On Wednesday 08 February 2006 12:18, Silviu Zilberman wrote: > I have been running calculations on Lemieux which is an alpha cluster > super computer in Pittsburgh. For some reason that is still mysterious > to me, writing these density files on the scratch space took very long > time, ~30 (!) minutes for a 68MB file.
maybe you should rename your machine "Lepire" :-) The charge density file should be written only when the wavefunctions are written, every "isave" steps and at the end of the run. If it is written at each time step, this is definitely wrong. The charge density in a parallel calculation is collected to a single node and written from there. Since it is not wise to collect it into a single array, each slice from each processor is collected and written. Maybe this algorithm is not optimal (maybe it is even "pessimal"). You should try to understand where exactly the machine spends all this time and why Paolo -- Paolo Giannozzi e-mail: giannozz at nest.sns.it Scuola Normale Superiore Phone: +39/050-509876, Fax:-563513 Piazza dei Cavalieri 7 I-56126 Pisa, Italy
