[Mauiusers] Questions regarding "tasks" and the cfg file.

Garrick Staples garrick at usc.edu
Wed Sep 17 13:15:01 MDT 2008

On Wed, Sep 17, 2008 at 11:12:41AM -0500, Michael Homa alleged:
> In order to test, I wrote a simple hello_world program in C. When I submit
> the program for execution, I see that the number of tasks is 6:
> Job ID    Username Queue    Jobname    SessID NDS   TSK Memory Time  S Time
> 317       mhoma    dedicate hello_worl    --   1     6    --- 00:30  Q --

What did the job actually request?  nodes=1:ppn=6?  ncpus=6?  Neither of those
requests can be answered with quad-proc machines.

> and the job remains queued because:
>  "job cannot run in partition DEFAULT (idle procs do not meet requirements
> : 0 of 6 procs found)"

The job is requesting resources that can't be met by your nodes.

> The dedicated queue has three dual CPU, dual cores and was established in
> torque:
>   argo17-1 np=4 Linux2.i86pc dualcore amd smp dedicated
>   argo18-2 np=4 Linux2.i86pc dualcore amd smp dedicated
>   argo18-3 np=4 Linux2.i86pc dualcore amd smp dedicated

I don't see nodes here that can satisfy the request of nodes=1:ppn=6.

> According to the admin manual, "by default, a task maps directly to a
> single processor within a job."
>  A few questions:
>    1) What configuration variable controls this setting? In other words,
>       how does one change maui so that a single processor can handle
>       multiple tasks from the same job. By its very nature, a hello_world
>       stub should not require six processors. Of course, my job will
>       queue; it's asking for six processors and there are only four
>       available. But, I'm surprised that the message says "0 of 6 found".

Don't change the number of CPUs in a task.  Down that road lies madness.

>    2) I'm unclear as to how the "task" number is derived? I noticed that
>       my hello_world has a PE of 6. Is that a coincidence or does the
>       resulting PE become the number of tasks? Why six processors for
>       hello_world?

We would need to see that actual request.

Garrick Staples, GNU/Linux HPCC SysAdmin
University of Southern California

Please avoid sending me Word or PowerPoint attachments.
See http://www.gnu.org/philosophy/no-word-attachments.html
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