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 -- Clean custom Red Hat Linux rpm packages : http://freshrpms.net/ Fedora Core release 2 (Tettnang) - Linux kernel 2.6.8-1.521 Load : 1.00 1.08 1.11
