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RE: [Xen-devel] Time skew on HP DL785 (and possibly other boxes)

To: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "Xen-Devel (E-mail)" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Time skew on HP DL785 (and possibly other boxes)
From: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
Date: Tue, 31 Mar 2009 16:21:40 -0700 (PDT)
Cc: john.v.morris@xxxxxx
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> >> Then instead user'd better to enable NUMA aware bits with Xen which
> >> imposes some affinity limitation but looks a reasonable model
> >> on large
> >> scale system.
> >
> >Are you suggesting that only NUMA-aware guests should be
> >run on systems like this?  If not, what do you mean by
> >"NUMA aware bits"?
> >
>
> No. I meant the physical NUMA features in Xen. IIRC, once
> NUMA support is
> turned on in Xen (by "numa" boot option), one guest is
> limited in one node
> automatically, meaning both cpu affinity only matching to
> that node and also
> memory allocated locally within that node.
>
> Thanks,
> Kevin

OK, I see.  That seems too restrictive when the
interprocessor link is very fast like HT or QPI.
I hope there is a solution that will allow xen system
time to be fairly accurate and synchronized in this
kind of system without depending on tsc.

Dan

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