[MPI3-IO] I/O working group Notes

[Rajeev Thakur]

Fab is interested in generalized requests for a different use case.

Rajeev

On Mar 13, 2013, at 3:24 PM, Rob Latham wrote:

> On Wed, Mar 13, 2013 at 03:09:22PM -0500, William Gropp wrote:
>> Relevant to this is that enhancing generalized requests also came up.  Part of the discussion is this: would an enhancement to generalized requests, which would have broader benefit, be a more general solution?
>> 
>> Background: The Forum is increasingly concerned about the creation of routines to solve specific problems rather than stepping back and trying to find a more general and powerful solution. 
> 
> With the disclaimer that I am not a Forum participant...
> 
> "rule of three" is a nice guideline for the specific/general approach.
> Find three use cases and now you've properly motivated taking the time
> to design a general solution.
> 
> We have "rule of one" right now.  The only grequest client is I/O.
> The only extended grequest client is I/O.  
> 
> Torsten's nonblocking collectives could have been case number two.  He
> found standard grequests unworkable and apparently found it easer to
> advocate for nonblocking collectives via the forum than to adopt and
> advocate for extended grequests. 
> 
> I'd say delete or deprecate grequests if one is concerned with API
> bloat to make room for non-blocking I/O routines!   In 15 years there
> has been but one paper examining grequests (ours).  There has been but
> one grequest client -- ROMIO (ours) -- and that only because ROMIO was
> implemented as a stunt: implement the MPI-IO chapter on top of
> (instead of integrated into) an MPI-1 implementation.
> 
> Said differently: improve grequests and MPI will still likely have
> zero grequest consumers.  improve I/O and MPI will have at the very
> least HDF5 as a customer. 
> 
> ==rob
> 
> -- 
> Rob Latham
> Mathematics and Computer Science Division
> Argonne National Lab, IL USA
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