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

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

>-----Original Message-----
>From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Juergen Gross
>Sent: Wednesday, November 10, 2010 4:43 PM
>To: Keir Fraser
>Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
>Subject: Re: [Xen-devel] How to detect HAP from DomU?
>
>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.

Will this works for Live Migration? After LM, your previous check will be 
invalid. (Can we migrate between system w/wo HAP?)
Or you can check after each LM.

--jyh

>
>
>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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