[torqueusers] scheduling cycle

Ronny T. Lampert telecaadmin at gmail.com
Fri Aug 3 02:00:58 MDT 2007


> So there is no job start or job finish trigger. Scheduler tries to schedule
> in each scheduling cycle.  Am I right?

First, what kind of scheduler are you using, pbs_sched or maui/moab?

Don't forget that anything can change at any time! I frequently down 
nodes for maintainance. I frequently re-add nodes or change their settings.
Also consider that when a lot of jobs finish, every job finish would 
mean that you would have to contact the scheduler and update it. This 
works for few objects (nodes, jobs, ...) but not for big setups.

The scheduler should not re-schedule at any job exit or job entrance, 
but only update the already made scheduling decisions when there is 
really a need (e.g. a new high-priority job). Usually it is quite rare 
that a new job is to be run NOW. Also there is usually a scheduling 
window, e.g. only a certain amount of objects is considered at once, to 
limit complexity and runtime.

Torque was meant to be scalable, and in my setting it has proven that 
quite well (using it since the 1.0 days :)


> Then how do we decide the scheduling interval? 

Am I right that you are trying to optimize your settings/configuration?
Considering that I have only 14 Nodes, but sometimes up to 50.000 jobs 
in the queue I find a scheduling intervall for maui of 45 seconds to be OK.
Also take into account that when you have a lot of short jobs (I 
sometimes do, sometimes even only 20sec runtime per job) a shorter poll 
intervall helps improving the utilization of your compute nodes.

Cheers,
Ronny




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