From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755008Ab1LBUi6 (ORCPT ); Fri, 2 Dec 2011 15:38:58 -0500 Received: from vms173001pub.verizon.net ([206.46.173.1]:36702 "EHLO vms173001pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751584Ab1LBUi5 (ORCPT ); Fri, 2 Dec 2011 15:38:57 -0500 Message-id: <4ED93750.7080801@verizon.net> Date: Fri, 02 Dec 2011 15:38:40 -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 Cc: Tejun Heo Subject: 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, who is cc'd, 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? Dave