Re: [Condor-users] Re: split processors among multiple jobs

[Derek Wright <wright@xxxxxxxxxxx>]

On Tue, 22 Mar 2005 09:49:22 +0000  Matt Hope wrote:

> Does this apply if the jobs are, in essence, running only via the
> ranking by the execute machines... So if the schedd puts another job
> to the top of its list which is ranked lower by the execute machines
> this will not cause the currently running job previously at the top
> (which presumably had at least as good a machine rank) to be
> preempted.

machine RANK expressions will *always* result in preemption.  if any
job in the system is ranked higher by a given machine, the startd will
preempt whatever it's doing for the "better" job.  the only thing that
can prevent this kind of preemption from killing a job is the
MaxJobRetirementTime stuff we added in 6.7.x.

job priorities on their own will *never* result in preemption.

user priorities will only result in preemption if
"PREEMPTION_REQUIREMENTS" evaluates to TRUE.

> I have behaviour like the above I assumed what was happening was
> down to this mismatch (which did exist on their schedd) and educated
> the user on making sure their TIER levels matched their user
> supplied priority but if I was wrong I probably need to find out why
> the preemption occurred.

if you're using machine rank for anything, then yes, you have to watch
out for possible preemption.  hope this helps.  sorry preemption is
such a confusing topic...

-d