[fedora-virt] Disk device performance in F11

Richard W.M. Jones rjones at redhat.com
Thu Jul 2 15:10:50 UTC 2009

On Thu, Jul 02, 2009 at 08:40:58AM -0600, Jerry James wrote:
> On Wed, Jul 1, 2009 at 2:37 AM, Richard W.M. Jones<rjones at redhat.com> wrote:
> > libvirt isn't just a wrapper around qemu-kvm, it drives half a dozen
> > different virtualization systems, giving you the benefit of
> > abstracting the details of the hypervisor from the management tools.
> > So for that reason we don't support tweaking the qemu command line
> > arbitrarily.  However if there are particular features of qemu or KVM
> > that you think we should support, please raise them.
> 1) Higher resolution.  My boss gave me two big monitors that can do
> 1920x1200, and all I can get for my guest machines is tiny little
> windows with hardly any room to work inside.

This is a limitation of the emulated Cirrus Logic graphics card.  In
the days or yore when those real graphics chipsets existed [I even had
one] 800x600 and 1024x768 in 16 bits was regarded as the cutting edge.

Eventually we'll have open source SPICE support (PV graphics driver)
which massively improves resolution and performance.  For example,
SPICE can stream videos by recompressing them on the fly between the
guest and host.

> 2) The ability to see what options qemu-kvm was invoked with.  Even if
> I can't change them, at least I can understand what I am getting.
> Right now, it's a black box to me.

I believe this is being worked on in upstream libvirt.  Also the other
way around (turn a qemu command line into a libvirt configuration


Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://et.redhat.com/~rjones/libguestfs/
See what it can do: http://et.redhat.com/~rjones/libguestfs/recipes.html

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