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    SubjectRe: [PATCH 1/5] Skip timer works.patch
    Andi Kleen wrote:
    >> That is the one that can panic, for now. Fixing the paravirtualized
    >> case is easy, but we can't assume paravirtualization just yet.
    >>
    >
    > Hmm, this means standard vmware boot is not reliable unless that magic option
    > is set? That doesn't sound good.
    >

    It doesn't happen often, but it is a possibility that the kernel
    calibrates the delay wrong because of timing glitches caused by CPU
    migration, paging, or other phenomena which are supposed to be
    transparent to the kernel (but cause temporal lapse). In that case, the
    kernel may not make enough progress in a spin delay loop to properly
    reach the number of microseconds required for N number of timer ticks to
    occur. In theory this can happen on a real machine, as SMM mode could
    be active, doing USB device emulation or something that takes a while
    during the lpj calibration and throwing the computation off.

    By changing the parameters (N ticks at K Hz in T seconds), it is easy to
    create an unstable measurement that can achieve high failure rates,
    although in practice the Linux parameters appear to be reasonable enough
    that it is not a major problem.

    Zach
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