Re: how to use the dual-processor machines

From: Gengbin Zheng (gzheng_at_ks.uiuc.edu)
Date: Sat Jul 30 2005 - 17:52:42 CDT

Hi,

Try with nodelist file like:

group main
host node1
host node1
host node2
host node2

It may help a little. Charmrun selects nodes in round-robin fashion.
In any case, yes, we found it is a little slower using both CPUs on a node. This may be due to network card contention or O.S. interference, etc. However, it may not be that bad if you think of the second case which you occupied 4 nodes 8 processors to get that a little performance improvement.

Gengbin

Xiaoqing Wang wrote:

>Hi,
>
>I run NAMD_2.6b1 Linux-amd64 binary on AMD64 opteron cluster.
>There are two cpus per node.
>How to use the dual-processor machines.
>
>Is it as follows?
>
>If the nodelist file contains
>--------------------------------------
>group main
>host node1
>host node2
>----------------------------------------
>running NAMD as:
>charmrun namd2 +p4 <configfile>
>
>But the CPU speed is slower than that when the nodelist file contains
>----------------------------------------
>group main
>host node1
>host node2
>host node3
>host node4
>-----------------------------------------
>running NAMD as:
>charmrun namd2 +p4 <configfile>
>
>
>Any tips would be greatly appreciated!
>Thanks in advance!
>
>Sincerely
>Xiaoqing
>
>
>
>
>

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