From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-x236.google.com (mail-pb0-x236.google.com [IPv6:2607:f8b0:400e:c01::236]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 5160B21F107 for ; Wed, 29 May 2013 08:52:07 -0700 (PDT) Received: by mail-pb0-f54.google.com with SMTP id ro12so9340193pbb.27 for ; Wed, 29 May 2013 08:52:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:subject:from:to:cc:date:in-reply-to:references :content-type:x-mailer:content-transfer-encoding:mime-version; bh=4ltkB1uMSYKLntvZyjNYhr4brcPU5tx84xWzLecCnHg=; b=GpV2sWZ/nyoEPthc+ja9Vj6JgnYRwNBQm19VgN3tC6T4JJggSbdyZKjyY9caUxT7nt FVObZR+sabodx20dbjWf3pAx5sGpzFRAiVPQkpv1OAcJcDwzoVgvCZDmxQSj4VSeeGpn wgBlw8dZVsQaNLy9n7AV7aGDbMXSSTZQ1JiUD4z40fEo8nVTqic4dL23z84nMcCuk2Xf 2qVN0nQ24cr9t8SIHXkd2zb0Ug4utGMjbzL4BDb5RwIOe8ONVULYaPDKL4NbjPMuITxM zBC/1KXzN1nW14Nwzh2RFU1PyHRvpXjEvP19ql8tuKGnjLVgbSZ/HW8VXc78TOq+lOKH iN7A== X-Received: by 10.66.159.66 with SMTP id xa2mr4143358pab.36.1369842726584; Wed, 29 May 2013 08:52:06 -0700 (PDT) Received: from [172.29.163.116] ([172.29.163.116]) by mx.google.com with ESMTPSA id 10sm37753250pbr.45.2013.05.29.08.52.04 for (version=SSLv3 cipher=RC4-SHA bits=128/128); Wed, 29 May 2013 08:52:05 -0700 (PDT) Message-ID: <1369842724.5109.44.camel@edumazet-glaptop> From: Eric Dumazet To: Jesper Dangaard Brouer Date: Wed, 29 May 2013 08:52:04 -0700 In-Reply-To: <20130529151330.22c5c89e@redhat.com> References: <20130529151330.22c5c89e@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Cc: Toke =?ISO-8859-1?Q?H=F8iland-J=F8rgensen?= , Mike Frysinger , Jiri Benc , Jiri Pirko , netdev@vger.kernel.org, Patrick McHardy , Steven Barth , bloat@lists.bufferbloat.net, David Miller , Jussi Kivilinna , Felix Fietkau , Michal Soltys Subject: Re: [Bloat] tc linklayer ADSL calc broken after commit 56b765b79 (htb: improved accuracy at high rates) 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: Wed, 29 May 2013 15:52:07 -0000 On Wed, 2013-05-29 at 15:13 +0200, Jesper Dangaard Brouer wrote: > I recently discovered that the (traffic control) tc linklayer > calculations for ATM/ADSL have been broken by: > commit 56b765b79 (htb: improved accuracy at high rates). > > Thus, people shaping on ADSL links, using e.g.: > tc class add ... htb rate X ceil Y linklayer atm overhead 10 > > Will no-longer get ATM cell tax/overhead adjusted. > > How can we solve/fix this? > Perhaps we can change to use the "stab" system instead (as it does > not seem to be broken by the commit). > > But how do we facilitate a change to use "stab" system (for all the > scripts using the old option)? > > Can we change the iproute2/tc command to handle this transparently, or > should we give an error/warning if someone uses "tc" and "linklayer" on > a kernel above v.3.8. ? > > > History: > - My linklayer ATM changes appeared in kernel 2.6.24 (and iproute2 2.6.25) > - The STAB changes appeared in kernel 2.6.27 > Hi Jesper stab suffers from the same problem : its table driven, so works only for packet smaller than a given size. I am not sure it will solve the ATM logic (with the 5 bytes overhead per 48 bytes cell) btw, even on old kernels :