CUDA with CFX

jmcatelen · August 18, 2009, 14:31

Does anyone know if it's possible to use CUDA with CFX? I imagine Glenn can give me an answer.

ghorrocks · August 18, 2009, 18:42

My fame precedes me?

CFX cannot run under CUDA. The solver needs to be totally rewritten to use the system and that is a major task. I remember somebody mentioning that ANSYS is doing a preliminary investigation of CUDA to establish its feasibility but it was stressed that this was preliminary and a release of CFX on CUDA was along way off - if it gets released at all.

The CUDA system is not ideal for CFX. CFX, being an implicit solver runs best on a relatively small number of powerful CPUs as the simulation time is used constructing and solving a large matrix. CUDA works far better on explicit numerics where inter-node communications are much reduced as this suits the huge number of lower power CPUs in the CUDA system.

Also don't forget CFX in parallel is licensed per process. If you are paying for 100+ processes (serious dollars) there is no point running it on a computer worth only a few thousand dollars. A compute cluster of more traditional machines will cost more but perform far better and give you a much better return on your software investment.

So in short I don't think CUDA is going to help CFX much. There are a small number of explicit CFD codes out there and they will get a huge performance boost on this type of system, eg the Fluent density based solver or Powerflow - they are the ones to use on CUDA.

Glenn

mjatalla · August 26, 2009, 22:29

Maybe this is not the right thread, but seeing it made me wonder whether OpenFoam would benefit from a GPU implementation. Thoughts? Thanks in advance.

ghorrocks · August 26, 2009, 22:36

That question would be better posted on the openfoam forum. Also note the solver needs to be rewritten on the CUDA system. Not just compiled on the CUDA system, totally rewritten to take advantage of the CUDA system. This is no small issue!

But in general, the simulation software which will run best on CUDA will be explicit numerics.

jmcatelen · August 27, 2009, 08:42

Well, thanks for both anwers. I'll keep insisting to see if a cluster can be bought.
Bye.

ghorrocks · August 27, 2009, 19:33

Sounds fun - but don't expect to run CFX on it. It has not been compiled to run on it and won't be for a long time yet.

mjatalla · August 28, 2009, 17:01

Thanks for the quick reply!

August 18, 2009, 14:31	CUDA with CFX	#1
jmcatelen New Member Juan Martín Catelén Join Date: Mar 2009 Location: Buenos Aires, Argentina Posts: 4 Rep Power: 17	Does anyone know if it's possible to use CUDA with CFX? I imagine Glenn can give me an answer.

August 26, 2009, 22:29	OpenFoam	#3
mjatalla New Member Mauro Join Date: Aug 2009 Posts: 2 Rep Power: 0	Maybe this is not the right thread, but seeing it made me wonder whether OpenFoam would benefit from a GPU implementation. Thoughts? Thanks in advance.

August 27, 2009, 08:42	Cuda	#5
jmcatelen New Member Juan Martín Catelén Join Date: Mar 2009 Location: Buenos Aires, Argentina Posts: 4 Rep Power: 17	Well, thanks for both anwers. I'll keep insisting to see if a cluster can be bought. Bye.

August 28, 2009, 17:01	Thanks	#7
mjatalla New Member Mauro Join Date: Aug 2009 Posts: 2 Rep Power: 0	Thanks for the quick reply!

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August 18, 2009, 18:42		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	My fame precedes me? CFX cannot run under CUDA. The solver needs to be totally rewritten to use the system and that is a major task. I remember somebody mentioning that ANSYS is doing a preliminary investigation of CUDA to establish its feasibility but it was stressed that this was preliminary and a release of CFX on CUDA was along way off - if it gets released at all. The CUDA system is not ideal for CFX. CFX, being an implicit solver runs best on a relatively small number of powerful CPUs as the simulation time is used constructing and solving a large matrix. CUDA works far better on explicit numerics where inter-node communications are much reduced as this suits the huge number of lower power CPUs in the CUDA system. Also don't forget CFX in parallel is licensed per process. If you are paying for 100+ processes (serious dollars) there is no point running it on a computer worth only a few thousand dollars. A compute cluster of more traditional machines will cost more but perform far better and give you a much better return on your software investment. So in short I don't think CUDA is going to help CFX much. There are a small number of explicit CFD codes out there and they will get a huge performance boost on this type of system, eg the Fluent density based solver or Powerflow - they are the ones to use on CUDA. Glenn

August 26, 2009, 22:36		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	That question would be better posted on the openfoam forum. Also note the solver needs to be rewritten on the CUDA system. Not just compiled on the CUDA system, totally rewritten to take advantage of the CUDA system. This is no small issue! But in general, the simulation software which will run best on CUDA will be explicit numerics.

August 27, 2009, 19:33		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Sounds fun - but don't expect to run CFX on it. It has not been compiled to run on it and won't be for a long time yet.