[torqueusers] oversubscribing

Gareth.Williams at csiro.au Gareth.Williams at csiro.au
Tue Sep 14 18:33:32 MDT 2010


> -----Original Message-----
> From: Will Nolan [mailto:will at headlandstech.com]
> Sent: Wednesday, 15 September 2010 12:36 AM
> To: Torque Users Mailing List
> Subject: Re: [torqueusers] oversubscribing
> 
> >> You can get TORQUE to oversubscribe by setting the the
> >> number of processors for the node in the
> >> $TORQUE_HOME/server_priv/nodes file using  the np=x option.
> >> Set x to the number of nodes you want TORQUE and Maui
> >> to think are available.
> >
> >Remember don't build Torque with cpuset support in that
> >scenario as I believe it will assume that it can assign
> >a physical core for each one that is allocated to a job.
> 
> So, I actually did try setting the np value to a higher number than the
> number of available cores per node a while ago, and still observed the
> behavior that the number of jobs running was still being constrained to
> the number of cores.
> 
> I don't 100% understand what you're saying but it _sounds_ like what you
> mean is that by default Torque only assigns jobs to physical cores?  That
> would certainly be an explanation for the behavior I observed.
> 
> However, checking the torque ./configure script I see an option "--enable-
> cpuset", and I know I did not set this when building...
> 
> Any thoughts?  Perhaps it's maui somehow?
> 
> Will

Hi Will,

It could be the scheduler configuration.  You can choose to schedule based on allocation (ie one task per slot... though the terms are overloaded) or you can choose to schedule based on load (but I think one task per slot will be the ceiling anyway). For maui see: http://www.clusterresources.com/products/maui/docs/5.4nodeavailability.shtml

-- Gareth



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