Messages in this thread | | | Date | Wed, 06 Jun 2007 12:52:59 +0100 | Subject | Re: [Xen-devel] [patch 14/33] xen: xen time implementation | From | Keir Fraser <> |
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On 6/6/07 12:00, "Jan Beulich" <jbeulich@novell.com> wrote:
>> If the error across CPUS is +/- just a few microseconds at worst then having >> the clocksource clamp to no less than the last timestamp returned seems a >> reasonable fix. Time won't 'stop' for longer than the cross-CPU error, and >> that should always be a tiny value. > > Are you sure this is also true when e.g. a CPU gets throttled due to thermal > conditions? It is my understanding that both the duty cycle adjustment and > the frequency reduction would yield a reduced rate TSC, which would be > accounted for only the next time the local clock gets calibrated. Otherwise, > immediate calibration (and vcpu update) would need to be forced out of the > thermal interrupt.
Yes, this could be an issue. Is there any way to get an interrupt or MCE when thermal throttling occurs?
-- Keir
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