[Fedora-xen] CPU management

[John Summerfield]

Augusto Castelan Carlson wrote:
> Hi!
> 
> I will have servers with different CPU specification:
> Quad core, dua core, one core.
> 
> Each core appears as one VCPU for xen?
Yes

> 
> How the management works when there is only one core, dual core and quad core?
> 
> Suppose that I have 2 guests and for the quad core processor I give 2
> VCPU to the dom0 and one for each domU. How it is managed? If DomU
> needs more CPU, it can use idle CPU from Dom0?  If DomU is using idle
> CPU from Dom0 and Dom0 starts to need CPU, it will have their slice
> back?

The CPUs are not dedicated. I've not tried specifying more CPUs than I 
have, but I'm sure it's mentioned in the docs. I would expect it to work.

If you give any guest only one CPU, it will only use one CPU at a time, 
but not necessarily the same one all the time. If you want a guest to be 
able to use more than one CPU at a time, you need to specify two (or 
more) CPUs.

I think you can dynamically change the number of CPUs, but you would 
need to check each guest OS to see whether it's supported by that guest.



-- 

Cheers
John

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