Re: Should we build i386 or i686 rpms?

[Aleksandar Milivojevic <amilivojevic pbl ca>]

Didier Casse wrote:
> Hello people!
>                     I have question that's on my mind for some time now:
> Does i686-optimized packages really give us improved performance over
> some of our i386-optimized cousins?

In most cases they don't.  The additional post-i386 instructions are 
mostly limited to things such as atomic locking, SMP support, and so on. 
 Therefore, only packages such as kernel and/or GNU C library benefit 
from being compiled as i586/i686.  Normal applications do not use atomic 
locking directly (they use API calls to things such as POSIX mutexes, 
that are implemented inside C library), and really don't need SMP 
specific instructions (those things are handled by the kernel and C 
library).

Of course, when we move to AMD64, it is completely different story.  For 
that platform, there is benefit if we want to utilize 64-bit data types, 
so we have almost all packages recompiled specifically for that 
platform.  Although, I would be much happier if Linux folks took 
approach from Digital Unix for Alpha processors and/or the approach 
OpenBSD folks have for 64 bit processors, and not the one from 64-bit 
Solaris (where there's also that terrible mix of 32-bit and 64-bit 
stuff).  IMO, wanna run 64-bit, do it clean, don't mix and match.

--
Aleksandar Milivojevic <amilivojevic pbl ca>    Pollard Banknote Limited
Systems Administrator                           1499 Buffalo Place
Tel: (204) 474-2323 ext 276                     Winnipeg, MB  R3T 1L7