[Mauiusers] Urgent jobs

Torsten Wolf t.wolf at tu-bs.de
Thu Mar 31 09:23:48 MST 2005


Hi!

I am about to get more and more confused about this issue which is -most
like^Whopefully- an easy one to you. So please kill me but give me a
hint before...

Say I have the burden of managing a small smp-cluster (8node, 2 cpus
each) with OpenPBS on it. Declaring all nodes as exclusive nodes works
fine and there will be only one task per cpu. But now, we have the need
for a "test-queue" for users that need e.g. 5 minutes on 8 cpus
immediately and the other users do not mind to share their allocated
cpus and running jobs with this roadhog.

Using mpirun and a machinefile and thus bypass the batch system looks
like an ugly hack and is deprecated as users for sure will begin to game
with this and lock the whole thing up.

My first guess was, to divide the nodes into one half of exclusive nodes
and another half of timeshared nodes. Then I could use loadleveling with
a value of 2 per node and would have the same behaviour on the system as
before. But with this I hoped that, I could create a queue/scheduler
policy which allows me to extend the maximum load for such urgent jobs.
A user would request 5 minutes in that special queue, the maximim load
would be increased to e.g. 4 and his job could start at once. Yes, there
should be an upper load limit, so that the machine is not flooded by
such jobs. But actually, I have no idea how to do this with OpenPBS. The
ideal and maximum load is configured per mom and cannot be altered by
queues/jobs.

So I came across to Maui and would like to know, if this scheduler would
fit my needs. Or can this be achieved even with the scheduler shipped
with OpenPBS? Hopefully, I have not bothered you too much.

Best wishes,
Torsten


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