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RE: [Xen-users] present domU with 1 CPU with multiple cores

  • To: "Jonathan Salomon" <jonathan@xxxxxxxxxxxxx>, <xen-users@xxxxxxxxxxxxxxxxxxx>
  • From: Jeff Sturm <jeff.sturm@xxxxxxxxxx>
  • Date: Tue, 23 Jun 2009 08:12:33 -0400
  • Cc:
  • Delivery-date: Tue, 23 Jun 2009 05:14:20 -0700
  • List-id: Xen user discussion <xen-users.lists.xensource.com>
  • Thread-index: Acnz3MbiKr+s+D4iQ1GJnhrdYib6NwAHZWcg
  • Thread-topic: [Xen-users] present domU with 1 CPU with multiple cores

> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Jonathan
> Sent: Tuesday, June 23, 2009 4:30 AM
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] present domU with 1 CPU with multiple cores

> However to make sure that Dom0 will always respond even when
> the DomU instances have a high load, I want to keep CPU 0 available
> only for Dom0. Therefore in the DomU config files I'm using the
> CPU definition: cpus="1-3". Does it makes sense to do this?
> Or would Xen handle this better on its own?

I think it's a good idea.  If your domU load is CPU-intensive, dom0 may
not need to run often.  However that is often not the case, and each
domU may frequently need to perform either disk or network I/O.  Dom0
needs to be scheduled on an available CPU to complete that I/O, since it
hosts the driver backend.

> Also how do I see on which physical CPU a DomU instance is running?

Take a look at "xm vcpu-list".


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