[Mpi3-ft] Transactional Messages

[Greg Bronevetsky]

At 09:38 AM 2/23/2008, Richard Graham wrote:
>So I think we are some what talking past each other.  I think that 
>what you really care about
>  with respect to communications errors is information on messages 
> that have not completed,
>  and, more important, can't complete ?  Is this correct ?
>I have focused more on errors that occur, but the low-level can 
>handle them and does not need
>  to pass information about them back up to the user.  I believe 
> this is where we said that we
>  may want to be able to give the app some indication on performance 
> degradation, at their
>  request.  Is this correct ?

Exactly. My point was that the former belongs in the transactional 
memory API, while the latter belongs in the QoS API. Kannan and I are 
tasked with drafting something for the latter. One thing to note 
though is that identical low-level events may fall under either API. 
In particular, a single-bitflip may result in a message drop in one 
MPI implementation and a seamless recovery with minor performance 
degradation in another. The MPI implementation gets to choose the 
mapping between low-level events and their high-level manifestations. 
Right now we are just trying to define a reasonable interface for the 
high-level manifestations.

Greg Bronevetsky
Post-Doctoral Researcher
1028 Building 451
Lawrence Livermore National Lab
(925) 424-5756
bronevetsky1 at llnl.gov 
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