[GE users] 16GB and 4GB Queue?

reuti reuti at staff.uni-marburg.de
Tue Dec 9 18:17:55 GMT 2008

Hi, again,

Am 09.12.2008 um 17:31 schrieb seca2 at freenet.de:

> hi thank you for your responses.
> i think a) is the best way for our purpose. we use matlab on the  
> hosts. matlab can be run in multithreading mode or no threading. in  
> dependance of how it is run it uses the 4 cpus of a host or only  
> one. so we want to use matlab without multithreading if a job with  
> 4G is requested. so that there can run 4 matlab sessions with each  
> 4G on one host. otherwise if someone requests 16G then matlab  
> should run multithread and also use the 4 cpus since, no other job  
> can be started on this machine.
> this should be possible going with a) ?

in principle: yes, but you have to adjust your jobscript from run to  
run anyway, or will Matlab switch to a parallel run on it's own? It's  
also in some way a personal preference of mine, to advice parallel  
jobs also to SGE as parallel ones, instead of using more cores than  
granted just by assuming that nothing else is running there.

> we don't plan to use real parallel jobs.

Also threaded applications are parallel ones - they use just a  
different type of implementation for the parallelism. I don't use  
Matlab, but if it's working with OpenMP, then you could better use b)  
and request a PE (which doesn't have to do anything for this type),  
and you can always use $NSLOTS in your jobscript, it's set to the  
number of threads:


This will then work even in the serial case as $NSLOTS is always set.  
It's just a matter to tell your users to request a PE instead of  
h_vmem. The memory they will get then automatically.

-- Reuti

> thank you again.
> bubbas
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