For a moderate number of processes -pc_type bjacobi -sub_pc_type icc -sub_ksp_type preonly
or -pc_type asm -sub_pc_type icc -sub_ksp_type preonly Barry On Mon, 12 Feb 2007, Shi Jin wrote: > Hi All, > > Thank you very much for the help you gave me in tuning > my code. I now think it is important for us to take > advantage of the symmetric positive definiteness > property of our Matrix, i.e., we should use the > conjugate gradient (CG) method with incomplete > Cholesky decomposition (ICC) as the pre-conditioner (I > assume this is commonly accepted at least for serial > computation, right?). > However, I am surprised and disappointed to realize > that the -pc_type icc option only exists for seqsbaij > Matrices. In order to parallelize the linear solver, I > have to use the external package BlockSolve95. > I took a look at this package at > http://www-unix.mcs.anl.gov/sumaa3d/BlockSolve/ > I am very disappointed to see it hasn't been in > development ever since 1997. I am worried it does not > provide a state-of-art performance. > > Nevertheless, I gave it a try. The package is not as > easy to build as common linux software (even much > worse than Petsc), especially according their REAME, > it is unknown to work with linux. However, by > hand-editing the bmake/linux/linux.site file, I seemed > to be able to build the library. However, the examples > doesn't build and the PETSC built with BlockSolve95 > gives me errors in linking like: > undefined referece to "dgemv_" and "dgetrf_". > > In another place of the PETSC mannul, I found there is > another external package "Spooles" that can also be > used with mpisbaij and Cholesky PC. But it is also > dated in 1999. > > Could anyone give me some advice what is the best way > to go to solve a large sparse symmetric positive > definite linux system efficiently using MPI on a > cluster? > > Thank you very much. > Shi > > > > > ____________________________________________________________________________________ > Don't get soaked. Take a quick peak at the forecast > with the Yahoo! Search weather shortcut. > http://tools.search.yahoo.com/shortcuts/#loc_weather > >
