[jsdl-wg] TileSize and ProcessCount

[Andreas Savva]

Claudio

> And so what is a "group of processes (tasks)" ?

TileSize specifies the unit that should be used when partitioning the 
processes across the nodes.  For example,
    TileSize=2
    ProcessCount=8
means that the 8 processes should be partitioned across nodes in tiles 
(units) of 2; for a total of 4 tiles.

If [ResourceCount=4] then each node would receive 1 tile (2 processes).
If [ResourceCount=3] then one of the  nodes would receive 2 tiles and 
the other two nodes 1 tile each. (It would not be possible to partition 
the processes as two nodes receiving 3 processes and one node 2 processes.)

> Is there a way to specify "threads per task (process)" ? 

Not directly. You can specify the number of cpus to be equal to or more 
than the threads that your application will use. To use your example:

ProcessCount=3
CpuCount=8
ResourceCount=2

See also some examples that Michel send out last December
http://www-unix.gridforum.org/mail_archive/jsdl-wg/2004/12/msg00006.html

I am working (ever so slowly) on a revision of the ProcessTopology 
section for the specification. Hopefully it will be ready for review 
early next week.

Thanks.
Andreas

claudio cacciari wrote:

> Dear All,
>
> I 'm trying to understand the meaning of TileSize and ProcessCount 
> elements to describe a MPI + OpenMPI job.
> For example, in a job submission request for a batch scheduler 
> (LoadLeveler, PBS and so on) I can specify :
>
> tasks per job=3
> threads per task=4
> processors per task=4
>
> in order to get 1 thread per processor ( processors per task = threads 
> per task ).
> I can set "nodes per job"=2 (with a a configuration of 8 cpus per 
> node) or leave the scheduler sets this value.
> For what I understand in JSDL there are :
>
> [tileSize]             tasks (processes) per group
> [ProcessCount]   tasks (processes) per job
> [CPUCount]        processors per job (with ResourceCount=1)
> [CPUCount + ResourceCount] processors per node + nodes per job
>
> from which I can get :
>
> tasks per job = [ProcessCount] = 3
> threads per task = [ ? ] = 4
> processors per task = [ CPUCount * ResourceCount / ProcessCount ] = 4
> nodes per job = [ ResourceCount ] = 2
>
> And so what is a "group of processes (tasks)" ?
> Is there a way to specify "threads per task (process)" ?
>
> Best Regards,
> Claudio Cacciari
>
> =========================================================
> Claudio Cacciari                               CINECA - Via Magnanelli 
> 6/3 40033
> High Performance System Group    Casalecchio di Reno - Bologna - ITALY
> e-mail: c.cacciari at cineca.it              http://www.cineca.it
>                                                         Tel: 
> 051/6171411 - Fax: 051/6132198
> =========================================================
>

-- 
Andreas Savva
Fujitsu Laboratories Ltd