[Beowulf] Re: Pretty High Performance Computing

[Mark Kosmowski]

>
> Given the recent discussion of whether running
> multiple services and other such things affects
> the running of a cluster, I'd like to propose
> a new classification of computing.
>
> I call this Pretty High Performance Computing (PHPC).
> This is a style of computing where you sacrifice
> absolute high performance because of issues relating
> to any combination of convenience, laziness, or lack
> of knowledge.
>
> I know I've been guilty of all three but the funny
> thing is that science seems to get done anyway.
> There's no doubt computations would get done a little faster
> if I or the scientists spent more time worrying
> about microsecond latency, parallel barriers,
> or XML overhead but reality always gets in the way.
> In the future I hope to sin less often but it's a
> growing experience. Reading this, and other, email
> lists sometimes helps.
>
> Cordially,
>
> --
> Jon Forrest

My naive understanding of this recent discussion seems to indicate
that, perhaps serendipitously, these service level delays due to nodes
not being completely optimized for cluster use don't result in a
significant reduction of computation speed until the size of the
cluster is about at the point where one would want a full-time admin
just to run the cluster.  So, if you're a scientist and are able to
manage your small cluster without sacrificing too much research time,
don't worry about these service details too much, just do your work
knowing that you're maybe losing 2% speed (this number is a total
guesstimate).

However, if you're putting together a big cluster, you need to be
aware enough of these details to hire an admin who can do this sort of
optimization for you as well as keep the cluster running smoothly.

I'm sure someone will chime in if I've misunderstood something.

Mark Kosmowski