[petsc-users] [Slepc] eigensolver not running in parallel

[Jose E. Roman]

Which version of SLEPc are you using?

You should get an error unless you have configure PETSc with a parallel direct linear solver. Which option did you use to configure PETSc?

Send the output when using the option -eps_view_pre

Jose


> El 23 ago 2022, a las 2:11, Patrick Alken <patrick.alken at geomag.info> escribió:
> 
> I am trying to solve a symmetric generalized eigenproblem with slepc (n = 40500) using 8 processors. The command I use is:
> 
> mpiexec -n 8 ./main -eps_nev 10 -eps_target 0 -st_type sinvert
> 
> The program assembles the two matrices (A,B), sets up the eigensolver and then calls EPSSolve. The issue is that the matrix assembly runs fine in parallel. And for about 1 minute or so, the EPSSolve call uses all 8 processors (according to the top program). But then after around 1 minute or so, the program collapses to just 1 thread and just runs that way for a long time (still in the EPSSolve call).
> 
> Is there a way to diagnose what is going on, and how to make the program use all 8 processors for the eigensolver?
> 
> 
>