[Mpi3-ft] New RMA functions

[Joshua Hursey]

Thanks for checking. I'm glad that the model we are pushing forward with regard to fault checking at synchronization points seems to work for the RMA folks.

So I was thinking about adding an optional status object (rather than a request object) to put/get/accumulate operations that is filled in at the synchronization event. This is slightly different than the way we use status objects in other places in the standard, but I don't know if they need to be a full request. In particular, we want to provide the user with the option to disregard the parameter if they don't care about the specific operation which can be done with a MPI_STATUS_IGNORE, but there is no equivalent for requests. Since the synchronization operations are effectively waitall's on all requests posted during the epoch, we really only care about the status (and we want to avoid a conversation about canceling a one-sided request). What do you all think about that?

So is this (status objects for put/get/accumulate) something that they have already put in the RMA proposal, or just something they would be open to adding?

As I mentioned on the call, I am hesitant to change the one-sided interfaces currently in the standard to add the status object since the new RMA functionality is bring brought forward. Is the intention of the new RMA proposal to replace the current one-sided chapter, or to sit beside it? If the latter, then we may want to consider a smaller proposal just to add the status object to the one-sided operations. If the former, then we can just wait for the new semantics.

Thanks,
Josh

On Feb 23, 2011, at 2:43 PM, Darius Buntinas wrote:

> 
> After today's concall, I talked to Pavan about fault-tolerance and the new RMA functions.  He said that it would be appropriate to check for/report errors at synchronization points (like the end of epochs and things like flush), and for operations that take requests (like puts with requests).
> 
> This sounds like what was suggested during the call.
> 
> -d
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------------------------------------
Joshua Hursey
Postdoctoral Research Associate
Oak Ridge National Laboratory
http://users.nccs.gov/~jjhursey