[Mpi-forum] MPI_Count

[Rajeev Thakur]

> IIRC, HP cited a small number of customers who wanted to do 
> this.  I know that send/receive were specifically mentioned, 
> but I don't know if it was a side effect of actually wanting 
> to fix the MPI_File stuff or not (i.e., was the real desire 
> to fix the MPI_File stuff and all the rest was done for consistency?).

Ticket 117 is the opposite of the current proposal. It doesn't address I/O functions at all, only communication functions.

Rajeev

 
> I do know that #117 is woefully out of date; it has many 
> holes -- some of which were partially updated by Dave.
> 
> 
> 
> On Jan 24, 2010, at 6:51 PM, Rajeev Thakur wrote:
> 
> > I don't know who wants to communicate >2GB at a time, but 
> HP seemed to 
> > have enough users wanting it to cause Kannan to create and 
> pursue ticket #117 until he moved to a different project.
> > 
> > Rajeev
> > 
> > 
> > > -----Original Message-----
> > > From: mpi-forum-bounces at lists.mpi-forum.org
> > > [mailto:mpi-forum-bounces at lists.mpi-forum.org] On Behalf Of 
> > > Underwood, Keith D
> > > Sent: Sunday, January 24, 2010 5:20 PM
> > > To: Main MPI Forum mailing list; mpi3 at lists.mpi-forum.org
> > > Subject: Re: [Mpi-forum] MPI_Count
> > >
> > > > Still seems a little odd to have a solution for I/O
> > > functions and not
> > > > for communication functions (the original ticket was for
> > > communication
> > > > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/117).
> > > > If > 2GB can be written from a single process in a single
> > > call, they
> > > > can also be communicated. If it is tedious to break up the
> > > write into
> > > > smaller writes, the same applies to communication.
> > >
> > > "can be" and "will be" are very different phrases.  The feeling 
> > > within the group that was there Thursday morning was that 
> the "way 
> > > 64 bit is done" (TM) is to replicate all of the function 
> calls.  The 
> > > group felt like a compelling case had been made for I/O, 
> because you 
> > > would want to write all of your memory to file (e.g. 
> checkpointing) 
> > > and memory per node is growing beyond 2 GB.  However, it was much 
> > > harder to make the case that you really wanted to send that much 
> > > data from a contiguous location to any other node.  In 
> fact, someone 
> > > made the statement "all of the application users 
> understand that you 
> > > can't do that and still scale on any network in the foreseeable 
> > > future".
> > >
> > > Your interoperability comments may be a more motivating 
> example, but 
> > > as of Thursday morning, it was clear that there was not consensus 
> > > among the forum members who were - especially given the 
> pain that is 
> > > going to be involved in fixing this for the general case.
> > >
> > > Keith
> > >
> > > _______________________________________________
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> > >
> > 
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> > 
> 
> 
> --
> Jeff Squyres
> jsquyres at cisco.com
> 
> 
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