It is a standard eigenvalue problem, and I'm only using default algorithm options, so I don't think I'm using any nontrivial spectral transformation.
The program is just ex1.c from the documentation, available here: http://www.grycap.upv.es/slepc/documentation/current/src/eps/examples/tutorials/ex1.c FAQ #6 mentions MUMPS, which I don't have the moment, so I'll have to look into that. - Torquil On 18 October 2013 16:46, Jose E. Roman <[email protected]> wrote: > > El 18/10/2013, a las 16:42, Torquil Macdonald Sørensen escribió: > > > Hi! > > > > I'm just starting to use SLEPc on a quad-core workstation computer > (Intel Core i5-2500 CPU @ 3.30GHz). > > > > But I'm not getting the speedup that I was expecting, when increasing > the number of cores. E.g. when running ex1.c from the documentation, on 1, > 2, 3 and 4 cores. When asking for the 500 eigenvalues of smallest > magnitude, for a 5000x5000 matrix, I'm getting the following approximate > timings: > > > > # n_core time_usage > > 1 480s > > 2 400s > > 3 500s > > 4 580s > > > > Should I not expect a speedup for n_core > 2? > > > > The example is using the krylovschur algorithm. For all four runs, the > program states "Number of iterations of the method: 33". > > > > I'm using PETSc 3.4.3, SLEPc 3.4.3, OpenMPI 1.6.5, and everything is > compiled using GCC 4.8.1 or 4.8.2. > > > > Best regards > > Torquil Sørensen > > > > Is it a generalized eigenproblem and/or are you doing shift-and-invert? In > that case, have a look at FAQ #6 > http://www.grycap.upv.es/slepc/documentation/faq.htm > > Jose > >
