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

[Alon Levy]

On Wed, Jun 15, 2011 at 04:58:21PM -0400, John A. Sullivan III wrote:
> On Wed, 2011-06-15 at 16:08 -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.
> > 
> > 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
> 
> I checked my Xorg.0.log file and noticed that I was getting persistent
> messages about cache failures and out of memory.  It looks like the vram
> parameter was set to something like 9216.
> 
> So I changed it to 256000.  To my surprise, the SPICE client connected
> but I had no mouse and no keyboard.  I stopped the VM and redefined it
> with 128000 and I now had keyboard and video but still had the same
> excessive X utilization - John

hmm.. yes, this is a well known problem - I thought libvirt fixed it. What
version of libvirt are you using? The default memory is 64MB btw.

> 
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