begin  quote
On Fri, 9 Jan 2004 09:09:17 +0100 (CET)
Pawel Maczewski <[EMAIL PROTECTED]> wrote:

> Hi,
>  I finally compiled my first gentoo system. right now, it's quite
>  small, cause I was thinking about not to compiling anything that I
>  won't
> need. But I'd like to get better performance, optimize some compiler
> flags... So, that's my question: what kind odf mcpu and march should I
> choose as I have AMD Duron CPU? my /proc/cpuinfo is this:
> 

> model name      : AMD Duron(tm) processor
> stepping        : 1
> cpu MHz         : 800.045
> cache size      : 64 KB
> flags           : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca
> cmov pat pse36 mmx fxsr syscall mmxext 3dnowext 3dnow

I'd suggest 
CFLAGS="-march=athlon -O2 -fomit-frame-pointer -pipe" 

(-march implies -mcpu, so stating cpu would be redundant)
i wouldn't suggest -O3 for this system as you are low on CPU cache, 
which means that you'd be far better off with the smaller, tighter,
binaries of -O2 .

> and, one more thing - if I wanted to change the compiler flags (maybe
> the-mcpu and -march also) do I have to go through all the compilation
> once again (bootstrap, etc)?

No, you don't need to. Just rebuilding the packages (if you really see
the need , then rebuilding all packages can be done with emerge -e
world)

However, there is little performance to gain between -march=i686 and
-march=athlon,  though there might be bordercases.  the cache issue with
-O3 vs. O2 is bound to give you a better boost though.

//Spider 


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