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    SubjectRe: [Patch] Fix the possibility of insane return value of hpet_calibrate() against SMI.
    Yasunori Goto wrote:
    > Sorry for late response.
    >> Yasunori Goto wrote:
    >>>> I've no sense of feel for how long each calibration run would take.
    >>>> Would doing it 5 times show up as a significant increase in the boot
    >>>> time for those that care about boot time being as quick as possible?
    >>> Hmm. The loop times is trade off against reliable value....
    >>> Though SMI is rare interruption, I don't know how frequent
    >>> hypervisor's switch is.
    >> Could you, just for testing, run the calibration five thousand times or
    >> so instead of five times, and count how often you get insane values?
    >> (And how much delay does such an SMI add?)
    > I tried 50000 times. But insane value was nothing.
    > I think SMI is very rare.
    >>> Each calibration of this has 1 milli second.
    >>> Do you think 5 msec is too long?
    >> This shouldn't matter when booting. Anyway, I think it's possible to
    >> increase TICK_CALIBRATE without losing too much accuracy.
    > Hmm. If the person who is trying to reduce boot time for fastboot dislikes this impact,
    > then I'll try Vojtech-san's way.

    That probably makes sense -- if it is extremely rare, and if you get two
    values that are the same (within some small delta) then you probably
    are 99.99% confident that you have the right data.


    > Thanks.

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