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-   -   Parallel efficiency and speedup info (http://www.cfd-online.com/Forums/openfoam-solving/67805-parallel-efficiency-speedup-info.html)

lakeat August 27, 2009 02:21

Parallel efficiency and speedup info
 
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 10:48

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 11:05

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

wow, they got superlinear speed up using 64 processors!


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