[CentOS-virt] Windows Xen VM's have high guest CPU usage and poor performance

Pasi Kärkkäinen pasik at iki.fi
Thu Jan 21 21:28:43 UTC 2010

On Thu, Jan 21, 2010 at 11:37:02AM -0500, Ryan Pugatch wrote:
> Eric Searcy wrote:
> >> The install worked beautifully except that my VM now has an ip assigned
> >> of which I'm guessing is in relation to virbr0 which is
> >> on the host (and subsequently has no internet
> >> connectivity).  Is it possible for me to pass through to my network like
> >> before so my VM can have an ip on my local network?
> > 
> > Unless you specify a bridge in the xen conf file, it uses the first one 
> > it finds alphabetically, I believe.  Do you use virbr0 for anything 
> > else?  As an easy way of making sure xenbr0 is used, I removed the file 
> > /etc/libvirt/qemu/networks/autostart/default.xml which was auto-starting 
> > this DHCP (and NATted?) bridge, and I only was using direct access.  But 
> > you can also make it explicit on the interface line, one of my HVM VMs 
> > has the following:
> > 
> > vif = [ 'mac=00:16:3e:0a:4c:d2, bridge=xenbr0' ]
> > 
> > Eric
> That worked.. thanks Eric.  However, even with the GPLPV drivers, I am 
> seeing a lot of CPU usage when I do anything on the Windows VM.  It 
> isn't just the guest that is reporting CPU usage, though.  When I watch 
> xm top, the CPU usage jumps on that VM.  Not really sure what else can 
> be done to improve performance.

Check these tips:

And also this:

-- Pasi

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