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    SubjectRe: [PATCH 5/5] cpufreq: Add support for actual freq
    From: Thomas Renninger <>
    Date: Tue, Mar 23, 2010 at 04:12:18PM +0100

    Hi Thomas,

    > would return the average freq of the last seconds, exactly the same
    > what you can do with cpufreq-aperf from userspace.
    > But if another user app does the same, it's messed up.
    > You can find out the pid of the process doing the cat and remember
    > aperf/mperf for it if it does not exist yet..., but now it gets to a
    > point where cpufreq-aperf is really more convenient and straight foward.
    > Possibly documenting cpufreq-aperf in Documentation/cpu-freq would
    > be worth it. Also mentioning "boost" somewhere would be great:
    > grep -i boost Documentation/cpu-freq/ -r
    > Documentation/cpu-freq/pcc-cpufreq.txt:This is due to "turbo boost" ...
    > Another idea is to have a separate cpufreq_avg_freq and update it on
    > every target() call, but that's overhead...

    you got me persuaded - if we want to have the effective frequency
    reported in the kernel, we have to come up with a slick solution that
    wouldn't incur overhead and won't be disrupted by others accessing those
    MSRs. Let's leave it to cpufreq-aperf for now and revisit this when



    Advanced Micro Devices, Inc.
    Operating Systems Research Center

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