Hi Matt, On Wed, Jun 1, 2011 at 4:06 PM, Matthew Knepley <knepley at gmail.com> wrote: > It looks like the calls are taking 0.5 microseconds, but there are 89G > insertions > against only 13K MatMults that take about 1s apiece. > This seems like an awful lot of insertions into a matrix that can be applied > in 1s.
Unless I'm reading it wrong, there are 89M insertions. This is from 10 timesteps with nonlinear iteration on each timestep, with ~1.5M elements. The matrices are reconstructed at virtually every substep. I don't quite understand what you mean by "can be applied in 1s", doesn't it take ~1ms per call? Anyways, I agree that this is a poor ratio of work to assemble/use of the matrices. We had thought about constructing the matrix outside of PETSc and then passing PETSc pointers to the matrix, but maybe matrix-free would be better for some of the equations where jacobi preconditioning is sufficient. Thanks, John
