[Wien] VLM's (very large matrices)

[Torsten Andersen]

Dear Kevin,

you are not stating what system that is... if it is opteron, you might 
want to have a look at a 64-bit compiler (I think Sun, PGI, and NAG have 
some). It is the "good old-fashioned 32-bit limit" you ran into. We 
previously had this problem also with the vector files...

Best regards,
Torsten.

Jorissen Kevin wrote:
> Thanks.  This is obviously true.  I was merely trying to make the best of our current configuration.
>  
> Thanks,
>  
> Kevin.
>  
> 
> 	-----Oorspronkelijk bericht----- 
> 	Van: Peter Blaha [mailto:pblaha at zeus.theochem.tuwien.ac.at] 
> 	Verzonden: do 7/1/2004 4:21 
> 	Aan: wien at zeus.theochem.tuwien.ac.at 
> 	CC: 
> 	Onderwerp: Re: [Wien] VLM's (very large matrices)
> 	
> 	
> 
> 	Well, PCs come to some limit and sequential codes too.
> 	
> 	Such an example (if it really requires such large matrices ?) would be worth
> 	to try with the mpi-parallel version on a shared memory maschine.
> 	(I recommend to use at least 4 processors, because the mpi version will
> 	require twice as much memory)
> 	
> 	Of course I undestand that installing scalapack-pblas is not so simple,
> 	but that's the way to go.
> 	
> 	> Dear WIEN users,
> 	> I'm using the wien code compiled with ifc7 and statically linked with mkl6, and I'm trying to push nmatmax as far as it will go.  I get crashes (for real system, ie lapw1) above about nmatmax = 12500 (nume is set to 2000 - okay, for systems with few electrons I could gain a little there), corresponding to about 1.7 GB of memory used.  At higher values, I get allocation errors, though there is about twice that amount of RAM available.
> 	>
> 	> This appears to be a compiler limitation :  on http://support.intel.com/support/performancetools/fortran/linux/sb/CS-007795.htm we read that for IA32 the ifc does not allow arrays larger than 2 GB.
> 	> Documentation on the PGI website suggests the same thing will happen.
> 	>
> 	>
> 	> How do you work around this?
> 	> Thank you very much,
> 	>
> 	> Kevin.
> 	>
> 	>
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> 	
> 	
> 	                                      P.Blaha
> 	--------------------------------------------------------------------------
> 	Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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-- 
Dr. Torsten Andersen        TA-web: http://deep.at/myspace/
AG Hübner, Department of Physics, Kaiserslautern University
http://cmt.physik.uni-kl.de    http://www.physik.uni-kl.de/