From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: bizarre network timing problem Date: Fri, 02 Nov 2007 15:58:24 -0700 Message-ID: <472BAB90.8020306@hp.com> References: <20071017205127.GA21334@codeblau.de> <47167BDE.4000103@redhat.com> <20071017220019.GA22765@codeblau.de> <471689BF.2040909@hp.com> <20071018094230.GA2978@codeblau.de> <4717964A.8080100@hp.com> <20071102221146.GA4354@codeblau.de> <472BA5BC.6000901@hp.com> <20071102223856.GA5121@codeblau.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Chuck Ebbert , linux-kernel@vger.kernel.org, Netdev To: Felix von Leitner Return-path: In-Reply-To: <20071102223856.GA5121@codeblau.de> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Felix von Leitner wrote: > Thus spake Rick Jones (rick.jones2@hp.com): > >>>Oh I'm pretty sure it's not my application, because my application performs >>>well over ethernet, which is after all its purpose. Also I see the >>>write, the TCP uncork, then a pause, and then the packet leaving. >> >>Well, a wise old engineer tried to teach me that the proper spelling is >>ass-u-me :) so just for grins, you might try the TCP_RR test anyway :) And >>even if your application is correct (although I wonder why the receiver >>isn't sucking data-out very quickly...) if you can reproduce the problem >>with netperf it will be easier for others to do so. > > > My application is only the server, the receiver is smbget from Samba, so > I don't feel responsible for it :-) Might want to strace it anyway... no good deed (such as reporting a potential issue) goes unpunished :) > Still, when run over Ethernet, it works fine without waiting for > timeouts to expire. Past performance is no guarantee of current correctness :) And over an Ethernet, there will be a very different set of both timings and TCP segment sizes compared to loopback. My guess is that you will find setting the lo mtu to 1500 a very interesting experiment. > > To reproduce this: > > - smbget is from samba, you probably already have this > - gatling (my server) can be gotten from > cvs -d :pserver:cvs@cvs.fefe.de:/cvs -z9 co dietlibc libowfat gatling > > dietlibc is not strictly needed, but it's my environment. > First built dietlibc, then libowfat, then gatling. > > Felix