BEOWULF cluster hangs

[Jeffrey B. Layton]

John Hearns wrote:

>On Thu, 26 Sep 2002, G.de-With wrote:
>
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>>Hello
>>
>>Since a month we have a LINUX BEOWULF cluster, the clusters contains 7 P4
>>dual processor 2GHz computers, with 8Gb of RAM per machine. For our network
>>we have used Gigabit ethernet.
>>
>>
>>2) To my understanding the most important indicators to indicate the
>>computer usage are:
>>- memory usage
>>- cpu usage
>>    
>>
>
>I'm sure someone on the list knows the exact answer.
>
>I would start by looking at the network, using ifconfig and
>netstat to look at the network status.
>You are using top and ps to get the process status, right?
>
>Me, I'm no expert, but for CFD why not use e.g. Myrinet?
>Network performance isn't all about bandwidth - and gig E may
>not be the best choice here.
>

It depends on the CFD code. The code we use scales very well
with just plain FastE. At 200 processors on FastE we get about 90%
of the theoretical scaling. Oh, it's an external aerodynamics CFD
code (unstructured inviscid/viscous). The above scaling number
is for a viscous run.

When we tested Myrinet we got less than a 1% improvement
in speed (wall clock time for an entire run).

Jeff

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