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

Pavan Balaji balaji at mcs.anl.gov
Wed Feb 9 09:05:02 CST 2011

Hi Doug,

On 02/09/2011 08:54 AM, Douglas Miller wrote:
> The problem is that none of these INFO options represent the mode I was
> discussing in our last meeting. These are different interpretations of
> how helper threads will be used and implemented.
> I am not at all comfortable with this concept of adding synchronization
> to all MPI calls. In fact, I'm not at all sure what it means to set
> balanced to true and then go into computation. How do computation
> threads get synchronized in those cases? It sounds the same as
> balanced=false.

This is based on what we had discussed in the call -- we even had a 
discussion on why the term was called "balanced" and Bronis clarified 
that the computation was balanced across threads allowing the MPI 
implementation to use all threads for any MPI call (this "using all 
threads" is what I'm calling "synchronizing").

Marc had also pointed out that each thread should independently be able 
to make progress to MPI_HELPER_TEAM_LEAVE even if a thread is expecting 
help from other threads thus requiring synchronization between them 
(e.g., you cannot wait on a pthread_barrier). Even this part is captured 
in the description that the threads might synchronize with other threads 
during an MPI call.

I don't think we are saying two different things -- it's just a 
word-smithing issue but I think your description is restricting it more 
than you require by saying that the application can only call MPI 

  -- Pavan

Pavan Balaji

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