[GE users] PE allocation rules

Shannon V. Davidson svdavidson at charter.net
Fri Jul 20 15:45:58 BST 2007


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Andreas (et al),

Thank to all for your comments and quick responses.  I'll submit an RFE 
and hopefully I'll be able to contribute some work toward a solution.

Cheers,
Shannon


Andreas.Haas at Sun.COM wrote:
> Hi Shannon,
>
> On Thu, 19 Jul 2007, Shannon V. Davidson wrote:
>
>>
>> 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.
>>
>> 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.
>
> A syntax enhancement with allocation rule were doable: The 
> PE_allocation_rule is carried around as a plain string within SGE.
> Remaining question thus is merely how to enhance
>
>    parallel_tag_queues_suitable4job()
>    parallel_make_granted_destination_id_list()
>
> but this can also be done without acutally sparking an earthquake ;-)
>
> Regards,
> Andreas
>
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-- 
____________________________________________

Shannon V. Davidson <svdavidson at charter.net>
Senior Software Engineer               Appro
636-633-0380 (office)     443-383-0331 (fax)
____________________________________________


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