> > > I used it for PyLith and saw this. I did not think any AMG had scalable > setup time. > > OK, I am guessing it was scaling poorly, weak scaling, but it was sublinear after some saturation at the beginning.
I have not done a weak scaling study on matrix setup (RAP primarily) ever, but I did on Prometheus in the GB work. Prometheus' RAP was pretty simple also and PETSc's is probably faster, and hence may look less scalable. I don't think there is anything fundamentally unscalable about RAP, it is just a complicated algorithm and we have never gotten around to doing all the things that we would like to do with it.
