From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: 2.6.19-rc1: Volanomark slowdown Date: Wed, 8 Nov 2006 15:00:07 -0800 Message-ID: <20061108150007.49eaea68@freekitty> References: <1162924354.10806.172.camel@localhost.localdomain> <1163001318.3138.346.camel@laptopd505.fenrus.org> <20061108162955.GA4364@suse.de> <1163011132.10806.189.camel@localhost.localdomain> <20061108221028.GA16889@suse.de> <1163023652.10806.203.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Olaf Kirch , Arjan van de Ven , linux-kernel@vger.kernel.org, davem@sunset.davemloft.net, kuznet@ms2.inr.ac.ru, netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.4]:21167 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1423864AbWKHXBI (ORCPT ); Wed, 8 Nov 2006 18:01:08 -0500 To: tim.c.chen@linux.intel.com In-Reply-To: <1163023652.10806.203.camel@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, 08 Nov 2006 14:07:32 -0800 Tim Chen wrote: > On Wed, 2006-11-08 at 23:10 +0100, Olaf Kirch wrote: > > > > > In fixing performance issues, the most obvious explanation isn't always > > the right one. It's quite possible you're right, sure. > > > > What I'm saying though is that it doesn't rhyme with what I've seen of > > Volanomark - we ran 2.6.16 on a 4p Intel box for instance and it didn't > > come close to saturating a Gigabit pipe before it maxed out on CPU load. > > > > I am running Volanomark in a loopback mode on a 2P woodcrest box > (4 cores). So the configuration is a bit different. > > In my testing, the CPU utilization is at 100%. So > increase in ACKs will cost CPU to devote more > time to process those ACKs and reduce throughput. > > > > > You could count the number of outbound packets dropped on the server. > > > > As I'm running in loopback mode, there are no dropped packets. > Optimizing for loopback is perversion; perversion can be fun but it gets to be a obsession then it's sick. -- Stephen Hemminger