Please read the doku about parallelization in the WIEN2k usersguide. mpi-parallelization is NOT done over k-points.
mpi-parallelization is useful ONLY for bigger cases, where "big" depends on your machine, accuracy and number of processes you want to use. Typically, the "blocksize" of an mpi-block should still be at least 1500x1500, better a bit larger. If your matrix size is 10000, you may use up to 6x6=36 (or 6x4=24 in your case) cores, which gives you 10000/6 as "blocksize". Probably scaling becomes already problematic ... If your matrix size is smaller/bigger, you have to adjust the number of cores which are useful. Eventually, mpi-parallelization is NOT useful at all. When you say: "This machine does not allow passwordless ssh" what exactly do you mean by that ?? I guess you have to use a queuing system ?? Which one ?? Could it be, that ssh is blocked interactively, but it works fine within a batch-job ? Sometimes, rsh works within batch-jobs,... You need to have some doku or some expert on the specific machine. I'm pretty confident that there are rather simple ways to overcome any restrictions due to a special sysadmin-setup, but most one needs to know all kinds of details and testing ... Am 01.04.2011 14:05, schrieb David Tompsett: > Dear All, > > I have recently moved my Wien2k calculations to a new machine (Hector in the > UK). This machine does not allow passwordless ssh and therefore disables the > k-point parallel part of > Wien2k. I therefore want to clarify some points about how MPI (chiefly > lapw1_mpi) works in Wien2k. > > If I run a calculation with say 5 k-points using 5 nodes that each have 24 > cores, then will the MPI call of lapw1_mpi split the 5 k-points over the 5 > nodes? Or will it simply run > the k-points one at a time, using all 120 cores for each one? > > Is there any documentation I can read about the MPI parallel strategy more > generally? > > Many thanks, > David Tompsett. > > > > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien -- P.Blaha -------------------------------------------------------------------------- Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna Phone: +43-1-58801-15671 FAX: +43-1-58801-15698 Email: blaha at theochem.tuwien.ac.at WWW: http://info.tuwien.ac.at/theochem/ --------------------------------------------------------------------------
