[petsc-users] LU Performance

[Jared Crean]

Hello,

     I am getting very bad performance from the Umfpack LU solver when I 
use it via Petsc compared to calling Umfpack directly. It takes about 
5.5 seconds to factor and solve the matrix with Umfpack, but 140 seconds 
when I use Petsc with -ksp_type preonly -pc_type lu 
-pc_factor_mat_solver_type umfpack.

     I have attached a minimal example (test.c) that reads a matrix from 
a file, solves with Umfpack, and then solves with Petsc.  The matrix 
data files are not included because they are about 250 megabytes.  I 
also attached the output of the program with -log_view for 
-pc_factor_mat_solver_type umfpack (fout_umfpacklu) and 
-pc_factor_mat_solver_type petsc (fout_petsclu).  Both results show 
nearly all of the time is spent in MatLuFactorNum.  The times are very 
similar, so I am wondering if Petsc is really calling Umfpack or if the 
Petsc LU solver is getting called in both cases.


     Jared Crean

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