[MPI3-IO] I/O working group Notes

[Quincey Koziol]

On Mar 13, 2013, at 3:09 PM, William Gropp <wgropp at illinois.edu> 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?

	Yes, that would be a fine direction to go.

> 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. 

	Wholeheartedly agree!  :-)

		Quincey

> 
> Bill
> 
> William Gropp
> Director, Parallel Computing Institute
> Deputy Director for Research
> Institute for Advanced Computing Applications and Technologies
> Thomas M. Siebel Chair in Computer Science
> University of Illinois Urbana-Champaign
> 
> 
> 
> 
> On Mar 13, 2013, at 2:56 PM, Rob Latham wrote:
> 
>> On Wed, Mar 13, 2013 at 02:46:34PM -0500, Quincey Koziol wrote:
>>>> Can something be done with generalized request?
>>> 	Someone always brings this up.  :-)  We should get up to speed on the GRQ routines and know what they can do...
>> 
>> They cannot do much.  I am, reluctantly, the worlds expert on
>> generalized requests, having written a paper about it 5(!!!) years
>> ago.
>> 
>> http://dx.doi.org/10.1007/978-3-540-75416-9_33
>> 
>> pdf: http://www.mcs.anl.gov/~robl/papers/latham_grequest-enhance.pdf
>> 
>> Standard Generalized requests have a "all progress must happen outside
>> of MPI" progress model.  Perhaps in this modern surfeit of cores era,
>> it is no longer a big deal to spawn a thread ?
>> 
>> The paper I linked proposes generalized request extensions designed to
>> play better with posix, pvfs, and NTFS async i/o routines.  These
>> routines can make progress in the background, but do need someone to
>> call a completion function (aio_suspend, PVFS_sys_wait, or
>> WaitForMultipleObjectEx).
>> 
>> ==rob
>> 
>> -- 
>> Rob Latham
>> Mathematics and Computer Science Division
>> Argonne National Lab, IL USA
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