[torquedev] nodes, procs, tpn and ncpus

Ken Nielson knielson at adaptivecomputing.com
Fri Jun 11 10:44:06 MDT 2010

On 06/11/2010 10:41 AM, Martin Siegert wrote:
> On Fri, Jun 11, 2010 at 09:59:47AM -0600, Ken Nielson wrote:
>>     On 06/10/2010 09:36 PM, Christopher Samuel wrote:
>>     Hash: SHA1
>>     On 11/06/10 04:47, Glen Beane wrote:
>>     >  In my opinion, I think nodes=X,procx=Y should generate
>>     >  a syntax error...
>>     Agreed.
>>     I am not swayed one way or another yet. What if a user makes a request
>>     like the following
>>     -l nodes=4:ppn=2+procs=6
>>     The user wants four nodes with two processors each and then 6
>>     processors anywhere they are available.
>>     -l nodes=4+procs=4
>>     The user wants 4 nodes plus 4 processors anywhere. This one makes less
>>     sense than the first, but if we allow the first we need to allow this
>>     as well.
>>     Thoughts anyone?
> It all depends on whether we want to break the meaning of nodes=N being
> totally equivalent to nodes=N:ppn=1.
> 1) if we stick to the meaning of nodes=N just being a shorthand for
>     nodes=N:ppn=1 then -l nodes=4+procs=4 makes just as much sense as
>     nodes=4:ppn=2+procs=6, i.e., there is no problem.
> 2) if we change the meaning of nodes=N to become "give me exclusive
>     access to N nodes" then we need to define what -l nodes=N+procs=M
>     means.
> I actually vote for (1). E.g., what is the default if neither nodes nor
> procs is specified? Currently that is nodes=1:ppn=1, i.e., the default
> for nodes is 1 and the default for ppn is one. That logical extension is
> that if only nodes is specified then the default value for ppn should be
> used. I.e., nodes=N means nodes=N:ppn=1.
> But that leaves us with the problem of how to specify exclusive access
> to a node. What about a keyword ALL as in nodes=4:ppn=ALL ? It is a
> logical extension of the current syntax and is easy to understand.
> And then things like -l nodes=1:ppn=ALL+procs=42 make total sense
> (at least to me).
> Cheers,
> Martin
> _______________________________________________
With nodect not defined the current meaning of nodes=x is 
nodes=x:ppn=1.  I see no reason to change this behavior. To allocate a 
node exclusively I think ppn=ALL makes sense.


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