Dear Baris Thanks a lot for your answer. how many scf steps "do you perform in these 3 hours? Does your system have some convergence problems?", It take 12 iteration to perform, And there is no convergence problem "This is especially important if you are using a low memory bandwidth architecture.", I can not understand your hint, We use a P4 machine with 8 core, I think you say we must use Half of them, Is it true? And finally thanks for your answer Moshen Modaresi
On 5/20/10, O. Baris Malcioglu <baris.malcioglu at gmail.com> wrote: > Dear Mohsen, > Please notice that you have asked a rather vague question regarding > performance, > > First of all, please notice that since PW is a plane wave code, it is > not just the number of atoms that determine the "size" of the system. > You have to take into account the number of plane waves you are using. > This depends on your cutoffs and simulation supercell. Exaggerating > the situation unnecessarily, for example putting only an ethane > molecule in a 500x500x500 Bohr box (even with modest cutoff) will > result in a system size that will certainly give a hard time to the > computer you are describing. In the same sense, using very high > cutoffs will lead to same problem. > > Secondly, "3 hours" is not a good enough criteria, how many scf steps > do you perform in these 3 hours? Does your system have some > convergence problems? > > Finally, 8 cpu is not a good enough identification nowadays, if the > "cpu" you are mentioning is due to hyper-threading, it is usually > better if you use only 4, since you waste your precious memory > bandwidth. This is especially important if you are using a low memory > bandwidth architecture. > > Some general guidelines : > > -Make sure that your computer is not using swap, > -Use architecture dependent acceleration libraries such as MKL. For > example you can setup fftw 3.x to utilize instruction sets such as > sse2. > -If this is a parallel compiler check wall times, how much do you > loose communicating? > > Best, > Baris > > 2010/5/20 Phillip Nyawere <pnyawere at gmail.com>: >> You need high speed computer. I tried with 96 atoms and it was taking even >> longer. >> Success. >> >> On Wed, May 12, 2010 at 10:07 PM, mohsen modaresi >> <modaresi.mohsen at gmail.com> wrote: >>> >>> Dear Developers and users, >>> I run a SCF calculation with 71 atoms on a camputer with 8 cpu and 8GB >>> RAM, i expect it run in some minutes, But it take 3 hours to run. >>> Is it regular? >>> >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >> >> >> >> -- >> Phillip W. Otieno Nyawere, >> Kabarak University, >> Dept of Physics & Mathematics, >> P.O Box Private Bag - 20157, >> Kabarak, Kenya. >> Tel +254728342054 >> pnyawere at gmail.com, potieno at kabarak.ac.ke >> >> The battle belongs to the Lord. >> >> _______________________________________________ >> 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 >
