[petsc-dev] plans for preconditioners for SeqSELL

[Jed Brown]

Richard Tran Mills <rtmills at anl.gov> writes:

> I haven't experimented very thoroughly with it (hmm... should probably do
> such experiments), but I believe that, once matrix rows become sufficiently
> long, then SELL doesn't provide an advantage over AIJ. 

What is the performance model that explains why SELL doesn't benefit
from long rows?  It's clear for large blocks where BAIJ can be compiled
to vectorized loads and stores, but much less clear when AIJ is
producing basically scalar code.