Jason Holmes wrote:
Joe Landman wrote:
I have it on good authority that with the other chipset (we have a
Blackford here), we should see higher numbers. Not exceeding the
Opteron 275 though.
We have both a greencreek based (the one with the snoop filter.. I guess
they're calling it the 5000x now) and a blackford based system and I'm
not seeing any difference beyond a percent or two of performance either
in stream or in real applications. Maybe we just haven't hit the magic
app that greencreek helps yet.
There is some magic incantation to turn on some super-magic feature. I
think it is like an "11" setting for the memory system for specific
workloads. Since I don't have that one, I can't play with it :(
What I can say is that Woodcrest is interesting. It just may be
overhyped by a "compliant" media.
I'd say it's a bit overhyped, but it is giving us some good real
application numbers compared to the opterons. On NAMD, Amber, and VASP
so far, we've seen 2.66 GHz Woodcrest between 10-20% faster than our 2.4
GHz dual-core Opterons while using all 4 processors in a box. It's not
the 50% media hype numbers, but it's definitely an improvement on the
Intel side.
I agree its an improvement for Intel. My question is how much of that
is due to a larger cache per core on woodcrest? Memory bandwidth
doesn't look like its quite where I wanted it to be. I am seeing some
anomolous results with GAMESS that I need to try to understand better.
Some things the 275 is within a percent or so of the 2.66 GHz woodcrest,
and others, the Woodcrest is like 70% faster. The latter it is not
demonstrating with all, or even a majority of workloads.
10%=20% ain't bad, but if it is all due to clock, or all due to cache,
then thats not as good. Thats an ephermal lead. Will change.
While I would like to take the hype at face value, it is after all hype,
and marketing fluff. The only important data is where the binary meets
the silicon ... :) running real apps with real input decks they way
people really want to run them. Nothing correlates as well with
application performance as the application itself.
I want to get as much testing in with the 2.66 before I change up to
3's. Once I have that hopefully will be able to get a clearer sense for
what is clock dependent and what is better architectural changes.
Joe
Thanks,
--
Jason Holmes
--
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: [EMAIL PROTECTED]
web : http://www.scalableinformatics.com
phone: +1 734 786 8423
fax : +1 734 786 8452 or +1 866 888 3112
cell : +1 734 612 4615
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