[Mauiusers] node allocation issue

Jeff Anderson-Lee jonah at eecs.berkeley.edu
Thu Dec 2 10:22:28 MST 2010

On 12/2/2010 9:07 AM, Abhishek Gupta wrote:
> Our job scheduler is acting little weird. The jobs submitted are going
> on only a few nodes and each node is running more jobs than the total
> number of CPUs on that node. We have not changed anything recently.
> Can anyone suggest what is the best node allocation policy that make
> sure we do not run more jobs than number of cores available on a node
> and jobs are evenly distributed on all the nodes and not on the few nodes?
> Thanks,
> Abhi.

We find that many users understate the number of cores/procs needed in 
their requests.  They ask for a single cpu, then spawn multiple tasks, 
or run Java in a way that runs two or more active threads instead of 
one.  Maui does not seem to set any cpu affinity to prevent interference 
nor enforce the requested number of cores as far as I know.

Do you know for certain that you are getting multiple jobs allocated to 
the same logical cpu and not just user task forks?

If you use Torque as your underlying scheduler, the following should 
help you to find true duplicate assignments:

qstat -f | grep exec | sort | uniq -c | sort -n

Jeff Anderson-Lee

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