Re: [condor-users] job priority question

[Colin Devine <devinec@xxxxxxxxxxxxxxxx>]

On Thu, 27 May 2004, Alain Roy wrote:
 
> Colin, are you talking about the job priorities that are set by the user on 
> a per-job basis? I think so, but I just want to clarify that you aren't 
> talking about user priorities.

Yes, in this case I am talking about job priorities set by the user on a 
per-job basis.
 
>  From your description, a couple of things could be happening.
> 
> 1) These are priorities per-user. If there are two users, Condor will first 
> pick a user that can run jobs, then pick a job for that user. It does not 
> look at the job priorities when picking a user, so job priorities will only 
> affect the order in which a single users's jobs are run with respect to 
> each other, but not the order in which jobs are run with respect to other 
> users.

Interesting.  That does help my understanding.  I do have a few more 
questions if you don't mind, but if any of this is documented somewhere 
please let me know.  I have read the manual and it does not go into the 
details of how priority of the queue is determined internally.

Do jobs with a higher priority (user priority now, not per-job)  preempt 
other user jobs with a lower user priority?

If that is so then do the lower per-job priority jobs get preempted before 
the higher per-job priority jobs?

Thanks again for the help, from you as well as Dan.

--Colin Devine


> 2) For a single user, just because one job has a higher priority than 
> another does not mean that it will run first. This is because jobs can have 
> different requirements, and the higher priority job may not be able to run 
> as soon as the lower priority job.  Here's a simple example: if you have a 
> high priority job that requires Linux and a low priority job that requires 
> Windows, but no Linux computers are available, then the Windows job may run 
> first. More subtle requirement differences may also have an impact.
> 
> >Can anyone explain to me what might be causing this?  Should higher
> >priority jobs preempt lower priority jobs of the same user?
> 
> Job priorities do not preempt running jobs, they only affect the order in 
> which jobs are started.
>


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