[Beowulf] Southampton engineers a Raspberry Pi Supercomputer

Prentice Bisbal prentice.bisbal at rutgers.edu
Wed Sep 12 10:26:36 PDT 2012

I agree with Ellis 100%. Ellis, if you're still a student, you've got a 
bright future ahead of you.


On 09/12/2012 12:02 PM, Ellis H. Wilson III wrote:
> On 09/12/2012 11:42 AM, Vincent Diepeveen wrote:
>> On Sep 12, 2012, at 5:24 PM, Lux, Jim (337C) wrote:
>>> So, the question is...   what's the smallest number of nodes in a
>>> "demo/toy" cluster that gives you the "big iron" feeling.  I'm
>>> going to guess that 4 is too few.
> I'd say even 16 would get you where you wanted to go, provided you get a
> few smaller switches so the students can understand/run into network
> topology problems (like why full bisection bandwidth really matters) as
> well.  If it's all on one switch networking will not really matter,
> which it does a lot in "big iron."
>> But most important: working with junk slow old hardware is not
>> interesting to students. They want to be FASTER than their home PC.
>> So give them a cluster where the software running on it is FASTER
>> than their home PC.
>> That's your  first priority, or they wll be all total desinterested.
> As someone who is still a student and who first put together his first
> Beowulf cluster in 2008 made from "totally crap" PIII's that were in
> some science building's attic of my University, and can speak from
> experience that this vantage point is totally wrong.  I was perfectly
> excited overcoming the issues to get the 4 PIIIs I had to go 4x faster
> than 1 PIII, since after all, you are going to run into very similar
> infrastructure problems with a newer machine anyhow.  I was just
> learning the ropes about scalability then, learning how to code in MPI,
> how to properly profile and monitor my system, how to install things in
> parallel, etc -- I wasn't trying to set a flop record or anything.  This
> would be like taking a collegiate mechanical engineering class and
> expecting kids to make a go-kart that was all-around better than their
> car sitting back in their parking lot -- totally unrealistic.
> In short, you've shared this negative, "if it's not faster then forget
> about it" sentiment before Vincent, and it's neither constructive to the
> conversation nor to be reasonably expected from Professors trying to run
> a solid class on a budget.  If I was the teacher, had a constrained
> budget, and had the choice between 2 standard machines to share with the
> whole class that WOULD go faster than the student's machines at home or
> 16 Raspberry Pi's that WOULDN'T go faster (for most workloads) than the
> home computer, I would of course choose the latter.
> When you are trying to educate people about cluster computing, the most
> important thing is conveying the difficulties (both performance and
> infrastructure related) working at scale -- not simply showing off that
> the thing is "faster."  Remember, students are paying CUSTOMERS for the
> education; you should assume they are already interested in the concepts
> and theory.  It's not the educators job to spark this interest or feed
> some flop-lust, but it is their job to expose as much of the theory and
> pragmatics to the student as possible.  This IS possible with MANY
> slower machines, but ISN'T possible with FEW faster machines.  If a few
> students are being stubborn like you and want to drop the class because
> the cluster isn't "fast enough," their loss.
> Best,
> ellis
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