[Beowulf] top command problem in 2 and 4 way nodes !!!

Ufuk Utku Turuncoglu turuncu at be.itu.edu.tr
Thu Jul 28 04:42:02 EDT 2005


i try to test the performance of the cluster. i am using simple "top" 
command to getting load information of the cpu. My problem is as fallowing,

when i run the openmp job in 2-way nodes (OMP_NUM_THREADS=2) the output 
of the "top" commands show the ~%90 load in each cpu (cpu 0 and 1) and 
overall cpu usage ~%180-190 for a job.

but in 4 way nodes (OMP_NUM_THREADS=4) the result of the "top" command 
is different. The load of the each cpu is %25 percent (total %100 for 4 
cpu). But i expect that total load of the node %400 or close to this 
value, when i get the similar behaviour of the "top" command as 2 way nodes.

The versions of the top command is same (top -v, procps version 2.0.17). 
I think this is realted to karnel versions of the operating systems. Any 
suggestions and information will be  helpful for me.

Architecture, HP cluster 2 way and 4 way nodes
Operating System, Redhat Linux AS v3.0
2 way nodes, uname -a command output,
Linux cn07 2.4.21-20.0.1.ELSFS #1 SMP Wed Mar 30 09:12:30 GMT+2 2005 
x86_64 x86_64 x86_64 GNU/Linux

4way nodes,
Linux cn41 2.4.21-27.ELSFS #1 SMP Mon Jun 13 13:57:23 EEST 2005 x86_64 
x86_64 x86_64 GNU/Linux


Ufuk Utku Turuncoglu
Istanbul Technical University
Informatics Institute, HPCC Group

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