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    SubjectRe: [RFC PATCH] x86:Use cpu_khz for loops_per_jiffy calculation
    Hi!

    > On X86 platform we can use the value of tsc_khz computed during tsc calibration
    > to calculate the loops_per_jiffy value. Its very important to keep the error in
    > lpj values to minimum as any error in that may result in kernel panic in
    > check_timer.
    > In virtualization environment, On a highly overloaded host the guest delay
    > calibration may sometimes result in errors beyond the ~50% that timer_irq_works
    > can handle, resulting in the guest panicking.

    How did you adress 'khz has nothing to do with loops per jiffie'
    comment?

    Some cpus can do loop in cycle , some need two cycles, some need half.

    Pavel

    > @@ -421,6 +422,10 @@
    > return;
    > }
    >
    > + lpj = ((u64)tsc_khz * 1000);
    > + do_div(lpj, HZ);
    > + lpj_tsc = lpj;
    > +
    > printk("Detected %lu.%03lu MHz processor.\n",
    > (unsigned long)cpu_khz / 1000,
    > (unsigned long)cpu_khz % 1000);
    >


    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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