Create examples for Distance-1 and Distance-2 Graph Coloring

[william76]

Create examples for Distance-1 and Distance-2 graph coloring.

They should be put in:

• example/graph/KokkosKernels_Example_Distance1GraphColor.cpp
• example/graph/KokkosKernels_Example_Distance2GraphColor.cpp

Requirements:

• Basically do what the perf_test samples do but keep it as 'bare bones' as possible for an exmaple.
• Load MatrixMarket graphs.

[srajama1]

This is good to do ...

[srajama1]

@william76 Was this ever done ?

[william76]

@srajama1 I never did get a chance on that... I got buried with doing Xpetra ETI work this summer. The distance-2 graph coloring perf test is actually a pretty good example... I'll see if I can strip it down a little and remove some dependencies from the test_common/ files. Do you know of any code infrastructure that's baked into Kokkos or Kokkos-Kernels to load MatrixMarket data into a CrsMatrix or StaticGraph? The perf_test codes leverage test_common/MyCRSMatrix.hpp but for an example, I'd rather avoid relying on test headers if possible.

[ndellingwood]

@william76 - here is some glue for an internal impl matrix market reader that takes a filename and store as a CrsMatrix. It won't handle matrix market files of "pattern" type properly right now but I think @brian-kelley is working on a fix.

#include <KokkosKernels_IOUtils.hpp>
 
typedef KokkosSparse::CrsMatrix<scalar_t, lno_t, execution_space, void, size_type> crsmat_t;
crsmat_t triMtx = KokkosKernels::Impl::read_kokkos_crst_matrix<crsmat_t>(lfilename.c_str());

[mhoemmen]

@brian-kelley If you need an example of how to handle "pattern" matrices, check out the Tpetra Matrix Market reader.

[william76]

I put in a PR with a somewhat stripped down version of the D2GC code from the perf_test directory...

@brian-kelley the D2GC code is also used in the MueLu Aggregation routines. I think it's still using the D2_SERIAL algorithm but changing it there should be just a matter of changing which enum is passed in.

[brian-kelley]

@william76 KokkosKernels PR #466 with the full MatrixMarket support will probably be merged in the next few days. Then you don't even need to deal with CrsMatrix, you can just do

crsGraph_t graph = KokkosKernels:Impl::read_kokkos_crst_graph<crsGraph_t>("file.mtx");

and that will read a pattern file (or any matrix, and discard the scalar values).

[william76]

@brian-kelley ooh, cool! I'll hold off mucking around with this D2GC example till that's in =) When that's merged in can you shoot me a note?

[brian-kelley]

@william76 It was just merged.