[Spice-devel] SPICE Fedora 15 guest X running at 100%

John A. Sullivan III jsullivan at opensourcedevel.com
Wed Jun 15 13:08:43 PDT 2011

Since we were having some trouble as just outlined on our Windows tests,
we thought we would let SPICE put its best foot forward and try a Fedora
15 guest running on a Fedora 15 KVM host.

When it worked, it was amazing.  However, most of the time, the system
was barely responsive and the X process was consuming 100% of the CPU.
We initially thought this might be from KDE4 so we installed twm and
experienced the same.  We then launched a few applications without any
Windows Manager at all and saw the same results.

Alon was helpful on IRC and mentioned that it was because there was no
kernel module for the driver.

Does this mean that there is no driver for the QXL driver and thus it
runs in user space and drives up the utilization? If so, what are people
doing who are running this in production?

This leads to another question.  Our understanding is that rendering is
done on the client and not the guest unless the client is unable to do
so (haven't read enough on the protocol to understand how this is
determined).  Does this mean that, in cases where rendering is happening
on the guest that a high end graphics card in the physical host would
improve performance? Our experience with using NX is that the physical
hardware is never involved but that is a completely different paradigm.

If the rendering is taking place on the client, why is the lack of a
kernel module for QXL causing a problem? Thanks - John

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