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. Jakub
