[Mpi3-rma] Updated Proposal 1

William Gropp wgropp at illinois.edu
Wed Dec 8 10:57:17 CST 2010

Since the ordering default is a major change from MPI 2.x, this needs  
to be mentioned early and often; it might help to have an advice to  
users that details the changes between MPI 2.x and 3.0.


On Dec 8, 2010, at 10:28 AM, Torsten Hoefler wrote:

> On Wed, Dec 08, 2010 at 12:22:45AM -0600, Pavan Balaji wrote:
>> On 12/07/2010 11:32 PM, Torsten Hoefler wrote:
>>> 1) moved the lockfree (or conflictfree) mode to the JoD
>> Sorry, Torsten :-).
> No worries at all :-). It was only a naming issue and I think the  
> current
> name is horrible and disgusting. But we would have to have that anyway
> and adding a second name for makeup was also suboptimal ;-).
>>> 2) added a discussion about ordering (Section 11.8.2)
>> The new discussion is better, but:
>> (a) I think the ordering discussion requires some edits to some  
>> places
>> earlier in the chapter too (see proposal 2).
> Yes, there are some places that now need forward-references (I  
> didn't do
> the complete cleanup yesterday because it was late, but I have a  
> note).
>> (b) Do we know any network (except ones that emulate one-sided
>> communication over two-sided messaging) that provide strict  
>> ordering? As
>> far as I know, most networks only provide ordering between PUTs (or
>> atomic PUTs). Ordering between GETs is also not provided, unless the
>> user does a flush after each GET operation. Is this only for  
>> convenience?
> I don't know. Just that you're aware: the current default would force
> the MPI implementation to flush after each get. However, I am also
> planning to add an advice to users somewhere *very visible* that the
> user should really strive to provide these info arguments if possible
> (because the performance difference could be hideous). So the  
> editing is
> not finished but 11.8.2 is ready for discussion ;-).
> Best,
>  Torsten
> -- 
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> Torsten Hoefler         | Performance Modeling and Simulation Lead
> Blue Waters Directorate | University of Illinois (UIUC)
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William Gropp
Deputy Director for Research
Institute for Advanced Computing Applications and Technologies
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign

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