[petsc-users] Profile a matrix-free solver.

Song Gao song.gao2 at mail.mcgill.ca
Thu Jan 14 15:01:00 CST 2016


I am profiling a finite element Navier-Stokes solver. It uses the
Jacobian-free Newton Krylov method and a custom preconditoner LU-SGS (a
matrix-free version of Symmetic Gauss-Seidel ). The log summary is
attached. Four events are registered.  compute_rhs is compute rhs (used by
MatMult_MFFD). SURFINT and VOLINT are parts of compute_rhs. LU-SGS is the
custom preconditioner. I didn't call PetscLogFlops so these flops are

 I'm wondering, is the percent time of the events reasonable in the table?
I see 69% time is spent on  matmult_mffd. Is it expected in matrix-free
method? What might be a good starting point of profiling this solver? Thank
you in advance.

Song Gao
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