[mpich-discuss] mpi_scatter

[Jeff Hammond]

I don't know exactly what information you want, but you will find a lot of
useful comments in the source files here:
http://git.mpich.org/mpich.git/tree/HEAD:/src/mpi/coll.  In particular, if
you run 'grep -i "we use" *.c', you will see statements about Rabenseifer's
algorithm, Bruck's algorithm, recursive doubling, pairwise exchange, etc.

Best,

Jeff

On Thu, Dec 3, 2015 at 8:24 AM, Jen B <jenbna at gmail.com> wrote:

> Hello,
>
> I am trying to understand how the mpi_scatter is implemented according to
> MPICH2 for long messages. I went through the paper of R. Thakur, et al.,
> titled "Optimization of Collective Communication Operations in MPICH." It
> is stated there that for long messages mpi_bcast is composed of scatter and
> allgather (where latter two are based on the Van de Geijn's algorithm).
> However I wasn't able to find the mpi_scatter details. Could you please
> explain this? Also, the another thing is that I think for long messages
> (that are not divisible exactly by the number of processes) this part would
> use a scatterv + allgatherv. Am I right? Thank you!
>
> Best,
> Jen
>
>
>
>
>
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-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/
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