[jsdl-wg] TileSize and ProcessCount (fwd)

[Ali Anjomshoaa]

Bounced ?


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        Ali Anjomshoaa
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---------- Forwarded message ----------
Date: Wed, 02 Mar 2005 09:26:56 +0000
From: A S McGough <asm at doc.ic.ac.uk>
Cc: jsdl-wg at gridforum.org
Subject: Re: [jsdl-wg] TileSize and ProcessCount

OK,

Reading this thread (sorry for the use of the term...) it seems as 
though we have confusion between a number of different terms. Personally 
in this case I like to think in diagrams.

Attached is the example
ProcessCount = 12
TileSize = 4

 From the document this suggests that we have 12 processes (not 
processors) in the job and that each set of 4 processes are allocated to 
a resource. Thus requiring 3 resources. Presumably if we request in the 
resource section that each resource must have at least 4 processors then 
each process _could_ be mapped down to a different processor. Is this 
correct? Are people happy with this? Does it describe all situations?

I've attached a figure showing this - sorry it's so naff.

steve..

Christopher Smith wrote:

>Thanks for the clarification Andreas. I guess I need to do some reading up
>on some of the changes. :-)
>
>-- Chris
>
>
>On 1/3/05 18:41, "Andreas Savva" <andreas.savva at jp.fujitsu.com> wrote:
>
>  
>
>>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
>>>
>>>      
>>>
>
>
>  
>


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