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

[John A. Sullivan III]

On Sat, 2011-07-02 at 04:57 +0200, Alon Levy wrote:
> On Fri, Jul 01, 2011 at 04:29:50PM -0400, John A. Sullivan III wrote:
> > 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
> > 
> Well, I want to reproduce this, so I guess if you could point out something specific,
> what is the client hardware, which client are you running, what is the guest doing?
> Also, could you try both spicec and spicy/vinagre?
I created a Windows netbook and compiled spice client from 0.8.1.  I
connected to the Fedora 15 guest and still had the same excessive CPU
utilization with our very simple test of opening konsole to run top and
then opening kwrite.  I did not expect this would solve the problem basd
upon Alon's statement that it is a guest driver problem and I was not
disappointed! The problem remained.  Is there any further information I
can supply to help solve this problem? Thanks - John