[GE users] PE allocation rules

Andreas.Haas at Sun.COM Andreas.Haas at Sun.COM
Fri Jul 20 10:12:41 BST 2007


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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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