[mpiwg-p2p] [MPIWG Fortran] FP16 16-bit-floating-point

[Kawashima, Takahiro]

Hi,

I don't know the status of C standardization nor contact person
but the suggestion of 'short float' was seem to made in a WG.

  http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0192r0.pdf
  http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2016.pdf

Regards,
Takahiro Kawashima,
Fujitsu

> 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" <tony at runtimecomputing.com>
> > To: "MPI WG Point To Point Communications working group" <mpiwg-p2p at lists.mpi-forum.org>
> > Cc: "Reinhold Bader" <Reinhold.Bader at lrz-muenchen.de>, "Atsushi Hori" <ahori at riken.jp>, "fortran standards email list
> > for J3" <j3 at j3-fortran.org>, "MPI-WG Fortran working group" <mpiwg-fortran at lists.mpi-forum.org>
> > 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:rabenseifner at hlrs.de | rabenseifner at hlrs.de ] > 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