> > Can you narrow down where the time is lost?
These two lines added_sp.block(0, 1).copy_from(col); added_sp.block(1, 0).copy_from(row); account for about 60% of the bottleneck (considering only the runtime for the piece of code in the original post). The other 40% of the bottleneck is from the line added_Jacobian_matrix.block(1, 0).reinit( single, partitioning, added_sp.block(1, 0), MPI_COMM_WORLD, false); Interestingly, the reinit for the block(0,1) matrix is negligible. I assume this is related to block(1,0) living on a single processor, and block(0,1) being distributed. All the other lines have negligible contribution to the runtime. > The linear solver itself averages about 40 seconds per call. > > To solve the entire system? Yes, when I say one call of the linear solver, what I mean is one complete solve of the entire block system using deal.ii's GMRES. What do you actually later put into the (1,0) and (0,1) blocks of the > matrix? The row and col vectors you build above, which are just ones? Later, I assemble two TrilinosWrappers::MPI::Vector, like one would for assembling a rhs. I fill the (1,0) and (0,1) blocks with the entries of these vectors. That step is fast, and takes about 0.01 seconds. The reason I fill the row and col vectors with ones (correct me if I'm misunderstanding) is so the sparsity pattern will have non-zero entries. The vectors I use to fill the (0,1) and (1,0) matrices are dense, so this seemed like the safest choice. -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
