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@llnl.gov