kline at tao.thought.org
Thu Mar 15 05:39:03 UTC 2007
On Thu, Mar 15, 2007 at 02:47:42AM +0100, Karol Kwiatkowski wrote:
> 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)
> % [...]
Dunno anything about the Xeon, but the Kayak is nuilt like a
tank and has got to be == a 686 also. I'll check my dmesg
too. --Until very recently, I've gone wit the default (i386??);
like: how much faster is gcc tweaking going to be? I guess I'll
> > 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).
Martin Tournoij pointed out what (fine-print) I didn't see
[never read/very seldom read] that the world and kernel should be
left at O, O2 or their default. I signal to gcc to unroll loops
and know that the compiler writers are going to use their
learned and practical wisdom regarding loop unrolling... .
It has and thanks much. Gotta rebuild, but no big deal!
> Karol Kwiatkowski <karol.kwiat at gmail dot com>
> OpenPGP 0x06E09309
Gary Kline kline at thought.org www.thought.org Public Service Unix
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