[mpich-discuss] MPI_Isend/MPI_Irecv on shared memory

[Pavan Balaji]

This is an artifact of MPI's progress semantics. Posting a bunch of 
Isends/Irecvs does not guarantee that the data is actually communicated 
till the next test/wait operation.

Unfortunately, I can't tell much without seeing the code. Is there a 
small benchmark you can write up that reproduces the problem?

  -- Pavan

On 11/11/2011 01:34 PM, Ioannis Papadopoulos wrote:
> Hi,
>
> I have a program that does a number of MPI_Isends to 4 processes on a
> quad-core machine. I can see using MPE that the messages are received by
> the (preposted) MPI_Irecvs only after the MPI_Requests of the MPI_Isends
> have been MPI_Tested. Is there any rule/preference that changes the
> priority of how messages are sent inside implementation depending on if
> MPI_Test/MPI_Wait has been called?
>
> I am using MPICH2 1.2.1p1. Unfortunately I cannot share my code, but it
> will try to create a small example if possible.
>
> Thanks
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-- 
Pavan Balaji
http://www.mcs.anl.gov/~balaji