Re: Re: glibc recompile - optimized for G5 cpu target

[Peter Saisanas <psaisanas@gmail.com>]

Hi Brock,
I have tried lmbench and recompiled glibc 2.21-6 with -O3 and -O2 
optimizations with the cflags below:
extra_cflags = -mcpu=G5 -mtune=G5 -maltivec -mabi=altivec

I haven't actually seen any marked difference to the results coming out 
of lmbench when using the default Debian glibc and my recompiled glibc 
with cflags above and -O2 and O3 optimization levels.

In other words, i can equate my naive attempts at ricing out glibc the 
equivalent of just adding a sports muffler and big spoiler. :)

My Debian install does seem to be running quite well, it does seem to 
perform a just that little bit better, but perhaps it is just a placebo 
effect!

So unless I'm using the wrong benchmark, or the chosen cflags have no 
effect on the compilers output of glibc, i have nothing to show for my 
efforts! :(

Am i doing something wrong, or is there simply no extra performance to 
be had just by playing with the cflags and recompiling glibc?

Cheers,
Peter