[jsdl-wg] Process Topology

[Karl Czajkowski]

On Apr 20, Andreas Savva loaded a tape reading:

> I meant that if a resource description is given as
> <Resource>
>   <CPUCount> <Exact> 2.0 </Exact>  </CPUCount>
> </Resource>
> 
> it means a 2-cpu host. Not 2 CPUs from a possibly larger N CPU machine.
> 

Yes, this is indeed the "latter" case from Chris.  I had hoped we
didn't care about the aspects of a resource _not_ allocated to us.

Why do you actually care whether your 2 CPUs are a whole host or not?
Is this actually some sort of selection preference sneaking in, like
do not give me the more rare nodes?  Or is it a QoS issue like
"exclusivity" of the resource?  I think it is important that we
understand why you want to express this, now that it is clear what you
are expressing.

Do you expect to express similar physical constraints on other
resources not necessarily allocated to you, e.g. amount of RAM or
virtual memory space not necessarily allocated to you?  I'm not trying
to be snarky but this avenue does confuse me lots!


> If on the other hand I said
> <Resource>
>   <CPUCount> <LowerBoundedRange> 2.0 </LowerBoundedRange>  </CPUCount>
> </Resource>
> 
> I would accept any machine with at least 2 CPUs.
> 

I find this ambiguous again... you need to distinguish again
acceptance of an allocation from acceptance of characteristics of a
resource that have not been allocated to you!


> So the (my?) definition would be closer to Chris' second definition.
> 
> Maybe we should leave the rest until we can clarify what is the correct 
> definition of resource multiplicity (and what other people think the 
> correct meaning of the above fragments are....)
> 
> Andreas
> 

It seems to me the issue of resource element mulitplicity is
orthogonal... it is whether we support heterogeneous resource
requirements or not, e.g. some number of resources that look like THIS
and some other number of resources that look like THAT.

As for you parenthetic comment, I think it is useless to investigate
"what people think the correct meaning of [...] fragments are" but
rather we should focus on what meanings do we want to convey in JSDL
and then fix the syntax to do so unambiguously.

It sounds to me like you are advocating the full set of concepts I
suggested in my earlier message:

  allocated CPUs per resource
  total allocated CPUs 

  installed CPUs per resource (your 2-cpu machine)

As Chris said, using range value expressions on "allocated CPUs per
resource" will give us tile size, e.g. I want 2,4,8,16 CPUs per
resource (but not 7 etc.) and I want between 32 and 128 CPUs total.

One thing that confuses me is whether there needs to be a way to
express symmetry or "strict homegeneity" e.g. 

   4 nodes, each with 4 cpus
     OR
   4 nodes, each with 8 cpus

versus

   4 nodes, each with 4 or 8 cpus

I think the latter is what we know how to express right now using
exact resource counts, by considering them equivalent to unrolling
into a fixed number of resource elements.  I do not know if others
intended this or the stricter symmetric interpretation.

karl

-- 
Karl Czajkowski
karlcz at univa.com