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    SubjectRe: [PATCH 11/17] Fix a possible backwards warp of kvmclock
    On 06/16/2010 04:58 PM, Glauber Costa wrote:
    > On Wed, Jun 16, 2010 at 04:11:26PM +0800, Jason Wang wrote:
    >
    >> Zachary Amsden wrote:
    >>
    >>> Kernel time, which advances in discrete steps may progress much slower
    >>> than TSC. As a result, when kvmclock is adjusted to a new base, the
    >>> apparent time to the guest, which runs at a much higher, nsec scaled
    >>> rate based on the current TSC, may have already been observed to have
    >>> a larger value (kernel_ns + scaled tsc) than the value to which we are
    >>> setting it (kernel_ns + 0).
    >>>
    >>>
    >> This is one issue of kvmclock which tries to supply a clocksource whose
    >> precision may even higher than host.
    >>
    > What if we export to the guest the current clock resolution, and when doing guest
    > reads, simply chop whatever value we got to the lowest acceptable value?
    >

    The clock resolution can change, and while we can expose it reliably
    through pvclock, do we need a notification so that the guest can update
    other internal structures?

    --
    error compiling committee.c: too many arguments to function



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