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

[John A. Sullivan III]

On Thu, 2011-06-16 at 01:39 +0200, Alon Levy wrote:
> On Wed, Jun 15, 2011 at 04:08:43PM -0400, John A. Sullivan III wrote:
> > 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.
> 
> Heh, seeing as windows support is much more advanced that is not quite how
> I'd put it. Certainly we are working on putting linux on equal footing, but
> the most work so far has gone into the windows driver, not the linux one.
> 
> > 
> > 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.
> 
> Maybe that seemed implied, but I didn't mean it like that. I just mentioned
> this in passing, that a kernel module doesn't exist. The main thing we could
> use a kernel module for is interrupt support. But spice works without that as
> well, since the communication is done asynchronously most of the time from
> host to guest (and this is the only place where an interrupt is useful - to
> wakeup the guest occasionally).
> 
> > 
> > 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.
> > 
> 
> Rendering is done on the client always. It is also done on the server if
> the guest requires the results of rendering, which can happen for instance
> when you do a print screen.
> 
> > If the rendering is taking place on the client, why is the lack of a
> > kernel module for QXL causing a problem? Thanks - John
> 
> Not the problem. The problem is simply in the X driver, and perhaps you can supply
> some more details to allow to reproduce the 100% cpu scenario?
<snip>
Hello, all.  This is still an issue for us.  What additional information
can we provide to help resolve this problem? Thanks - John