Re: [Xen-devel] CR4.TSD in guest kernel vs userland

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

It's only likely to be reasonable for PV 64-bit guests, which transition via
the hypervisor already for guest-kernel <-> guest-app transitions (i.e.,
those transition times suck already).

 -- Keir

On 21/09/2009 23:49, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> I was fretting about the overhead of emulating TSC in
> guest kernels.  Is it possible (and relatively inexpensive)
> to change CR4.TSD on every transition between guest
> kernel and userland?  I suspect not, but thought
> I'd check.  If so, what about HVM vs PV and 32-bit
> vs 64-bit guest.
> 
> Thanks,
> Dan
> 
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