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    SubjectRe: bogomips discrepancy on Intel Core2 Quad CPU
    Bill Davidsen wrote on 03-09-07 16:47:
    > Bauke Jan Douma wrote:
    >> $> uname -a
    >> Linux skyscraper 2.6.22.5 #7 SMP PREEMPT Sun Sep 2 12:12:25 CEST 2007
    >> i686 GNU/Linux
    >>
    >> $> cat /proc/cpuinfo | grep bogomips
    >> bogomips : 4813.46
    >> bogomips : 4810.91
    >> bogomips : 4810.91
    >> bogomips : 10583.94
    >>
    >> The latter seems way off base.
    >> Prod me for more info.
    >>
    > I see this occasionally on a dual, speedstep (or similar) finds a way to
    > throttle down the cores under light load. I suspect that if you load the
    > system:
    >
    > for n in 1 2 3 4; do
    > nice -19 bash -c 'while true; do a=$RANDOM; done' &
    > done
    >
    > Then you should see your bogomips rise on all cores.

    Sorry for now getting back on this sooner. Other matters forced it to
    the backburner.

    I don't have Speedstep enabled on this machine's kernel (as a matter
    of fact, the entire cpufreq Kconfig subtree is unchecked). Needless to
    say running your bash script doesn't change the values in any way.

    I'd say the 4800-something bogomips value is the correct one (for a
    2.4GHz CPU -- at least that's what I recall on single-CPU machines,
    mostly bogomips being approx. twice the rated CPU speed), and the
    10000-something is the one off base.

    Btw., the 10000 can be something like 12000-odd after a machine reboot,
    and readout on a different CPU. The rest are all ca. 4810. Odd indeed.

    bjd

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