[Pw_forum] R: Re: scalability of the code

giacsport at libero.it giacsport at libero.it
Tue Feb 7 11:46:26 CET 2012

Very useful information. 

Grazie Paolo,

>----Messaggio originale----
>Da: giannozz at democritos.it
>Data: 07/02/2012 10.57
>A: "giacsport at libero.it"<giacsport at libero.it>
>Cc: <pw_forum at pwscf.org>
>Ogg: Re: [Pw_forum] scalability of the code
>On Tue, 2012-02-07 at 09:38 +0100, giacsport at libero.it wrote:
>> I would like to know which is the highest number of processors
>> used and reported for running PWscf code.
>I have seen a test run on 65536 processors (cores, I mean).
>Unfortunately I do not find any longer a test on a 8000-atom 
>system recently done: I guess it was also run on more than 
>just a few processors.
>> Are there data or reports on the scalability of the code (well) 
>> above 1000 processors?
>there is something in the Benchmark section of the new web site
>( http://testwp.qe-forge.it/wordpress-3.1.4/?page_id=44 ). 
>More data will (maybe) come (subject to my allergy to both benchmarks 
>and wordpress, and to everybody's allergy to documentation)
>> We are indeed interested in installing the code in a massively parallel 
>> machine, but before doing it we would like to have more information.
>QE has been installed (with little effort) on several BlueGene machines.
>It works (i.e. it has ben used for real scientific purposes and has
>produced published results in at least one case I am aware of). You 
>have to be careful with I/O, which can become easily a limiting factor.
>You may need to use all available parallelization levels, in particular
>OpenMP, to satisfy the machine owners who, for sure, wants you to run 
>on a number of cores vastly exceeding what you actually need
>Paolo Giannozzi, IOM-Democritos and University of Udine, Italy

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