Redistributes a matrix for load balancing, removing the rows (and the corresponding columns) that only have a diagonal entry and then applies a KSP to that new smaller matrix


Options for the redistribute KSP and PC with the options database prefix -redistribute_

Usually run this with -ksp_type preonly

If you have used MatZeroRows() to eliminate (for example, Dirichlet) boundary conditions for a symmetric problem then you can use, for example, -ksp_type preonly -pc_type redistribute -redistribute_ksp_type cg -redistribute_pc_type bjacobi -redistribute_sub_pc_type icc to take advantage of the symmetry.

This does NOT call a partitioner to reorder rows to lower communication; the ordering of the rows in the original matrix and redistributed matrix is the same.

Developer Note#

Should add an option to this preconditioner to use a partitioner to redistribute the rows to lower communication.

See Also#

PCCreate(), PCSetType(), PCType, PCRedistributeGetKSP(), MatZeroRows()





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