[torqueusers] MPI jobs not tied to nodes/ppn configuration

rozelak at volny.cz rozelak at volny.cz
Fri Oct 16 00:43:10 MDT 2009


> This is dependent on how the scheduler is setup  (
> if you allow multiple
> jobs on a single node etc ).
> 
> But I believe you can use:
> qsub -l ncpus=X ...  where X is the total number of
> cpus you need.
> 
> Jerry

AFAIK, it does not work with PBSpro on cluster with multi-core/processor
nodes (I think it works on SMP machines, but I did not try it, as it
is not my case ...)

Dan

> 
> rozelak at volny.cz wrote:
> > Hallo,
> >
> > I have access to heterogeneous clusters with many
> > multi-core/processor
> > > nodes, where PBSPro is installed. When I want to
> > start MPI job, I need
> > > to specify how many nodes, and how many CPUs per
> > node I want. E.g.,
> > > when I require 32 MPI processes, I need to run it
> > as:
> > >
> > qsub -l nodes=16:ppn=2 ...
> >
> > The problem is, that PBS will wait until there are
> > at lest 16 nodes,
> > > each with 2 cores free, even if there are more that
> > 32 cores free (e.g.
> > > 15 nodes with 2 free cores each + 2 and more nodes
> > with one free core,
> > > giving 32+ free cores available). This can be found
> > for any nodes/ppn
> > > combination, e.g.:
> >
> > qsub -l nodes=32:ppn=1 ...
> >
> > will not be started on 31 nodes with 4+ free cores
> > (having 124 cores
> > > free!). What I need is just to say -- I need XY cores/processors
> > > > > > > > for
> > > my job in a cluster, and I do not care how many nodes
> > it will be started
> > > on, while each node may allocate different number
> > of cores.
> > >
> >
> > So, the question is: is 'torque' able to handle such
> > cases? And how?
> > > If so, I will talk about it with our clusters admins,
> > as I remember
> > > that they considered the migration from PBS and they
> > are opened to our(users)
> > > wishes.
> >
> > Thank you very much for your answer,
> > Dan T.
> >
> > _______________________________________________
> > torqueusers mailing list
> > torqueusers at supercluster.org
> > http://www.supercluster.org/mailman/listinfo/torqueusers
> > >
> >
> >   
> 




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