Has Supercomputing Hit a Brick Wall?

anzha writes "Horst Simon, Deputy Director of Lawrence Berkeley National Laboratory, has stood up at conferences of late and said the unthinkable: supercomputing is hitting a wall and will not build an exaFLOPS HPC system by 2020. This is defined as one that passes linpack with a performance of one exaFLOPS sustained or better. He's even placed money on it. You can read the original presentation here."

Comments

Re:Ha, not the first

[ssam]

moore's law only talks about transistor counts. building a supercomputer means getting thousands of CPUs to cooperate which is a much harder challenge.

Anyone (with a large wallet) can stick an exoflop worth of CPUs in a large room. by 2020 you'll be able to do that with a not so large wallet. but that does not result in a useful exoflop computer

Were blaming the wrong things.

[Anonymous Coward]

Supercomputing has hit a brick wall, and yet for some reason we keep blaming the construction company that built the wall, not the reckless driver who hit it.

Re:Ha, not the first

[fuzzyfuzzyfungus]

It's a particular nuisance because the speed of light is pretty strictly enforced...

Even if you went full-on-nuts and replaced fiber interconnects with little tubes full of hard vacuum, to squeak out that slight improvement over the speed of light in glass or air, you'll still see latency that meaningfully hinders the cooperation of multi-GHz CPUs and RAM across systems of any nontrivial size.

For loosely coupled problems, that barely matters; but not all problems are loosely coupled.

Re:Clarke's Three Laws

[Anonymous Coward]

So, since Freeman Dyson said "Faster-than-light travel is rubbish" that means he's probably wrong, and we'll be warping around the galaxy soon enough?

Re:Ha, not the first

[fuzzyfuzzyfungus]

I'm no expert on the refined world of supercomputers; but my money would be on latency. If you are made of money, bandwidth is a problem that you can substantially brute force. Not 100% efficiently; and layout gets to be a real headache; but if the state of the art in serial interconnects isn't good enough, you can bolt a bunch of them together and have a parallel interconnect(it'll be harder to do board layout for, the wiring will suck more, and it'll cost more; but the major sticking point is money).

If you want to cut latency, even the most exotic photonics-on-die-with-hollow-fiber arrangement imaginable still gives you surprisingly short distances before you start losing CPU cycles to waiting for the return photon.

so what?

[markhahn]

I'm an HPC professional, and do not see much value in these "hero" machines. Yes, you can go on all you want about the march of progress and tier-1 and grand challenges, but you're just reiterating an unquestioned manifest destiny-based view of history. Why do we need an Exaflop machine? is it because some particular set of applications need it? where is the threshold for those applications where the compute facility will be fast enough to achieve some breakthrough?

it's hard to find areas that are primarily limited by compute facilities. for instance, genetics/proteomics/metabilomics/whatever are *not* compute-limited, especially at the high end. they're laboratory-limited, the same way weather simulations are good and getting better, but not past the quality of their input data.

we need more compute in general, but not necessarily in one machine. a single exaflop machine will cost much more than a thousand petaflop machines. letting a thousand flowers bloom is much prettier than one excruciatingly beautiful flower...

and no, hero machines do not provide an efficient way to improve the tech of lesser or later machines. they have to be justified by their own need.

Re:so what?

[Nite_Hawk]

I'm an HPC professional too.

I don't totally disagree with your premise, but what the heck are you doing talking about genetics and proteomics in reference to giant supercomputers? If you know anything about proteomics codes, you know that the commonly used search engines like sequest and mascot were never designed to run on systems like that. Hell, they barely run on small clusters and yet people are getting enough science done that they just don't care. That doesn't mean that it's hard to find problems that need supercomputers though.

If you want to talk about the really big systems, you are talking about things like nuclear weapons simulations, astrophysics, molecular dynamics, and quantum mechanics. There are only a handful of guys that will actually make really good use of those systems and scores of folks that would otherwise be perfectly fine running on significantly smaller ones. Having smaller jobs backfill on the big machines when the really hardcore guys are off doing something else isn't such a bad situation though. It lets you get the big science done and still keep the machines being used efficiently in the interim.

Beyond that, just because some researchers aren't scaling their codes to those levels yet doesn't mean we should give up on big systems. There will always be people pushing the envelop and others playing catch up. Our job is to help the slow guys scale their codes when possible so they can do even better and more intensive science. Yes, not all problems require the big systems, but there are many that do, many that can be made to scale even when they don't appear to at first, and others that can serve as backfill to keep the systems busy. They have their place just as smaller clusters, cloud resources, and big data resources do.

Re:If you ignore the best news in supercomputing .

[Anonymous Coward]

Even if you ignore all the controversy over D-Wave's system and its nature, and take it all at face value, it is still only applicable to a narrow class of problems. CMOS or not, it amounts to something similar in principle to an ASIC. It is no surprised that a custom built chip can solve a specific class of problems orders of magnitudes faster than a general purpose processor. This used to be slightly more popular for a while in the 80s, where a few custom computers were built that were specifically designed for doing things like orbital calculations. And it pops up every so often, like custom chips for playing chess, and now bit coin mining chips. That is great for a small computer, but when your price gets into the millions or billions of dollars, the people bankrolling it will probably want to build a system that can be used for a wider class of problems even if it means running slower.

Re:The Nanosecond

[DNS-and-BIND]

To you, an amusing anecdote. To the rest of us, a terrifying tale of a ruling-class asswipe ordering her subordinates to dance and entertain her. This person graduated Phi Beta Kappa from Vassar and got a Master's from Yale. How would one even get in to Vassar, much less Phi Beta Kappa, much less be admitted to Yale to pursue a Master's? Seriously.

Sure, we enjoyed this tale. How many other tales will we never hear where she ordered her underlings to dance, when they failed to meet her expectations and were fired? We'll never know, will we? Those sorts of stories don't add to legends. They don't name Navy ships after people who don't meet with the approval of the ruling class, no matter if they invent COBOL or not. The freaking Navy broke its own rules to keep her on active duty far, far beyond mandatory retirement age - they didn't even do that for MacArthur. Hurrah for the privileged!