RE: [Xen-devel] RE: Saving/Restoring IA32_TSC_AUX MSR

[Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>]

> It's possible, and the way guest NUMA supposed to be. We are 
> working on that.

I'd be very interested in learning more about your plans.

> -----Original Message-----
> From: Nakajima, Jun [mailto:jun.nakajima@xxxxxxxxx]
> Sent: Friday, December 11, 2009 11:38 AM
> To: Dan Magenheimer; Xu, Dongxiao; Keir Fraser; Zhang, Xiantao;
> xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Dugger, Donald D
> Subject: RE: [Xen-devel] RE: Saving/Restoring IA32_TSC_AUX MSR
> 
> 
> Dan Magenheimer wrote on Fri, 11 Dec 2009 at 08:12:00:
> 
> >>> Yes, but code which uses fast vgetcpu is expecting
> >>> to get physical cpu and physical node number.  Since
> >>> an HVM guest OS only has access to virtual cpu and
> >>> virtual node number, the information written to TSC_AUX
> >>> by a guest OS is misleading and may silently break any
> >>> userland code that assumes it is getting physical
> >>> information.
> >> 
> >> This is depend on how the node info is virtualized.
> >> If the virtual node could reflect the physical
> >> node info, what rdtscp returns is valuable to applications.
> > 
> > If it is possible to ensure that the cpu/node info
> > is virtualized so that TSC_AUX always correctly provides the
> > information needed by apps, I agree this would be
> > valuable.  I don't see how this is possible, but maybe
> > you have some creative ideas?
> 
> It's possible, and the way guest NUMA supposed to be. We are 
> working on that.
> 
> Jun
> ___
> Intel Open Source Technology Center
> 
> 
> 
> 
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