Just to follow up, I think that the ³right² thing to do with respect to some
sort of
transactional model is to have some sort of standard way to request such
communications take place probably at init time. We have had such an MPI
implementation running in production for several years on a multi-thousand
process cluster, and the only thing that needs to be exposed to the users
is the
ability to turn on/off the functionality all the rest is taken care of
just fine within
the context of the MPI 2.0 standard, and is 100% standard compliant.
This does not deal with hints on the network ³state².
Rich
On 2/22/08 10:22 PM, "Greg Bronevetsky" <bronevetsky1_at_[hidden]> wrote:
>
>
>> >I've read the Transactional Messages proposal and I am a ittle confused
>> >here. Is there a reason why we believe that message faults themselves
>> >should be handled by the application layer instead of the MPI library?
>> >Using the latter model allows one to reduce the error conditions
>> >perculated up to the user to revolve around loss of the actual
>> >connection to a process (or the actual process itself).
>
> Actually, one aspect of the proposal is that I made sure not to
> define message faults at a low level. They may be any low-level
> problems that the implementation cannot efficiently deal with on its
> own and that are best represented to the application as message
> drops. One example of this may be process failures. Although we will
> probably want to define a special notification mechanism to expose
> those failures to the application, we will also need a way to expose
> the failures of any communication that involves the process. Another
> example may be simplified MPI implementations that do not have
> facilities for resending messages because the probability of an error
> is rather low and performance is too important. In fact, applications
> that can tolerate message drops may explicitly choose those MPI
> implementations for the performance gains.
>
> Greg Bronevetsky
> Post-Doctoral Researcher
> 1028 Building 451
> Lawrence Livermore National Lab
> (925) 424-5756
> bronevetsky1_at_[hidden]
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