os that rather uses the gpu?

JD jd1008 at gmail.com
Sat Jul 17 03:25:13 UTC 2010

  On 07/16/2010 08:04 PM, Robert Myers wrote:
> On Fri, Jul 16, 2010 at 10:35 PM, JD <jd1008 at gmail.com 
> <mailto:jd1008 at gmail.com>> wrote:
>     So, what would you say is/are the class/classes of problems that would
>     benefit greatly from a high flops gpu, but without the sort of bus
>     bandwidth you would like to see?
> Almost any problem that is embarrassingly parallel or nearly so is 
> potentially a candidate for low-bandwidth computing.  Ray tracing is 
> the primo example.  Almost any linear problem is potentially 
> embarrassingly parallel, and, if you don't want to go through the work 
> of exposing the embarrassingly parallel nature of the problem, there 
> are the tricks that make the linpack benchmark so popular for selling 
> "supercomputers" that have absurdly small bisection bandwidths.
> My question, though, is, if that's the kind of problem you have, why 
> not do it on a distributed platform and teach students how to use 
> distributed resources?  If you're Pixar, I understand why you'd want a 
> well-organized farm of GPU's, but if you just want to replicate what 
> LLNL (Lawrence Livermore) was doing, say, ten years ago, are you doing 
> your students any favor by giving them a GPGPU instead of the 
> challenge of doing real distributed computing?  Conceivably, watts per 
> flop (power consumption) makes GPGPU's the hands down winner over 
> distributed computing for problems that are embarrassingly parallel or 
> nearly so.  Inevitably, though, people will want clusters of GPUGPU's, 
> so you'll wind up doing distributed computing, anyway.
> If you rewrite your applications for the one-off architectures typical 
> of GPU's, so that you have to do it all over again when the next 
> generation comes out, have you really done yourself any favors?
> I don't claim that there are simple or obvious answers, but it's just 
> too easy for people to be blown away by huge flops numbers.  What I'm 
> afraid of has already started to happen as far as I'm concerned, which 
> is that all problems will be jammed into the low-bandwidth mold, 
> whether it's appropriate or not.
> Robert.
Dude, I am not a teacher.
I am a hacker of sorts.
But you opine that problems that others are excited to solve with the 
SLI gang of gpu's are "embarrassingly parallel", guess you will just 
have to sweat it and wait for your dream machine to be built, perhaps in 
your next life time. Meanwhile, all you will be able to do is complain 
about other people's excitement with the technology at hand.

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