From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David H. Durgee" Subject: Request for assistance - excessive kworker CPU wakeups Date: Fri, 09 Dec 2011 16:26:19 -0500 Message-ID: <4EE27CFB.8020301@verizon.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Sender: cpufreq-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: cpufreq@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