[petsc-users] Slepc JD and GD converge to wrong eigenpair

[Jose E. Roman]

> El 30 mar 2017, a las 9:27, Toon Weyens <toon.weyens at gmail.com> escribió:
> 
> Hi, thanks for the answer.
> 
> I use MUMPS as a PC. The options -ksp_converged_reason, -ksp_monitor_true_residual and -ksp_view  are not used.
> 
> The difference between the log_view outputs of running a simple solution with 1, 2, 3 or 4 MPI procs is attached (debug version).
> 
> I can see that with 2 procs it takes about 22 seconds, versus 7 seconds for 1 proc. For 3 and 4 the situation is worse: 29 and 37 seconds.
> 
> Looks like the difference is mainly in the BVmult and especially in the BVorthogonalize routines:
> 
> BVmult takes 1, 6.5, 10 or even a whopping 17 seconds for the different number of proceses
> BVorthogonalize takes 1, 4, 6, 10.
> 
> Calculating the preconditioner does not take more time for different number of proceses, and applying it only slightly increases. So it cannot be mumps' fault...
> 
> Does this makes sense? Is there any way to improve this?
> 
> Thanks!

Cannot trust performance data in a debug build:

      ##########################################################
      #                                                        #
      #                          WARNING!!!                    #
      #                                                        #
      #   This code was compiled with a debugging option,      #
      #   To get timing results run ./configure                #
      #   using --with-debugging=no, the performance will      #
      #   be generally two or three times faster.              #
      #                                                        #
      ##########################################################