[petsc-users] KSPSolve doesn't seem to scale. (Must be doing something wrong...)

[William Coirier]

I've written a parallel, finite-volume, transient thermal conduction solver using PETSc primitives, and so far things have been going great. Comparisons to theory for a simple problem (transient conduction in a semi-infinite slab) looks good, but I'm not getting very good parallel scaling behavior with the KSP solver. Whether I use the default KSP/PC or other sensible combinations, the time spent in KSPSolve seems to not scale well at all.

I seem to have loaded up the problem well enough. The PETSc logging/profiling has been really useful for reworking various code segments, and right now, the bottleneck is KSPSolve, and I can't seem to figure out how to get it to scale properly.

I'm attaching output produced with -log_summary, -info, -ksp_view and -pc_view all specified on the command line for 1, 2, 4 and 8 processes.

If you guys have any suggestions, I'd definitely like to hear them! And I apologize in advance if I've done something stupid. All the documentation has been really helpful.

Thanks in advance...

Bill Coirier

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