[GE users] PE allocation rules

Reuti reuti at staff.uni-marburg.de
Thu Jul 19 19:29:48 BST 2007


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Am 19.07.2007 um 19:41 schrieb Shannon V. Davidson:

>
> Here's a simple problem.
> I have four 8-CPU hosts.
> I run serial jobs and distributed parallel MPI jobs on the hosts
> I want to schedule a 10 CPU distributed parallel job.
> For efficiency reasons, I need to run no less than 2 MPI tasks  
> (slots) of the job on each host.
>
> What PE allocation rule can I use?
>
> If I use $fill_up or $round_robin, I'll likely schedule an odd  
> number of MPI tasks on a host.  If I create several PE's with a  
> specific number for the allocation rule ("mpi2", "mpi4", and "mpi8"  
> PEs with allocation_rules of 2, 4, and 8 respectively), and submit  
> the job with a wildcard PE (-pe "mpi*" 10), the job will sit in the  
> pending queue forever, since none of these individual PEs will  
> support the scheduling of 10 CPUs.

Correct.

> Am I missing something obvious?

No.

> Perhaps it's possible to force the scheduling of 2 slots per host  
> by using $fill_up with some strange resource definition and  
> request, but I haven't resorted to trying that yet.  Instead, I'm  
> working on an RFE to support a flexible PE allocation rule.

I also thought already of such "ranges" for limits in a more general  
way by using resource requests:

http://gridengine.sunsource.net/issues/show_bug.cgi?id=2148

So it could be put there by a new entry in the resource quotas like:

limit pes my_special_pe hosts {*}  to pe_allocation_rule=(2,10,2)

-- Reuti

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