Faster graphics in KVM guest

kvm

Is there any way to improve the graphics performance of a KVM guest?

I suspect that the question is too general, so I will give my setup and requirements.

My ultimate goal is to use an Ubuntu guest as my primary OS. The only graphics-intensive things I do are watching videos and playing state-of-the-1990s games.

Current setup: Debian host (X+Fluxbox), KVM guest with SDL graphics, (emulated) vmware graphics card (the other one has >0.5s redraw times), and a standard Ubuntu installation. I can watch videos, but games are a bit choppy.

What doesn't seem to work: Non-SDL graphics (both VNC and X forwarding are very choppy), VGA passthrough (not implemented in KVM; Xen requires IOMMU, which my computer doesn't seem to support)

What I am thinking about (but I have very little knowledge on the subject): Trying to eliminate X from the host. I've heard myths about something called "framebuffer", but I don't know much else.

Best Answer

SDL is ok, but you should also try SPICE. Check out the wikipedia page for more info as well.

Related Solutions

KVM – How to Create KVM Guest with SPICE Graphics and TLS Disabled Using Virt-Install

Okay, I worked around it on my own. In the option:

--graphics spice,port=20001,listen=127.0.0.1

remove the port parameter such that it becomes:

--graphics spice,listen=127.0.0.1

You need to configure the <graphics /> element in the libvirt XML configuration file then. My invocation of virt-install gave me this:

<graphics type='spice' autoport='yes' listen='127.0.0.1'>
  <listen type='address' address='127.0.0.1'/>
</graphics>

There is one caveat. I finished the installation while SPICE was still connected to the default auto-connected port (5900 in my case). If you shut down the guest prior to finishing the installation the whole process initiated by virt-install will be interrupted.

In order to change it one should shut down the guest and the edit the XML to something like the following, using virsh edit vmname (where vmname should be replaced with your name):

<graphics type='spice' autoport='no' port='20001' listen='127.0.0.1'>
  <listen type='address' address='127.0.0.1'/>
</graphics>

Possible workaround for "port in use" conflicts. Use any of the local net addresses other than 127.0.0.1 from 127.0.0.0/24, e.g. 127.0.0.2 etc to listen on.

NOTE: If someone can come up with a better (i.e. actual) solution, I'll accept that other answer. This writeup is mostly for others that may run into the same issue.

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