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    Subjectexcessive kworker CPU wakeups
    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:

    <idle>-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?


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