[mpich-discuss] nonblocking collectives, progress thread

[Dave Goodell]

Try setting "MPICH_ASYNC_PROGRESS=1" in your environment to get background progress.  This is a fairly simplistic background progress mechanism though, so you may find that you need to run half as many processes per node as you would without this setting.

-Dave

On Apr 6, 2012, at 3:14 PM CDT, Pieter Ghysels wrote:

> Dear,
> 
> I'm replacing calls to MPI_Allreduce by calls to MPIX_Iallreduce. 
> I'm compiling with -mpe=mpilog and look at the communication pattern
> with jumpshot. The MPI_Allreduce's are gone now of course, but
> mpe/jumpshot does not show MPIX_Iallreduce. Instead, where the
> MPI_Allreduce used to be, now a lot of time is being spent in
> MPI_Win_create and MPI_Win_free, where before the MPI_Allreduce was
> taking place. Is this normal?
> 
> Can I configure MPICH2 to use a progress thread for the nonblocking
> collectives, as in libNBC?
> Do I have to use MPI_Init_thread()?
> 
> Pieter
> 
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