[mythtv] CPU detection/optimization

[Tom Lichti]

Daniel Kristjansson wrote:

>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
>  
>
Not sure what that is supposed to show, other than it takes 60 seconds 
to play 60 seconds? Anyway, the results of that test (using a CVS build 
from the 23rd, one from this afternoon, both with 'pentiumpro' as the 
march, and one from today with 'athlon-xp' as the march) didn't show any 
appreciable difference doing the above test. I just catted /dev/video1 
to tmp.mpg for 60 seconds, and then used that as the source for the test.

Tom