Re: [Condor-users] how are jobs assigned?

[Ian Chesal <ICHESAL@xxxxxxxxxx>]

> I have 400 hosts and it seems most of my jobs are always going to a
> host where there is a lot of load where other hosts rarely get the
> jobs. Is there a way to control this or does condor pick hosts by what
> the class ads are?

It's ClassAd based matching, but you can end up with a list of hosts that all match the requirements of the job. In this scenario Condor uses the NEGOTIATOR_POST_JOB_RANK expression. Here's what I use in my system. It steers jobs towards machines that have been idle longer, prefers faster machines and fills up separate machines before loading up one machine with jobs:

##  The NEGOTIATOR_POST_JOB_RANK expression chooses between
##  resources that are equally preferred by the job.
##  The following example expression steers jobs toward
##  faster machines and tends to fill a cluster of multi-processors
##  breadth-first instead of depth-first.  In this example,
##  the expression is chosen to have no effect when preemption
##  would take place, allowing control to pass on to
##  PREEMPTION_RANK.
#NEGOTIATOR_POST_JOB_RANK = (RemoteOwner =?= UNDEFINED) * (KFlops - VirtualMachineID)
##
##  Break ties by looking for machines that have Idle longer than others
##  and use them first. Also try and use faster machines before slower
##  machines and assign jobs to separate machines before we start putting
##  two jobs on a machine.
NEGOTIATOR_POST_JOB_RANK = (((Activity =?= 'Owner') * (State =?= 'Idle')) * 1000000000) + ((Activity =?= 'Unclaimed') * 100000000) + (KFlops * 0.001) - (SlotID * 10)

- Ian

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