From mboxrd@z Thu Jan 1 00:00:00 1970 From: Harry Edmon Subject: Re: Network performance degradation from 2.6.11.12 to 2.6.16.20 Date: Mon, 19 Jun 2006 09:40:29 -0700 Message-ID: <4496D37D.7090400@atmos.washington.edu> References: <4492D5D3.4000303@atmos.washington.edu> <20060617153511.53a129a3.akpm@osdl.org> <44948EF6.1060201@atmos.washington.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: Received: from dew1.atmos.washington.edu ([128.95.89.41]:47070 "EHLO dew1.atmos.washington.edu") by vger.kernel.org with ESMTP id S964792AbWFSQkk (ORCPT ); Mon, 19 Jun 2006 12:40:40 -0400 To: Jesper Dangaard Brouer In-Reply-To: Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Jesper Dangaard Brouer wrote: > >>> Harry Edmon wrote: >>> >>>> I have a system with a strange network performance degradation from >>>> 2.6.11.12 to most recent kernels including 2.6.16.20 and >>>> 2.6.17-rc6. The system is has Dual single core Xeons with >>>> hyperthreading on. > > > Hi Harry > > Can you check which "high-res timesource" you are using? > > In the kernel log look for: > kernel: Using tsc for high-res timesource > kernel: Using pmtmr for high-res timesource > > I have experinced some network performance degradation when using the > "pmtmr" timesource, on a Opteron AMD system. It seems that the > default timesource change between 2.6.15 to 2.6.16. > > If you use "pmtmr" try to reboot with kernel option "clock=tsc". > > On my Opteron AMD system i normally can route 400 kpps, but with > timesource "pmtmr" i could only route around 83 kpps. (I found the > timer to be the issue by using oprofile). > > We have CONFIG_HPET_TIMER=y, so we do not see these messages.