[Mauiusers] Fairshare -- Explanation

Lennart Karlsson Lennart.Karlsson at nsc.liu.se
Sat Jul 18 01:47:51 MDT 2009


P.Peartree at postgrad.manchester.ac.uk said:
> This may not be the place for this, but I can't fathom it myself. I'm
>  trying to implement fairshare on a cluster, currently we have 5
> execution queues and a routing queue set up in torque, the queues are
>  prioritised starting from 50 down to 10. What I want to do is prevent
>   any user from using more than their fair percentage of the cluster
> (i.e. time averaged over, say a week, that each user is entitled to
> 1/total users of that time) This is to prevent a recurring problem
> where users load up the queue with lots of jobs and thus prevent other
>   users from using the cluster. I don't know if fairshare is the best
>  way to do it, or quite how to set up the policy. Could anyone offer
> any guidance? 


Phil,

I presume that you today give queue priority mostly from time in queue.

My proposal is that you set a limit on the number of jobs per user that
gets queue time priority added, with a MAXIJOB declaration, e.g.

	USERCFG[DEFAULT]	MAXIJOB=10

That is the most straightforward solution to your queue stuffing
problem. Even if a user submits 5000 jobs, only ten of them will
compete with other jobs on your system. On one of our systems, we
have set MAXIJOB as low as two.

Cheers,
-- Lennart Karlsson <Lennart.Karlsson at nsc.liu.se>
   National Supercomputer Centre in Linkoping, Sweden
   http://www.nsc.liu.se




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