[jsdl-wg] TileSize and ProcessCount

[Andreas Savva]

Hi Chris,

Just to give you some background on why this is the way it is.

At the last F2F after a lengthy discussion on topology and what it 
really means the group reached the conclusion that topology is part of 
the application definition rather than part of the hardware 
requirements. (That is, it is independent of the hardware resources to 
be allocated to the job and should be described separately and in terms 
that are not hardware specific.)
So the topology tags describe the number of processes and their desired 
grouping/tiling and appear in the Application section rather than the 
Resource section. The Resource section (may) contains tags to describe 
the hardware resources required: CPUCount and ResourceCount.

I have some doubts about the current definition (in particular I think 
we either overloaded the term 'Process' or we defined TileSize the wrong 
way). But I think it is easier to bash this out on a call or f2f (hand 
to hand? :-) at GGF13.

Andreas


Christopher Smith wrote:
> Perhaps there are naming issues here, or there are too many terms defined
> here. 
> 
> JSDL is only concerned with specifying the resource requirements for the
> allocation request, not with how those resources end up being used (i.e.
> using threads or processes). So the TileSize indicates how many cpus need to
> be allocated as a unit within one OS image (i.e. a group of cpus), and the
> CPUCount would tell you how many cpus are needed in total. I don't believe
> you need any more. If the job chooses to use processes or threads is
> independent of the allocation.
> 
> So given this example:
> 
> 
>>tasks per job=3
>>threads per task=4
>>processors per task=4
>>
> 
> TileSize = 4
> CPUCount = 12
> 
> This can translate to the PBS syntax "nodes=3:ppn=4" or the LSF syntax "-n
> 12 -R 'span[ptile=4]'", and I'm sure others as well.
> 
> To the entity making the allocation, processes or threads doesn't matter.
> 
> -- Chris
> 

-- 
Andreas Savva
Fujitsu Laboratories Ltd