[Beowulf] SGI to offer Windows on clusters

[Richard Walsh]

Ashley Pittman wrote:
> On Wed, 2007-01-17 at 08:50 +0100, Mikael Fredriksson wrote
>> Yes, it is.  And more so if this cluster/LAN can also utilize som type
>> of "MOSIX" system.  This will substatially increase the throughput of
>> "standard serial" processes.
>>     
>
> I find this statement hard to comprehend, how can any OS substantially
> improve throughput of jobs unless what it replaces is incredibly
> deficient in some way?  The limiting factor on clusters is the speed of
> the hardware, even if some OS magically manages to be say 50% more
> efficient doing it's bit than another OS it's still only a tiny percent
> of time used, substantial improvements in job throughput can only come
> about from better parallel algorithms, better code or faster hardware.
>
>   
     While I agree with this argument, especially at small scale, at 
very large scale operating
     system derived load imbalance (so-called skew, due to the random 
nature of system
     call driven interrupts) can destroy scalability, and thus 
efficiency.  This is worth mentioning,
     although I would not expect Windows to improve on Linux in this 
context.  You need
     a light-weight kernel like Catamount to reduce skew.

     There is a very good paper showing the effects of skew at scale by 
Kerberyson, et al from
     Sandia. 

     rbw

-- 

Richard B. Walsh

"The world is given to me only once, not one existing and one
 perceived. The subject and object are but one."

Erwin Schroedinger

Project Manager
Network Computing Services, Inc.
Army High Performance Computing Research Center (AHPCRC)
rbw at ahpcrc.org  |  612.337.3467

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