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Optimized Seti@Home apps => Windows => Topic started by: Vyper on 05 Dec 2006, 01:31:58 am

Title: Possibility to split up FFT data into smaller chunks
Post by: Vyper on 05 Dec 2006, 01:31:58 am

Does anyone here know if there is possible in a clean manner to convert a 65536 & 131072 point FFT data to only use 16384 points as a maximum at a time, or perhaps splitting them up in a 16K maximum FFT points at a time?

Kind Regards Vyper

Title: Re: Possibility to split up FFT data into smaller chunks
Post by: Vyper on 05 Dec 2006, 11:58:38 am

With points i mean FFT plans, how large plans do the S@H client use..

65536 or 131072 or perhaps even more??

Someone with the knowledge, Josef.. Ben.. Heeelp  :)

Title: Re: Possibility to split up FFT data into smaller chunks
Post by: Josef W. Segur on 05 Dec 2006, 02:47:12 pm

Quote from: Vyper on 05 Dec 2006, 11:58:38 am

With points i mean FFT plans, how large plans do the S@H client use..

65536 or 131072 or perhaps even more??

Someone with the knowledge, Josef.. Ben.. Heeelp  :)

131072 is the maximum in use, but that's controlled by values in the workunit header and a properly designed program should be able to do larger ones too.

All practical FFT algorithms do divide the work into smaller units and combine them for the final result. But the way it is split and recombined is not trivial. I can't go any further since I haven't studied the algorithms in detail.

One possible area you might search is the projects trying to find Mersenne primes. They use very long FFTs in a method for multiplying huge numbers, and it's likely someone in those communities has investigated using a GPU.
                                                                                Joe

Title: Re: Possibility to split up FFT data into smaller chunks
Post by: Vyper on 06 Dec 2006, 06:33:26 am

Hans found an interesting article here at FFTW's homepage about splitting FFT chunks..

That approach may be useable for him (us), getting back with response l8r..

http://www.fftw.org/pruned.html

Btw, thanks Josef for your concern.. Much appreciated with theoretical input to get past stuck problems..


Kind Regards Vyper

Title: Re: Possibility to split up FFT data into smaller chunks
Post by: Nebby on 05 Mar 2007, 08:28:04 pm

According to the link below, nVidia plans on increasing it's FFT size restrictions in a later release of CUDA.

http://forums.nvidia.com/lofiversion/index.php?t28384.html