RE: [Xen-users] Xen 3.0 Dom0 Smp enable?

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> >> I have a 2 way machine.  Soliciting folks opinion on 
> whether it makes 
> >> sense to smp enable DOM0 so that IO handling can be balanced over 
> >> both CPU's...
> >
> >Its generally not helpful to have an SMP dom0. In high IO situations 
> >it's typically best to dedicate a hyperthread or core to dom0.

> How does one make the dedication of a CPU to dom0?   Seems 
> like pincpu is 
> the control mechanism, but if I understand pincpu correctly, 
> it doesn't 
> prevent other domains from sharing the chosen CPU.   It pegs 
> the domain to 
> the CPU, but not the reverse.   

If you create a pincpu mask for the over domains/VCPUs that doesn't
include the CPU in question, they won't use it. I guess a shorthand
command for this would be useful.

> Also, how can one distinguish an ht CPU vs a core CPU?

All hyperthreads of a core are enumerated before moving on to the next
core; All cores are enumerated before the next socket. We've proposed
changing the CPU naming convention to a '.' seperated form to make this
more explicit.

I thought Ryan may have even knocked up a patch for this at one point
(?)
Ryan, if so, please can you dust off and resend. As I recall, the key
fix it needed was that it should be xend (not xm) that does the
translation from the dot'ed form into CPU numbers.

Thanks,
Ian

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