[libvirt-users] getting oriented/networking

Dominique Ramaekers dominique.ramaekers at cometal.be
Fri Mar 20 06:21:58 UTC 2015

Dear Boyland,

In collaboration with some of this mailing list users, I had put some effort in optimising the guest settings in function of a windows guest. The libvirt-gui doesn't include these options. You'll have to edit the XML in virsh. This was my conclusion on 15-03-2015 but I added the hugepages tip in this list today. As for networking, I only use or bridged or the default virtual network (NAT), so can't help you more here. 

Here below, a summary of tips:
- Setting video to QXL and the display channel to Spice
		 <model type='qxl' ram='65536' vram='65536' heads='1'/>
		<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
	<channel type='spicevmc'>
		<target type='virtio' name='com.redhat.spice.0'/>
		<address type='virtio-serial' controller='0' bus='0' port='1'/>
- Using HyperV enlightenemt timer
			<relaxed state='on'/>  
			<vapic state='on'/>  
			<spinlocks state='on' retries='8191'/>  
	<clock ...>  
		<timer name='hypervclock' present='yes'/>  
- Delete the tablet entry in the input section or set the USB-bus to USB2 or USB3
- Use hugepages

Again thanks Daniel and Andrey.

Hope this helps.

Grts, Dominique.

-----Oorspronkelijk bericht-----
Van: Boylan, Ross [mailto:Ross.Boylan at ucsf.edu] 
Verzonden: vrijdag 20 maart 2015 1:52
Aan: libvirt-users at redhat.com
Onderwerp: [libvirt-users] getting oriented/networking

I've been using virt-manager and kvm with a disk image (as in the raw bits) from a physical windows 7 machine.  Initial performance was dreadful, but improved as I switched to virtio and spice.  I've been running linux VM's somewhat longer (much longer if you count kvm without libvirt).

There are lots of choices exposed by virt-manager.  How do I find out what the choices mean, and which are good ones?  This was true for the video (resolved by following instructions for spice, though I still wonder what the other settings are for), disks and the network.

In particular, I have a choice of lots of interfaces for my network; I picked eth1:macvtap because I wanted to bridge eth1.  But there is a "Source Mode" which I left at VEPA, even though Bridged was another choice.  But the bridge would already seem implicit in picking a source device of eth1:macvtap.  I don't know what "source mode" means.  The choices in the GUI seem like some of the options listed under forward on http://libvirt.org/formatnetwork.html; is that a good place to look for clarification.

I started a 2nd VM that also used eth1:macvtap (with virtio) and it had almost no network throughput.  So maybe I should use some other method?  I notice the network manager connection gui allows creation of bridges on the network; should I be using that?

I have been reading documentation, but I haven't found either a task-oriented discussion ("to get a windows machine working well, use these options" or "follow these steps") or an easy way to go from the choices in the GUI to a discussion of their meaning.

Thanks for any help you can offer.
Ross Boylan

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