[Spice-devel] How much CPU load will spice server take? Is it possible to take spice client to do more processing?

[Hans de Goede]

Hi,

On 11/17/2010 09:24 AM, Sigbjorn Lie wrote:
> I believe what you're asking for is one of the core functions of Spice (see reference below).
> However I have seen the same result as yourself, when playing a 1080P video, the server is using
> 230%! CPU power of my Core i7 920 lab server.
>

The problem with playing back video, is that it needs to be decoded first, which happens inside
the guest (so on the host) then when *the decoded results* get send to the screen spice picks
them ups, detects its a video stream, mjpeg's it and sends it over the wire.

If you were to play back a lower resolution video and play that upscaled to 1080p, using the
qxl video card to do the upscaling. Then the decoding of the lower res. video (which is much
cheaper) would happen in the guest, the lower res video would be mjpeg-ed and send over
the wire, and then the spice-client would do the actual upscaling.

Video decoding is not accelerated by spice. And there is a reason most modern higher end
graphics card have video decoding acceleration. That reason being that doing hd video decoding
on the cpu is very expensive, which is what you are seeing here.

> http://www.spice-space.org/features.html
> Graphic commands - processes and transmits 2D graphic commands

Correct, and video decoding is not a 2d graphics command (otoh upscaling is).

Regards,

Hans


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> On Wed, November 17, 2010 09:09, xuzhinong999 wrote:
>> Hi, All,
>>
>>
>> We have VM performance issue during using of spice with QEMU/KVM. It seems only a few VM can run
>> on the host. After studying spice server source code, i find spice server will do all 2D graphic
>> processing and video decoding, so when VM starting and playing video, it sometimes use 100% cpu.
>>
>> My question is : can spice server share or even push the 2D and video processing to spice client?
>> Will spice community has this development plan?  In my point view, i think this may be possible.
>>
>>
>> Thanks.
>>
>>
>> Bill
>>
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