[petsc-dev] Dealing with off-processor aij-matrices not having preallocation information

[Matthew Knepley]

On Thu, Mar 21, 2013 at 11:25 AM, Karl Rupp <rupp at mcs.anl.gov> wrote:

> Hi guys,
>
>
> >     I vote a). No new function, gets rid of a stupid optimization that
> >     does no one any good, and is the simplest.
> >
> >
> > I also think (b) is becoming over-complicated. If someone knows their
> > stencil and cares about memory usage, they can just pass the correct
> > values. The defaults are terribly for anything but a 5-point stencil
> anyway.
>
>
> for completeness, here's how b) would look like:
>
> https://bitbucket.org/petsc/**petsc/commits/**
> 814b6bb1ec0ea67e05a42f7f07cab1**169a9be913<https://bitbucket.org/petsc/petsc/commits/814b6bb1ec0ea67e05a42f7f07cab1169a9be913>
>
> This has the additional freedom of being able to deal with different
> defaults for on- and off-processor blocks correctly at the expense of a
> separate function MatSeqAIJSetPreallocation_**SeqAIJAlloc()
>
> I can confirm that this fixes the issues with GPUs. If, on the other hand,
> we pick a), then code gets substantially simpler even than it is now. As
> noted, the only drawback is that the default preallocation for on- and
> off-processor values is the same. I can live with that.
>

Still want simpler.

   Matt


> Best regards,
> Karli
>
>
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20130321/fe6ae8be/attachment.html>