[mythtv-users] CPU usage on an athlon64 3200 ...

[Michael T. Dean]

On 10/11/06 14:45, Chico Makani wrote:

> I've been running Myth for about 4-5 months on Ubuntu Dapper and an 
> ASUS P1AH1 (nvidia 6150) Athlon64 3200 and 1GB memory.  I'm running 
> the front/backend on this system with a PVR-150.  Last week I updated 
> from version .19 to .20.
>
> Recently I noticed that the cpu fan roars when I am playing video back 
> and transcoding at the same time.  (girlfriend complained.)  I'm using 
> standard resolution, not HD.   This may not be new because I wasn't 
> transcoding as frequently in the past.
>
> This lead me to look into the issue.  For reference, I recompiled the 
> from the 9/11 source and built the source using  --arch=k7 
> --enable-xvmc --enable-opengl-vsync.
>
> After some testing I settled on the standard video decoder with kernel 
> deinterlacing.  xvmc and libmpeg2 seemed to use more cpu as measured 
> using 'top'.
>
> Playback of medium resolution clips (480x480) requires 25-50% of the 
> processor (it jumps around a fair about).  Live TV requires a bit 
> more.   Whenever I play and transcode at the same time the CPU fan 
> comes on very loudly.  This happens even when the mythfrontend is 
> using 25%.
>
> I played the same clips using mplayer and xine and according to top 
> both used about 1/3 the cpu as mythfrontend -- about 10%.  If I'm 
> transcoding and play back with either of these players the system is 
> quiet.   I can understand that mythfrontend would be slightly less 
> efficient than these players but 3x indicates that I might not have 
> something configured properly.
>
> Any suggestions on what might be causing this?  Do I need to rebuild 
> w/ more optimization.  (considered using --k8 but I don't want to 
> introduce 64 bit issues).


As long as your compiling yourself, you /should/ update to something 
more recent than a month-old version of the code.  There have been many 
bugfixes since then.  Try again with an Oct 11 or later version.

However, as far as the performance goes, it sounds like you've disabled 
MMX usage--probably through all your "performance tuning" flags.  My 
recommendation is to recompile (a current version) using just 
"--enable-proc-opt" (and any other "--enable" arguments (like for 
opengl-vsync or xvmc or ...), but without things like "--tune", "--cpu", 
"--arch", etc.).  Optimizing away features is not really optimizing.  :)

Mike