[Beowulf] MS Cray

Joe Landman landman at scalableinformatics.com
Wed Sep 17 11:54:35 EDT 2008


Eric Thibodeau wrote:
> Joe Landman wrote:
>> Gus Correa wrote:
>>
>>> Otherwise, your "newbie scientist" can put his/her earbuds and pump 
>>> up the volume on his Ipod,
>>> while he/she navigates through the Vista colorful 3D menus.
>>
>> Owie .... I can just imagine the folks squawking about this at SC08 
>> "Yes folks, you need a Cray supercomputer to make Vista run at 
>> acceptable performance ..."
> Maybe they have a "tune options for performance" option ;)
>>
>> The machine seems to run w2k8.  My own experience with w2k8 is that, 
>> frankly, it doesn't suck.  This is the first time I have seen a 
>> windows release that I can say that about.
> A few questions (not necessarily expecting a response):
> 
> POSIX?
> VERBS?
> Kernel latency and scheduler control?

Don't mistake me for a w2k8 apologist.  I reamed them pretty hard on the 
lack of a real posix infrastructure (they claim SUA, but frankly it 
doesn't build most of what we throw at it, so it really is a non-starter 
and not worth considering IMO).  They need to pull Cygwin in close and 
tight to get a good POSIX infrastructure.  It is in their best 
interests.  Sadly, I suspect the ego driven nature of this will pretty 
much prevent them from doing this.  Can't touch the "toxic" OSS now, can 
they ...

IB Verbs?  Well through OFED, yes.  Through the windows stack?  Who 
knows.  We were playing with it on JackRabbit for a customer test/benchmark.

Kernel latency?  Much better/more responsive than w2k3.  Scheduler 
control?  Not sure how much you have.  I don't like deep diving into 
registries ... that is a pretty sure way to kill a windows machine.

> 
> These are the real barriers IMHO, without minimally supporting POSIX 
> (threads), there is very little incentive to use the machine for 
> development unless you're willing to accept the code will _only_ run on 
> your "desktop".
>>
>> The low end economics probably won't work out for this machine though, 
>> unless it is N times faster than some other agglomeration of 
>> Intel-like products.  Adding windows will add cost, not performance in 
>> any noticeable way.
>>
>> The question that Cray (and every other vendor building non-commodity 
>> units) is how much better is this than a small cluster someone can 
>> build/buy on their own?  Better as in faster, able to leap more tall 
>> buildings in a single bound, ... (Superman TV show reference for those 
>> not in the know).  And the hard part will be justifying the additional 
>> cost.  If the machine isn't 2x the performance, would it be able to 
>> justify 2x the price?  Since it appears to be a somewhat well branded 
>> cluster, I am not sure that argument will be easy to make.
> I just rebuilt a 32 core cluster for ~5k$ (CAD) (8*Q6600 1Gig RAM/node + 
> gige netwroking). Bang for the buck? I can't wait to see the CX1's 
> performance specs under _both_ windows and Linux.

The desktop CPUs/MBs will get you best bang per buck, as long as you 
don't mind no ECC, and 8GB ram limits per node.  For your applications, 
this might be fine.  For others, with large memory footprint and long 
run times, I see people need/require ECC (as memory density increases, 
ECC becomes important .... darned cosmic rays/natural decays/noisy power 
supplies/...)

> 
> Eric


-- 
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: landman at scalableinformatics.com
web  : http://www.scalableinformatics.com
        http://jackrabbit.scalableinformatics.com
phone: +1 734 786 8423 x121
fax  : +1 866 888 3112
cell : +1 734 612 4615
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