Optimizationn questions?

Karol Kwiatkowski karol.kwiat at gmail.com
Thu Mar 15 01:48:08 UTC 2007

Gary Kline wrote:
> 	Two quick one for kernel and/or compiler wizards:  first, is
> 	a 400Mz processor considered a 586 (for my KERNELCONF file)?

That depends on processor architecture rather than clock frequency. Have
a look at dmesg output - for example, Intel Celeron 400Mhz is a 686
class processor (I686_CPU in the kernel configuration file):

% dmesg
% [...]
% CPU: Pentium II/Pentium II Xeon/Celeron (400.91-MHz 686-class CPU)
% [...]

> 	Second, is it safe to do a buildworld with -O3?  If there are
> 	stability concerns, I'll go with the default when I rebuild my
> 	6.2 systems.

If you're going to do stability/performance/compatibility tests go
ahead. In any other situation just stick with the defaults, which on
6.2-RELEASE for my Celeron are:

# (cd /usr/src && make -V CFLAGS )
-O2 -fno-strict-aliasing -pipe -march=pentiumpro

Note that '-march=pentiumpro' comes from setting 'CPUTYPE=i686' in
/etc/make.conf (examples in /usr/share/examples/etc/make.conf).



Karol Kwiatkowski   <karol.kwiat at gmail dot com>
OpenPGP 0x06E09309

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