[Pw_forum] How to estimate the memory requirement of ph.x?

[lfhuang]

Dear prof. P. Giannozzi:
    Thank you very much for your helpful and clear response! I appreciate very much!
Best Wishes!
Yours Sincerely
L. F. Huang

> Date: Fri, 10 Dec 2010 12:33:20 +0100
> From: Paolo Giannozzi 
> 
> lfhuang wrote:
> 
> > it is understandable that ph.x requires more memory than pw.x.
> >  But how  to estimate it to be qualitatively precise?
> 
> sum the size of large arrays. I do not know any other way. If the
> code runs, a call to "memstat" returns the size of dynamically
> allocated memory (on operating systems that support it). Not sure
> how much of the total memory is reported, though. Apparently the
> question "how much memory does a process use" has become difficult
> to answer in modern operating systems.
> 
> > How can a 3GB processor breaks down when doing a ph.x job, when the 
> > requirement of it pw.x job is just 500MB?
> 
> the phonon code uses more arrays and distributes less of them across
> processors.
> 
> > By the way, is it better to assign the N_pr to be m**2 (m=2,3,4...) than 
> > other values (e.g. 6, 10, 11, 14...) if I want to divide the R-&G-space 
> > in parallelization?
> 
> I think it depends upon the specific communication hardware and
> MPI implementation. Not sure though.
> 
> Paolo
> -- 
> Paolo Giannozzi, Democritos and University of Udine, Italy


------
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L.F.Huang(黄良锋) DFT and phonon physics
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Add: Research Laboratory for Computational Materials Sciences,
Instutue of Solid State Physics,the Chinese Academy of Sciences,
P.O.Box 1129, Hefei 230031, P.R.China
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Our group: http://theory.issp.ac.cn
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