[gmx-users] Scaling on dual athlon

Stefano Piana piana at inorg.chem.ethz.ch
Mon Oct 21 10:59:03 CEST 2002

David wrote:

> First off, you may improve the scaling somewaht by recompiling LAM with
> different options:
>   --with-tcp-short=BYTES  use BYTES as the size of the longest TCP short
>                           message
>   --with-shm-short=BYTES  use BYTES as the size of the longest shared
>                           memory short message
> set both these values to 500000 or so).

Thanks for the suggestions! This actually improved the scaling quite a lot. 
Here are the new numbers:

(39941 Atoms - PME)           steps    1 proc   2 proc 1/2 ratio
Standard LAM setting:          1000     628      427     1.46
BYTES=512000        :          1000     620      345     1.80

I think it would be useful for the new users to put a sentence in the Gromacs 
manual about the optimal settings for the LAM compilation as it seems to be 
rather crucial for the parallel performance on the PCs!



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piana at inorg.chem.ethz.ch

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