[petsc-dev] new P^1.5 algorithm in VecAssembleBegin?
Barry Smith
bsmith at mcs.anl.gov
Fri May 29 15:16:31 CDT 2015
> On May 29, 2015, at 2:56 PM, Jed Brown <jed at jedbrown.org> wrote:
>
> Mark Adams <mfadams at lbl.gov> writes:
>> Yea, I realized that VecAssembly should see this load imbalance unless it
>> had a barrier before its timer. So I'm not sure what is going on.
>
> Since you don't have any outgoing entries, I think the huge
> MPI_Allreduce is expensive. No surprise.
This explanation matches the known information.
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