[mythtv-users] More XvMC data points

Tom Lichti tom at redpepperracing.com
Mon Dec 4 16:35:13 UTC 2006

Michael Tiller wrote:
> On 11/29/06, *Michael Tiller* <michael.tiller at gmail.com 
> <mailto:michael.tiller at gmail.com>> wrote:
>     Just out of curiosity...when you say 65-75% CPU utilization, how is
>     that partitioned between the X server and the frontend?  I ask
>     because if I try and watch without XvMC on my system, the X server
>     is something like 30% and the frontend is like 70%.  I'm wondering
>     if this load on the X server can be avoided somehow.  Then I might
>     have a chance to watch HD natively. 
> I just wanted to circle back on this issue of X server utilization.  I 
> installed a 2.4GHz P4 in my machine to replace the Celeron that was 
> there.  Now when I attempt non-XvMC playback, I get something like 47% 
> CPU for the frontend and 50% CPU for the X server.
>  From all the data I have seen, this seems like extremely high 
> utilization of the X server.  I just have this sense that perhaps there 
> is something poorly configured here that it requires so much CPU from 
> the X server.  I know the XvMC gives you access to the motion 
> compensation framework but am I perhaps missing something more 
> fundamental like some acceleration that would allow direct writes to the 
> framebuffer or something?!?
> --
> Mike

I was doing some playing around with my main frontend last night, and 
playing an HD signal without XvMC enabled, I had (on a dual core P4) 99% 
usage on core one (MFE) and 56% usage on core two (X). With XvMC 
enabled, I had about 45% CPU combined, so XvMC *is* working for me on my 
main system. This was with current SVN as of last night, and the latest 
nVidia beta drivers (9742). I had no stuttering, no prebuffer pauses, or 
any other issues, aside from what *seems* like frame skipping, but I see 
nothing in the logs to indicate that, so I'm not sure if it's real or not.

My backup frontend I have not tried yet.


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