From mboxrd@z Thu Jan 1 00:00:00 1970 From: Auke Kok Subject: Re: IBM (Lenovo) T60: e1000 driver high latency Date: Mon, 31 Jul 2006 08:05:27 -0700 Message-ID: <44CE1C37.2090001@intel.com> References: <20060731093433.GF2576@cip.informatik.uni-erlangen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org Return-path: Received: from mga01.intel.com ([192.55.52.88]:39200 "EHLO fmsmga101-1.fm.intel.com") by vger.kernel.org with ESMTP id S1750879AbWGaPGn (ORCPT ); Mon, 31 Jul 2006 11:06:43 -0400 To: Thomas Glanzmann In-Reply-To: <20060731093433.GF2576@cip.informatik.uni-erlangen.de> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Thomas Glanzmann wrote: > Hello, > > [ resend because .config and the used kernel version was missing ] > > Linux Kernel Version: Linus Vanilla Tree; .config attached. > > I recently aquired a Lenovo (IBM) T60 with a e1000 network card. I > experience high latency with this networkcard: Pings last upto 1 second > where the ping should be around 25 ms. I googled a bit and found the > following: > > - Enable NAPI, which didn't worked for me. > > 64 bytes from 192.168.0.223: icmp_seq=30 ttl=64 time=1004 ms > 64 bytes from 192.168.0.223: icmp_seq=31 ttl=64 time=0.444 ms > 64 bytes from 192.168.0.223: icmp_seq=32 ttl=64 time=1006 ms > 64 bytes from 192.168.0.223: icmp_seq=33 ttl=64 time=0.739 ms Someone reported this problem on the e1000 bug tracker at e1000.sf.net. He also reported that the behaviour goes away completely if he disables the in-kernel irq balancer: : If I disable in kernel config Irq Balancing pings are : much better but not the best :-) : : 64 bytes from 192.168.3.74: icmp_seq=29 ttl=64 time=12.7 ms : 64 bytes from 192.168.3.74: icmp_seq=30 ttl=64 time=10.0 ms : 64 bytes from 192.168.3.74: icmp_seq=31 ttl=64 time=7.3 ms : 64 bytes from 192.168.3.74: icmp_seq=32 ttl=64 time=4.5 ms that's a large difference from >> 1000ms, and I cannot suspect otherwise that the kernel irqbalance is wreaking havoc in your system, trying to swap the entire context between each core (t60 is a core duo) every second or so. I've never believed much in the kernel irq balancer, the userspace daemon written by Arjan van der Ven just does a much better job, so can you try to disable the kernel irqbalancer? > CONFIG_IRQBALANCE=y turn that off ;) Cheers, Auke