[torqueusers] the way node are choosen

Troy Baer troy at osc.edu
Wed Oct 4 09:17:01 MDT 2006

On Wed, 2006-10-04 at 17:04 +0200, bill wrote:
> I have 8 boxes like that in $PBS/server_priv/nodes
> slave0 np=4
>   (...)
> slave7 np=4
> If I ask for 3 jobs requesting 1 CPU, all of three will go to slave0.
> Is there a way to randomizing CPU allocation? Or walk node by node 
> instead of cpu per cpu?
> This cluster is not always heavily loaded, so I could gain some time if 
> each node process only 1 job.
> I think this could drive to some problem, 8 job requesting 1 CPU and a 
> lot of job requesting 4ppn waiting, but for me it is acceptable.

This is largely dependent on what scheduler you use.  All other things
being equal, pbs_sched tends to load up nodes from the beginning of the
node list and work down, while Maui and Moab tend to start from the end
of the list and work up.  I think Maui and Moab both have settings that
will do what you want; I'm not sure about pbs_sched, because I haven't
used it in years.

Troy Baer                       troy at osc.edu
Science & Technology Support    http://www.osc.edu/hpc/
Ohio Supercomputer Center       614-292-9701

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