Re: RFC: Fedora Extras shipping ix86 optimized rpms?

[Matthias Saou <thias spam spam spam spam spam spam spam egg and spam freshrpms net>]

Jakub Jelinek wrote :

> On Tue, Aug 31, 2004 at 05:38:31PM +0200, Matthias Saou wrote:
> > Is then having the same library twice, the regular one in /usr/lib and
> > the SSE2 optimized one in /usr/lib/sse2, expected to "just work" at
> > runtime? If
> 
> Yes, it will just work.
> Both the dynamic linker and ldconfig know how to handle it.
> 
> > so, I didn't know the existence of this, and will definitely look into
> > it. What about MMX? Should one just simplify with SSE vs. non-SSE
> > instead and put (non runtime) MMX optimized libs there too?
> 
> ATM sse2 is the only "important" feature ld.so on IA-32 handles.
> Previously it used to be mmx, but as every added feature slows down
> library loading when not using ld.so.cache (e.g. when LD_LIBRARY_PATH
> is used or DT_RPATH; every feature doubles the number of stat'ed
> directories before the non-existing directory cache is filled),
> it was just changed to sse2 instead of adding sse2 to mmx.
> SSE2 was chosen because you can get quite a big speedup already
> by recompiling with -msse2 -mfpmath=sse.

Thanks for this valuable insight. I'll dig into a few relevant multimedia
packages and make a few "plain vs. optimized" tests of my own to see what
gives.

Matthias

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