Return-path: Received: from cpsmtpm-eml104.kpnxchange.com ([195.121.3.8]:50750 "EHLO CPSMTPM-EML104.kpnxchange.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752139AbZJEOOK (ORCPT ); Mon, 5 Oct 2009 10:14:10 -0400 From: Frans Pop To: Linux Kernel Mailing List Subject: Re: [.32-rc3] scheduler: iwlagn consistently high in "waiting for CPU" Date: Mon, 5 Oct 2009 16:13:31 +0200 Cc: Ingo Molnar , Peter Zijlstra , linux-wireless@vger.kernel.org References: <200910051500.55875.elendil@planet.nl> In-Reply-To: <200910051500.55875.elendil@planet.nl> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Message-Id: <200910051613.32631.elendil@planet.nl> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Monday 05 October 2009, Frans Pop wrote: > With .32-rc3 I'm getting occasional skips from amarok while playing > music from an NFS share (3 today so far), something I've not had in a > long time. > > The reason looks to be that latencytop consistently shows 'iwlagn' as > the top affected process with "Scheduler: waiting for CPU". > Values of 100-140 ms occur frequently, but I've also seen higher values > (180, 207). I don't remember seeing iwlagn high in the list before, but > I have not checked earlier kernels yet. > > Added to that 'phy0' also frequently shows high with values of 25-75 ms. > > The system is otherwise essentially idle. Other processes typically show > a latency < 5 ms. If I give the system some work to do (like compiling a kernel), the latencies on iwlagn and phy0 disappear (values < 5 ms). Is this related to ondemand frequency scaling?