[petsc-dev] new P^1.5 algorithm in VecAssembleBegin?

[David Trebotich]

We won't know until 64k and 128k jobs get thru the queue.  Will keep u
posted.  Thanks for your help.

David Trebotich
sent from mobile
(510) 384-6868
On May 29, 2015 8:32 AM, "Jed Brown" <jed at jedbrown.org> wrote:

> Mark Adams <mfadams at lbl.gov> writes:
>
> > I don't need your branch because 1) we are not doing any communication in
> > this VecAssembly
>
> There is still synchronization cost in determining that nothing needs to
> be done.  Moreover, using a size P MPI_Allreduce for that (in
> PetscMaxSum) is non-scalable.  My branch uses MPI_Reduce_scatter_block
> (scalable) when available (MPI-2.2).
>
> > and I added the IGNORE stuff
>
> So it takes no time now and everything is groovy?
>
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