[torquedev] nodes, procs, tpn and ncpus

"Mgr. Šimon Tóth" SimonT at mail.muni.cz
Fri Jun 11 12:19:39 MDT 2010


On 11.6.2010 18:41, 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:
>>
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>>    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).

That's not good enough. How do you tell Torque that you want at least a
4 CPU node, but when you get it, then you want all the CPUs?

-- 
Mgr. Šimon Tóth

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