Thanks a lot Dr. Stefano for your reply. On Fri, Dec 24, 2010 at 3:50 PM, Stefano de Gironcoli <degironc at sissa.it>wrote:
> It strongly depends on the particular calculation and on the > parallelization strategy you choose. Linear scaling would be the ideal > scaling which you never get. > The things to keep in mind are load balancing and communication > overhead. This last is affected by your communication network latency > and bandwidth ... As a general rule the bigger the calculation the > easier is to scale. > It may be useful to have a look at the final timing summary of a > calculation to see the fraction of time spent in communication (FFT > scatter/gather and reduce operations) compared with the total wall clock > time for your system and how this changes for different settings. > Another factor to keep in mind is RAM memory as with certain > parallelization strategies you can trade some speed with increased memory. > > stefano > > mohnish pandey wrote: > > Dear QE users, > > I am trying to see how the runtime scales with > > number of processors. I did the same calculation using one node with > eight > > processors on one cluster and 8 nodes with total 56 processors on other > > cluster but the time does not seem to scale linearly with the number of > > processors. Can anybody give me an idea how does the time scale with > number > > of processors. > > Thanks a lot in advance. > > > > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://www.democritos.it/mailman/listinfo/pw_forum > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Regards, MOHNISH, ----------------------------------------------------------------- Mohnish Pandey Y6927262,5th Year dual degree student, Department of Chemical Engineering, IIT KANPUR, UP, INDIA ----------------------------------------------------------------- -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20101224/e6654593/attachment.htm
