From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754716Ab1LIV1c (ORCPT ); Fri, 9 Dec 2011 16:27:32 -0500 Received: from vms173013pub.verizon.net ([206.46.173.13]:63331 "EHLO vms173013pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751299Ab1LIV1b (ORCPT ); Fri, 9 Dec 2011 16:27:31 -0500 Message-id: <4EE27D28.4040909@verizon.net> Date: Fri, 09 Dec 2011 16:27:04 -0500 From: "David H. Durgee" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0.1) Gecko/20111122 Firefox/8.0.1 SeaMonkey/2.5 MIME-version: 1.0 To: linux-kernel@vger.kernel.org Subject: Request for assistance - excessive kworker CPU wakeups Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I recently purchased a Lenovo IdeaPad Z560, model 09143YU, and as I am not a Windows fan I installed Linux Mint 11 Katya x64 to use instead of the supplied W7. I was encountering a known hang and had to upgrade to a later kernel, so I am now using the 2.6.38-11-generic #50-Ubuntu SMP Mon Sep 12 21:17:25 UTC 2011 x86_64 kernel. I had my first occasion to use the laptop for an extended period for the first time over the Thanksgiving holiday and I found it needed to be tuned. I downloaded powertop and used it to discover where my problems were. After addressing excessive i915 interrupts due to DRI the next most frequent cause of CPU wakeups is a kworker on the system. A search lead to a post by Tejun, indicating the need to trace such issues. Running the trace showed that 1933 of 2748 events were of the form: -0 [000] 22005.355346: workqueue_queue_work: work struct=ffff8800bb411188 function=do_dbs_timer workqueue=ffff88012b5d2c00 req_cpu=0 cpu=0 Tejun indicated that this is a workitem used by cpufreq and likely caused by something else hitting the CPU frequently. So how do I diagnose this further and isolate the cause for correction? If you would like a summary of this, download this spreadsheet: http://home.comcast.net/%7Eddurgee/Tracelog.ods If you would like to inspect the trace log itself: http://home.comcast.net/%7Eddurgee/tracelog.zip Dave