Hi,
I have a linear system with about 161^3=4,173,281 unknowns. I used the default
KSP solver(to my understand it is GMRES) to solve it. The relative tolerance is
set as 1.266e-9. The number of iterations is 5373 and the computing time
problem is about 23.65 mins with 128 processes. With the same problem, but I
selected a pre-conditioner such as hypre, the number of iterations can be
reduced dramatically, however, the computing time increases somewhat.
May someone give me some suggestions on selection of KSP solver to solve a
large scale linear system faster? Thanks a lot.
