[Mauiusers] Fairshare -- Explanation

Greenseid, Joseph M (IS) Joseph.Greenseid at ngc.com
Mon Jul 20 07:14:26 MDT 2009

The fairshare section of the docs should provide a good starting point: http://www.clusterresources.com/products/maui/docs/6.3fairshare.shtml
What we've configured in our environment is a pretty simple set of rules where each project group gets a fairshare target of 1/X where X is the total number of groups on the cluster (for example, 5 groups means the FSTARGET for a group is 20%).  Then you can configure the FSINTERVAL, FSDEPTH, FSDECAY, FSWEIGHT, FSGROUPWEIGHT and/or one or two other things and you're good to go (if you want to include expansion factor into your priority, etc).  
For us, this has worked out well, because sometimes the only one or two groups are running a lot, so the system doesn't sit idle, but as soon as another user comes on that hasn't run in a while, their priority jumps them to the top of the queue.


From: mauiusers-bounces at supercluster.org on behalf of Philip Peartree
Sent: Sat 7/18/2009 12:12 PM
To: mauiusers at supercluster.org
Subject: Re: [Mauiusers] Fairshare -- Explanation

Thanks to all that replied, I will try this suggestion here, is there 
any where I can get an explanation of fairshare though, I don't really 
understand how it affects the priority of the jobs yet!

Quoting Lennart Karlsson <Lennart.Karlsson at nsc.liu.se>:

> 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 <http://www.nsc.liu.se/> 
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