[Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012 Forum

[Underwood, Keith D]

Floating-point CAS is valid as a way to implement "if this hasn't changed, put the results of this operation in place".  It gives you a (moderately expensive, not very fair) way to build a form of arbitrary atomics.

Keith

> -----Original Message-----
> From: mpi3-rma-bounces at lists.mpi-forum.org [mailto:mpi3-rma-
> bounces at lists.mpi-forum.org] On Behalf Of Jeff Hammond
> Sent: Tuesday, July 17, 2012 7:26 PM
> To: MPI 3.0 Remote Memory Access working group
> Subject: Re: [Mpi3-rma] notes from 5pm Tuesday meeting @ July 2012
> Forum
> 
> I don't know that floating-point compare is well-defined.  You really have ask
> "if abs(x-y)<tolerance" and not "if x==y".
> 
> I think only fixed-point types should be valid for CAS.
> 
> Jeff
> 
> On Tue, Jul 17, 2012 at 6:14 PM, Dave Goodell <goodell at mcs.anl.gov> wrote:
> > Discussed the complex types in COMPARE_AND_SWAP issue.  "Fortran
> Integer" category is permitted, but "Complex" category is not, primarily
> because of width.  Since "Fortran Integer" contains wide types, shouldn't we
> just permit "Complex" and "Floating point" as well?  Consensus was to stick
> with the existing text which permits only "C integer, Fortran integer, Logical,
> Multi-language types, or Byte".
> >
> > Group review (esp. Jim & Sreeram):
> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/187
> >
> > incorporate Jim suggested change (Torsten):
> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/271
> >
> > we think we are unaffected, but need a second check (Jim):
> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/278
> >
> > Double-check that C++ is not referenced in the RMA chapter (Pavan):
> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/281
> >
> > Needs review (Dave):
> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/300
> >
> > Think unaffected, but slim chance of Rput/Rget being affected (Pavan):
> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/317
> >
> > Need to check implementation of various (4?) "flush is non-local"
> > changes (Dave):
> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/270
> >
> > Need to check disp_unit change (Jim & Sreeram):
> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284
> >
> > After the above items have all been dealt with, all chapter committee
> members should re-read the whole chapter in the *clean* document (the
> one _without_ the changebars and colored text) to look for obvious typos
> and inconsistencies.
> >
> > -Dave
> >
> >
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> 
> 
> 
> --
> Jeff Hammond
> Argonne Leadership Computing Facility
> University of Chicago Computation Institute jhammond at alcf.anl.gov / (630)
> 252-5381 http://www.linkedin.com/in/jeffhammond
> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond
> 
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