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Date: Mon, 24 Jun 2002 15:06:12 +0200
From: "J.A. Magallon" <jamagallon@able.es>
To: "Craig I. Hagan" <hagan@cih.com>
Cc: Sandy Harris <pashley@storm.ca>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Linux, the microkernel (was Re: latest linus-2.5 BK broken)
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On 2002.06.24 Craig I. Hagan wrote:
>> Also, it isn't as clear that clustering experience applies. Are clusters
>> that size built hierachically? Is a 1024-CPU Beowulf practical, and if so
>> do you build it as a Beowulf of 32 32-CPU Beowulfs? Is something analogous
>> required in the OSlet approach? would it work?
>
>a system of that size has many "practical" applications. It *can* be done
>without partitioning it into a tree hierarchy, however, you will need a very
>capable interconnect (quadrics and myrinet come to mind). Tt that you'll have a
>tiered switching hierarchy even if the nodes are presented in a flat layer.
>
>IMHO nearly any level of breakout for grid computing (basically a cluster
>hierarchy) starts to become interesting as a function of your app/problem size
>and how many simultanous jobs you are running.
>
>Of course, we can stop and hit reality for a second: not many people can afford
>a 1024 cpu cluster, hence the proliferation of smaller ones ;)
>

You do not have to go so far. Take a simple cluster of dual Xeon boxes (ie, 
4 'cpus' per box). Current clustering software (MPI, PVM) is not ready to
handle a 2-level hierarchy, one with slow communications over tcp and a lower
level working as a shared-memory thread-able cluster.
It would not be so strange nowadays (nor too much expensive) to have a 8-16
nodes with 4 cpus each.

-- 
J.A. Magallon             \   Software is like sex: It's better when it's free
mailto:jamagallon@able.es  \                    -- Linus Torvalds, FSF T-shirt
Linux werewolf 2.4.19-pre10-jam3, Mandrake Linux 8.3 (Cooker) for i586
gcc (GCC) 3.1.1 (Mandrake Linux 8.3 3.1.1-0.6mdk)
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