Re: [Xen-users] IO performance depends on number of DomU's?

["Olivier B." <xen.list@xxxxxxxxx>]

Hi,

is it always usefull if irqbalance is installed on Dom0 ?
Or maybe irqbalance is not usefull at all with Xen ?

Olivier

Fajar A. Nugraha a écrit :
> On Tue, Apr 28, 2009 at 8:22 PM, Robert Dunkley <Robert@xxxxxxxxx> wrote:
>   
> > Is it possible to dedicate one of the CPUs to Dom0 exclusively?
> >
> > Yes.
> > Add this to the kernel boot line: dom0_max_vcpus=1
> > Edit /etc/xen/xend-config.sxp  -  set “(dom0-cpus 1)”
> > Reboot Dom0
> >     
> Some additional info :
> - you might also want this line on kernel boot line :dom0_vcpus_pin.
> This would ensure that dom0's vcpu 0 (the active one if it only uses
> one vcpu) is assigned on physical cpu 0 (or core 0 on multicore
> system).
> - those steps does not actually dedicate one CPU to dom0 exclusively.
> What it does is it LIMITS dom0 to only use one CPU. To assign it
> exclusively, you also need to tell domUs to NOT use that particular
> CPU. Something like 'cpus="1-7"' (for 8-core system) on domU config
> would tell it to NOT use core 0.However since current xen scheduler is
> smart enough to assign cpu dynamically you might see the same result
> with only the above config if your system load is low enough.
> - to achive the same effect on your current session only without the
> need to reboot:
> xm vcpu-set 0 1
> xm vcpu-pin 0 0 0
>
> Regards,
>
> Fajar
>
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