Re: [Xen-devel] How to detect HAP from DomU?

[Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>]

On 11/10/10 09:36, Keir Fraser wrote:
> On 10/11/2010 08:22, "Juergen Gross"<juergen.gross@xxxxxxxxxxxxxx>  wrote:
>
> > is there any way for a HVM-domain to detect whether it is running with HAP
> > enabled? I couldn't find any interface for this information.
> >
> > Background: in our BS2000 domain (HVM with PV-drivers) we sometimes have to
> > copy complete pages between kernel and user. An alternative to the copy
> > would be a remapping of the page. The remap is faster than the copy with HAP
> > enabled, but much slower without HAP. So it would be best to copy without HAP
> > and remap with HAP.
> You could do a few remaps and copies and see how long it takes? Has the
> advantage that you aren't tied up to one policy based on one system's
> timings for those particuler ops. I don't think basing policy on static
> assumptions about hidden implementation features is a good idea.
Okay, that's a good idea.
I'm going this way.


Thanks, Juergen

--
Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 3222 2967
Fujitsu Technology Solutions              e-mail: juergen.gross@xxxxxxxxxxxxxx
Domagkstr. 28                           Internet: ts.fujitsu.com
D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

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