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 -- Dr. rer. nat. Christof Köhler email: [email protected] Universitaet Bremen/ BCCMS phone: +49-(0)421-218-62334 Am Fallturm 1/ TAB/ Raum 3.12 fax: +49-(0)421-218-62770 28359 Bremen PGP: http://www.bccms.uni-bremen.de/cms/people/c_koehler/
signature.asc
Description: Digital signature
