[GE users] user feels penalized by share tree

Andy Schwierskott andy.schwierskott at sun.com
Wed Jun 2 11:17:06 BST 2004


Sebastian,

> One of my users was complaining about being penalized by the share tree policy
> if he's using the cluster when otherwise it would be idle. Let us assume the
> following situation:
>
> There are 20 nodes, 15 of which are free (have no job running) at night. The
> user thinks it would be a good time to submit his jobs (which is not wrong).
>
> Say he submits 12 jobs which run all the night.
>
> On the next day, when other users are submitting jobs, he will have bad karma
> (=less tickets) and feel 'penalized' for using the idle time of the cluster.
>
> I couldn't find a way to argue against that nor could I find a way to
> 'fix' that behaviour in SGE.

This behavior can't be "fixed" in a clean way today - the fix would be to
introduce a brokerarge system where the "price" of resources depends on the
demand for them.

There are many good arguments why the implementation as it is today can be
seen as fair - see the analogy to an empty hotel: you usually pay the same
rate regardless of the number of guests. The user requested resources which
were granted - from a global perspective it's certainly fair to argue that
you have to pay for it.

> I'm running SGEEE 5.3p5 with a quite simple share tree and evenly distributed
> tickets. Does someone have an idea how I could make the system 'feel a bit
> more fair'?

If you are in the opinion that the behavior treats your users unfair, you
may reduce the halflife time of the sharetree. Setting it to a few hours
would decay past usage much faster.

You also might consider to reset the sharetree usage every morning if a mid-
or longterm fairs share is not an objective at your site. Or you may set the
sharetree to e.g. 24 hours during day time and to a very short time (a few
hours) during night time.

Andy

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