Re: Why does C3 CPU downgrade in kernel 2.4.20?

Pavel Machek (pavel@ucw.cz)
Thu, 12 Dec 2002 19:09:57 +0100


Hi!

> > > I believe someone (Jeff Garzik?) benchmarked gcc code generation,
> > > and the C3 executed code scheduled for a 486 faster than it did for
> > > -m586
> > > I'm not sure about the alignment flags. I've been meaning to look
> > > into that myself...
> >
> > Interesting. I have no clue about which C3 you're talking about here
> > but a VIA Ezra has all 686 instructions including cmov and thus
> > optimising for PPro works best for me.
> >
> > Prolly I would have to do more benchmarking to find out about
> > aligment advantages.
>
> I heard cmovs are microcoded in Centaurs.
>
> s...l...o...w...

It still might be faster then a branch... or not if centaurs are
really that simple.
Pavel

-- 
Worst form of spam? Adding advertisment signatures ala sourceforge.net.
What goes next? Inserting advertisment *into* email?
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/