On Fri, May 21, 2010 at 11:51:34PM +0800, lei yang wrote:
> On Fri, May 21, 2010 at 11:46 PM, Pasi Kärkkäinen <[1]pasik@xxxxxx> wrote:
>
> 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][2]keir.fraser@xxxxxxxxxxxxx> wrote:
> >
> > On 21/05/2010 04:09, "lei yang" <[2][3]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 I don't use "xm vcpu-pin" does it will use core 0 1 2 3 by default not
> can use 3 4 5 6?
>
Yes, it'll use 0 1 2 3 as a default. It cannot be changed, unless you do
custom pinning after the system has started.
> if so, does core 0-4 just can used by dom0? domU can't use it?
>
domU can (and will) use them, so you need to also pin the domUs so that they
won't
try to use the dom0 cores, if you absolutely want to dedicate 4 cores only for
dom0.
Just play with "xm vcpu-pin" and "xm vcpu-list" and you'll figure it out.
-- Pasi
> Thanks
> Lei
>
>
> > if remove "dom0_vcpus_pin" just use " dom0_max_vcpus=4 " can it be
> 3 4 5
> > 6 ?
> >
>
> Yes, set up the pinning yourself.
>
>
> again. if just use "dom0_max_vcpus=4" not use "dom0_vcpus_pin" and I
> don't use "xm vcpu-pin", can 't be 3 4 5 6,
>
> Thanks
> Lei
>
>
> -- 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:[4]keir.fraser@xxxxxxxxxxxxx
> > 2. mailto:[5]yanglei.fage@xxxxxxxxx
> > _______________________________________________
> > Xen-devel mailing list
> > [6]Xen-devel@xxxxxxxxxxxxxxxxxxx
> > [7]http://lists.xensource.com/xen-devel
>
> --
> "We learn from failure, not from success!"
>
> References
>
> Visible links
> 1. mailto:pasik@xxxxxx
> 2. mailto:keir.fraser@xxxxxxxxxxxxx
> 3. mailto:yanglei.fage@xxxxxxxxx
> 4. mailto:keir.fraser@xxxxxxxxxxxxx
> 5. mailto:yanglei.fage@xxxxxxxxx
> 6. mailto:Xen-devel@xxxxxxxxxxxxxxxxxxx
> 7. http://lists.xensource.com/xen-devel
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home