[Beowulf] how Google warps your brain

Mark Hahn hahn at mcmaster.ca
Thu Oct 21 15:01:23 PDT 2010

>> I'm pretty convinced that, ignoring granularity or political issues, shared
>> resources save a lot in leadership, infrastructure, space, etc.
> OTOH, it's just those granularity and cost accounting issues that led to
> Beowulfs being built in the first place.

I'm not really sure I understand what you mean.  by "granularity", I just
meant that you can't really have fractional sysadmins, and a rack with 1 node
consumes as much floor space as a full rack.  in some sense, smaller clusters
have their costs "rounded down" - there's a size beneath which you tend to
avoid paying for power, cooling, etc.  perhaps that's what you meant by cost-

but do you think these were really important at the beginning?  to me,
beowulf is "attack of the killer micro" applied to parallelism.  that is,
mass-market computers that killed the traditional glass-house boxes:
vector supers, minis, eventually anything non-x86.  the difference was 
fundamental (much cheaper cycles), rather than these secondary issues.

> I suspect (nay, I know, but just can't cite the references) that this sort
>of issue is not unique to HPC, or even computing and IT.  Consider
>libraries, which allow better utilization of books, at the cost of someone
>else deciding which books to have in stock.

well, HPC is unique in scale of bursting.  even if you go on a book binge,
there's no way you can consume orders of magnitude  more books as I can,
or compared to your trailing-year average.  but that's the big win for HPC 
centers - if everyone had a constant demand, a center would deliver only 
small advantages, not even much better than a colo site.

> And consider the qualitatively
>different experience of "browsing in the stacks" vs "entering the call
>number in the book retrieval system".. the former leads to serendipity as
>you turn down the wrong aisle or find a mis-shelved volume; the latter is
>faster and lower cost as far as a "information retrieval" function.

heh, OK.  I think that's a bit of a stretch, since your serendipity would 
not scale with the size of the library, but mainly with its messiness ;)

>get paid for. And this is because they've bought a certain amount of
>computational resources for me, and leave it up to me to use or not, as I
>see fit.

I find myself using my desktop more and more as a terminal - I hardly
ever run anything but xterm and google chrome.  as such, I don't mind 
that it's a terrible old recycled xeon from a 2003 project.  it would seem
like a waste of money to buy something modern, (and for me to work locally)
since there are basically infinite resources 1ms away as the packet flies...

regards, mark.

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