[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] What's the different for "dom0_max_vcpus=4 dom0_vcpus_pin" and "dom0_max_vcpus=4" ?


  • To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
  • From: lei yang <yanglei.fage@xxxxxxxxx>
  • Date: Fri, 21 May 2010 23:39:50 +0800
  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Xen Mailing List <xen-users@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Fri, 21 May 2010 08:43:20 -0700
  • Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=F+crUfMTfcTPH4vEz4afWZ0s+iA6/JQhPdroTWoecffc/A/505uycKgiJQPrVue/w6 iH4JNmgSLz+IhT6tek8WI3zQLVxwAhi7okjRXxfkl/LKsq3KR9lGrS3OlsvfGIx4vJji n4QWV851MTb2b7vAqmHK1BBFRjfsNDSSijpeM=
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>



On Fri, May 21, 2010 at 2:57 PM, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:
On 21/05/2010 04:09, "lei yang" <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? can it be 3 4 5 6?
if remove "dom0_vcpus_pin" just use "  dom0_max_vcpus=4 " can it be 3 4 5 6 ?
 
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!"
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.