Re: [gentoo-user] Best way for good video performance in virtual machines

[Ralf]

Oh, I forgot about the gtk and sdl displays... I'll test them together
with QXL.

Thanks for your hint!

But anyways, I'll need two X servers when using this setup - one on the
VM and one on the hypervisor.
Shouldn't X11 forwarding be less overhead?

Thank you
  Ralf

On 06/25/2015 05:44 AM, wabenbau@×××××.com wrote:
> Ralf <ralf+gentoo@×××××××××××××××××××.de> wrote:
>
>> Hi out there,
>>
>> assume the following situation:
>>
>> I do have a minimalistic hypervisor running a minimalistic virtual
>> machine (qemu with kvm, qxl and spice).
>> Both systems, hypervisor and VM are able to run X servers and
>> apllications. The graphics card of the hypervisor is connected to a
>> monitor. This monitor only has to show one single standalone QT
>> application which is running on the virtual machine.
>>
>> What will give me more video performance?
>>
>> 1. Running a minimalistic X server on the virtual machine showing the
>> application AND running a minimalistic X server on the hypervisor
>> running remote-viewer
>> or
>> 2. Running a minimalistic X server on the hypervisor and using
>> X11-Forwarding via bridged ethernet
>>
>> Or maybe even someone knows a better solution?
>>
>> Thank you folks!
>>
>> Cheers
>>   Ralf
> On my system, qemu-kvm has the best performance with X11 on guest.
> I've also tested vnc and spice with qxl video driver on guest, but X11
> was faster.
>
> I can imagine that this depends on the hardware and screen resolution.
> So maybe on your system an other setup is better.
>
> My host GPU is a Radeon Ultimate R7 250, resolution is 3840x2160@60Hz,
> driver is xf86-video-ati.
> X11 compositing is deactivated on host as well as on guest.
>
> As "video card" on guest I use vmware (-vga vmware). Screen resolution
> on guest is 2386x1770. That seems to be the highest possible screen size
> that is available with this settings. I also tested other guest video
> drivers (std and cirrus) but vmware was the fastest and also the one with
> the highest resolution.
>
> Before I bought an UHD monitor, I used sdl as qemu display (-display sdl)
> in borderless fullscreen mode (-no-frame -full-screen). I used the same
> screen resolution on host and guest (1920x1200) and qemu was running on
> one of my virtual XFCE desktops.
> This was very handy. But as I've written before, it seems not possible for
> me to run qemu with UHD screen size. So fullscreen mode isn't possible any
> longer and now qemu runs in a window on my desktop (-display gtk).
>
> But with none of my setups it was/is possible to run a fullscreen video
> on the guest vm. Performance is much to slow for that. I've spent some
> time to make it faster, but I failed.
>
> I would be happy for any hints about better video performance with qemu.
>
> --
> Regards
> wabe
>