[Moabusers] Re: [torqueusers] OpenMP with Torque
prakash.velayutham at cchmc.org
Mon Mar 10 12:53:02 MDT 2008
On Mar 10, 2008, at 2:48 PM, Garrick Staples wrote:
> On Mon, Mar 10, 2008 at 02:44:26PM -0400, Prakash Velayutham alleged:
>> Hello All,
>> I sent an email on this topic some days ago, but did not get any
>> response. So decided to rephrase my question to see if this invokes
>> any response.
>> When a user requests just 1 CPU for a job (qsub -lnodes=1) and does
>> not specify OMP_NUM_THREADS explicitly, and if the node has 4 CPUs,
>> does the job get restricted to 1 CPU that was allocated to the user
>> does it spread to the 4 CPUs (if the other CPUs are not taken by
>> My scheduler is Moab, so I am copying Moab users list here too.
> No, torque doesn't set OMP_NUM_THREADS. Torque doesn't know
> anything about
> OpenMP, MPI, or anythen else that jobs do.
> Garrick Staples, GNU/Linux HPCC SysAdmin
> University of Southern California
But, does the job get restricted to just 1 CPU or does it get outside
of its allocation during OpenMP calls?
If OMP_NUM_THREADS is required to be set for the restriction to work,
is there a way I can do it using prolog scripts or some other mechanism.
Currently, when a user requests just 1 CPU and start his OpenMP code,
the code hikes the load on the machine up to 4 (on a 4 CPU system) and
no further jobs get allocated on that system because of the high load.
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