Tony, we try to find the type names used in C and Fortran before we define the new predefined MPI datatype handles for representing those language types. Who knows, whom we can contact on the C standardization side? Best regards Rolf ----- Original Message -----

From: "Anthony Skjellum" <[email protected]> To: "MPI WG Point To Point Communications working group" <[email protected]> Cc: "Reinhold Bader" <[email protected]>, "Atsushi Hori" <[email protected]>, "fortran standards email list for J3" <[email protected]>, "MPI-WG Fortran working group" <[email protected]> Sent: Friday, June 16, 2017 2:50:00 PM Subject: Re: [MPIWG Fortran] [mpiwg-p2p] FP16 16-bit-floating-point

Rolf, apart from the Fortan angle, may I strongly encourage that we adopt this datatype for MPI-4. It is part of real MPI codes already, but now we have to fake transfer datatypes as 16-bit integers or bytes... which means not really right if heterogeneous interoperability were to be maintained. And this is a canonical IEEE type now, as you note. There is also the "2 half-float" datatype (32-bits) at least in CUDA to be looked at; maybe ignored or maybe supported, but it is there too. Key to this MPI users and applications use half floats and 2 half-floats :-) in practice.

May I also suggest a forward look at the types in AVX-512, in case any of these become particularly relevant in future. At least 8-bit integers are conceptually new, apart from BYTE. [ https://en.wikipedia.org/wiki/AVX-512 | https://en.wikipedia.org/wiki/AVX-512 ]

Regards, Tony

On Fri, Jun 16, 2017 at 6:52 AM, Rolf Rabenseifner < [ mailto:[email protected] | [email protected] ] > wrote:

Hi all together,

I'm sitting in the MPI Forum Meeting and we discuss the new IEEE FP16 datatype.

Questions to the Fortran atandardization body:

- Does the Fortran Standardization Body has already a proposal for the new name in Fortran for this IEEE FP16?

- Will be REAL*2 identical to IEEE FP16?

Best regards Rolf

-- Dr. Rolf Rabenseifner . . . . . . . . . .. email [ mailto:[email protected] | [email protected] ] . High Performance Computing Center (HLRS) . phone [ tel:%2B%2B49%280%29711%2F685-65530 | ++49(0)711/685-65530 ] . University of Stuttgart . . . . . . . . .. fax [ tel:%2B%2B49%280%29711%20%2F%20685-65832 | ++49(0)711 / 685-65832 ] . Head of Dpmt Parallel Computing . . . [ http://www.hlrs.de/people/rabenseifner | www.hlrs.de/people/rabenseifner ] . Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room 1.307) . _______________________________________________ mpiwg-p2p mailing list [ mailto:[email protected] | [email protected] ] [ https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p | https://lists.mpi-forum.org/mailman/listinfo/mpiwg-p2p ]

-- Tony Skjellum, PhD RunTime Computing Solutions, LLC [ mailto:[email protected] | [email protected] ] direct: +1-205-918-7514 cell: +1-205-807-4968

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-- Dr. Rolf Rabenseifner . . . . . . . . . .. email [email protected] . High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530 . University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832 . Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner . Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room 1.307) .