From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-21-ewr.dyndns.com (mxout-068-ewr.mailhop.org [216.146.33.68]) by lists.bufferbloat.net (Postfix) with ESMTP id E57222E0117 for ; Fri, 25 Feb 2011 09:15:30 -0800 (PST) Received: from scan-21-ewr.mailhop.org (scan-21-ewr.local [10.0.141.243]) by mail-21-ewr.dyndns.com (Postfix) with ESMTP id C15A515E6 for ; Fri, 25 Feb 2011 17:15:13 +0000 (UTC) X-Spam-Score: 0.0 () X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 87.72.215.196 Received: from lanfw001a.cxnet.dk (lanfw001a.cxnet.dk [87.72.215.196]) by mail-21-ewr.dyndns.com (Postfix) with ESMTP id 2E331F87; Fri, 25 Feb 2011 17:15:07 +0000 (UTC) Received: from [87.72.44.6] (lanvpn001a.cxnet.dk [87.72.215.222]) by lanfw001a.cxnet.dk (Postfix) with ESMTP id B08251635EB; Fri, 25 Feb 2011 18:15:05 +0100 (CET) Subject: Re: GSO (was: Please enter issues into the issue tracker - Issue system organisation needed) From: Jesper Dangaard Brouer To: Eric Dumazet In-Reply-To: <1298651627.2659.84.camel@edumazet-laptop> References: <4D6668F4.5010705@freedesktop.org> <4D668827.8060508@freedesktop.org> <1298567313.2814.7.camel@edumazet-laptop> <87sjvds2r7.fsf@cruithne.co.teklibre.org> <1298575769.2659.10.camel@edumazet-laptop> <1298632912.21810.33.camel@traveldev.cxnet.dk> <1298634859.2659.44.camel@edumazet-laptop> <1298648937.28000.41.camel@traveldev.cxnet.dk> <1298651627.2659.84.camel@edumazet-laptop> Content-Type: text/plain; charset=ISO-8859-1 Organization: ComX Networks A/S Date: Fri, 25 Feb 2011 18:15:04 +0100 Message-Id: <1298654104.28000.52.camel@traveldev.cxnet.dk> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 8bit Cc: bloat-devel@lists.bufferbloat.net, herbert@gondor.apana.org.au, Van Jacobson , shalunov@shlang.com, bloat@lists.bufferbloat.net X-BeenThere: bloat-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: "Developers working on AQM, device drivers, and networking stacks" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 25 Feb 2011 17:15:31 -0000 On Fri, 2011-02-25 at 17:33 +0100, Eric Dumazet wrote: > Le vendredi 25 février 2011 à 16:48 +0100, Jesper Dangaard Brouer a > écrit : > > > Yes, both servers (/proc/sys/net/ipv4/tcp_sack = 1). > > > > I think that the bufferbloat theory is that SACKs will not work, due to > > the long delays introduced by buffers(bloat). In this case, you can > > see on the graph, a max RTT around 150 ms and an average of 20 ms. > > > > While another, more well behaved path in the network to the speed > > server, I would only see a max RTT around 25 ms and an average of 15 ms, > > see: > > http://people.netfilter.org/hawk/dropbox/bloat_vs_GSO/speed-to-pc314a-1.png > > > > You can also see this path had an ave of 90Mbit/s, but with significant > > throughput drops (the 92Mbit/s line is an artificial line on the graph). > > This behavior is probaly caused by the GSO effect. > > > > Disabling GSO on speed server fixed the problem as can be seen on graph: > > http://people.netfilter.org/hawk/dropbox/bloat_vs_GSO/speed-to-grantoften-solved.png > > > > The really strange part when troubleshooting this issue was that the > > throughput as fine between the two customer end-boxes ("grantoften" and > > "pc314a") as can be see here: > > http://people.netfilter.org/hawk/dropbox/bloat_vs_GSO/pc314a-to-grantoften-1.png > > > > > > Its a bit hard to interpret these graphs, I am a bit lost... > What exactly is sampled ? Is it from tcpdump analysis or output from > HTB/SFQ stats ? The graph is generated (with GNUplot) with data from the throughput-latency tool called "thrulay". Its created by Stanislav Shalunov, and its homepage is here: http://shlang.com/thrulay/ I really love this "thrulay" tool, as it measure both the throughput and records the TCP sessions experienced delay. And the output can be used directly by GNUplot. Nice! :-) -- Best regards Jesper Brouer ComX Networks A/S Linux Network Kernel Developer Cand. Scient Datalog / MSc.CS Author of http://adsl-optimizer.dk LinkedIn: http://www.linkedin.com/in/brouer