Yes, modern direct solver do block factorization as super node method. Can ASM type preconditioner use superlu ILUT on each subdomain? At preset, my solver (BCGS) only works with ASM+ILU(1) on a "smart partitioned" mesh.
> The ILUTP in SuperLU (4.2 and up) exploits blocking (supernodes) in > > the (approximate) L & U factors. Note the block boundary is > > discovered on the fly, which is usually larger than the block size > > from the input matrix A. So the efficiency is pretty good. It uses > > threshold dropping with partial pivoting, numerically is quite good > > too. It's available only in the serial version. > > > > Sherry Li > > > > > > On Sun, Oct 30, 2011 at 11:18 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote: > > > On Sun, Oct 30, 2011 at 23:50, Gong Ding <gdiso at ustc.edu> wrote: > > >> > > >> I had also considered use max block size. But it is not efficient here. > > >> Hope petsc support nonuniform block size one day. > > > > > > Inodes do a sort of partial blocking. There has to a clear performance > > > benefit to explicit variable blocking in order to justify the implementation > > > and interface complexity. I have not yet seen a demonstration of this. > >
