On Fri, 16 Mar 2012, Jed Brown wrote: > On Fri, Mar 16, 2012 at 14:52, <Nan.Jia at dartmouth.edu> wrote: > > > Dear PETSc Group, > > I am tuning the efficiency of my PETSc code for a while, but get very > > little progress. So can anyone help me to analysis the log? Any suggestions > > will be appreciated. > > > > My problem is time dependent. At every time step, two about 6000 by 6000 > > sparse matrices need to be solved, which come from a Poisson equation. I > > use both sequential and parallel AIJ format to store matrices, but the > > performances are both not very good. > > > > 1. You need to heed the huge warning > > ########################################################## > # # > # WARNING!!! # > # # > # This code was compiled with a debugging option, # > # To get timing results run config/configure.py # > # using --with-debugging=no, the performance will # > # be generally two or three times faster. # > # # > ########################################################## > > > > 2. You only spend 18 of 880 seconds in the solver. What do you want? > > 3. The problem is too small to get significant parallel speedup. > > http://www.mcs.anl.gov/petsc/documentation/faq.html#slowerparallel
4. MatSetValues() is not logged by default - you should run with -info and make sure there are no mallocs during assembly. Also check http://www.mcs.anl.gov/petsc/documentation/faq.html#efficient-assembly satish
