PCREDISTRIBUTE#
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
Notes#
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. Rows are moved between MPI processes inside the preconditioner to balance the number of rows on each process.
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()
Level#
intermediate
Location#
src/ksp/pc/impls/redistribute/redistribute.c
Index of all PC routines
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Index of all manual pages