[fedora-virt] kvm "tablet" device burning cpu cycles

[Andrew Cathrow]

----- Original Message -----
> From: "Eric Blake" <eblake at redhat.com>
> To: "For testing and quality assurance of Fedora releases" <test at lists.fedoraproject.org>
> Cc: virt at lists.fedoraproject.org
> Sent: Tuesday, December 6, 2011 6:33:43 PM
> Subject: Re: [fedora-virt] kvm "tablet" device burning cpu cycles
> 
> [redirecting to the fedora virt list]
> 
> On 12/06/2011 03:36 PM, Dennis Jacobfeuerborn wrote:
> > Hi,
> > I noticed that when you install a virtual system with virt-manager
> > it
> > always installs a tablet device by default.
> > The problem is that this device consumes 10% of cpu resources of
> > the host
> > according to "top" which should probably be considered a bug.
> 
> The poor behavior of a tablet device should be raised against the
> qemu
> team, to see if it can be made more efficient.
> 
> > What is worse is that removing the tablet also means no mouse
> > pointer
> > showing up in a centos 6 guest which means you are pretty much
> > forced to
> > use the tablet device.
> 
> Meanwhile, sufficiently new qemu provides USB device emulation, which
> is
> more efficient than the PCI tablet emulation; although it is not as
> apparent whether typical guests support that device driver in their
> default install (one of the reasons we default to the older tablet
> emulation is that it is likely to have a driver pre-installed on most
> guest OSs).  The idea of swapping the default to a USB pointer should
> be
> raised against virt-manager and/or python-virtinst, when installing a
> new-enough guest OS with new enough qemu support, while continuing to
> provide the compatible fallback of the tablet for older setups.

Also we've found Spice more efficient in our testing.

> 
> --
> Eric Blake   eblake at redhat.com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
> 
> 
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