Re: [Libmesh-users] Quick question - bandwidth minimization?

[Jed B. <je...@je...>]

John Peterson <jwp...@gm...> writes:

> On Thu, May 2, 2019 at 12:35 PM Yuxiang Wang <yw...@vi...> wrote:
>
>> Dear all,
>>
>> A quick question - when using libmesh, should I consciously do bandwidth
>> minimization when I number my node IDs? Or, are those taken care of at
>> pre-processing stage of PETSc and other solvers?
>>
>
> I wouldn't try and do anything manually since PETSc has a number of
> renumbering algorithms that I think you can play around with pretty easily
> to see if they make any difference...

You can run factorizations in a different ordering, but low-bandwidth
orderings make a difference for cache reuse in MatMult.  PETSc can't
reorder that without making a copy.  But don't put too much effort into
it.