and ATM link=2E With a link that disappears >> often I currently would recommend sqm-scripts as weapon of choice >> (you should be able to get cake into sqm-scripts) as the IFB needs to >> be set up again after the =E2=80=9Cconnected=E2=80=9D interface reappea= rs, which >> current sqm-scripts should do for you=2E=2E=2E > >That is true, the ATM overhead on ADSL is very important to get right >for your ratelimiting work as intended (that is you gain control over >the queue)=2E > I want to add that Jesper was essential in teaching the Linux kern= el to properly account for all the quirks in the ATM/aal5 Linklater=2E So w= e are standing on his shoulders, so to speak ;) to be able to see as far as= we do=2E=2E=2E His original thesis is still findable under http://www=2Ead= sl-optimizer=2Edk/ and certainly worth reading for ATM "sufferers"=2E >The iproute2 "tc" have supported option "linklayer atm" and "overhead" >for quite some time now (since 2008)=2E All the rate_tables based >schedulers (e=2Eg=2E HTB, TBF) have these options=2E > >There is also the more generic "stab" that allow linklayer adaptation >to >work for any qdisc=2E See man tc-stab [1] Cake has its own independent implementation of per-packet-overhead= and atm-celling accounting, in the spirit of making shaper setup easy for = mortals=2E Sqm-scripts allows to select which of the link layer accounting = methods to use and calls them htb_private and tc_stab I believe=2E Best Regards Sebastian --=20 Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E