Parallel efficiency and speedup info

lakeat · August 27, 2009, 03:21

Dear all,

Could you share a little about your parallel efficiency and speedup? I just want to know what's going wrong with my case set-up.
I have read pyFoam, http://openfoamwiki.net/index.php/Be...ks_standard_v1. But I want to know more.

Mine is a flow past a circular cylinder, grid number 860000, mpich1.
And the speedup is far from linear, using 8 processors, the speedup is only about 3.5, and using 16 processors, the speedup is only 9.1, ie. a sublinear speedup of 43.1%. It's very very bad, isn't it?

Any information and comments are welcomed.

tehache · August 31, 2009, 11:48

I think it may depend on your hardware - I have seen people reporting bad scaling w. ethernet interconnection, but good scaling e.g. using Infiniband.
Here an example:

http://www.cresco.enea.it/Documenti/...-Science/9.doc

We also get rather bad scaling currently w. ehternet, and are now installing infiniband.

I cant await the results

lakeat · August 31, 2009, 12:05

Ya, I just want to know what's the best results with openfoam...

wow, they got superlinear speed up using 64 processors!

August 27, 2009, 03:21	Parallel efficiency and speedup info	#1
lakeat Senior Member Daniel WEI Join Date: Mar 2009 Location: Beijing, China Posts: 689 Blog Entries: 9 Rep Power: 22	Dear all, Could you share a little about your parallel efficiency and speedup? I just want to know what's going wrong with my case set-up. I have read pyFoam, http://openfoamwiki.net/index.php/Be...ks_standard_v1. But I want to know more. Mine is a flow past a circular cylinder, grid number 860000, mpich1. And the speedup is far from linear, using 8 processors, the speedup is only about 3.5, and using 16 processors, the speedup is only 9.1, ie. a sublinear speedup of 43.1%. It's very very bad, isn't it? Any information and comments are welcomed. __________________ ~ Daniel WEI ------------- Email Last edited by lakeat; August 27, 2009 at 04:33.

August 31, 2009, 12:05		#3
lakeat Senior Member Daniel WEI Join Date: Mar 2009 Location: Beijing, China Posts: 689 Blog Entries: 9 Rep Power: 22	Ya, I just want to know what's the best results with openfoam... wow, they got superlinear speed up using 64 processors! __________________ ~ Daniel WEI ------------- Email Last edited by lakeat; August 31, 2009 at 21:58.

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August 31, 2009, 11:48		#2
tehache Senior Member Thomas Jung Join Date: Mar 2009 Posts: 102 Rep Power: 18	I think it may depend on your hardware - I have seen people reporting bad scaling w. ethernet interconnection, but good scaling e.g. using Infiniband. Here an example: http://www.cresco.enea.it/Documenti/...-Science/9.doc We also get rather bad scaling currently w. ehternet, and are now installing infiniband. I cant await the results