On Tue, 15 Jul 2014 12:15:30 +0000 Taras Shapovalov <taras.shapova...@brightcomputing.com> wrote:
> Hello, > > Do you know if it is possible to get a number of nodes that will be > allocated for a parallel job if the job is in "qw" state? > > I see this number is calculated based on allocation_rule parameter, > but also in some unclear (to me) cases one more node can be allocated > for a master queue. In the majority of all other workload managers In general it is impossible to do this for a several reasons chief amongst which are: i)Grid Engine doesn't allocate nodes but slots within queues on the nodes. If you don't request exclusive access to the host (via an appropriate resource) your job can be scattered all over the place. ii)You can request a range of slots so the number of slots (and therefore nodes) the job will take up can vary. iii)Consumables are allocated per slot by default so the number of slots you can fit on a node will vary with resource requests/availabilty (this just adds a bit of maths to the problem but the first two issues are enough to make the problem insoluble in the general case). The job_is_first_task parameter on PEs controls how many SLAVE(qrsh) sessions the job can launch: either as many as the slots allocated to the job or one fewer. This is also reflected when the job is displayed by qstat. AFAIK apart from the extra qrsh session it doesn't affect resource allocation (unless you request a per job consumable I guess). With the above said our cluster at UCL has a JSV that: i)Prevents the use of a range with a PE. ii)Ensures jobs either fit on one node(requring a PE with a $pe_slots allocation rule) or request exclusive access to nodes. That allows the JSV to calculate how many nodes/slots they will block and enforce an appropriate policy. We then stuff the caculated blocked slots value into the account string for later processing by our reporting software. William > this parameter is possible to get before the job is started (that is > useful sometimes), but I cannot find it in the both OGS and UGE. > > Thanks, > Taras
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