typodupeerror

## Low Energy Supercomputing159

Faith Singer at TACC writes "The term 'supercomputing' usually evokes images of large, expensive computer systems that calculate unfathomable algorithms and run on enough energy to support a small city. Now, imagine a supercomputer, but run on the electrical equivalent of three standard-size coffee-makers. This year's international supercomputing conference, SC10, will feature the Student Cluster Competition that challenges students to build, maintain, and run the most-cutting edge, commercially available high-performance computing (HPC) architectures on just 26 amps."
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## Low Energy Supercomputing

• #### Amps = current, not energy.... (Score:5, Informative)

by Anonymous Coward on Wednesday August 25, 2010 @04:02PM (#33373084)

Amps = current, not energy....

• #### Re:Amps = current, not energy.... (Score:5, Informative)

on Wednesday August 25, 2010 @04:06PM (#33373144)
Assuming P=IV, RMS, and in-phase:

P = (26 A)(100E6 V) = 2.6GW, more than twice the amount of power required to travel from 1985 to 1955 or vice versa.

And energy is measured in joules, not amperes...
• #### Times voltage times session time (Score:5, Informative)

<tepples@gmail.BOHRcom minus physicist> on Wednesday August 25, 2010 @04:15PM (#33373260) Homepage Journal

Current * voltage = power. In the United States, alternating current from the wall is nominally 115 volts, and 115 V * 26 A = 2990 W. So I think the actual figure was supposed to be 3 kW of power. Run this for one eight-hour day* for 24 kJ of energy per session.

* This can be business hours (if interactive) or the most efficient cooling hours (if batch).

• #### Re:I hope they're smarter than the article writer (Score:4, Informative)

on Wednesday August 25, 2010 @04:22PM (#33373362)

It's like saying someone weighs 686 Newtons.

Nope, because that would be correct (other than capitalization). Newtons are a unit of force, and weight is the force of gravity on a thing.

It's not even like saying someone weights 100 kg, which is conventional but wrong: weight is not mass, weight is mass*acceleration.

It's more like saying someone weights 150 m/s. That is, it makes no sense whatsoever without supplying some additional information. If I had an instrument that accelerated objects under a constant force for a fixed time I could get a value in m/s that would allow me to compute the weight if I had the force and the time, in the same way it would be possible to get the energy from the amperage if you had the voltage and the time.

• #### The limit is 26 amps @ 120VAC (Score:5, Informative)

on Wednesday August 25, 2010 @04:42PM (#33373580)
From the project website (http://sc10.supercomputing.org/?pg=studentcluster_rules.html)

The computational hardware (processors, switch, storage, etc.) must fit into a single rack. All components associated with the system, and access to it, must be powered through the two 120-volt, 20-amp circuits, (each with a soft limit of 13 amps) for a total of 26 amps, provided by the conference. Power to each system will be provided via metered power distribution units The equipment rack must be able to physically hold these metering power strips.

This makes it even harder since theyir hardware has to be power balanced between the two power strips. They'll have to come up with some dynamic load balancing between cluster nodes based on power consumption. I guess dual power supplies might help (do dual power supplies draw perfectly balanced power between both power inputs?), but at a loss of power efficiency.

• #### Re:I hope they're smarter than the article writer (Score:2, Informative)

on Wednesday August 25, 2010 @05:33PM (#33374310)

Why assume 110V?

Because as stated before, 110 times 26 ~ 3 kW. And a coffee maker is about 1 kW, so three coffee makers is 3 kW, in agreement with the summary.

• #### Re:Times voltage times session time (Score:3, Informative)

<delirium-slashdot.hackish@org> on Wednesday August 25, 2010 @06:07PM (#33374842)

How many computers do you know that plug into 7200V 3-phase outlets? It's pretty standard when plugging computers into power-limited circuits to measure the allocated power by amperage. That's how power allocations are quoted at colocation facilities, for example: you rent a rack with a 20-amp circuit, or with a 30-amp circuit, or whatever. Unless stated otherwise, in North America it's implied that the circuit is at 110-V.

• #### Re:Sure Thing! (Score:1, Informative)

by Anonymous Coward on Wednesday August 25, 2010 @06:14PM (#33374952)

I was part of Purdue University's team last year. No, you don't get 240V power like in a proper machine room. You don't even really get 120V all that well, at least on the mediocre power system at the conference center we were at. With the load we had, voltage dropped to around 100V, and so current accordingly rocketed up and we had to scale back in order to avoid tripping the breaker.

• #### I was captain of the team that won last year... (Score:5, Informative)

on Wednesday August 25, 2010 @09:07PM (#33376564)
...Stony Brook University, and the piece that's missing from the summary is 26 amps@120v, (dual circuits, soft capped at draw of 13 each)

Links to more info from the conference: SC10 CC Page [supercomputing.org], rules [supercomputing.org], and app list [supercomputing.org].

The competition is harder than it sounds, you have to build a cluster from the ground up, fit it into the power requirement (which means stripping out redundancies among other things), strip down a distro (we used Debian as a starting point), get the apps optimized, and then run through the data sets. Your team needs to *understand* the apps, the OS, and the hardware in order to win. There are several people from various teams from past years who have moved on to doing their PhDs in comp sci based on work from this competition (At Carnegie Mellon, MIT, and UMich off the top of my head).

It's important too, in a few ways. For one I know I learned more about clusters the first day I started working on the team for this competition back in 2007 than I ever knew before. That knowledge has led to research fellowships, jobs, and knowledge of what I want to (biochemical modeling). It's an experiance that very few undergrads get, and I think that's a shame.

For the industry it's an important highlight of what can be done with a lot of dedication and a focus on wringing the most from your hardware and software. and in doing that we showcase a lot of work that people dont think about. For example our cluster last year ran off a single disk, plus a large ramdisk as scratch exported over QDR infiniband to the compute nodes. No, it's not new, but it was novel to a lot of people who dropped by our booth.

For another, the ASU team was the first time *I* and many others ever saw a windows cluster in the wild.

Competitions like this are important, they showcase technology and introduce it to undergrads early, with positive benefit!
• #### Re:Article Doesnt Say (Score:2, Informative)

on Wednesday August 25, 2010 @09:10PM (#33376572) Homepage

See, this is why some people are sticklers for grammar, spelling, and capitalization rules. Of course they're using atoms. But are they using Atoms? Your error is needlessly confusing and detracts from your point.

If I had capitalized Atom do you think anyone would have thought I meant the car?
Or the Christian martyr?
Or the unit of medieval time?
Or the 1983 educational game for the TRS-80?
Or the comic book?
Or the alias of German musician Uwe Schmidt?
Or the album by Carbon/Silicon?
Or the Acorn Atom, an early 1980s home computer?
Or the card game?
Or the sports teams of Annandale High School?
Or the XML-based Web syndication format?

It could mean ANYTHING! Oh how will anyone deduce the meaning of my convoluted sentence??!

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