On Fri, May 21, 2010 at 11:39:50PM +0800, lei yang wrote:
> On Fri, May 21, 2010 at 2:57 PM, Keir Fraser
> <[1]keir.fraser@xxxxxxxxxxxxx> wrote:
>
> On 21/05/2010 04:09, "lei yang" <[2]yanglei.fage@xxxxxxxxx> wrote:
>
> > Hi experts,
> >
> >
> > Q1:What's the different for "dom0_max_vcpus=4 dom0_vcpus_pin" and
> > "dom0_max_vcpus=4" ? which will get better performance
>
> The former restricts Xen to only run Dom0 VCPUs 0-3 on physical CPUs
> 0-3.
>
>
> dom0_max_vcpus=4 dom0_vcpus_pin will just to core0-3?
>
Yes.
> can it be 3 4 5 6?
>
Yes, modify the pinning when the system has booted up using "xm vcpu-pin".
> if remove "dom0_vcpus_pin" just use " dom0_max_vcpus=4 " can it be 3 4 5
> 6 ?
>
Yes, set up the pinning yourself.
-- Pasi
>
> It's not really a performance thing, but instead is to mean that some
> things
> like cpufreq management can work directly from dom0. We don't really use
> the
> dom0_vcpus_pin option much.
> > Q2: dom0_max_vcpus=4 means "core0-3 will be just used by dom0" or
> means "4
> > cores(not dedicate cores) will be used by dom0, eg: core2-5 or
> core3-6?
>
> Dom0's VCPUs can be scheduled on any physical CPU at any time, unles
> dom0_vcpus_pin is specified.
> > Q3.what does mean "nosmp" , xen, dom0,domU, will just use one
> core????if so,
> > can we specify the use different core. eg: dom0=core2 domU=core3? xen
> will use
> > just one core?
>
> It brings Xen up on the boot CPU only. Nothing in the system will use
> the
> other CPUs. You don't want to use this option really.
> -- Keir
>
> --
> "We learn from failure, not from success!"
>
> References
>
> Visible links
> 1. mailto:keir.fraser@xxxxxxxxxxxxx
> 2. mailto:yanglei.fage@xxxxxxxxx
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