[Mpi3-rma] Updated Proposal 1

[James Dinan]

On 11/26/10 4:37 PM, Jeff Hammond wrote:
> What is the use case multi-element RMW anyways?  I'm definitely going
> to need message-atomic put, but I'll do the portable i.e. MPI version
> with RMW-lock + put + RMW-unlock.

For dynamic windows, a portable pointer will be something like <process, 
displacement>.  If you want to build lock-free data structures, you'd 
want to do swap on pointers.  If you can't do both atomically, then you 
will need to do things differently anyway.  Providing a count for this 
function could be misleading, I'd suggest some text to clarify.

Jeff, unless you need trylock there are more efficient ways to do 
one-sided locking on top of existing MPI-2 RMA that don't require 
polling over the network.  I can point you to code if you're interested, 
I think it's in an MPICH example somewhere.

  ~Jim.