[petsc-users] Block-ILU in Petsc

[behzad baghapour]

I think so. Keeping the size of blocks as what is in the original matrix
would be a safe choice. Here maximum gain is belonged to naturally
block-wize matrices.

On Fri, Oct 14, 2011 at 6:17 PM, Satish Balay <balay at mcs.anl.gov> wrote:

> On Fri, 14 Oct 2011, Jed Brown wrote:
>
> > On Fri, Oct 14, 2011 at 09:09, behzad baghapour
> > <behzad.baghapour at gmail.com>wrote:
>
> > > 2- "the block size is the same the matrix block size" means that there
> is
> > > no way to combine the matrix elements to build blocks of possible
> maximum
> > > size like Hash method or something like this?
> > >
> >
> > For AIJ, there are "Inodes" which automatically detect identical rows
> where
> > blocking can be used. This helps more or less, depending on the hardware.
> > There is no such thing for BAIJ, but it wouldn't offer much improvement
> in
> > memory performance anyway. BAIJ performance approaches dense mat-vec as
> long
> > as the ordering is such that the vector can be reused.
>
> I view AIJ+inode as variable-blocking in 1 dimenstion. Doing variable
> blocking in 2 dimensions is perhaps very difficult - and not worth the
> exta cost of keeping track of these blocks during each arithmetic
> operation [and parallel partitioning of such variable blocks has its
> own additional issues]
>
> Satish
>



-- 
==================================
Behzad Baghapour
Ph.D. Candidate, Mechecanical Engineering
University of Tehran, Tehran, Iran
https://sites.google.com/site/behzadbaghapour
Fax: 0098-21-88020741
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