Santos Teixeira Frederico <fsantost at student.ethz.ch> writes: > Hi, > > I am using PETSc with MUMPS and based on the time required for each > iteraction (it is almost the same amount of time), I suspect MUMPS is > not using the information about the nonzero pattern. My question is: > how do I make sure it is correctly configured? I am already setting > "KSPSetOperators(ksp, A, A, SAME_NONZERO_PATTERN)".
Profile, don't speculate. If you see something like this, then symbolic factorization is indeed reused. MatLUFactorSym 1 1.0 5.0068e-06 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 0.0e+00 0 0 0 0 0 0 0 0 0 0 0 MatLUFactorNum 3 1.0 1.2076e-03 1.0 0.00e+00 0.0 0.0e+00 0.0e+00 0.0e+00 4 0 0 0 0 4 0 0 0 0 0 The vast majority of the work is in numeric factorization. MUMPS has a sequential stage in symbolic factorization so symbolic can be significant at high core count, but otherwise, it's negligible.
