[mythtv] Compiler opt flags

[Isaac Richards]

On Friday 16 May 2003 12:52 am, Ben Bucksch wrote:
> I see that strong optimizing tops are enabled in settigns.pro for
> "release" (optimized) builds. That's a good idea, given that MythTV is
> very CPU-hungry.
>
> Given that gcc 3.0 and later has special optimizations for Athlon, even
> distinguishing between Athlon types as I just saw, maybe add a note
> about that to the HOWTO
> <http://www.mythtv.org/docs/mythtv-HOWTO-5.html#ss5.1>?
>
> But more importantly, it seems to me that avcodec and avformat, which
> are used to compress the video and do the actual hard and CPU-intensive
> work (right?), don't use these flags. The only opt flag I noticed was
> -O3, no CPU opt. The step from -march=pentium to -march=pentiumpro can
> mean 5-10% performance increase (tested with gcc 2.95 and Mozilla), so
> it seems significant, esp. considering that you build the rest of MythTV
> with those flags anyways.

Well, a lot of the most important parts of libavcodec are already written in 
mmx, so you don't really see much gain, if any, from compiling with different 
opts.

Isaac