Zoltan only work in parallel so zoltanDecomp can only be used for redistribution
but is much more flexible than ptscotch and provides a range of geometric, graph
and hypergraph methods which can operate in either "partition" or "repartition",
the latter being particularly useful for dynamic load-balancing by migrating
cells between processors rather than creating a completely different
decomposition, thus reducing communication.
Class
Foam::zoltanDecomp
Description
Zoltan redistribution in parallel
Note: Zoltan methods do not support serial operation.
Parameters
- lb_method : The load-balancing algorithm
- block : block partitioning
- random : random partitioning
- rcb : recursive coordinate bisection
- rib : ecursive inertial bisection
- hsfc : Hilbert space-filling curve partitioning
- reftree : refinement tree based partitioning
- graph : choose from collection of methods for graphs
- hypergraph : choose from a collection of methods for hypergraphs
- lb_approach The desired load balancing approach. Only lb_method =
hypergraph or graph uses the lb_approach parameter. Valid values are
- partition : Partition without reference to the current distribution,
recommended for static load balancing.
- repartition : Partition starting from the current data distribution
to keep data migration low, recommended for dynamic load balancing.
- refine : Quickly improve the current data distribution
Default values
- debug_level 0
- imbalance_tol 1.05
- lb_method graph
- lb_approach repartition
Usage
To select the Zoltan graph repartition method add the following entries to
decomposeParDict:
distributor zoltan;
libs ("libzoltanRenumber.so");
The Zoltan lb_method and lb_approach can be changed by adding the
corresponding entries to the optional zoltanCeoffs sub-dictionary, e.g.:
zoltanCoeffs
{
lb_method hypergraph;
lb_approach partition;
}
An example of using Zoltan for redistribution during snappyHexMesh is provided
commented out in
tutorials/incompressible/simpleFoam/motorBike/system/decomposeParDict
and fordynamic load-balancing in
tutorials/multiphase/interFoam/RAS/floatingObject/system/decomposeParDict.
Note that Zoltan must first be compiled in ThirdParty-dev by downloading from
the link in the README file and running Allwmake and then compiling zoltanDecomp
by running Allwmake in src/parallel/decompose.
340856ad38