[torqueusers] setting Resources_min while queue has running jobs

Andrew Mather mathera at gmail.com
Tue Nov 12 20:16:38 MST 2013

Hi All

I'd like to modify one of our queues by using resources_min to enforce
a minimum requirement for a specific single queue on our cluster.  I'd
like to use this parameter to force all jobs sent to this queue to
'ask for' 2 CPUs.

The thing I am not sure about is what will happen to jobs already
queued and more particularly, currently running, if they've requested
only 1.  Will the running ones be killed off for violating the minimum
requirements and will the queued ones simply be held forever ?

Is it safe to do this while these jobs exist, or should I stop the
queue and allow those jobs to drain before making this type of change
?  There's currently a thousand or so jobs queued or running via this
queue, some of which are hundreds of hours into their 1500hour
walltime run, so I don't want to kill them off !

Also, once this change is made, would a specific request for 1 CPU in
the submission script override this value ?

The reason for the change is that this particular queue is currently
sending a large number of small, CPU intensive jobs onto our nodes,
which currently have hyperthreading enabled, which is causing the
machines to bog down and performance drops right off.  This is likely
to be a long-term state of affairs due to the nature of some of the
current projects using the cluster.

In general, we get sufficient benefit from the hyperthreading that
we'd prefer to leave it on cluster-wide if we could.

Since all the problem jobs are coming down one particular queue, I
figured that if we could tweak the levers of this queue, we wouldn't
need to mess with the rest, which on the whole is working fine.

Thanks for any help you can provide and see you in Denver next week !

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