[petsc-users] Convergence/accuracy degradation with increasing number of procs

[Alexander Grayver]

I have tested default GMRES+ILU(0) solver for problem of size ~200000 
and I observed that both convergence rate and accuracy degrade when I 
increase number of processes.
E.g., number of iterations almost doubles when going from 1 to 4 
processors.

I noticed that ILU(0) is somehow represented by sequential matrices 
internally and feel that this might be a reason?

Regards,
Alexander