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SubjectRe: Use of barriers in pvclock ABI
Glauber Costa wrote:
> On Mon, Aug 11, 2008 at 4:08 AM, Gerd Hoffmann <kraxel@redhat.com> wrote:
>> Due to the TSC being involved here I don't expect cross-cpu time updates
>> will ever happen. IMHO it is fine to change that.
>
> Okay for guest vcpu, but what about physical cpus?
>
> IIRC, the checks are there, and so strict, to account for the
> possiblity of the vcpu to be migrated to another cpu in the middle of
> the
> clock reading.

This is about the check in pvclock_get_time_values() that it got a
consistent snapshot. Dropping that is fine.

pvclock_clocksource_read() will still notice when being migrated to
another pcpu in the middle of the clock reading.

cheers,
Gerd

--
http://kraxel.fedorapeople.org/xenner/


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