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Hamburgers, Beer, and Clusters

I find Pablo Picasso's famous response on computers, "Computers are useless. They can only give you answers," interesting and provocative. I also believe there is a grain of truth in that statement — namely, that it's really important to ask the right questions of computers. I have a hard time with the useless part, however.

I find Pablo Picasso’s famous response on computers, “Computers are useless. They can only give you answers,” interesting and provocative. I also believe there is a grain of truth in that statement — namely, that it’s really important to ask the right questions of computers. I have a hard time with the useless part, however.

We ask important and world-changing questions of computers (and clusters) everyday. I call these the what questions. For instance, “What is the lowest energy state of this molecule?” or “What happens when I try an align these two genome sequences?” or “What does this seismic data tell us about possible oil in the ground?”. These questions yield important information.

The How Questions

When discussing HPC clusters, and computing in general, other questions arise. I call these the how questions. These question often need to be answered before computation begins. For instance, “How do I solve this problem quickly?” or “How do I solve this problem within my research budget?” or “How to program 128 cores?”

The answers often begin with hardware choices and end up with software issues (i.e. telling the computer how to solve a problem). The how questions are often include many dimensions and can have a lasting effect on future decisions and costs. That decision to write everything in Turbo Pascal probably seemed like a a good idea at the time. Thinking carefully about how we do things in HPC is important and, as I found out last week, goes well with hamburgers and beer.

Hamburgers and Beer

If you recall, I had announced the formation of the NYCA-HUG (New York City Area HPC Users Group). We held our first meeting last Thursday. Seven people, including myself, attended and after some hamburgers and beer the discussions moved to some of the most important howquestions about cluster and HPC.

The first question is a classic, “How does one define a supercomputer?” Should it be based on cost or performance or some other metric? We had no clear answer, but all agreed that the target is moving rapidly. Next there was a question about power usage, like how could one turn off unused nodes and then turn them back on when needed and other such strategies. Most academic sites seem to concede that their clusters are not fully utilized, but are still using plenty of electricity. Perhaps the most provocative question was “How do we teach high school students about cluster programming so that what they learn today will work tomorrow’s technology?”

Such great open-ended questions, and so little time. Discussing questions that don’t have a single answer (non-deterministic in programming terms) is a great exercise. As a group we did not really have any solid answers, but I think we came away more enlightened and better informed.

So what did I learn? I gleaned some interesting insights from the discussion. Everyone seemed to agree that in academic/university situations power and cooling is often considered Someone Else’s Problem. The facilities budgets are often different from the research budgets (because “university overhead” is a big up-front part of most research grants). The consensus was that because power and cooling are out of the equation often the number of nodes/cores is the goal of the procurement process.

My views on software were confirmed as well. Everyone agrees it is a big issue as we move forward. Nothing new here, except that multi-core architecture does not seem to play big in procurement decisions while some of my tests have shown CPU architecture can be important in scaling. It seems the more nodes/cores the better.

And finally, after discussions like these, I like to think of how I better understand the how questions about clusters. Putting the self reference issue aside for now, the answer is simple — conversations. Whether it be small groups around the table or a mailing list, the two way conversations and even good arguments are at the core of the HPC revolution we are now experiencing. The fact that much of the HPC infrastructure is open helps quite a bit, but I’ll leave that for another column.

Our next meeting is December 6, if you are in the NYC area stop by. Check the NYCA-HUG page for more information.

In regards to Picasso, dear Pablo, there is only one answer really (42). And, to borrow a phrase from Deep Thought, a supercomputer character from Douglas Adams’ Hitchhiker’s Guide to the Galaxy series:

I think the problem, to be quite honest with you, is that you’ve never actually known what the question is.

More Conversations (and Beer)

It is that time again. SC07 is here. This year the HPC hoards descend upon Reno Nevada. In the name of shameless promotion I wanted to mention two events that will probably feature a few HPC conversations as well as beer and maybe a hamburger.

Monday Night (November 12) after the Gayla you don’t want to miss the SC07 LECCIBG pool tournament (pool playing is not required). Those of you that have attended these in the past know the drill. Most people usually don’t get arrested. Check out the cool invite.

Tuesday Night (November 13) The equally infamous Annual Beowulf Bash will be held at Third Street Blues in downtown Reno from 6-8 p.m. Most of the early Beowulf pioneers show up at this event. Plenty of conversations for everyone. The club is close to several of the conference hotels, but you’ll need one of the conference shuttle buses from the Sparks convention center. The address is 3rd Street Blues, 125 W 3rd St, Reno, NV Next to the ElDorado Casino, (on-street parking readily available).

If you can’t make the SC07 show, stay tuned to Today’s HPC Clusters for plenty of coverage.

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