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There is a simple workaround for this - in slurm.conf set your partition "OverSubscribe=FORCE:1" This will ensure users cannot lock an entire node implicitly or
by use of the "--exclusive=" argument, while practically disabling
oversubscription of the node's cpus. On 01/09//2016 14:06, Christof Koehler
wrote:
Hello, On Thu, Sep 01, 2016 at 02:23:57AM -0700, Benjamin Redling wrote:You might want to (re)read 1. http://slurm.schedmd.com/cons_res.html 2. http://slurm.schedmd.com/cons_res_share.html[1] right at the beginning explains the default behaviour (exclusive mode) [2] should explain best that OverSubscribe (fka. Shared) is depended on the "Selection Setting". If you skim the column "Resulting Behavior" you should know really fast what you aim for. We share nodes between jobs of different users (but: all one trusted group, my colleagues -- really easy case) without any conflict and neither use OverSubscribe nor cgroups (but cgroups is a ticket).Rereading with your pointers I think I am starting to understand now. Is the following correct: Quoting [1]: "The only changes, users see when using the select/cons_res plugin, are that jobs can be co-scheduled on nodes when resources permit it." which taking [2] and manpage of sched.conf (OverSubscribe defaults to "NO") into account means that in your configuration only jobs from different partitions/queues can share a node. Now assume that there is only a single partition, which I think we would prefer ad hoc. Then: 1. The default (select/linear, OverSubscribe=NO) is always exclusive. So the job of course gets billed for the whole resources of a node. 2. With a single partition select/cons_res and OverSubscribe=YES must be simultaneously set so that jobs can share nodes. A user may allow other jobs on a node allocated to his job by explicitely setting "--shared", in which case only the actually allocated resources are billed to each different job on that node. If he does not share the full resources are billed to him. The option "--exclusive" is never needed. 4. Only if OverSubscribe=FORCE is set on the partition the argument "--exclusive" would make sense to prevent the default sharing of nodes. With "--exclusive" all resources of the node would be billed to the exclusive job automatically, right ? I would appreciate it if you could confirm so that I can introduce this into the local discussion we have. Thank you very much in advance ! Best Regards Christof |
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