[mythtv] CPU detection/optimization

[Daniel Kristjansson]

On Wed, 2005-03-30 at 15:45 -0500, Tom Lichti wrote:
> When running the configure script I notice that my CPU (model name 
> : AMD Sempron(tm)   2200+) is detected and compiled as 'pentiumpro'. 
> There was a script posted to one of the lists called gccopts, which on 
> my system reports:
> 
>   -march=athlon-xp -mfpmath=sse -msse -mmmx -m3dnow
The "-msse -mmmx -m3dnow" are redundant with "-march=athlon-xp"
and will not improve performance much without -mfpmath=sse.
I'm not adding -mfpmath=sse as a default unless Issac wants
it. ffmpeg is uses hand optimized assembler and -mfpmath=sse
may trigger bugs in the compiler or ffmpeg which are difficult
to debug.

But if you can show -march=athlon-xp is faster than the default
I'll certainly make that change. Just play the same video with
each both sets of flags give me the results of 
  time mythtv 60_second_video_file.mpg

BTW -mfpmath=sse gives approximately a 10-20% speed boost to MythTV
depending on various factors.

-- Daniel