[Moabusers] Re: [torquedev] Re: [torqueusers] Allocating resources by CPUs

Glen Beane glen.beane at gmail.com
Mon Mar 19 10:18:36 MDT 2007


On 3/19/07, Joshua Bernstein <bjosh at lpl.arizona.edu> wrote:
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> On Mar 18, 2007, at 9:23 PM, Chris Samuel wrote:
>
> > On Mon, 19 Mar 2007, Joshua Bernstein wrote:
> >
> >> On Mar 18, 2007, at 7:56 PM, Chris Samuel wrote:
> >>> On Tue, 13 Mar 2007, Glen Beane wrote:
> >>>> I agree that we should add a '-l cpus=x'  option to torque
> >>
> >> Forgive me for being out of the loop and perhaps not following the
> >> threads as closely as possible, but isn't there an -l ncpus=x option
> >> in Torque?
> >
> > There is, but that only determines how many CPUs on an SMP node you
> > want, not
> > how many CPUs across the whole cluster you may need.
>
> You figure out how many CPUs you want across the the entire cluster
> by simply multiplying the nodes times the ppn. Otherwise simply
> notating nodes=x says that you want x number of cpus, since the nodes
> argument specifies the number of default number of "virtual cpus",
> not nodes (as is often confused). Adding another confusing option
> seems a bit excessive. People are already very well confused between
> the difference of nodes, ncpus, and ppn and how they all related.
>
> On that note, both the nodes, and ppn arguments are nicely documented
> (including the virtual host idea), though ncpus wasn't listed last I
> looked at the Torque documentation.

we've already been over this

the reason we are talking about yet another option is some users want
the job to run exactly how they specify, and others just want it to
run on X number of CPUs as quickly as possible and they don't care how
many nodes are used

you can not satisfy both users with maui/moab and torque.  To get
something like -l nodes=64 and have it run on any combination of nodes
that equals 64 CPUs to work you have to disable the exact node match
exact policy

It would be acceptible to me if there were a maui and moab option that
would enforce the exact node match policy if :ppn is specified,
otherwise it wil provide any distribution of CPUs across whatever
number of nodes are needed to satisfy the request


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