[ovirt-users] Mask the CPU model

[Michal Skrivanek]

On Jun 26, 2014, at 13:42 , Sven Kieske <S.Kieske at mittwald.de> wrote:

> 
> 
> Am 26.06.2014 13:28, schrieb Michal Skrivanek:
>> 
>> On Jun 26, 2014, at 13:18 , Dan Kenigsberg <danken at redhat.com> wrote:
>> 
>>> On Wed, Jun 25, 2014 at 11:19:17AM +0000, Sven Kieske wrote:
>>>> 
>>>> 
>>>> Am 25.06.2014 11:43, schrieb Punit Dambiwal:
>>>>> Hi Sven,
>>>>> 
>>>>> Please let me know which VDSM hook can be used for the same,is there any
>>>>> hook available for the same... ??
>>>> 
>>>> I don't know any hook that does this, it should be relatively simple,
>>>> though.
>>>> Maybe someone else can assist, CC'ing Dan:
>>>> 
>>>> Do you know of a hook that manipulates the emulated CPU model?
>>> 
>>> Within the Vdsm code tree, only faqemu does that (and it only drops,
>>> causing qemu to do its best). You can build on top of faqemu to set to
>>> your favorite guest cpu.
>>> 
>>> However, I think that Engine was once capable of setting a specific
>>> cpuType - is it still possible without hacking its DB, Arik?
>> 
>> I'm not sure what do you actually mean
>> hide what from whom?
>> the guest sees particular CPU, there's nothing like "Virtual xyz", it either sees flags matching e.g. Nehalem or not. You can select different CPU at the cluster level if you wish, and that's what the guest will see, regardless what your host has
>> 
>> faqemu is changing the configured CPU type to fully emulated CPU…I don't think you meant that...
> 
> I guess he refers to the cpu_model mentioned here:
> http://docs.openstack.org/trunk/config-reference/content/list-of-compute-config-options.html

yes, that's what we have at cluster level and there is an RFE for per-VM level

> 
> But I still do not see the benefit of "faking" a certain cpu model.

there is no faking, it is always real for the guest.
so yes, you can make it look(and actually perform) less capable so you can migrate across heterogenous hosts; or make it less capable just if you wish so, but that's it.

Thanks,
michal

> 
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> 
> Sven Kieske
> 
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