[Mpi3-rma] Updated Proposal 1

Pavan Balaji balaji at mcs.anl.gov
Fri Nov 26 18:05:37 CST 2010


RMA Query still combines unified public/private window semantics with 
progress semantics. We discussed this in the last telecon.

The progress semantics are only required if the target process wants to 
read data put by the origin without calling an MPI function. This has no 
use case especially since MPI_Put followed by a local load from the same 
location gives you garbage based on MPI semantics. Since I believe there 
is no plan to add such semantics, it'll be best to get rid of the 
progress part and only have RMA_QUERY as follows:

MPI_RMA_QUERY(win, model)


  -- Pavan

On 11/26/2010 01:46 PM, Torsten Hoefler wrote:
> Hi All,
> We updated the items in proposal 1 that we discussed at the last
> telecon. The updated proposal is attached to the Wiki.
> There are some open issues:
> 1) Pavan and I still need to talk about a good strategy to handle the
> lock-free vs. lock-all/shared naming/syntax issues.
> 2) Keith and Brian, could you please elaborate on the arguments against
> allowing multiple elements (count>1) in MPI_Get_accumulate? I remember
> there was some discussion about buffering and failures if one wanted to
> support it in hardware but I don't remember what the issues were. It
> seems like one could simply pipeline the hardware operations or just
> fall back to a software implementation if count is bigger than a certain
> threshold.
> Thanks&  All the Best,
>    Torsten

Pavan Balaji

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