[Mpi3-hybridpm] New draft of the EI chapter uploaded

Pavan Balaji balaji at mcs.anl.gov
Wed Feb 9 09:48:27 CST 2011

Hi Doug,

On 02/09/2011 09:23 AM, Douglas Miller wrote:
> Maybe we really are saying the same thing. The talk about making all MPI
> call synchronzise might be throwing me off. I was thinking of this (the
> 'balanced' INFO var) as being information that the user was giving to
> the implementation telling it that the code between JOIN and LEAVE was
> taking a "deliberate" approach towards progress, and that the user was
> saying that they understand that the performance of their JOIN-LEAVE
> block will directly relate to how much/frequently they make MPI calls
> (or get to LEAVE). Not sure what the right words are, but I feel we must
> make it more obvious to users why they want to use 'balanced' and how
> they should select what code to put between JOIN and LEAVE in that case.

Note that the synchronization between the threads can happen only when 
all threads are within MPI calls. So, I'm saying the same thing, but I 
agree the wording is not very clear. But we should avoid saying that you 
can *only* make MPI calls within JOIN/LEAVE. As long as the user is 
aware there *might be* a synchronization step between threads, (s)he can 
decide whether it's the right model for the application or not.

  -- Pavan

Pavan Balaji

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