From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f176.google.com (mail-pd0-f176.google.com [209.85.192.176]) (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 29EB821F107 for ; Wed, 29 May 2013 15:50:39 -0700 (PDT) Received: by mail-pd0-f176.google.com with SMTP id r11so9561582pdi.35 for ; Wed, 29 May 2013 15:50:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=date:from:to:cc:subject:message-id:in-reply-to:references:x-mailer :mime-version:content-type:content-transfer-encoding :x-gm-message-state; bh=iYR5pJLdjp44qj3UoFG6Cgi8NYwZ7ptMxOBUwzc9G78=; b=VAii1BpwrdrzYwL9eixw+HgOPkdscIlrQxQIVxShJLn5540w2tz9Qq4Z0oTyn9m78+ UFgi5FzX8Dx/pPlQoUMnPgczskyqJeu2BEqC/YZb4r2pXXrZet5J7wVtrmU1808h1ZUC 4j4HlVzGKTosijd/Zw833Lqx6wctmfHgt7SMrLxL8GecDQ20+eO2gCOXaT9sTUv7S346 ZggNkx8FA9jMGKaCyEWLHPke1mNySFN+qGPPKqoXaakWrsJM/99EQw5Genfo2ez6hO3+ tm41mAS9+fEJk0t5jGQI0AuiebFLKc61cEphmkJF6YvGQgScS/zQ9B8sjW04HeERcrKI vrIA== X-Received: by 10.66.252.4 with SMTP id zo4mr5663920pac.100.1369867839375; Wed, 29 May 2013 15:50:39 -0700 (PDT) Received: from nehalam.linuxnetplumber.net (static-50-53-71-109.bvtn.or.frontiernet.net. [50.53.71.109]) by mx.google.com with ESMTPSA id cq1sm38961569pbc.13.2013.05.29.15.50.38 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Wed, 29 May 2013 15:50:38 -0700 (PDT) Date: Wed, 29 May 2013 15:50:34 -0700 From: Stephen Hemminger To: Eric Dumazet Message-ID: <20130529155034.334092c5@nehalam.linuxnetplumber.net> In-Reply-To: <1369842724.5109.44.camel@edumazet-glaptop> References: <20130529151330.22c5c89e@redhat.com> <1369842724.5109.44.camel@edumazet-glaptop> X-Mailer: Claws Mail 3.8.1 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Gm-Message-State: ALoCoQkEX0rg5PEOo3Rc5inwV+YByItetUMegwlZ9wD7PVmhtbfg9eLu7Va6Hjb93k3JNT4PtxnB Cc: Toke =?ISO-8859-1?B?SPhpbGFuZC1K+HJnZW5zZW4=?= , Mike Frysinger , Jiri Benc , Jiri Pirko , netdev@vger.kernel.org, bloat@lists.bufferbloat.net, Patrick McHardy , Steven Barth , 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 22:50:40 -0000 On Wed, 29 May 2013 08:52:04 -0700 Eric Dumazet wrote: > 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 : How bad is the failure? If it is fixed, will it break existing installations? Which probably means, is anyone but the original developers ever using it and therefore likely to notice?