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Re: The new scheduler and x86 CPUs
- To: Toon Moene <moene at knmi dot nl>
- Subject: Re: The new scheduler and x86 CPUs
- From: Vladimir Makarov <vmakarov at redhat dot com>
- Date: Wed, 29 Aug 2001 11:15:12 -0400
- CC: gcc at gcc dot gnu dot org
- References: <3B8CAF7C.691F6BF0@knmi.nl>
Toon Moene wrote:
> Vladimir Makarov wrote:
> > As for the data, I see the following
> > http://www.spec.org/osg/cpu2000/results/res2001q2/cpu2000-20010604-00681.html
> > Alpha 833Mhz: base : 643
> > http://www.spec.org/osg/cpu2000/results/res2001q2/cpu2000-20010522-00660.html
> > Itanium 800 Mhz: base: 701
> > If 342 for Itanium were for gcc, I would not be surprised.
> <Shrug> Look again. The 342 for Itanium vs. 544 for Alpha is for the
> _apsi_ program.
> This makes it (again) clear why it is so dangerous to *only* look at the
> bulk number for SPEC, something that SPEC keeps pointing out.
> The reason why it is interesting to look at a weather forecasting
> program (actually, apsi is a dispersion model based on a weather
> forecasting model) is that these programs tend to *not* have a single
> hotspot that you can easily design your compiler for.
> Of course, this doesn't rule out that OOO implementations wouldn't run
> out of steam eventually against newer paradigms, but the Itanium is
> definitely not proof of that.
I don't know why this test is better on Alpha. But I think this is
not merit of OOO. May be because Alpha has a bigger L2 cache (8Mb vs.
4Mb of Itanium). Or may be because Compaq used KAP optimizer. Intel is
a novice in high performance computing. Compaq (former DEC) are one of
the most experienced in this field. They was the first which adopt
Fortran90 (actually they bought a company for this). I agree that if
you are going to buy computer for given task, you need a solution not a
Actually I did not want to start a war about what architecture is
better. As probably you, I like diversity and do not like a monopoly.