Hello, It is not a computer. It is a cluster and I am doing parallel computing on 3 nodes each with 8 processors which is a total of 24 processors; this is why I am surprised that the calculation is slow . I tried performing the calculations on different nodes but in vain. N.B: I did calculations on one server with only 8 processors for the Gamma point and the calculations finished in three weeks (though with some negative frequencies, this is why I decided to minimize the tr2_ph) But now that server is down. I thought on more nodes things would be faster; apparently not
Regards Elie > Date: Mon, 19 Mar 2012 10:00:37 -0400 > Subject: Re: [Pw_forum] parallel computation too slow > From: akohlmey at gmail.com > To: elie.moujaes at hotmail.co.uk > CC: pw_forum at pwscf.org > > On Mon, Mar 19, 2012 at 9:45 AM, Elie M <elie.moujaes at hotmail.co.uk> wrote: > > Professor Giannozzi, > > > > Thanks for the reply. The CPU time is 1 hr 26 min (2hrs 2 min normal time) > > for the scf calculation on the nodes (3 of them). If I have 42 atoms then > > this is equivalent to almost 8 days CPU time or 10 days normal time. Four > > days have passed and I am still in representation 6 out of 126 which i guess > > is not the normal situation...Can anything be done (or checked) in this > > case? > > get a real computer! if you already lose a quarter of the time due to > swapping for the scf calculation, you'll be seriously out of memory > for anything more advanced. your laptop is obviously not suitable > to carry out this kind of calculation. sorry. > > axel. > > > > > Regards > > > > > > Elie > > > >> CC: pw_forum at pwscf.org > >> From: giannozz at democritos.it > >> Subject: Re: [Pw_forum] parallel computation too slow > >> Date: Fri, 16 Mar 2012 21:48:15 +0100 > >> To: elie.moujaes at hotmail.co.uk > > > >> > >> > >> On Mar 16, 2012, at 19:14 , Elie M wrote: > >> > >> > I am running phonon calculations for a supercell of 60 atoms at the > >> > gamma point [...] > >> > What could the possible causes of this slowness be? Is it something > >> > to do with the > >> > nodes or with phonon calculations in general? Is there a way to check? > >> > >> > > >> > >> a phonon calculation for N atoms requires a CPU time of the order of > >> 3N the time of > >> the correspoding scf calculation. Does yours? if it does, there is > >> nothing that can be > >> done. > >> > >> P. > >> --- > >> Paolo Giannozzi, Dept of Chemistry&Physics&Environment, > >> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy > >> Phone +39-0432-558216, fax +39-0432-558222 > >> > >> > >> > >> > > > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://www.democritos.it/mailman/listinfo/pw_forum > > > > > > -- > Dr. Axel Kohlmeyer > akohlmey at gmail.com http://goo.gl/1wk0 > > College of Science and Technology > Temple University, Philadelphia PA, USA. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120319/f965267d/attachment-0001.htm
