From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by huchra.bufferbloat.net (Postfix) with ESMTP id 6F88621F150 for ; Tue, 27 Aug 2013 04:10:32 -0700 (PDT) Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r7RBASPN010799 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 27 Aug 2013 07:10:28 -0400 Received: from localhost (ovpn-116-39.ams2.redhat.com [10.36.116.39]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r7RBAPOR029261; Tue, 27 Aug 2013 07:10:27 -0400 Date: Tue, 27 Aug 2013 13:10:23 +0200 From: Jesper Dangaard Brouer To: Dave Taht Message-ID: <20130827131023.263ad4ad@redhat.com> In-Reply-To: References: <56B261F1-2277-457C-9A38-FAB89818288F@gmx.de> <2148E2EF-A119-4499-BAC1-7E647C53F077@gmx.de> <03951E31-8F11-4FB8-9558-29EAAE3DAE4D@gmx.de> <9A9B094D-CA07-48B0-85FE-FA7C759FEDE3@gmx.de> <5BEF0C7C-C2F4-45A9-9FF2-E32A05B8D67B@gmx.de> Organization: Red Hat Inc. Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 Cc: "cerowrt-devel@lists.bufferbloat.net" Subject: Re: [Cerowrt-devel] some kernel updates X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 27 Aug 2013 11:10:32 -0000 On Fri, 23 Aug 2013 13:29:25 -0700 Dave Taht wrote: > Does anyone have a date/kernel version on when linklayer overhead > compensation stopped working? ADSL/ATM linklayer shaping were broken in kernel release from 3.8 to 3.10 by commit 56b765b79 ("htb: improved accuracy at high rates") in v3.8-rc1~139^2~455. > There was a bug even prior to 3.8 that looked bad. Eric Dumazet also found a general "linklayer atm" regression (dating way-back), which could cause rate-tables to get wrongly shared between the same rates with-and-without linklayer atm settings. Addressed/fixed in (3.10-rc6:): - commit 40edeff6e1c (net_sched: qdisc_get_rtab() must check data[] array) When configuring two completely equal rates, the kernel detects that these two equal rates can share the same rate-table. But the kernel didn't check if the rate-table data had been modified, which is done in the linklayer atm case. In practice, this often isn't a problem, as overhead parameter is usually combined with the linklayer parameter. See my description here: http://thread.gmane.org/gmane.linux.kernel.stable/62528 -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer