Umut, Have you tried slepc for eigenvalue problems? Why do you need mumps in your eigensolver? Shift-and-invert?
Hong On Mon, Apr 21, 2014 at 9:39 AM, Matthew Knepley <[email protected]> wrote: > On Sat, Apr 19, 2014 at 2:13 PM, Umut Tabak <[email protected]> wrote: >> >> Dear all, > > > For any timing question, we need to see the output f -log_summary. Also, if > you have significant > time in routines you wrote, we need you to create PETSc events for these. > > Matt > >> >> I am experiencing lately some issues with a symmetric Lanczos eigensolver >> in FORTRAN. Basically, I have test code in MATLAB where I am using >> HSL_MA97(MATLAB interface) at the moment >> >> When I program Lanczos iterations in blocks in MATLAB by using HSL_MA97, >> as expected my overall solution time decreases meaning that block solution >> improves the solution efficiency. >> >> Then, to apply the same algorithm on problems on the orders of millions, I >> am transferring the same algorithm to a FORTRAN code but this time with >> MUMPS as the solver then I was expecting the solution time to decrease as >> well, but my overall solution times are increasing when I increase the block >> size. >> >> For a check with MUMPS, I only tried the block solution phase and compared >> 120 single solutions to >> >> 60 solutions by blocks of 2 >> 30 solutions by blocks of 4 >> 20 solutions by blocks of 6 >> 15 solutions by blocks of 8 >> >> and saw that the total solution time in comparison to single solves are >> decreasing so I am thinking this is not the source of the problem, I >> believe. >> >> What I am doing is that I am performing a full reorthogonalization in the >> Lanczos loop, which includes some dgemm calls and moreover there are some >> other calls for sparse symmetric matrix vector multiplications from Intel >> MKL. >> >> I could not really understand why the overall solution time is increasing >> with the increase of the block sizes in FORTRAN whereas I was expecting even >> an improvement over my MATLAB code. >> >> Any ideas on what could be going wrong. >> >> Best regards and thanks in advance, >> >> Umut > > > > > -- > What most experimenters take for granted before they begin their experiments > is infinitely more interesting than any results to which their experiments > lead. > -- Norbert Wiener
