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-   -   Parelleling Efficiency (http://www.cfd-online.com/Forums/openfoam/65595-parelleling-efficiency.html)

kassiotis June 19, 2009 14:12

Parallel Efficiency
 
2 Attachment(s)
Hello everybody,

I want to measure the efficiency of the paralleling for different mesh sizes. My problem is quite simple: a flow in a tube divided in 6 domains by METIS (the 6 processor are on the same machine). It is quite surprising for me to see that when one augments the refinement, the efficiency decreases after an optimum. I was thinking that the efficiency increases in such a case.

The efficiency is here measured as: TCPU(1) / ( 6 * TCPU(6) ), where TCPU(N) is the CPU time for parallel computations on N processors.

I thought first it was linked to the fieldTransfer=1 (fieldTransfer are inverted on the attached graph), so I change it. The results are a little closer to what expected, but I still observe the general behavior depicted above. Finally, maybe are my results normal, but I have no explanation for them. What do you think about this ?

Thank you,

--
ck


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